Transom needs re-enforcement somehow

[souljour2000]

My new good ol' boat .... a 1971 McCurdy/Rhodes "Seafarer" 24....is indeed a good ol' boat and I'm still filled with puppy love for her..but she has one big issue ..her transom has begun to become rather "misshapen" or is visibly bulging outward in the area where the old-style motor-mount bracket (see photo) mounts to the hull... Also...the transom has way,way...(way) too much flex as a whole . There are wooden 1x3" backing plates" for the motor mount and they certainly need to be replaced with aluminum or steel extruded at very least which should help a bit. Replacing the old-style motor mount might help a bit but I think it would still not correct the "bubbled-out" area of fiberglass on the transom.... if you follow ....where the motor weight has over the years created the most dynamic loads. and created this bulge of sorts as I mentioned....I'm wondering if anyone has had any similar issues with a sailboat transom before.?..especially one of these reverse transoms?

(zoom in a bit on the transom of photo below if you can).

You can't see the deformity in the transom skin unfortunatey ...BTW there are no real structural members..the entire stern is basically a hollow shell relying on the cockpit mold to give most of the upper strength and plain old heavy roving down below...I do feel I have the skills to do the transom "repair" as long as I don't interfere with the natural flex expected of the skin that the design team factored in...I suspect adding a "sub transom "of sorts that might look alot like a bulkhead in an WWII bomber or submarine might help if added about a foot or so inward from the existing transom...I could leave a big access hole in the middle of this sub transom so i can access the backing plates and rudder gudgeon backing plates and so forth..Any thoughts?

[BATAAN]

Back in the day I watched a few of these being done when I was the "wood guy" at the local San Francisco boatyard. One whiz at it would strip the paint/gel coat from the inside of the transom and affected areas with paint remover instead of grinding for the most part. This gave a lovely fuzzed glass surface after washing and thorough drying with a heat gun that was then repaired and beefed up with glass reinforcement without the horror of the grinding prep process. As I was usually changing a thru hull or fixing a broken toilet in the same boat at the same time I really approved. Occasionally I was called on to fit a plywood laminate to the inside and once did one with a varnished lam on the outside. The secret was West system epoxies (at the time, and it still works) and good technique which means lots of fiber and as little resin as you can manage in the laminate. Forget the sub idea, fix the real problem which seems to be a wimpy transom by making it non-wimpy.

[souljour2000]

.....Sounds like a plan....if it hasn't been painted..it should just be raw 22 oz. roving there and no gelcoat...I can add layers from the inside....it'll need to be heavily sanded and cleaned..,.I have some good epoxy ..but sounds like I'll might look into vacuum-bagging this time...in any case... I could simply double up with another layer of heavy roving and tab over the corners onto the sides of the hull a good foot or so on either side and tab onto her inner bottom..thats always been a great plan in the past afterall......Thanks Bataan...I think you said it...

[BATAAN]

The trick with the paint remover preps the glass for cold lamination without the grinding.

I disagree and likeeverything BAATAN said but wud still grind a little. You are going to remove the offending rotten piece of ply and glass in another? The bulge? can you force it back where it belongs before glassing the inside? I wudn't bother with vacuum bag unless you already do this a lot -seems like a fairly awkward place to do that.

Originally Posted by mark775

I disagree and likeeverything BAATAN said but wud still grind a little. You are going to remove the offending rotten piece of ply and glass in another? The bulge? can you force it back where it belongs before glassing the inside? I wudn't bother with vacuum bag unless you already do this a lot -seems like a fairly awkward place to do that.

Concur,

you will not get a good bond without sanding.

Bagging is not wrong when easily possible there. (but might be a task)

Then I would reinforce the engine mount with a SS backup plate bedded in Sikaflex.

To the resin: it must not be any major brand, the cheapest resin will do that job very fine! But make sure you buy Epoxy! 3M sells some stuff named "Glassfiber Epoxy" which is nothing but polyester.

Regards
Richard

[souljour2000]

Thanks for the replies everyone...I looked at the "bubble" yesterday and it was much" better "ably because I had recently run a length of chain around the motor and back to a bolteye on the stern...this was to protect against theft of my 9.9 Merc but since I got the chain fairly tight I was interested to note how much it reduced the bubbling out of the transom right around the motor mount atatchemnt area....makes me think that I should still do another layer of glass and tab it well onto the sides of the stern but also make sure and get a really long set of the stainless backing plates Apex spoke in favor of...

.the wood crap that is serving as backing plates may be 70 percent of the whole problem...but there would still be a need for more stiffness in the transom evidenced by the flex that occurs when I have the tiller all the way down and lean on it a bit..makes the transom flex a bit too...so it's not just the motor ..the whole transom needs beefing up and stiffening..we'll try the added layer of heavy glass and good .long and wide SS backing plates and go from there...and see if that also helps the rudder gudgeon area to stiffen up maybe...
I appreciate the feedback from you guys..It is good to have a sounding board/echo chamber to bounce ideas and notions and such things around in...Boatdesign.net and Jeff and you guys are indispensable...