Transoms

[andrew]

When removing the transom from a boat, can the transom be removed in one piece like sliding it out, or is it fiberglassed in place. i am getting two 3/4" marine board and screwing them together, then cutting them out to shape. Do I fiberglass them together after i screwed them and cut the out. Also do i mark the holes for the engine mount and take it out and drill the holes then drill bigger holes in he board then fill he holes with epoxy and then drill again so that there will be no leakage. Could someone explain how they did their transom and holes?
thanks,
Adnrew

[tja]

Hello Andrew, Depending on the condition of the current transom it may or may not come out in one piece. If it doesn't just make a template out of cardboard and transfer to the wood. Cut out one piece from the plywood and test fit and trim to final fit. Then make another one to match it. You didn't say but i'm thinking that you have a IO . If so put the wood in place and draw the hole for the drive unit. Cut it out about an inch smaller then the original hole. Grind the inside of the transom with 24grit til it's smooth , clean, and dry. I usually put in two layers of one and a half oz. mat then wood then one layer of mat then second layer of wood. This is then all clamped in place through the out drive hole with either square steel channel or wood two bys or 4x4s on the inside and outside of the transom. Then take and wedge two x fours between the new transom and the original floor and stringers which usually have to be cut out about one foot forward of the transom. Leave this setup over night and then glass the inside of the transom with mat and woven roving or biaxial fiberglass. When all of this is hard cut out the transom hole to size and drill for the drive unit. See nothing to it. H

[tja]

I hit the wrong botton. I hope my above post helped, Tom.

[tja]

Andrew, I kust saw your previous post and see that you have a outboard setup. Most of the time you have to remove the deck to get to the transom. Putting in the wood is about the same as an IO there just isn't a hole in the back. Make sure that you do a dry fit with both pieces of wood so you can setup all your clamps and wedges. Put it back the way it was from new. Good luck, Tom.

[PAR]

I'm guessing you have a fiberglass boat with a bad transom?

The plywood core inside your transom is bonded in place, so it will not slide out.

The fast way is to take an angle grinder to the outboard face of the transom and cut through the outer 'glass skin about 3" in from the edges. You may have to go over the top of the transom, into the deck cap, but try to do it as one step, as this will limit the amount of damage needing repair because of the core replacement. Save the piece(s), as you'll re-install later. It will need to be pulled off the rotting plywood, which may take some cussing and jaw clenching. The lovely task of removing the rotted ply is made rather easy at this point. Get it all out of there, no sense trying to save it, or pieces of it, just cut, grind and hack the ply away. The inside of the transom, must be clean, I mean really clean and the easiest way to do this is with the grinder again. Abate (sand) every inch of the inside surface. The grinder will get most of it, you're not trying to remove much material, just provide a clean and roughed up surface for the goo to stick too, but there will be areas that will require hand sanding.

Cut your ply to fit inside the transom. This may be done in layers and pieces, but one piece is best, if possible. Set this aside, after the fit has been checked and adjusted, you're not ready to install it yet. Do not alter the size of the transom, not the thickness nor the width, as this is a critical area and shouldn't be fooled around with.

Now you have to bond the ply into the transom cavity. I strongly recommend the use of epoxy and reinforcement (fillers) There will be areas (not many I hope) that the plywood doesn't fit very well. The inside surface of the transom will be rough and the ply will not land against it perfectly, there will be voids which must be avoided and this is where the epoxy and fillers come in. I'd use colloidal silica as the filler (like West System 406) as it has excellent wet out, bond and high strength properties. Coat the inside of the transom and the face of the ply that goes against this part of the transom with unthickened epoxy (this is called wetting out) then using a notched trowel spread thickened epoxy over the surface of the inside of the transom where the ply hits. Place the plywood core piece in the transom and apply light clamping pressure to the ply. You don't need a lot of pressure, just enough to insure the ply is bedded in the goo (this is real important) Some folks like to use screws to temporarily hold the ply in place as the goo sets, then fill the holes. I find, I can't get screws in all the places I want and I have to go back and fill even more holes, so I work around this by using clamps, braces, props, sand bags, whatever will provide some pressure. Fill any gaps that may still be around with thickened epoxy.

Now your transom has a new core bonded in place and needs the outer skin re-attached. You will do a similar job to refasten the outer skin, but you'll not need the mixture toweled on, just enough of a coating to insure good contact with the adhesive. You'll have a gap the width of the grinder blade around the edges of the transom that needs filling. Grind back on both sides of the gap a few inches until you have a nice taper, being deepest at the gap and tapering out to the surface a few inches away. This is why I asked you to leave the room around the edges when it was cut away.

The now widened gap can be filled with epoxy and cloth/mat in typical fashion.

Log onto the www.westsystem.com site and have them send you their free booklets on working with epoxy and reinforcements. You'll want to do some other things while you have the transom opened up and after she's closed. Bond all of the holes, even the stern drive hole (will require engine removal if not done yet) The repair as I described will well out live the factory job if all holes are bonded. Bonding is coating the edges of a hole with thickened epoxy so that in the event of a leak the epoxy prevents the moisture from getting into the core and causing rot. It should be done to all fasteners and hardware and saves a lot of potential pain down the road. Then keep an eye on the fasteners and the caulk beads around stuff so water can't get back in. A good look see every month will catch things long before they become problems, trust me . . .


Good Luck,