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Just Say N20
03-26-2009, 12:18 PM
I believe I can save the back seat bottom by cutting off the top layer of glass, and rebuild it from the bottom up, rather than split the deck, flip it and work on it from the bottom.

My thought was to cut around the edge of the seat bottom, maybe an inch from the radius where it changes to seat back.

Suggestions?

What tool/bit is the best one for this job?

A picture of the seat bottom with cracks labeled; the cracks go through the glass.

A cross section shot.

The crack in the corner of the L-seat.

dwiggl
03-26-2009, 12:25 PM
Seriously consider popping the deck & fixing it from the back side. From the looks of things this would save you total repair time, time in contorted positions, and cosmetic repair which is painstaking. You would then be able to reassemble and properly support the $ockpit.

Planetwarmer
03-26-2009, 12:27 PM
I bet a Rotozip would work well. Or a die grinder with a cut off wheel.

Speed Racer
03-26-2009, 12:51 PM
I too have had good luck with the rotozip, but it does generate a good deal of heat, and goes through bits pretty quickly, but it is precise.
I also have used a heavy duty cuto-off wheel on a large dremel like tool that I found in my Dad's toolbox!

For some reinforcement ideas, go back to my web album and see how we did it. The seating area is pretty rugged on my 16.

The other advantage to pulling the deck and flipping it is that you can actually get a really good look at any other areas that might have some soft spots. On mine.. there were lots!

I too did not want to pull the deck, but the smart folks on this forum strongly recommended that I do, and now, I am glad I did!

MOP
03-26-2009, 12:59 PM
Another option is to use a router to cut the top layer of glass loose, assuming the bottom of the seat is cored like most horizontal surfaces on the boat. EWith a router you can screw a straight edge in place and do a very neat job, I must admit that pulling the deck may well be worth the effort.

Phil

gcarter
03-26-2009, 01:34 PM
Best all around tool for glass is a 4 1/2" right angle grinder with 35 paper or, in some cases an abrasive wheel, on it.
When laying in new glass, the old glass needs to be scarfed at a 12:1 ratio first. Then layout and trim your new glass to fit, smaller pieces in the bottom, then larger pieces as you move outward. Be sure and use some stitch mat of some sort.

Just Say N20
03-26-2009, 01:42 PM
Thanks for the suggestions. I was thinking Rotozip, but my one experience with one in fiberglass was a broken bit in about 3". I used one of the bits that came with the tool, and that probably was not up to the task.

I don't know about the cockpit floor with regards to coring; it seems very solid. I do know that there is PVC under all of the deck and engine hatch.

That is why I was thinking I might try to do this without splitting the hull. I didn't think I would find any other trouble areas, as it is PVC. The fuel tank has already been replaced and looks good.

Is there something else I am missing with regards to splitting the deck/hull?

Just Say N20
03-26-2009, 01:49 PM
When laying in new glass, the old glass needs to be scarfed at a 12:1 ratio first.

Neophite glass person here. I don't know what "scarfed at a 12:1 ratio" means.

I do know from my time at Tiara that glass mat won't make/doesn't like corners, so convex corners should be rounded, and concave surfaces should be "filled" with something like triangularly shaped pieces of wood to effectively round the corner.

Just Say N20
03-26-2009, 05:08 PM
I never started the boat when I went to buy it, based on the trustworthy comments from many people here. And there was no battery.

Now there is a battery. And happy sounds.

http://s26.photobucket.com/albums/c111/streb2005/videos/?action=view&current=DonziFirstStart.flv

mike o
03-26-2009, 05:41 PM
Neophite glass person here. I don't know what "scarfed at a 12:1 ratio" means.

I do know from my time at Tiara that glass mat won't make/doesn't like corners, so convex corners should be rounded, and concave surfaces should be "filled" with something like triangularly shaped pieces of wood to effectively round the corner. This works good, unless ya like to itch:yes:.http://www.fein.de/fein-multimaster/us/en/applications/index.html. Use some 10 oz fiberglass cloth for the radius's.:biggrin.:

Just Say N20
03-26-2009, 05:49 PM
I have a 90 degree, 4.5" angle grinder, that I have almost exclusively used with a fiberglass cut off wheel to cut metal. I think it would work, but be cumbersome. I will look into the product you linked. Thank you.

I most definitely don't like to itch. :frown:

mike o
03-26-2009, 05:57 PM
I have a 90 degree, 4.5" angle grinder, that I have almost exclusively used with a fiberglass cut off wheel to cut metal. I think it would work, but be cumbersome. I will look into the product you linked. Thank you.

I most definitely don't like to itch. :frown:. It cuts like what the doc uses to cut a cast. Tooo bad ya not closer... id let ya borrow mine.:yes: good advice to flip it look it all over. Alot easier. I like ya boat:yes:

yeller
03-26-2009, 08:01 PM
Neophite glass person here. I don't know what "scarfed at a 12:1 ratio" means.
I believe he means that whatever depth you grind down, you have to fair outwards by a factor of 12. i.e.: if you grind down a depth of 1/8" you should fair outwards 1/8" x 12 or 1 1/2".

gcarter
03-26-2009, 09:15 PM
Sorry I didn't get back to this sooner, but this is a very complicated subject.
Actually any handy person can do it, but good guidance is required.
I'd like to reccomend a book to study;

"The fiberglass boat repair manual"
by Allan Vaitses

http://www.amazon.com/Fiberglass-Boat-Repair-Manual/dp/0071569146/ref=sr_1_10?ie=UTF8&s=books&qid=1238120036&sr=1-10

This book is invaluable for repairs like this and many others.

I have a copy somewhere, but I can't seem to find it....

Planetwarmer
03-26-2009, 09:16 PM
Basically, when you repair fiberglass or carbon fiber you have to cut out the delaminated parts at a 45 degree angle. The wider part needs to be at the top of the opening. Don't just cut it at a straight 90 degree, or there wont be sufficient area for your new glass to "hold" on to. Try checking out "fiber glass repair" on you tube. Your repair should look like a wedge if you looked at from a side profile.

You can cut the bad area out at a 90 deg angle, you will just need to file or sand an a 45 deg angle to the cut after wards prior to layup.

Just Say N20
03-26-2009, 10:09 PM
"The fiberglass boat repair manual"
by Allan Vaitses

http://www.amazon.com/Fiberglass-Boat-Repair-Manual/dp/0071569146/ref=sr_1_10?ie=UTF8&s=books&qid=1238120036&sr=1-10



Ordered. Thank you! I really appreciate all the helpful advice.

RickR
03-27-2009, 07:59 AM
There is a wealth of information here
http://www.boatdesign.net/forums/fiberglass-composite-boat-building/ski-boat-stringer-sole-replacement-20668.html

This might be some help also (My Project)
http://www.supraboats.com/bbs/showthread.php?t=2855

Materials (I used Epoxy resin and 1708)
uscomposites.com

Tools and Roloc Discs
http://www.mcmaster.com/

To cut fiberglass I use a reciprocating saw with an laminate blade (teeth are upside down) w/lots of masking tape.

For grinding small areas an angle grinder with 3M Roloc discs. For larger areas a DA (in grind mode) or a full size commercial buffer with 9" backing pad and sanding discs.

Just Say N20
03-27-2009, 09:55 AM
There is a wealth of information here
http://www.boatdesign.net/forums/fiberglass-composite-boat-building/ski-boat-stringer-sole-replacement-20668.html
This might be some help also (My Project)
http://www.supraboats.com/bbs/showthread.php?t=2855
Materials (I used Epoxy resin and 1708)
uscomposites.com
Tools and Roloc Discs
http://www.mcmaster.com/
To cut fiberglass I use a reciprocating saw with an laminate blade (teeth are upside down) w/lots of masking tape.
For grinding small areas an angle grinder with 3M Roloc discs. For larger areas a DA (in grind mode) or a full size commercial buffer with 9" backing pad and sanding discs.

Fantastic Job! You must have itched for months!

ENG40
03-28-2009, 09:17 PM
We have used many different methods of cutting fiberglass and this 4 1/2" angle grinder with a thin disc seems to work the best for me.


http://i215.photobucket.com/albums/cc223/ENG40/moynihan/th_2209010.jpg (http://i215.photobucket.com/albums/cc223/ENG40/moynihan/2209010.jpg)