Have to agree with you on that one. I installed two extra anodes to stop corrosion, which it did do that. Those two little holes since I didn't seal them up correctly sure helped with the rot. Then add the leak around the bottom bolt and he we go.

Trying decide the best way to repair the transom, haven't done much in this line of work. Helped replace the whole transom on a old house boat, but that was about it. Since the port side is up next to the stringer I'm thinking about cutting some of the glass away from the very back. Give me enough room to put some layers of new plywood in layers then glass over. Could also do it on the other side, should make it stronger, but as before I haven't dome much of this type of work

Not a huge fan of partial transom replacements but if they are done correctly and with Epoxy I believe they are more than sufficient.

I think cutting the plywood back to the stringers like you are doing is the ticket . I would than grind about 6 inches back into the glass from where the plywood is going to be replaced and also 6 inches back on the stingers and the bottom of the boat and also aggressively grind the area where the new plywood will be adhered to.

When I replaced transoms and cut my new plywood I would cut off the bottom of the Vee of that area where the drain plug goes through and than just meticulously lay up that small area with extra glass after the plywood was in. Now you have a solid fiberglass area that the drain plug runs through so no need to ever worry about the plywood soaking up water again. I feel in a boat like this that spends most of it's time in a slip with a couple inches of water that never seem to get out of the bilge that this is a nice preventive measure.

Template for your plywood and stagger the joints but towards the top not the bottom and laminate these together out of the boat with thickened epoxy and possibly a layer of 17 biaxe if you want to go crazy. Make sure you presoak the ply with resin and let it kick before you do the laminating and clamping of the 2 pieces but go easy on your clamping pressure so you don't squeeze everything out.

Let them dry overnight.

Again precoat the inner transom area and the plywood piece that you are setting and after it goes off mix up some thickened epoxy and set the plywood and clamp and bolt it in .after it is positioned and clamped fill any voids where the ply meets the old transom with more thickened epoxy.
Next day check your work for goobers that need to be knocked down if not proceed to laminate the inner portion with 3 layers of 17 ox biax laid in epoxy. . Cut your cloth so it comes back 5 inches onto the boats bottom and the stringers and also the old transom area.

I usually save the little cutout area where the drain plug goes for last and diligently work that.

I know Glass Dave is the resident guy but figured I would save him a lot of typing and I am bored. I know you have experience already doing a transom ,thought I would just give you my point of view. If Dave has any other pointers or feels there is a better way I would listen to him he has far more experience.

A little thing that always bothers me on boats is they mount the bilge pump on a pad so you are always stuck with 2 inches of water in the bilge. So If I was redoing a bilje or transom what I would do is this.

I position a new pump pad forward of the engine where it is accessible .. Than I measure from a couple inches back from my pump pad to about 4 inches in front of the drain plug . Than i take a scrap of divinycell and laminate it on both sides out of the boat. Now cut this piece after it has cured to the front to back dimensions you have and out about 6 to 8 inches.Cut and fit this piece so now you have a raised section that is an inch or 2 above your pump pad. So now you are left with a little sump area for your pump.

Laminate the piece in after grinding the bilge area back a few inches and also laminate the ends to seal it tight.

Now the most water you will ever have in your bilge is a cup full back by the drain and a half cup in the pump sump area.

Sure appreciate the write up Tommy, going to have to re-read it several times to try to understand all you put in. I was told Formula uses ASME 5000 resin and haven't heard of 17 biaxe, 17 ox biax or divinycell. Sure I can find them with google.

Like the idea of building the pad to reduce water but there is a tube which has holes in it about a foot up from the drain plug. The holes one on each side of the center drain pipe which is under the glass has always had a bit of water in them. There is three ribs crossways in the area and I think they help get the water to the plug. Go figure, water goes to the plug for draining but boat doesn't come out very often.

See if I can find some kind of saw which I can use to get a clean cut. As for behind the stringers, this will be an issue, may have to use a drill and little by little dig it out. I drilled into the bottom of the stringers down low and back, and the wood came out blond and appears very dry. Have a moisture meter coming to do some further checks. Another mentioned that if I cut into the glass on the back of the stringers it will be more difficult to get the but joint right. I'm unable to get to the other side of the stringers due to they are sealed up by boxing it the other side

I'd hate to do it but if all else doesn't seem to work out, I guess I can cut through the back going in and then re-glass and gel-coat. Really don't want to do that

Oh forgot, All the grinding you mentioned, was that just to ruff it up?

The drain plug is just glassed and gel-coat, there is no wood behind it

this is not a friend of a friend story, it is a guy i know that works at a machine shop and several years ago (1989) he took his 27 wellcraft cabin cruiser aft deck and put a blower on his small block. he never really gave an answer on speed but i would venture to say 60 mph.
the most bang for your buck would be a whipple super charger. it is a side mounted one for 454 and 502 fuel injection.
take it from someone who in 1997 tried everything they could do to get some decent horsepower from that efi system in a heavy boat, for a single engine. after i put a blower on it. it was a completely different boat. put a blower/ supercharger on it. the cost would be close to the same as doing the heads cam etc. and you would probably get double the added horsepower. meaning if you got a 100 hp out of a cam and heads you will get 150 -200 hp out of a whipple super charger.
personally i would try a bravo 3 knowing it may grenade if you abuse it.

Thanks for the input hullofjustis, appreciate it. Don't have the room for a blower and even a whipple would cause some more space issues. Have to stand on my head to change the impeller. Have turned the engine over to Eddie


More glass questions.
Figuring I need to get behind the stringers I have thought of this. In the pic below I marked were the main stringers are. To each side of it I can cut through the hull and get at the wood. Do you think this may be a good plan? Pros Cons ??

For the ease of it i would not cut it out any further than where the transom wood meets the stringers.. In all reality all the stress is transferred from the transom area between the stringers directly to the stringers and the bottom of the hull .Any area of the transom outside to right or left of the stringers is more or less there to keep the water out.

I assume the rot on the transom does not seem very severe as you get close to the stringers and you feel the remaining wood could simply be filled with some thickened epoxy and laminated over.

Yes do it with 36 grit though so it has some real teeth but clean and wipe the area down real well 1st so you don.t contaminate the area and grind oil into the old laminate.

Maybe Dave will pop in here but what I would do the transom is go out 5 inches from where your new plywood is going and grind that glass down to the old transom plywood so when you re laminate with glass you have a nice scarf without building your thickness up to much and this will attach the new ply to the old ply incase the old ply has a delaminating issue

Looked at your pics with some magnification . How is the transom wood where it gets close to the stringers?

The rot on the starboard side I think is fine, but the port side may take a bit more looking into. I can still see some black in there. Could get a multi tool or use a drill to see if I can get behind the stringer. Guess I don't need a smooth joint where the new wood will meet the old behind the stringer. Fill with some epoxy when putting it together?