Transom and floor replacement

[todhunter]

If you're not going to remove the cap, cut the boxed in area out and dig out all the foam. When you rebuild the boxed in area, cut a hole about 3" in diameter near thr top edge and fill with 2-part pourable expanding foam though the hole. Reinstall the plug you hole sawed out with PB or some other glue, then glass over it.

 

[Scott Danforth]

Yes, uncapping makes your job easier

 

[happy cruiser]

I appreciate all the info i would love to be able to lift the cap off but unfortunately have no way in doing so on a boat this big so it will be a little more difficult but i knew this was the place to go for the answer's! I am also curious about what i believe is end grain balsa, it was used in the outer edges of transom and the hull floor in engine compartment im guessing to follow the contours, would i be able to use sections or strips of plywood with resin and mat to rebuild? Tia

 

[Scott Danforth]

I appreciate all the info i would love to be able to lift the cap off but unfortunately have no way in doing so on a boat this big so it will be a little more difficult but i knew this was the place to go for the answer's! I am also curious about what i believe is end grain balsa

End grain balsa is still used today in low volume boats. It adds a lot of strength (by spacing the layers of fiberglass) without adding more than a pound or two

Plywood would be heavy

Building up with fiberglass matt will be heavier

There are other core materials out there. Foam core, nida core, etc

 

[tpenfield]

Plan on having the rot go about 5X further than you think. Cruiser style boat restoration is a bit more challenging than the smaller runabouts and bowriders since the hull structure and the cockpit structure are more separated by cabin space.

There was a member ( @bigdirty ) who had to do some hull and bulkhead restoration on a Crownline 25 footer. Here is the link.

https://forums.iboats.com/threads/9...dirty-but-now-shes-clean-and-splashed.621397/

This may be helpful in understanding some of the approaches.

Step 1 would be to get the engine/outdrive out of the boat.

 

[airshot]

When I helped a neighbor do his transom, we looked up the factory recomendations for transom thickness for his Mercruiser transom mount. Get your model and look it up, to thick or to thin is not good. Been a while but I seem to remember 2 - 21/4" but can't say for sure. They do give a tolerance on that thickness.

 

[happy cruiser]

When I helped a neighbor do his transom, we looked up the factory recomendations for transom thickness for his Mercruiser transom mount. Get your model and look it up, to thick or to thin is not good. Been a while but I seem to remember 2 - 21/4" but can't say for sure. They do give a tolerance on that thickness

I have looked and cant find anything, that info could come in handy for sure

 

[Scott Danforth]

When I helped a neighbor do his transom, we looked up the factory recomendations for transom thickness for his Mercruiser transom mount. Get your model and look it up, to thick or to thin is not good. Been a while but I seem to remember 2 - 21/4" but can't say for sure. They do give a tolerance on that thickness.

I have looked and cant find anything, that info could come in handy for sure

pretty sure post #14 covered that.

 

[happy cruiser]

pretty sure post #14 covered that.

Yes i now know what the transom thickness should be and i appreciate all the info you have shared, but the build spec sheet for this particular boat would tell me why the original transom was only 1" thick but with the unglassed wood spacers added made the 2 1/8" total thickness as well as aid in other parts of this demo process. I have never tackled a job of this nature so looking at every angle to avoid unnecessary work and surprises, again thanks for any and all input everyone! Cheers

 

[Scott Danforth]

Yes i now know what the transom thickness should be and i appreciate all the info you have shared, but the build spec sheet for this particular boat would tell me why the original transom was only 1" thick but with the unglassed wood spacers added made the 2 1/8" total thickness

Don't over think it

Boats in the 80 were slapped together

Build specs didn't exist.

Your boat most likely was scheduled for an OMC stringer setup and at the last moment they installed a Mercruiser

 

[JASinIL2006]

Yes i now know what the transom thickness should be and i appreciate all the info you have shared, but the build spec sheet for this particular boat would tell me why the original transom was only 1" thick but with the unglassed wood spacers added made the 2 1/8" total thickness as well as aid in other parts of this demo process. I have never tackled a job of this nature so looking at every angle to avoid unnecessary work and surprises, again thanks for any and all input everyone! Cheers

Your goal should be to rebuild it better than it was when it came out of the factory. (That's not hard to do, for many of our boats...)

There is much good info here to help you, and many patient folks to answer your questions along the way.

As @Scott Danforth noted, it does look like your boat was refitted with it's current drive and it doesn't look like they did the best job, honestly. You can do better and you'll have a safer and nicer boat.

 

[happy cruiser]

Your goal should be to rebuild it better than it was when it came out of the factory. (That's not hard to do, for many of our boats...)

There is much good info here to help you, and many patient folks to answer your questions along the way.

As @Scott Danforth noted, it does look like your boat was refitted with it's current drive and it doesn't look like they did the best job, honestly. You can do better and you'll have a safer and nicer boat.

Absolutely not a good job refitting, the plan moving forward is to indeed make it better than the mess the original builder has done, as scott Danforth stated other options for the end grain balsa nida core or foam core what would the better option be to follow the curved contour of the bottom hull and where would i find installation info on either one of these? I have read and watched all of frisco boaters threads and planned on ply but he did not have hull replacment on his project just transom and floor. Tia

 

[snowbrd84]

My first boat was a 90s Bayliner capri which came with rotted transom. I cut open top around motor well and gutted the rot with an electric chainsaw and shop vac. Once all clean, I poured Seacast and then fiberglassed the cap back on.

It came out solid enough to hang a Blackmax 150 off of it with zero flex.

Your bigger problem. Is your stringers are probably rotted. I've redone two decks and wouldn't ever do a third. It's dirty work and fiberglass dust sucks. But if you Re going to do it, check stringers. Not much point in all the effort to put nice deck and transom over soaked rotted stringers.