glassing transom ???

[bkeith66]

Hi all,<br />I"m in the process of replacing a transom in a starcraft american 16. It will need to support & handle a merc. 115 (270"?) when finshed.<br />The original transom was made up of 2 sheets of 3/4" ply. One being a full & the other about a foot deep going from side to side across the moterwell area. I have the new wood cut & test fitted. It is now 2 full 3/4 plys. <br />This project will be done with epoxy. Being a fiberglassing newbie, this is where i could use some advice. Such as what type & what oz. cloth & roving to use. Also, how it should be layed up (cloth-ply-cloth-ply-cloth-roving-cloth) etc? <br />Did pick up the west system manual & fiberglass boat repair & maintenance book to help me along after i get the material questions figured out. Wouldn't have started this project without 1st stumbling across this forum Any help will be appriciated. Oh yeah, what would be a good way to fill in corner gap in in 3rd pic.<br /> http://xs.to/xs.php?f=DSCN0061.JPG&h=xs64&d=06032 <br /> http://xs.to/xs.php?f=DSCN01b.JPG&h=xs64&d=06032 <br /> http://xs.to/xs.php?f=DSCN0142.JPG&h=xs64&d=06032

 

[lark2004]

Re: glassing transom ???

Sounds like you've got most of worked out! It's not really hard to do the transom. The lay up for a transom doesn't need the roving, two layers of 3/4 ply are extreamly strong. I would start by coating both pieces first, then once that has cured, laminate the two pieces together with a layer of 16oz cloth in between, it doesn't hurt to screw the halves together while the resin cures, srew holes can be filed with thickened resin after they are removed.<br /><br />After that has cured, you can then cover the outside faces of the transom. Let this cure then glue the whole thing into the back of the boat, use thickened epoxy (bog)for this (put the bog inside the hull and seat the transom into it. This will solve the problem of the gap in the corner). You can then lay glass strips down into all the corners and oat them with resin, also cover all the outside edges with glass and resin, this will seal the timber and help prevent any rot in the future.<br /><br />After that sanding, lots and lots of sanding! then some painting, sanding, painting sanding .......

 

[Chinewalker]

Re: glassing transom ???

The transom is looking good!<br /><br />I can tell you that mine was far from a perfect fit when installing my 15-American's transom. There were a few gaps along the edges, etc. Lots of filler, glass strips, epoxy, etc. I also did the new transom full width and height, doing away with the one full and one half thing.<br /><br />I'm jealous! You've gotten way ahead of me! I've been doing motor work and haven't done much at all on my 18-footer...<br /><br />- Scott

 

[epresutti]

Re: glassing transom ???

bKeith66,<br /><br />Like lark2004 said. Coat the slot where everything is going with a "peanut butter" consistancy paste of epoxy and filler. If you are using west systems, I believe they sell a structural filler.<br /><br />For my rebuild I sifted the glass that I ground out while removing old parts out of my shop vac, added epoxy and made the filler that way (for some reason it turned out green, go figure). People use sawdust, powder, micro baloons and a variety of other substances. Whatever you have available or can afford should work fine.<br /><br />Peace.<br /><br />Ed.

 

[bkeith66]

Re: glassing transom ???

Appreciate the responses. Have a couple more questions about cloth & cloth tape. Should e-glass or biaxial cloth be used between ply & skin? If biaxial, would one go with or without matt backing? I guess the same questions apply for the tape too. Also, should the tape be layered or would that be overkill?<br />Looking forward to getting started. Thanks again.<br /><br />Chinewalker,<br />I feel like i should be farther along on this project. The interruptions never cease to amaze.<br />Oh well, it's only mid january.

 

[surlyjoe]

Re: glassing transom ???

glassing is kinda like plywood. more thin layers of the same thickness will be stronger than the thicker layers if only because of the directional properties of the weave being oriented differently...to a point. once they get too thin it becomes harder when doing hand layups to get the excess resin back out without creating dry spots. use heavy enough glass to get your volume without doing an insane number of layers,(I usually shoot for 3-5) yet light enough to not make sticking the corners a nightmare. and be sure to stagger the edges to prevent hard spots in the transition

 

[lark2004]

Re: glassing transom ???

there is no right or wrong for the type of glass between the skin and ply, I use chopped strand. I use a combination of chopped strand and bi-axial cloth stitched together for the edges when I glass it into the hull. This stuff is rather thick, and it takes a bit of patience to get it right, but it is very strong. I tested some of it once doing a 90* butt joint with 1/4" ply. I then beat the crap out of it to see what would break. I demolished the ply, but couldn't damage the glass.

 

[bkeith66]

Re: glassing transom ???

Alright. So how about staggering three layers of 4" Biaxial Tape (15 oz. non-woven E glass fabric to secure new transom? To thick or overkill? <br />Also, would one layer each of 10 oz. cloth be adequate between plys and ply & transom skin? The original transom had a thick chunk of woven roving between motorwell & inner ply, so i think i could get away with two 10 ounce cloths. Sorry for all the questions. Just want to be sure & get the right material ordered. Thanks for the help & patience.

 

[Chinewalker]

Re: glassing transom ???

Hi Brian,<br /> In my 15-foot American I put a single layer of cloth between the inside sheet of plywood and the transom skin, and put on a really thick coat of epoxy. I then clamped it and screwed it all together, sending screws from the outside through existing holes, plus a few new ones (that would all be filled when done). <br /> My transom had a serious bow to it from the 85hp Chizzler that had been sitting on the rotted transom with no real support, so I installed my transom on layer at a time to help bring the shape back. I used 4 layers of 3/8" plywood with a layer of light cloth (approx. 8 oz.) between layers. I used several layers of the 8 oz cloth, alternated with similar 15 oz. tape on the edges to tie it into the sides and stringers. The transom is absolutely rock solid and I made sure the seal all edges and the face when done. When I pulled the boat in the Fall I ducked under the deck to check out how it had lasted the summer and it looked exactly as it did when I finished the job in the Spring.<br /> I figure pretty much anything you do with good plywood and epoxy will be better, stronger and last longer than the original transom which, as you probably well know by now, was far from perfect.<br />- Scott

 

[fishingdan]

Re: glassing transom ???

Here is a link to a nice transom replacement tutorial: <br /><br /> http://bateau2.com/content/view/144/28/ <br /><br />If you are using epoxy, you don't need the cloth between the plywood laminations. <br /><br />As you read the tutorial, the tape use to bond the new transom to the hull should be biaxial. That is joint is structural. You will also want a minimum of two laminations of tape on that joint. Typically, the first lamination is the narrower than the second. The first lamination needs to be wide enough to span from the plywood, across the fillet and to the hull. The second is wider and is applied over the first.

 

[bkeith66]

Re: glassing transom ???

Okay. Thanks again for all the help. Feel better now about what to order & how to lay it all up.<br /><br />Scott,<br />Thanks again for the replys here & from previous post to help me get where i am so far. Looking forward to seeing progress on your american 18.

 

[bowlin257]

Re: glassing transom ???

Will this work? replacing transom in 14 ft. fiberglass boat. Have removed the cap and the rotted plywood. Will cut new plywood to rough shape of transom and slide in place, then I plan on flooding the cavity with epozy resin and lightly clamping to bond new wood to inner and outer skins. Planning on slow hardner so resin can flow and fill all voids. Fitting against the inner and outer skins will be snug, expect up to 1/2" voids on sides.

 

[KRS]

Re: glassing transom ???

Purchasing enough epoxy and resin to free-flow into a 1/2" void on all sides of the transom will be $$$ MUCHO DINERO. That's a lot of material.<br /><br />The tighter the plywood fit, the better, I wouldn't leave a big gap and expect epoxy to make it good.<br /><br />Welcome to iboats! When you have a question, feel free to hit the "post a new topic" button at the top of the page, so people will find your question and help you out.

 

[andy6374]

Re: glassing transom ???

Make a template out of luan, cardboard...whatever. Then cut it a bit large. Then just keep taking a little off at a time until it fits nice a snug. You should round the edges between the hull/walls and the transom shell with some epoxy/cabosil fillets, it will make the eventual glassing much easier and better.