Clamping transom wood to hulls' outer skin question

Crappie_Fan · Mar 3, 2005

I have my boat ready to start putting things back together. From what I have read in the archives, is that most people use there motor bolts to suck the new transom up agianst the skin on the hull. However my transom has no such holes, my motor just clamps onto the transom, and my transom skin has developed its own shape( not flat, kinda wavy). I was thinking about laying a coupling sheets of saturated mat on first then soaking the new transom with thinned resin, then applying a thick resin and milled fiberglass mix to the new transom to help fill any voids that might be hidden since I have no real good way of sucking the wood up against the outer skin. Or should I drill some holes in the hull and use bolts, which I would rather not do unless I have to. And I'm using poly resin, not epoxy. If anyone has a better solution to this I would gladly accept your help. Thanks

flashback · Mar 3, 2005

Re: Clamping transom wood to hulls' outer skin question

Crappie fan, I have used drywall screws with fender washers where needed... after it has cured, remove the screws and fill the holes... I would like to find a way to do it without the holes, but so far no luck....maybe someone has the answer.....I have thought about temporarily glassing in a 2x4 across the boat about 2 feet in front of the transom then put several braces off of the 2x4 and wedge them against the transom..I have no idea if it would work or not...good luck

TenE307 · Mar 3, 2005

Re: Clamping transom wood to hulls' outer skin question

what i did because i didnt have clamps big enough to hold down the bottom. i used a rope and ran it through the drain hole up over the transom and tied it together. then with 2x6 at about half width of transom. one piece at top, and one piece at bottom. on outside of hull i used a srewdiver in the rope and twisted it to tightn it, not too tight to squease out all resin.

Crappie_Fan · Mar 3, 2005

Re: Clamping transom wood to hulls' outer skin question

I too thought about glassing in a board close to the transom and then using hydralic bottle jack to apply pressure to the transom. I dont have a drain hole right now, so theres no hole for the rope idea, and I cant put the hole in until I get the floor down, witch is waiting on the transom.

Thanks guys

Mark42 · Mar 3, 2005

Re: Clamping transom wood to hulls' outer skin question

One method to clamp something large like that is to make some large U shaped clamps out of 2x4. Make it about 1 foot wide and 4 or 5 feet long. Make the "corners" of the U shape pivot points by attaching the vertical legs to the bottom leg with bolts. When these U shapes are inverted over the transom, a loop of rope can be wrapped around the mid point of the legs and tightend by twisting them with a lenght of broom handle or the like. Tremendous pressure can be generated this way. Make sure the rope is fresh and thick enough to not break when twisted. Some 2x8's on each side of the transom will help distribute the clamping force and prevent damage to the transom. Mark.

prockvoan · Mar 3, 2005

Re: Clamping transom wood to hulls' outer skin question

I used drywall screws,with some blocks of 1/2" plywood,they were around 4"x4".After the cure,removed them,fill in the holes with gelcoat.

BillP · Mar 4, 2005

Re: Clamping transom wood to hulls' outer skin question

Mark42's idea is a cool one to me...twisting rope to tighten is known as a "spanish windless". I use screws to do the bottom areas and 8" C-clamps on the top with 2/2 steel angle pointed as neccessary. Tighten the clamp and it pulls the angle iron tight against the hull. Sometimes the hull gets distorted and the outer skin is too wide to pull in without puckers. I slit the skin to make it lay down and epoxy back.

Eggkr8 · Mar 4, 2005

Re: Clamping transom wood to hulls' outer skin question

Hey Mark, If I am picturing your device correctly, it will be acting like a large Jorgensen clamp? If you aren't familar with it, it is two pieces of wood (parallel to each other) with two pieces of threaded rod passing through the wood (actually through a pivoting threaded piece mounted into the pieces of wood). So, you set the distance that you want the two pieces apart with mostly the lower threaded rod, slide it onto the clampee and then force is exerted by opening the upper rod (pivoting on the lower one and you get a great clamping force!) I like your idea, I will take photos when I do it to mine (as soonas we FINALLY have spring here)

Mark42 · Mar 4, 2005

Re: Clamping transom wood to hulls' outer skin question

Eggkr8 Yep, in fact I have some of those clamps... somewhere. Actually found them in a pile of firewood I was cleaning out of a house that had been sold. I found that the low pressure flotation tires on ATV's and even garden tractors can be be seated by looping a rope around the circumfrence and twisting it. Crushes the tire in, and the bead out. But my all time favorite way of mounting a tire is to spray some starting fluid into the tire, then stand back and toss a match at it. Poof! it blows itself up and seals the bead in the blink of an eye. Plus it's nice and warm on a cold day! Saw some guys do this (on National Geographic) in the Antartic when they had to change a tire on a monster show machine in the middle of nowhere.

Crappie_Fan · Mar 4, 2005

Re: Clamping transom wood to hulls' outer skin question

I like the idea of using the 2x4 clamps you mention. I think I can fab some up and use some 2x6 to distribute the force across the transom. How does the idea of using thickend poly resin and 1/32 milled fiber to help fill in the voids, hopefully most of it will squeeze out and then use it as a fillet where the wood meets the outer edge of the hull. BTW I seen that show with the antartic toyotas, good show, my luck the tire would just burn like crasy then I would be really stuck. Thanks

Richard Petersen · Mar 4, 2005

Re: Clamping transom wood to hulls' outer skin question

I just coated my precut inside transom pieces with 1 tube of G E RTV. Same for the outside piece that holds side by side 28 hp and 9.9 hp and a trolling motor. Snugged them all snug 2 times 4 years ago. Perfect.

Mark42 · Mar 5, 2005

Re: Clamping transom wood to hulls' outer skin question

Richard, Do you mean you put in new plywood in your transom and used silicone as the adhesive? No resin? Maybe I'm not following you right.

Richard Petersen · Mar 5, 2005

Re: Clamping transom wood to hulls' outer skin question

You read right, GE RTV. I Replaced the outer clamp board once in that time. It is a 1/2 hour job. I did completly coat the inner board with the GE RTV. No shifting inside. I don't know how hard it will be to remove. I think a really good shot with a wood drift will break the seal.

flashback · Mar 6, 2005

Re: Clamping transom wood to hulls' outer skin question

I like the idea of the large 2x4 clamps and threaded rods...

Richard Petersen · Mar 6, 2005

Re: Clamping transom wood to hulls' outer skin question

As I recall there are bolt holes and bolts in the 28 hp clamp bracket that also help with this job.

Crappie_Fan · Mar 7, 2005

Re: Clamping transom wood to hulls' outer skin question

My motor is a 25hp and has no holes or bolts just a couple of clamps that secure it to the transom. I built a couple of the 2x4 u clamps, just waiting to use them at the right time now. Lots of others things to do before I can use them. Thanks for the help guys

thejeepster02 · Mar 7, 2005

Re: Clamping transom wood to hulls' outer skin question

I used angle steel 2 to 3 ft long, this reduced the amount of holes i had to drill. check the very last picture on this web site. http://home.mchsi.com/~thejeepster/wsb/html/view.cgi-home.html-.html

Clamping transom wood to hulls' outer skin question

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