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f_inscreenname
02-25-2017, 02:26 AM
Not doing anything special. Just re-coring the front deck and the two side near the motor box. Also plan on putting some plywood in the seat areas. Plan on using 3/8 end cut balsa and Poly resin with cabasil (sp?)to thicken it up to set the balsa in. Then going to cover it with either 1708, 24oz biaxial or something (recommendations are welcome). Anything has to be more then the newspaper they put over it in 1966.
Figure I have about 24 s/f of balsa to put down, about the same in plywood and then I have to cover it all.
How much resin should I order? I can get extra at the home depot if needed so don't worry about getting close. Don't want 5 gal of resin sitting around going bad for the next 10 years.
Recommendations on what to cover it with?

Last, I have put wood floors down for decades. Half were nail downs and the other were glue downs. I've glued down wood over wood, concrete, below grade, above grade, on walls, on ceilings, pool areas, bathrooms, steam rooms ..... And there still is no adhesive you can just buy a bucket of and trowel and set balsa in? shocking.

gcarter
02-25-2017, 10:48 AM
I'd get someone local to you to help answer your questions.
All you're gonna get here is a bunch of half baked opinions backed by
some really large egos.

Did you know my 22C deck was cored w/three courses of Coremat?
Really, really cheap and and adds a certain hardness to the upper
surface unobtainable w/foam or balsa core.

http://www.donzi.net/forums/attachment.php?attachmentid=85689&stc=1&d=1488037684

f_inscreenname
02-25-2017, 11:06 AM
I'd get someone local to you to help answer your questions.
All you're gonna get here is a bunch of half baked opinions backed by
some really large egos.

Did you know my 22C deck was cored w/three courses of Coremat?
Really, really cheap and and adds a certain hardness to the upper
surface unobtainable w/foam or balsa core.

Really? Very few people around here have done a 16's re-core.
As much as I wanted to go hi-tech there is just no reason to on this little boat.

Thanks for your help and I will have to find pictures of the hole I cut in the raceboat where the hull is 1-1/4 thick of solid glass.

gcarter
02-25-2017, 01:06 PM
The white material in the layup of the large plug I cut
from the foredeck of the TR is "Core Mat". The deck is only 28 years old.

Here's a link to what the material looks like:
http://shop.fiberglasssupply.com/Core_Materials-Core_Mat.html

Here's another link about the material and what it's used for.

http://www.compositesone.com/product/core-materials/core-mat/

It comes on a roll and has the consistency of felt.

Did I say it was inexpensive?

gcarter
02-25-2017, 07:19 PM
Can anyone see the picture I posted???
If you can't, I'll try to shoot a new one by Monday.
I'm trying to display a coring technique that Donzi used for years,
It's easy to lay up and very inexpensive.
I perfectly understand your goals and the problems of generating a good
Balsa core, labor, etc., etc.

tmdog
02-25-2017, 07:41 PM
If you are referring to post #2. Yes, they posted and of course lots of RED.

45171
02-25-2017, 10:08 PM
was the cutout of a piece that was replaced in that taped off area?

f_inscreenname
02-26-2017, 02:23 PM
G, I started looking into what you did. How much weight did that add to your boat? I would be worried about the couple extra layers of glass alone. The absolute last thing I want is another bow heavy boat. The last one took 500+hp and adding outdrive trim to fix it.

blacktruck
02-26-2017, 04:30 PM
Not doing anything special. Just re-coring the front deck and the two side near the motor box. Also plan on putting some plywood in the seat areas. Plan on using 3/8 end cut balsa and Poly resin with cabasil (sp?)to thicken it up to set the balsa in. Then going to cover it with either 1708, 24oz biaxial or something (recommendations are welcome). Anything has to be more then the newspaper they put over it in 1966.
Figure I have about 24 s/f of balsa to put down, about the same in plywood and then I have to cover it all.
How much resin should I order? I can get extra at the home depot if needed so don't worry about getting close. Don't want 5 gal of resin sitting around going bad for the next 10 years.
Recommendations on what to cover it with?

Last, I have put wood floors down for decades. Half were nail downs and the other were glue downs. I've glued down wood over wood, concrete, below grade, above grade, on walls, on ceilings, pool areas, bathrooms, steam rooms ..... And there still is no adhesive you can just buy a bucket of and trowel and set balsa in? shocking.

Love to see some pics of your 16. Like someone said, it can get contentious when people make suggestions on here.
To partially answer your question then, you can use ATC Core Bond, or ARJAY Core bonding compound for your core. Possibly Ashland Derakane epoxy. And you can contact those manufacturers for technical information, they know more than anyone and are happy to help often.

Gurit for example: http://www.gurit.com/Our-Business/Composite-Materials/Structural-Core-Materials/Gurit-Balsaflex

http://www.ashland.com/industries/corrosion-resistant/water-and-wastewater/derakane (http://www.gurit.com/Our-Business/Composite-Materials/Structural-Core-Materials/Gurit-Balsaflex)

Another source for guides, materials and stuff: http://netcomposites.com/

gcarter
02-26-2017, 05:03 PM
Mark, I didn't do that work, that's my 22c TR foredeck. The large core cut out
was for a new pop up bow light.
My deck weighs about 500#. When I had the deck supported on small, low
scaffolds, I could easily pick up either end of the deck on my back.
My foredeck is almost as long as your boat. What you see in the picture is gel,
a lot of resin and one course of random mat, one course of Core Mat,
another course of mat, another course of Core Mat, another course of mat,
another course of Core Mat, and finally one course of 1708 bi-directional stitchmat.
It would be great if you would post some pics of the bottom of your deck so we
could all see what your facing.
It would be good (if the bottom is very course) to do some filling and fairing,
followed w/some resin and a course of random mat. If it were me I would build
my deck minus one course of mat and Core Mat.
Core Mat is very fibrous and is designed to absorb a good bit of resin, but it
won't easily saturate..My 22C deck is about 3/4" thick, and we all know it will
easily support 3 or more full size adults.
What this process will accomplish is a very easy method of coring your 16 (much easier
than trying to install end grain balsa) and at a lower price and more flexibility of materials.
I still have that deck cutout if you'd like to see more picture, I can take them tomorrow.

gcarter
02-26-2017, 05:12 PM
Mark, it would be easy to build a 2' square test panel and
at a very low cost. Just start w/a sheet of plywood covered
w/polyurethane sheet so the resin doesn't stick.
Find out for yourself its strength qualities.
I wouldn't build a hull using this method, but it's great for decks.

gcarter
02-26-2017, 05:35 PM
was the cutout of a piece that was replaced in that taped off area?

The loose piece is a plug I cut out of my foredeck to fit a pop up bow light.
The taped off area is where an anchor light once was mounted.
I used a carefully selected hole saw to cut a plug from the loose piece
to use to fill in the round hole hole in the deck.
But that's a whole different story.

blacktruck
02-26-2017, 07:50 PM
G, I started looking into what you did. How much weight did that add to your boat? I would be worried about the couple extra layers of glass alone. The absolute last thing I want is another bow heavy boat. The last one took 500+hp and adding outdrive trim to fix it.

It would be very heavy and unnecessarily thick. Stick with Balsa or PVC foam. Whenever you get a chance to lighten a heavy boat, do it.
This is from a super durable 35 Sea Hunter, relatively light strength to weight, foam core. Saw this at the Miami Boat show, they cut this in half after dropping 20 feet from a crane on concrete.
http://i66.tinypic.com/35a6c1i.jpg

f_inscreenname
02-27-2017, 12:30 AM
Like someone said, it can get contentious when people make suggestions on here.

Man, it's not like the old days is it? I got the cold shoulder on here for months when I first got here so many years ago but damn people Iíve been on here for over a decade. No reason to get your panties in knot over a repair procedure. Iíll be honest balsa worked in this boat for at least 30+ years before the top was left off the boat outside in Maine for a few years. 1966 balsa where they didnít seal anything. Not even with a coat of resin. And there are really only two bad spots. But Iím always looking for easier and better and cheaper. Itís like my goal in life so there can be more than one right way of doing things. Just like when I flip over my 16's deck in my front yard and re-core it there. Iím sure to some is not the way to do it but I have limited options and so far it the best one. It may be done different but it will be done right.

[QUOTE=blacktruck;667179]Love to see some pics of your 16. QUOTE]

http://www.resurrectionmarine.com/2159af40.jpg

There is a movie of the progress about half way down the page. Itís just a typical 1966, 16. Itís surprisingly in good shape for a total wreck. What I mean by that is it has few hole in it that are not original. The last time I did my Nova it was a start over deal and strip it to it birthday suit. 72 holes from screws, pilot tubes, trim tabs, etc, etc Ö. in the transom. I only have 2 vents to fill in that Iím sure of so far. Having that original glass intact was a huge seller to me.
http://www.resurrectionmarine.com/current_resurrection.htm
Thanks for the heads up on the sites. The issues I am having are I have such a small area. They sell 5 gal pails at 30+sf a gallon spread rate. That is a lot of left overs.

f_inscreenname
02-27-2017, 12:53 AM
I was looking into foam. Really thought way back of putting down stick guides and just pouring US Composites 2 part closed cell foam, sanding it smooth to the guide sticks and then just glassing over that. If the surface is clean I know it will stick to it and it worked great for the motor cover I cored for my last 18. But I see they have sheets. Is it comparable to balsa? Like 3/8 foam is equal to or better ....

Morgan's Cloud
02-27-2017, 06:47 AM
I was looking into foam. Really thought way back of putting down stick guides and just pouring US Composites 2 part closed cell foam, sanding it smooth to the guide sticks and then just glassing over that. If the surface is clean I know it will stick to it and it worked great for the motor cover I cored for my last 18. But I see they have sheets. Is it comparable to balsa? Like 3/8 foam is equal to or better ....

When I re-cored the cockpit floor in the St T I used foam sheeting . It resembles the stuff you can see on the floor pics that blacktruck posted .
The original ply coring was probably 3/8 and I used 1/2" foam. I never knew what the brand was or who made it but it's great stuff to work with . To my surprise the stuff I used even had micro holes drilled in it so the resin could go right through to the other side.
(mind you , that was using epoxy which is less viscous than fiberglass resin)

I believe that one advantage of foam over balsa is that the foam does not absorb as much resin and that helps keep the weight down .

In the case of doing a deck that is curved you'd no doubt want to try and source the contoured foam , not the regular 'flat' sheets .

blacktruck
02-27-2017, 12:40 PM
Man, it's not like the old days is it? I got the cold shoulder on here for months when I first got here so many years ago but damn people Iíve been on here for over a decade. No reason to get your panties in knot over a repair procedure. Iíll be honest balsa worked in this boat for at least 30+ years before the top was left off the boat outside in Maine for a few years. 1966 balsa where they didnít seal anything. Not even with a coat of resin. And there are really only two bad spots. But Iím always looking for easier and better and cheaper. Itís like my goal in life so there can be more than one right way of doing things. Just like when I flip over my 16's deck in my front yard and re-core it there. Iím sure to some is not the way to do it but I have limited options and so far it the best one. It may be done different but it will be done right.

[QUOTE=blacktruck;667179]Love to see some pics of your 16. QUOTE]

http://www.resurrectionmarine.com/2159af40.jpg

There is a movie of the progress about half way down the page. Itís just a typical 1966, 16. Itís surprisingly in good shape for a total wreck. What I mean by that is it has few hole in it that are not original. The last time I did my Nova it was a start over deal and strip it to it birthday suit. 72 holes from screws, pilot tubes, trim tabs, etc, etc Ö. in the transom. I only have 2 vents to fill in that Iím sure of so far. Having that original glass intact was a huge seller to me.
http://www.resurrectionmarine.com/current_resurrection.htm
Thanks for the heads up on the sites. The issues I am having are I have such a small area. They sell 5 gal pails at 30+sf a gallon spread rate. That is a lot of left overs.

Ya, great looking boat. That is a lot of product for a small project. Maybe someone local has some leftover, or maybe the supplier has samples that will be enough???

Balsa is the best bang for your buck core, strength to weight and cost combined. High density PVC foam core is the lightest / strongest when utilized correctly. Completely up to you, weigh the costs and the goal of the project in the end. There is a reason why top builders use full composite and nothing wood "related."
http://www.gurit.com/Our-Business/Composite-Materials/Structural-Core-Materials/Gurit-Balsaflex

(http://www.corecomposites.com/products/core/balsa.html)http://www.corecomposites.com/products/core/balsa.html

woobs
02-27-2017, 04:50 PM
What about using a plywood core deck??? (A whole sheet is about 35lbs)
See thread here: http://www.donzi.org/forum/showthread.php/5855-Restoration-of-16-441/page2

blacktruck
02-27-2017, 05:39 PM
What about using a plywood core deck??? (A whole sheet is about 35lbs)
See thread here: http://www.donzi.org/forum/showthread.php/5855-Restoration-of-16-441/page2

It would be the least desirable. Balsa would be good in this application, easy to work with, much lighter, stronger. Because plywood wood is a laminar material, moisture spreads through quickly.

woobs
02-27-2017, 09:20 PM
It would be the least desirable. Balsa would be good in this application, easy to work with, much lighter, stronger. Because plywood wood is a laminar material, moisture spreads through quickly.
Debatable. Because so many transoms are cored with balsa...I'll give you that balsa is lighter though.

blacktruck
02-27-2017, 10:03 PM
Debatable. Because so many transoms are cored with balsa...I'll give you that balsa is lighter though.

What's debatable? Plywood is the least desirable and is not a good core at all. Not debatable at all.

blacktruck
02-27-2017, 10:28 PM
I was looking into foam. Really thought way back of putting down stick guides and just pouring US Composites 2 part closed cell foam, sanding it smooth to the guide sticks and then just glassing over that. If the surface is clean I know it will stick to it and it worked great for the motor cover I cored for my last 18. But I see they have sheets. Is it comparable to balsa? Like 3/8 foam is equal to or better ....

You don't want to use a 2 part expandable, that's a completely different product. You want dense PVC core sheets, like corecell.(there are others) They come in sheets that can be scored. Application is a little more of a process than balsa. ie. vacuum / infusion. It is technically lighter, stronger when sandwiched correctly. The latest corecell is extremely light but dense with tiny cells. No water absorption. But, balsa is excellent for cost and new balsa technology has very little absorption, so you will be light and strong for the price.

Foam - corecell S specs:
http://marineware.com/images/pdf/guritcorecell-sv10pdf.pdf

Low absorption Balsa:
http://www.materialstoday.com/composite-industry/news/gurit-launches-balsaflex-uvotec-low-resin-uptake/

Is it strong? Here's a 35 foot CC, you can hang triple 650 lbs. Verados no problemas. Same build, hangs 4 Yamaha V8's, no problem, no failures, offshore use.

http://i63.tinypic.com/2r6f82b.jpg






(http://www.materialstoday.com/composite-industry/news/gurit-launches-balsaflex-uvotec-low-resin-uptake/)

f_inscreenname
02-28-2017, 01:51 PM
I like the idea of foam but attachment is again an issue. Looks like you need to Vac Bag it to do it right. I wonder why they donít make a foam sheet like they do with the end grain balsa (little blocks with a scrim) so it will flex better? If I had a bigger project I would have to invest more into the idea.
I really wish I could figure a way to make the pour (closed cell foam) system work. Think of just pouring in your core. Something like you trowel it on with a certain tooth trowel. It expands 3/8 or Ĺ inch or whatever. Cover it with glass and you are done. No trying to get a core to stick to existing glass. No trying to make it all fit just right. Just spread it and forget it.
I have used the two part foam to replace some core around a couple cleats and other stuff on my 19. Taking the top off is not really an option with this boat so I cut the inner liner out under the deck in the bad places, got the bad balsa out, then put the inner liner back up in place and glassed it back in. From there I pumped in 2 part foam from dear park water bottles and sections of hose into the voids from the topside. It expands, fills all the voids and comes out the top, recut the hole for whatever is going back in (now foam completely surrounds the hole), seal it with a little resin and you are done. Instant core replaced. Been 6+ years now and no issues to report.

http://www.supernova19.com/e7e0d8a0.jpg

http://www.supernova19.com/e800d8a0.jpg

Again it flips me out that there is not an off the shelf glue for installing balsa to fiberglass. It really takes a 2 part epoxy or polyester thickened with cabasil just to stick balsa, to lightest most poorest wood on the planet to fiberglass, again shocking.
Found this website >>> http://www.fiberglasssite.com/how-much-resin-do-i-need-click-on-picture-not-on-quick-view/
Has a good list to average what you will need for different mats and cloth. Glad I did because I was estimating way high.
Woobs
I have been following that thread. The thought of running off to home depot and picking up my core is very tempting but I have fooled with wood and trying to stick it to stuff for years and trying to get plywood to stick to a compound curve is a little more then I want to deal with. Now the seats are another story. I already have the plywood for it.

Morgan's Cloud
02-28-2017, 02:46 PM
Airex ,who invented the whole foam core concept and from which all the others spring from has been making contoured foam sheets since the 1970's . They're all available now in 'straight sheets' and contoured .

I didn't need the contoured stuff when I re-did my floor as all the floor sections were flat , but on a curved deck the contoured stuff is just the ticket and probably just as easy to source as the regular flat sheets no matter who the supplier now is.
Easy as pie to work with as well . Only a set of box cutters , or devil knife needed .

Vacuum bagging not necessary either . I just put wax paper sheets down and placed heavy cinder blocks on top of mine to make the contact needed to the original surfaces.

And I can say this, the finished product bonds like nothing else and is strong as steel with great sound and moisture dampening as well .

When we re-did the Magnum we had to build from scratch an entirely new engine compartment including a large flat hatch that would become the 'lid' and cushion pad . It was made out of balsa core and that stuff soaks up 5x's the amount of resin that foam does . The new hatch is probably 40"x 60" and two people struggle to lift it .
By comparison 2 people can lift my entire re-cored floor tub/cockpit floor of the St T . No kidding !

blacktruck
02-28-2017, 05:16 PM
I like the idea of foam but attachment is again an issue. Looks like you need to Vac Bag it to do it right. I wonder why they donít make a foam sheet like they do with the end grain balsa (little blocks with a scrim) so it will flex better? If I had a bigger project I would have to invest more into the idea.
I really wish I could figure a way to make the pour (closed cell foam) system work. Think of just pouring in your core. Something like you trowel it on with a certain tooth trowel. It expands 3/8 or Ĺ inch or whatever. Cover it with glass and you are done. No trying to get a core to stick to existing glass. No trying to make it all fit just right. Just spread it and forget it.
I have used the two part foam to replace some core around a couple cleats and other stuff on my 19. Taking the top off is not really an option with this boat so I cut the inner liner out under the deck in the bad places, got the bad balsa out, then put the inner liner back up in place and glassed it back in. From there I pumped in 2 part foam from dear park water bottles and sections of hose into the voids from the topside. It expands, fills all the voids and comes out the top, recut the hole for whatever is going back in (now foam completely surrounds the hole), seal it with a little resin and you are done. Instant core replaced. Been 6+ years now and no issues to report.

http://www.supernova19.com/e7e0d8a0.jpg

http://www.supernova19.com/e800d8a0.jpg

Again it flips me out that there is not an off the shelf glue for installing balsa to fiberglass. It really takes a 2 part epoxy or polyester thickened with cabasil just to stick balsa, to lightest most poorest wood on the planet to fiberglass, again shocking.
Found this website >>> http://www.fiberglasssite.com/how-much-resin-do-i-need-click-on-picture-not-on-quick-view/
Has a good list to average what you will need for different mats and cloth. Glad I did because I was estimating way high.
Woobs
I have been following that thread. The thought of running off to home depot and picking up my core is very tempting but I have fooled with wood and trying to stick it to stuff for years and trying to get plywood to stick to a compound curve is a little more then I want to deal with. Now the seats are another story. I already have the plywood for it.

The foam core sheets are flexible; scored and easy to conform, it is what they are made for. Injecting insulation foam is not a core. Anything you buy at Home Depot is note core material for boat structures. Balsa core is easily bonded, (you don't want to glue it) did you contact the manufacturer for the recommendation? What about ATC Corebond?

f_inscreenname
02-28-2017, 11:56 PM
The foam core sheets are flexible; scored and easy to conform, it is what they are made for. Injecting insulation foam is not a core. Anything you buy at Home Depot is note core material for boat structures. Balsa core is easily bonded, (you don't want to glue it) did you contact the manufacturer for the recommendation? What about ATC Corebond?

I think you may have missed something. It is not something from Home Depot. Its 8 lb two part closed cell expansion foam from US Composites. It makes balsa look like tissue paper and sticks to fiberglass to the point that you need a hammer and chisel to get it off if you just pour it on top of it.
I've used it a few places on a couple boats. Mostly for filling in holes in decks and such where people installed things that are no longer there. I have found if you have a hole like where a vent was installed and you use anything to replace the balsa like plywood or something it will show through the paint later on. Never fails. Filling in the missing balsa with foam it wonít. I think it has something to do with the expansion and contraction of the core and the glass over time. A piece of plywood will expand and contract differently than balsa or foam will. I just think balsa and foam are a lot closer in properties.
The last 18 I did I made the whole core of the motor cover out of it. Gutted all the existing off the skin. Laid down some guide sticks to know where to stop grinding it down to and then poured the foam out and spread it around. Let it kick off and sanded the foam back down to the guide sticks. Glassed over it and you could do jumping jacks on the cover and it wouldnít have budged. The best thing, it floated, just in case.
The issues was it took a lot of foam and then you ground most of it back off because when it kicks off it doesnít do it evenly. That and itís really hard to get really smooth like a core normally looks.

woobs
03-01-2017, 08:49 AM
Has anyone considered a product like Sea Cast for deck coring?
https://www.youtube.com/watch?v=Ih13u8qkEmk

f_inscreenname
03-01-2017, 12:02 PM
Kind of the same issues with 2 part foam. It tends to run to low areas and level. Not good for a rounded deck.

blacktruck
03-01-2017, 12:34 PM
I think you may have missed something. It is not something from Home Depot. Its 8 lb two part closed cell expansion foam from US Composites. It makes balsa look like tissue paper and sticks to fiberglass to the point that you need a hammer and chisel to get it off if you just pour it on top of it.
I've used it a few places on a couple boats. Mostly for filling in holes in decks and such where people installed things that are no longer there. I have found if you have a hole like where a vent was installed and you use anything to replace the balsa like plywood or something it will show through the paint later on. Never fails. Filling in the missing balsa with foam it wonít. I think it has something to do with the expansion and contraction of the core and the glass over time. A piece of plywood will expand and contract differently than balsa or foam will. I just think balsa and foam are a lot closer in properties.
The last 18 I did I made the whole core of the motor cover out of it. Gutted all the existing off the skin. Laid down some guide sticks to know where to stop grinding it down to and then poured the foam out and spread it around. Let it kick off and sanded the foam back down to the guide sticks. Glassed over it and you could do jumping jacks on the cover and it wouldnít have budged. The best thing, it floated, just in case.
The issues was it took a lot of foam and then you ground most of it back off because when it kicks off it doesnít do it evenly. That and itís really hard to get really smooth like a core normally looks.

I didn't miss anything. In the first post I said ask the manufacturer of the products you are considering, they know them better than anyone. As to why you don't want to use a non structural foam that expands for a core?? hmmm. I wonder why. Ask US composites; looks like they don't recommend it either:
"Our 2LB density marine foam is recommended for void filling in nonstructural applications. This product can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy. This foam has been tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114 . This foam is approximately 95-98% closed cell which resists absorbing water, however continuous water submersion can eventually lead to loss of buoyancy over a period of years. We recommend this product strictly for flotation applications.

I'm not trying to sound like an jerk, it's just simple, pick your core, ask the manufacturer for the recommended accompanying materials and you're done. Plywood is not a core.

Ghost
03-01-2017, 04:38 PM
I didn't miss anything. In the first post I said ask the manufacturer of the products you are considering, they know them better than anyone. As to why you don't want to use a non structural foam that expands for a core?? hmmm. I wonder why. Ask US composites; looks like they don't recommend it either:
"Our 2LB density marine foam is recommended for void filling in nonstructural applications. This product can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy. This foam has been tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114 . This foam is approximately 95-98% closed cell which resists absorbing water, however continuous water submersion can eventually lead to loss of buoyancy over a period of years. We recommend this product strictly for flotation applications.

I'm not trying to sound like an jerk, it's just simple, pick your core, ask the manufacturer for the recommended accompanying materials and you're done. Plywood is not a core.


The quote you posted from US Composites is for 2lb/cubic-foot foam. The stuff F-in Mark is talking about is the 8lb/cubic foot stuff. Four times the density. Hard as a rock. Same basic stuff, but a different recipe that is much stronger and I believe is very much made for structural applications, at least of some kinds. Last I looked at their site, it had a parallel description for the 8 lb flavor. Here it is: "Common Applications: This 8LB density foam is extremely hard and rigid, like that of a soft wood. Your fingernail can penetrate its skin, however it cannot be dented by hand. Uses include casting, carving, sculpting, sign making as well as areas where an extremely durable and rigid foam is needed for support."

Regards,

Mike

f_inscreenname
03-01-2017, 11:56 PM
No big deal Mike. I think he thinks I'm making a boat out of floatation foam. Wait til I mention that I used the 16lb foam to replace the stringers in the race boat. :kingme:

Hey Black don't get bent over it. I'm just looking at options. It's not spring here and I will not be doing it for a couple more weeks so I have time to learn what people are doing and just what fits into my style and ability of doing things.
As for the 2 part foam sometimes you have to come up with other ideas. When it comes to my 19 there is no removing the top and the inner liner is part of the structure of the boat and is glassed in accordingly. The only way you are getting the deck upside down is flipping the boat over and crawling under (if it don't crush you doing it) or cutting it off with a chainsaw.
The whole concept came when I had another broken hull strike and they all kept getting water in them no matter how many times I fixed them. Someone from Donzi (when both boards were still together) came up with the US Composites idea of injecting foam in them to fill the cavities making the strikes solid. Worked better then I though it would. Found every tiny pin hole and crack in them and I have hit a few things with it (dirty bay) since and there is no damage. Before I was fixing strikes every other year.
As a matter of fact .....

I made a video thread (first time I know of anyone doing that) to ask the question on Donzi because it would have taken a year to type it back then and I could have never explained it anyway in just words. I still have it on you tube >>>>>


https://www.youtube.com/watch?v=5KmemM_uk0M

f_inscreenname
03-01-2017, 11:57 PM
This is how I fixed it. The video only shows that I did the area that needed fixing to get through the summer. The next spring the boat got a total makeover including all the strikes filled on both sides all the way to the bow. It's almost been a decade and I have had no issues since.


https://www.youtube.com/watch?v=yarQ-GF6zII

woobs
03-02-2017, 12:02 AM
Kind of the same issues with 2 part foam. It tends to run to low areas and level. Not good for a rounded deck.

The question was from a materials standpoint only. I like to keep an open mind and explore possibilities.

Clearly, a self leveling material could not just be poured on a horizontal deck. However, this material is used to pour transom cores that are both curved (rounded) and vertical. If a formed bulkhead was constructed and lined with a mold release agent then, fastened to the underside of the deck while the deck stood on edge, a uniform gap could be maintained to be filled with Sea Cast the same as a transom.

The main question is: Would the Sea Cast material be satisfactory if it was able to be applied.

Similarly, marine plywood as applied in the posted restoration forms to the compound curves of the deck due to being cut in strips (Think canoe building). Plywood is much stronger than balsa and while it initially weighs more, it absorbs less resin. I believe the resulting deck would be heavier than a balsa core but, not by much. If using epoxy anyways, correctly sealed and encapsulated plywood is an excellent choice from a cost, performance and durability standpoint. Further, entire hulls are made from marine ply (my hull lasted from 1972 to 2012 and my wood deck is original with no rot) with nothing to protect them but paint and varnish. Moisture transfer and rot only become an issue if not installed correctly.

I don't know what you will feel comfortable with or, finally will decide upon however, I think that there are many potentially suitable options (to name a few: balsa, plywood, expansion foam, Sea Cast, Coosa, cork and Coremat+++). It doesn't hurt to think them all through a bit.

blacktruck
03-02-2017, 12:18 AM
The quote you posted from US Composites is for 2lb/cubic-foot foam. The stuff F-in Mark is talking about is the 8lb/cubic foot stuff. Four times the density. Hard as a rock. Same basic stuff, but a different recipe that is much stronger and I believe is very much made for structural applications, at least of some kinds. Last I looked at their site, it had a parallel description for the 8 lb flavor. Here it is: "Common Applications: This 8LB density foam is extremely hard and rigid, like that of a soft wood. Your fingernail can penetrate its skin, however it cannot be dented by hand. Uses include casting, carving, sculpting, sign making as well as areas where an extremely durable and rigid foam is needed for support."

Regards,

Mike

Exactly, the 8 lbs. is not a core material either. Not structural at all.

blacktruck
03-02-2017, 12:27 AM
No big deal Mike. I think he thinks I'm making a boat out of floatation foam. Wait til I mention that I used the 16lb foam to replace the stringers in the race boat. :kingme:

Hey Black don't get bent over it. I'm just looking at options. It's not spring here and I will not be doing it for a couple more weeks so I have time to learn what people are doing and just what fits into my style and ability of doing things.
As for the 2 part foam sometimes you have to come up with other ideas. When it comes to my 19 there is no removing the top and the inner liner is part of the structure of the boat and is glassed in accordingly. The only way you are getting the deck upside down is flipping the boat over and crawling under (if it don't crush you doing it) or cutting it off with a chainsaw.
The whole concept came when I had another broken hull strike and they all kept getting water in them no matter how many times I fixed them. Someone from Donzi (when both boards were still together) came up with the US Composites idea of injecting foam in them to fill the cavities making the strikes solid. Worked better then I though it would. Found every tiny pin hole and crack in them and I have hit a few things with it (dirty bay) since and there is no damage. Before I was fixing strikes every other year.
As a matter of fact .....

I made a video thread (first time I know of anyone doing that) to ask the question on Donzi because it would have taken a year to type it back then and I could have never explained it anyway in just words. I still have it on you tube >>>>>


https://www.youtube.com/watch?v=5KmemM_uk0M

Not bent at all, was just trying to offer resources that can help. The manufacturers have people paid to help customers, might as well use them. When you use the wrong materials, it wastes your time, you get bad results and in boats, potentially dangerous. Was just trying to help. Too much misinformation out there. Just use proper core materials, install to mfgs specs and you can't go wrong. I am a perfectionist and like to do things properly, it pays off in the end. Why not a make a beautiful classic boat better than original? It actually cost less because you will never have to fix it again and it will be stronger and lighter, and you can sell it. Never meant to come off as a jerk! Was trying to be helpful. Good luck with the project.

f_inscreenname
03-02-2017, 12:51 AM
Black, I'm almost starting to feel offended here. Do you have any clue who I am and the boats I have restored? Not being an ass here either but I will trust in something they make highway road side signs out of over balsa any day. Sometimes you have to do what you have to do. Localized balsa rot around a couple cleats was not worth me taking a chainsaw to my boat. I would have cut the bottom glass and core out and just left the top fiberglass first.
I was told a long time ago just because you have a way of doing things it may not be the only way of doing things. If it was we would still be using rocks and sticks after the first guy did.

f_inscreenname
03-02-2017, 01:16 AM
I hear you Woobs, I grew up with wood boats. A couple that almost sunk every time we put them in in the spring. Scraping paint chips, bottom paint, varnishing until you were ready to puke or maybe that was the lead/copper/zinc bottom paint.
Anyway, it sounds like you are talking about injection molding. They do that now but like you said you have to do all the work for it to happen. A lot more than just sticking a core to the existing and covering it. Now if you were doing hundreds of them is another story. I have done a cruder version of it though. Had a motor cover the core was gone in the top. Cut the inner glass on 3 sides and pealed it back. Removed the balsa and put the glass back in place except for the very end and then proceeded to fill it until I got to the top. The box is 20 times stronger than it ever was from the factory and a lot lighter. The only thing was I was able to stand the motor box up on end so it was like filling a transom cavity. Now if I could treat the deck like the motor box tilting it in any direction it would be an option but thatís not going to happen with something this big.
Also thought of getting foam sheets and using the 2 part as an adhesive by spreading it real thin and sticking the sheet in it but Ö.
Think Iím going to use some sort of foam sheet with poly and cabisil to stick it down. Kind of an old school / new school mix but I do like reading about the options.

blacktruck
03-02-2017, 01:28 AM
The question was from a materials standpoint only. I like to keep an open mind and explore possibilities.

Clearly, a self leveling material could not just be poured on a horizontal deck. However, this material is used to pour transom cores that are both curved (rounded) and vertical. If a formed bulkhead was constructed and lined with a mold release agent then, fastened to the underside of the deck while the deck stood on edge, a uniform gap could be maintained to be filled with Sea Cast the same as a transom.

The main question is: Would the Sea Cast material be satisfactory if it was able to be applied.

Similarly, marine plywood as applied in the posted restoration forms to the compound curves of the deck due to being cut in strips (Think canoe building). Plywood is much stronger than balsa and while it initially weighs more, it absorbs less resin. I believe the resulting deck would be heavier than a balsa core but, not by much. If using epoxy anyways, correctly sealed and encapsulated plywood is an excellent choice from a cost, performance and durability standpoint. Further, entire hulls are made from marine ply (my hull lasted from 1972 to 2012 and my wood deck is original with no rot) with nothing to protect them but paint and varnish. Moisture transfer and rot only become an issue if not installed correctly.

I don't know what you will feel comfortable with or, finally will decide upon however, I think that there are many potentially suitable options (to name a few: balsa, plywood, expansion foam, Sea Cast, Coosa, cork and Coremat+++). It doesn't hurt to think them all through a bit.

Balsa is way stronger than ply when used as a core, it has the highest shear strength when it comes to most cores. Ply has compression strength but is inefficient strength wise and it's heavy. Plus it is a laminar structure, moisture spreads quickly it will rot. Sea Cast is garbage. Coosa is good. Corecell is excellent, comes in different densities for different use. Here's a rank and in your case I'd use balsa for the ease of use and value. Coosa is easy to work with as well. By 3rd doesn't mean balsa is bad, there is a reason why it's the most widely used core material.
1. corecell
2. coosa
3. balsa

the others, don't bother. This is an interesting read and will answer your questions why expandable foam and ply are not good core for sandwich construction in marine use. http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html

blacktruck
03-02-2017, 01:33 AM
Black, I'm almost starting to feel offended here. Do you have any clue who I am and the boats I have restored? Not being an ass here either but I will trust in something they make highway road side signs out of over balsa any day. Sometimes you have to do what you have to do. Localized balsa rot around a couple cleats was not worth me taking a chainsaw to my boat. I would have cut the bottom glass and core out and just left the top fiberglass first.
I was told a long time ago just because you have a way of doing things it may not be the only way of doing things. If it was we would still be using rocks and sticks after the first guy did.

I don't use balsa. I use Gurit products. In this case the OP was asking, where it was budget orientated it is an option and within the home builders ability. I don't know who you are and have no idea of the boats you've restored. If you use plywood, then your boats aren't that great. Post some pictures of your boat and materials used. And don't be offended, it makes no sense to use plywood.

f_inscreenname
03-02-2017, 02:02 AM
I don't use balsa. I use Gurit products. In this case the OP was asking, where it was budget orientated it is an option and within the home builders ability. I don't know who you are and have no idea of the boats you've restored. If you use plywood, then your boats aren't that great. Post some pictures of your boat and materials used. And don't be offended, it makes no sense to use plywood.

1, I am the O/P.
2, I don't use plywood. That is from another thread.
3, post some pictures .... sure.

Here's one.

http://www.resurrectionmarine.com/0d24fa10.jpg

Here is another,

http://www.resurrectionmarine.com/1d920250.jpg

Maybe a 3rd,

http://www.resurrectionmarine.com/21ea3a40.jpg

A 4th,

http://www.resurrectionmarine.com/0d455420.jpg

Maybe a Donzi?

http://www.resurrectionmarine.com/21da3a40.jpg

If you want a build sheet and such ... I may not have that exactly online but there is a lot more info then you will ever find on any other classic that has been restored. I even make movies of the whole thing good or bad. Resurrection Marine.com (http://www.resurrectionmarine.com/index.htm)
Go have a look and you can tell me how bad I suck when you get back.

Ghost
03-02-2017, 06:13 AM
Exactly, the 8 lbs. is not a core material either. Not structural at all.

Respectfully, I think on a closer read, the 4, 8, and 16 lb per cubic foot versions are all structural. "Structural" is a vague term though, and it really comes down to failure modes and suitability for a particular application. I'm not an expert on coring at all and I suspect we would agree there are better materials for some coring applications than the expanding foams discussed.

My question is whether the denser US Composites make sense for some coring applications, especially given the advantage of conforming to the shape of a mold. (It'd be pretty hard for Mark to have shored up his strakes with balsa or Coosa. :). )

The article you cited on sandwich construction was a good read--thanks for that.

IF someone is able to construct/install the foam properly, minimizing voids and getting a good bond, I would expect it might perform very well. That's not always easy as it's tricky to work with. But my experience is that done right it can bond very well. I have little data to assess whether that bond remains excellent over time or degrades. There's also a question of what bonds to what. If you use the foam on an existing glass surface, you're relying on the foam to bond to the glass. If the foam has cured and then you glass it in, the resin is bonding to the cured foam.

The 4lb foam is recommended for compressive structural applications, such as bedding in tanks or even supporting decking or flooring best I recall. The 8 and 16 flavors are considerably stronger still. Not sure which of the 5 failure modes in the article you cited concern you?

(a) Yielding or Fracture (http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html#Face Yielding) of the tensile face,
(b) Buckling or Wrinkling (http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html#Face Wrinkling) of the compression face,
(c) Failure of the core in shear all though there is also a lesser possibility of tensile or compressive failure of the core,
(d)The failure of the bond (http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html#Bond Failure) between the face and the core and
(e) the possibility of indentation of the faces and core at the loading points.

Thinking about these out loud....A and B are failures of the face material, not the foam. The high compression strength of the 8 and 16 should do well to support the face materials in resistance to buckling. Same with indentation at loading points. If construction made for a sufficiently void-free structure, those would likely be good.

Failure of the bond seems a concern. I suspect the biggest concern there might be construction methods. My guess is if done right, the bond would be good. I'd also expect it would remain good but I don't have much evidence or experience either way there. I'd be more concerned about getting it right than keeping it right. Getting it right, though, would be near the top of my list of concerns.

Failure if the core in shear is also a valid concern. The article suggests (like the center of an I-beam), the core is inherently less at risk of tensile or compressive failure than the faces. The 8 and 16 flavors have good compressive strength and tensile strength. Which leaves shear and flexural strength. Which instinctively seem ike the greatest concerns to me of the foam's strength.

Shear strength of the 16 foam is a bit above half that of comparably dense Coosa. So, not as good but certainly not non-structural. Flexural strength is far below the Coosa, though the nature of sandwich construction suggests that's potentially less significant because it is a sandwich--the outer layers are meant to see the highest flexural stresses, not the coring.

Again, not claiming to be a coring expert, but the USC foams above 3lb density are all structural. The 8 and 16 esprcially. I think the real question is "for what structural applications do they make sense?" Here are some specs on USC foam and Coosa products.

http://www.uscomposites.com/foam.html

http://coosacomposites.com/images/Test_Data_0412.pdf

Circling back, it sounds like you have some expertise here--curious what particular failure modes drive your thinking about the USC foam, and also about your view of suitable applications, such as the strake repair or adding some strength to a fairly curved piece of glass? What's the right way to use something like a Coosa, or other pre-formed sheets, as coring on complex curved pieces? I suppose perhaps one can cut it up unto small squares or strips, like with end-grain balsa, but I'm not sure what the best approaches are.

Regards,

Mike

blacktruck
03-02-2017, 11:05 AM
1, I am the O/P.
2, I don't use plywood. That is from another thread.
3, post some pictures .... sure.

Here's one.

http://www.resurrectionmarine.com/0d24fa10.jpg

Here is another,

http://www.resurrectionmarine.com/1d920250.jpg

Maybe a 3rd,

http://www.resurrectionmarine.com/21ea3a40.jpg

A 4th,

http://www.resurrectionmarine.com/0d455420.jpg

Maybe a Donzi?

http://www.resurrectionmarine.com/21da3a40.jpg

If you want a build sheet and such ... I may not have that exactly online but there is a lot more info then you will ever find on any other classic that has been restored. I even make movies of the whole thing good or bad. Resurrection Marin.com (http://www.resurrectionmarine.com/index.htm)
Go have a look and you can tell me how bad suck when you get back.

I think there was some confusion. It sounded like you were defending plywood. I never said your builds suck, never used that word. If they were plywood, then I would say that would be less than ideal. Great job, I really like Donzi Classics and other vintage glass boats.

My only main point was that the manufacturers of these materials and can be really helpful. Some of the products mentioned are not structural and can have voids, bad shear strength etc and to just be aware of that when using them. That was my only message. I'll checkout your site.

blacktruck
03-02-2017, 12:02 PM
Respectfully, I think on a closer read, the 4, 8, and 16 lb per cubic foot versions are all structural. "Structural" is a vague term though, and it really comes down to failure modes and suitability for a particular application. I'm not an expert on coring at all and I suspect we would agree there are better materials for some coring applications than the expanding foams discussed.

My question is whether the denser US Composites make sense for some coring applications, especially given the advantage of conforming to the shape of a mold. (It'd be pretty hard for Mark to have shored up his strakes with balsa or Coosa. :). )

The article you cited on sandwich construction was a good read--thanks for that.

IF someone is able to construct/install the foam properly, minimizing voids and getting a good bond, I would expect it might perform very well. That's not always easy as it's tricky to work with. But my experience is that done right it can bond very well. I have little data to assess whether that bond remains excellent over time or degrades. There's also a question of what bonds to what. If you use the foam on an existing glass surface, you're relying on the foam to bond to the glass. If the foam has cured and then you glass it in, the resin is bonding to the cured foam.

The 4lb foam is recommended for compressive structural applications, such as bedding in tanks or even supporting decking or flooring best I recall. The 8 and 16 flavors are considerably stronger still. Not sure which of the 5 failure modes in the article you cited concern you?

(a) Yielding or Fracture (http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html#Face Yielding) of the tensile face,
(b) Buckling or Wrinkling (http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html#Face Wrinkling) of the compression face,
(c) Failure of the core in shear all though there is also a lesser possibility of tensile or compressive failure of the core,
(d)The failure of the bond (http://www.mse.mtu.edu/~drjohn/my4150/sandwich/sp2.html#Bond Failure) between the face and the core and
(e) the possibility of indentation of the faces and core at the loading points.

Thinking about these out loud....A and B are failures of the face material, not the foam. The high compression strength of the 8 and 16 should do well to support the face materials in resistance to buckling. Same with indentation at loading points. If construction made for a sufficiently void-free structure, those would likely be good.

Failure of the bond seems a concern. I suspect the biggest concern there might be construction methods. My guess is if done right, the bond would be good. I'd also expect it would remain good but I don't have much evidence or experience either way there. I'd be more concerned about getting it right than keeping it right. Getting it right, though, would be near the top of my list of concerns.

Failure if the core in shear is also a valid concern. The article suggests (like the center of an I-beam), the core is inherently less at risk of tensile or compressive failure than the faces. The 8 and 16 flavors have good compressive strength and tensile strength. Which leaves shear and flexural strength. Which instinctively seem ike the greatest concerns to me of the foam's strength.

Shear strength of the 16 foam is a bit above half that of comparably dense Coosa. So, not as good but certainly not non-structural. Flexural strength is far below the Coosa, though the nature of sandwich construction suggests that's potentially less significant because it is a sandwich--the outer layers are meant to see the highest flexural stresses, not the coring.

Again, not claiming to be a coring expert, but the USC foams above 3lb density are all structural. The 8 and 16 esprcially. I think the real question is "for what structural applications do they make sense?" Here are some specs on USC foam and Coosa products.

http://www.uscomposites.com/foam.html

http://coosacomposites.com/images/Test_Data_0412.pdf

Circling back, it sounds like you have some expertise here--curious what particular failure modes drive your thinking about the USC foam, and also about your view of suitable applications, such as the strake repair or adding some strength to a fairly curved piece of glass? What's the right way to use something like a Coosa, or other pre-formed sheets, as coring on complex curved pieces? I suppose perhaps one can cut it up unto small squares or strips, like with end-grain balsa, but I'm not sure what the best approaches are.

Regards,

Mike



Thanks Mike, I appreciate the response. I would say if it is extremely difficult to bond in a repair piece or replace a piece, then you could look at the USC stuff for places that are not load bearing. A windshield repair, probably okay. When you inject something, you have no control over voids, how it disperses, and the cell structure is all over the place. Ask USC, I doubt they would recommend it for anything "structural" that has considerable load, factor that in with its uneven absorption and questionable fatigue, then I think it moves far down the list.

Coosa is good. very solid and light, depending on density. I believe they have really good customer service and help. Plus, you can cut and machine just like a wood product. Very easy to work with. Thin and less dense pieces can be used if you're trying to do a light build or specific repair: http://coosacomposites.com/technical-data/faqs

For PVC foam repairs or replacement, the scored Corecell M sheets are excellent and can be hand laid, vacuumed etc. can be fitted easily.

Balsa is easy to work with, easy to conform and relatively inexpensive too.

jvcobra
03-02-2017, 01:25 PM
I'm a little confused, is all this so you don't have to mix some thickened resin? It's seems to me getting rid of all the old coring is the hard part. After that mixing up a batch of resin will seem like childs play. Whether you use balsa or some composite the work is the same. Just pick what you are comfortable using concerning budget and skill set.

f_inscreenname
03-02-2017, 01:36 PM
I'm a little confused, is all this so you don't have to mix some thickened resin? It's seems to me getting rid of all the old coring is the hard part. After that mixing up a batch of resin will seem like childs play. Whether you use balsa or some composite the work is the same. Just pick what you are comfortable using concerning budget and skill set.

I hear what you are saying but I was just trying to find out what others have done and why. I thought that is what a message board was all about. I would feel pretty stupid if I did say Balsa and there was something else out there easier, cheaper and with better results and I didn't know because I didn't ask.

blacktruck
03-02-2017, 05:32 PM
I'm a little confused, is all this so you don't have to mix some thickened resin? It's seems to me getting rid of all the old coring is the hard part. After that mixing up a batch of resin will seem like childs play. Whether you use balsa or some composite the work is the same. Just pick what you are comfortable using concerning budget and skill set.

This exactly. Thank you. It was very confusing.

woobs
03-03-2017, 12:04 AM
... I was just trying to find out what others have done and why. I thought that is what a message board was all about.....

+1 :yes:

jvcobra
03-03-2017, 01:30 PM
I hear what you are saying but I was just trying to find out what others have done and why. I thought that is what a message board was all about. I would feel pretty stupid if I did say Balsa and there was something else out there easier, cheaper and with better results and I didn't know because I didn't ask.

No harm in that, I know you are vary capable guy and look forward to the progress reports.

blacktruck
03-04-2017, 01:42 PM
No harm in that, I know you are vary capable guy and look forward to the progress reports.

No harm in asking at all. It's just that suggestions were made, it's relatively straight forward and there was in insistence to use non-core materials. Asking is great, insisting to use bad materials and defending them is the confusing part.

gcarter
03-04-2017, 04:39 PM
Since questions are still being asked, I wanted to re-introduce the Core-Mat/glass
discussion.......
My left knee has almost incapacitated me for almost two weeks. That kept me from my
office and shop where the boat and deck plug were.
My 22C fore deck is about 11' long, 7' beam, and is in a long triangle shape. I've already .
posted a picture of the large plug I removed from the deck.
I have a very accurate electronic postal scale and used it to determine the plug weighed
.202 #. It's approximately .75" thick. I very carefully measured the plug and determined h
it weighs approximately 4.02#/sq'. Consider your outer skin is already in existence, so
your add on weight would be less.
My deck uses what appears to be mat and 1708 under the gel, then three courses of
(what I think is) 2 mm Core-Mat (but the first course of
Core-Mat may be 1 mm), and the bottom skin is probably also mat and 1708.
The reason I'm supporting this method is it's very strong, and it very easy to accomplish.
Since the Core-Mat is very flexible and non woven, it's ideal for building on old, rough
non-flat surfaces.
Since no one thinks twice about standing 2 or 3 folks on the fore deck of a 22, it should
work really well on an 18. In fact, you could probably get by w/2 courses of Core-Mat.

f_inscreenname
03-04-2017, 11:19 PM
Thanks G,
Iím glad to know it and will use it in the future Iím surebut I donít think Iím going to use it on this boat. I love how it installs andIím sure it is stronger than others being itís layered like it is but I amreally worried about weight. I would have to do all 3 layers to feel safe aboutit but that would be at least 2 more layers of glass that I wouldnít need to dowith other cores.
I also ordered the Balsa block and glass the other day.Figured I would keep it simple with this old little boat. Also figure I knowwhere all the cutouts are and will be able to seal them up this time.
Glad I asked cause I learned a lot

blacktruck
03-07-2017, 09:13 PM
Thanks G,
Iím glad to know it and will use it in the future Iím surebut I donít think Iím going to use it on this boat. I love how it installs andIím sure it is stronger than others being itís layered like it is but I amreally worried about weight. I would have to do all 3 layers to feel safe aboutit but that would be at least 2 more layers of glass that I wouldnít need to dowith other cores.
I also ordered the Balsa block and glass the other day.Figured I would keep it simple with this old little boat. Also figure I knowwhere all the cutouts are and will be able to seal them up this time.
Glad I asked cause I learned a lot


You are right, the core-mat would be heavy! And if dry, it is not strong. Good call.