my transom replacement.....mistake included

[bigbad4cyl]

so i replaced my transom that had a curve to it ...i used epoxy and 3 different additives ,,,,,,as i needed to fill the large gap i used colodial silica mixed with microfibers ,it made a yellow catsup type of mix ...it ran down the boards horribly ......i then used some fillet compound which was a bit better ......overall i made a huge mess but did ok..i felt like a mouse tending to a nest with all the small batches and mixing etc.........my problem is i used 2 - 3/4 inch marine plywood pieces and bolted them with pieces of all thread,, the boards bent good on the bottom ,but on top they diddnt bend so good and left a small gap ,,,i mixed up my last batch of fillet blend slurry like and injected it back there with a caulking tube .........seems ok structuraly firm etc.............but on the out side were the hull top and the cap meet there is a 2 inch gap toward the center fanning out and getting closer as it nears the corners ,,,am i going to beable to bolt the cap up ....ill go take a pic...

 

[bigbad4cyl]

Re: my transom replacement.....mistake included

; ; ;

 

[bigbad4cyl]

Re: my transom replacement.....mistake included

actualy the cap is on, im just wondering if i can make the gap go away,im thinking that once i cut out the hole for the out drive it should bend eaisier ,,,,maybee heat things up a bit and then screw together the cap and hull slowly from the outside corners..

 

[JasonJ]

Re: my transom replacement.....mistake included

Is there any way to apply force at the top to push it outwards until it lines up with the cap? You probably should have rigged something to push the top out while it was curing to achieve the curve, but it may not be too late. You may be able to rig something with a small bottle jack to push it out, then you could bolt the cap on. The question would be though is if the cap would be able to hold the curve and not crack or break. Good luck...

 

[bigbad4cyl]

Re: my transom replacement.....mistake included

thats a good idea ,,

 

[bigbad4cyl]

Re: my transom replacement.....mistake included

what if i were to cut some relief cuts in the transom wood on the inside ,,,it is two layers of 3/4 that i got anxious and did all up at once ,,,what if i were to set a circular saw for 3/4 and cut 3 relief cuts toward the top middle on the inside would that give her some room to bow out...

 

[Mark42]

Re: my transom replacement.....mistake included

I would not cut stress reliefs in the transom after doing all that work to fix it. I think if you heat the fiberglass cap (with a heat gun) it will soften and bend to match the new transom shape. <br /><br />It looks like you filled in the i/o hole and are switching to a outboard, right?

 

[bigbad4cyl]

Re: my transom replacement.....mistake included

no im going to cut out the hole this weekend..i was thinking of filling the stress reliefs with epoxy

 

[JasonJ]

Re: my transom replacement.....mistake included

Once you cut the hole out, I am willing to guess that you may be able to achieve the curve. I feel that the cap is not going to be as cooperative as the transom. I hope you get it figured out. The fact that you don't have the curve means that the I/O placement and engine placement will be off from what it was originally. Even though it will be a small amount, you could be presented with drivetrain mounting and alignment issues. I will stick with my idea of cutting the hole, then using some sort of force to push the top of the transom out enough to affix the cap. Good luck...

 

[Winger Ed.]

Re: my transom replacement.....mistake included

As Jason refered to, your engine alignment is the most critical part of the project.<br /><br />Stress wise, you could cut the whole top off the transom and the boat would be fine. The weight and 'push/pull' forces of the I/O powerplant are born, and transferd to the engine mounts & bottom of the hull itself when the boat is moving forward or backwards. Also the bottom of the transom's 'hole' bears some engine weight, and transfers it downward to the hull & rear portion of the engine mounts. <br /><br />The transom area around the 'hole', or more nearly it's sides and bottom as it joins the hull is what keeps the engine/outdrive from twisting or rotating in the opposite direction of the prop's rotation due to water resistance on the prop.<br /><br />The top of the transom a few inches above the hole for a I/O could be made out of painted duct tape and still be strong enough to work. A I/O transom doesn't have to be strong in the same way a outboard motor's mounting does, particularily at the top of it if the sides & bottom are sound & strong.<br /><br />**<br />I've said this before:<br />Years ago I was doing some work on a 1975 23' fiberglass Starcraft cruiser that had a 351 Ford in it with a Mercruiser outdrive. It had a thick piece of plywood about 3' wide in the center of the transom, and it extended a few inches past the motor mounts, and up within a few inches of the top of the inside of the hull to provide the mounting for a lifting eye at the rear of the deck/top cap---- a lifting eye for the whole boat. The rest of the transom beside the 'hole' and a few inches above it, inside the hull was a 2" thick of cardboard covered with one thin layer of fiberglass so it looked like it was solid wood going across the back of the boat---- yeah, CARDBOARD, the stuff like you make cardboard boxes out of.<br />**<br /><br /><br />I'd cut the stress relieving slots in it as needed, or chop the offending area off and mold it in with epoxy resin covered styrofoam if you need to. When the transom board top is the right shape to hold the cap-- throw a layer or 2 of resin/mat on it and move on. <br /><br />If you get a chance- look inside a Aluminum hull I/O. You can better see the way the hull/transom/top cap is mounted together to provide the right strength for the same forces as you're dealing with. Without everything being glassed over and covered, you should get a better idea and grasp of what's important, and what's done just because 'its always been done that way' or because 'that's what everyone expects to see'.