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wagspe208
04-20-2010, 11:18 PM
I have searched and read. I have a few issues. I will be tackling this project in the next few months. I like to think about things a lot before I start. It gives me time to over compliate them! :)

Deck core material. I think balsa was the original stuff used. Does anyone use a foam core now a days? Or evewn a 3/8 or 1/4" honeycomb. If not, what thickness balsa core? Is anyone using "e" or "s" glass (or even kevlar, carbon fiber, etc) instead of just roving for the covering of the baltek? It has to be lighter and stronger.
When coring....do folks just slop tons of resin on the original glass, then throw on the baltek? Or do some vacuum bag the pieces together? This would have to give better bond.

Foam will never rot. Baltek holds up for tons of years (as my buddy says..."at my age I will never have a problem" HA) Foam is lighter! I am up for reducing weight if I can improve strength.

Thanks
Wags

BTW... I will have tons of questions in the next few months.

Planetwarmer
04-21-2010, 01:13 AM
Obviously vacuum bagging would be the best option if you have a pump and a whole lot of bagging film/tape perf, etc. You can get some light and strong results with fiberglass if you bag it. The resin is what makes fiberglass weak and heavy.

Just Say N20
04-21-2010, 06:10 AM
I worked at Tiara Yachts for several years, and while not involved personally in the production of the hulls, I was very aware of what they were doing.

The process of vacuum bagging a hull is great because it allows for precise control of the amount of resin used (read = correct amount). If done correctly, it results in a lighter end product that is stronger.

If you were going into production, it would be worth "mastering" the vacuum bag/resin infusion process. For a one off, I would strongly recommend you stay away from it.

The learning curve is huge! You have to figure out the correct amount of vacuum to draw the resin in at the correct speed. Too slow and the resin begins to kick prematurely ending the process, too fast and it doesn't get the correct saturation into the materials (end grain balsa/glass/etc). You also have to figure out the timing of when to allow resin to begin being drawn into the different sections to insure proper saturation. I watched them go through several hull sections before coming up with the right combination of variables.

For someone with just one deck to do, it would be very unlikely that you would "get it right" on the first (and only) try. Getting it wrong would most likely produce a result worse than doing it the "old fashioned way."

gcarter has stayed as current as most regarding this stuff, and hopefully he will chime in.

I personally believe you will have much better luck with some of the other current high tech materials.

I believe Parnell used a very light weight, very strong composite in his 16 with great success. He will have to chime in regarding the specifics. And he was building a 16 capable of running in the mid-80s.

My 16 has no deck coring, as built by Donzi in 1967. There is what looks like 1.25" PVC conduit glassed to the underside of the deck, and it seems to have lasted fine since 1967.

I'm sure you will get lots of suggestions, which will lead to an informed decision as to how to move forward.

BlownCrewCab
04-21-2010, 06:29 AM
On the last one I did I put down 2 layers of 3/4oz mat (Generously wet) then placed all my pre-cut core back in their respective positions, used two shop vacs and some plastic to bag it, I wasn't trying to get the Vacuum bagged saturation effect, I was more using it for a clamp to hold all the core down tight while it cured, worked perfect:yes:

wagspe208
04-21-2010, 09:07 AM
I guess I was approaching the vac bagging from the calmping point of view also. Resin infusion is above my head. Glass to resin ratio is basically a determined amount isn't it. 1 to 1 or something like that? By weight?
I'd be interested in trying one of the honeycomb materials honestly. I am not stuck on it. I just like high tech materials. It is pricey, but in the maount I need.. no big deal. I was searching and saw a honecomb that looked cool. I will try to find it againa nd post a link.
Like I said...I am just thinking. I appreciate all the input. I am not dismissing anyone's opinions. It gives me other possible options I had not thought about to consider before jumping in head first.
Keep em coming!
Thanks
Wags

gcarter
04-21-2010, 09:37 AM
I agree that doing it manually and then bagging it is the way to go.
I watched my dad build a pair of wings for a high performance glider many, many years ago.
This was a kit plane and it came w/pre preg skins. The wings had to be shaped in some pretty dense foam that had to be bonded to the front and back of the wing spar.
So once the wings were completely fair (and each wing was over 20'long), the pre preg skin was bonded to the wing.
So here's how it was done;

A "sleeve" made from thin poly sheeting was made for each wing, the sheeting was taped along the long edge so that it would be air tight.
The pre preg skin is trial fitted to the wing, (this is one piece and wraps around the leading edge of the wing).
A very long, very flimsy coil spring is used as a air passage for maintaining a good vacuum over the entire surface.
Resin is applied to the entire wing (top and bottom) and the entire inner surface of the skin and the skin is applied to the wing.
The coil spring is stretched along the upper and lower surface of the wing and taped in place.
The poly sleeve is put in place and shop vac hose is taped to a slit in the sleeve near one end (also near the end of the spring) and the shop vac is used as a vacuum source.
The vacuum is pulled for as long as neccessary and any "massaging" of the skin over the wing core can be done through the sleeve, which is VERY tight over the skin.
It's amazing what a wonderful job that can be done w/such simple implements as these.

Just Say N20
04-21-2010, 09:53 AM
Never mind.

I can see I'm too smart by half. :biggrin:

wagspe208
04-22-2010, 02:09 PM
So what other core materials (and thickneses) have guys used for decks?
Thanks
Wags

Planetwarmer
04-22-2010, 02:39 PM
Yep! A pre-preg and vacuum bag is what I would do.

Rootsy
04-22-2010, 03:01 PM
for bedding the coring I used a bedding putty... A peanut butter consistency polyester resin based material. Put it on with a notched trowel onto a prepped surface then press the coring into it. I used a 24 oz biax weave stitchmat over the top of it...

MOP
04-22-2010, 04:22 PM
How many have used PL construction glue? It is even more tenacious then 5200, I bet it would also be a viable product for various coring. When I was a tin knocker in the good old USAF I did a fair bit of honey comb, that for it strength to weight ratio beat just about anything.

wagspe208
05-01-2010, 10:04 PM
I spoke with Plascore (SP) about some of their plastic honeycomb material. They sent me 2 1' square pieces 3/8" thick. It is what I would consider very stiff. I may try it. I am also looking at some nidacore.
Anyone use either one of these?
Thanks
Wags

Greg Guimond
05-02-2010, 06:48 AM
Here is a section of an old 16 Deck ..........

wagspe208
05-02-2010, 09:01 AM
Here is a section of an old 16 Deck ..........
What material was that originally?
Thanks
Wags

Greg Guimond
05-02-2010, 11:06 AM
I do not know what they used back in 1974, but I am sure that someone can comment.

dstew8
05-05-2010, 09:18 PM
i need something to put in my engine hatch any ida

gcarter
05-05-2010, 09:31 PM
From the outside;
gel
mat
coremat
3/8 thick end grain balsa
one course very light cloth.

Many times all the core isn't rotten, and you can piece the balsa in.

OFFSHORE GINGER
05-08-2010, 06:55 PM
From the outside;
gel
mat
coremat
3/8 thick end grain balsa
one course very light cloth.

Many times all the core isn't rotten, and you can piece the balsa in.
Not to be rude put i have seen core matt so many times causing de lamination and the only reason core mat was made was to hide print thru which i feel is total junk .

OFFSHORE GINGER
05-08-2010, 07:16 PM
Hey guys , i have worked at Thompson Boats ,P Q , S-2 YACHTS , Skater , and when ever i have done a repair were core has been removed i have always put down 2 layer's of glass then adding my core mixing a putty made with Cabosil appling it on the bottom side of the core and two more layers of glass .

gcarter
05-08-2010, 07:35 PM
Not to be rude put i have seen core matt so many times causing de lamination and the only reason core mat was made was to hide print thru which i feel is total junk .

Artie, what I quoted there was how Donzi built the hatches, not necessarily how it would be done from scratch.
I was just pointing out that if the repair could be localized, this is what to expect.
So often, the balsa end grain will rot in a few places, a lot of times from blow over onto the rear lifting ring.

OFFSHORE GINGER
05-08-2010, 07:52 PM
Artie, what I quoted there was how Donzi built the hatches, not necessarily how it would be done from scratch.
I was just pointing out that if the repair could be localized, this is what to expect.
So often, the balsa end grain will rot in a few places, a lot of times from blow over onto the rear lifting ring. Hey , its all good and how have you been ?

Greg Guimond
10-14-2010, 07:16 PM
TTT for core..........