I'm intimidated by this transom project...

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pmshoemaker

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This transom is sandwiched between the outer hull and an aluminum front piece that covers t the face of it, stopping short about 3" from the floor. It looks like I'll have to take the aluminum front piece off to get to where the old wood was and replace it -- it's completely rotted away. I'll also have to pull out the transom support, obviously.

I am great at tearing things apart -- it's the reconstruction that is scaring me. Those are massive rivets. Here's my question -- do I try to find massive rivets to replace those with? Or can I just replace them with bolts, washers and nuts? The latter seems to be the best
 

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in my world, I rarely put back the original hardware that is beyond
my capabilities and move on to the much simpler items that will
serve the same purpose with less hassle.
I would drill out the large fasteners and replace with stainless carriage bolts,
fender washers and nuts and seal with some 3M-5200 sealant.
cleaning out the cavity of any contamination and corrosion and
fabricating the new transom panel is another project in itself.

Try not to break anything during the "tearing out" process.
to have a replacement part custom made could be expensive.



.
 
Great advice, Johnny -- I'm sure I will fire off about a hundred more questions once the old rivets are out and we get to see the treasure that lies inside...
 
Johnny, you are a psychic! I was just about to ask "how do you resolve the issue with the square shank on a carriage bolt" lol
 
I forgot to note that you can also grind off the square shoulder with
an angle grinder . . . if you only have a few to do, you can grind off
the shoulder of 6 bolts quicker than you can go to the store and back.
[just don't grind below the thread level or you could compromise the strength].
Modified Carriage.jpg



.
 
There is another option to the truss head bolts and that is button head cap screws. They have a hex in the top to grab with an Allen key. Similar to a socket head cap screw but with a dome head.
https://www.fastenal.com/products/details/1173752?r=~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600039%20Sockets%22%7C~%20~%7Ccategoryl3:%22600043%20Button%20Socket%20Cap%20Screws%22%7C~%20~%7Csattr03:%5E%22Stainless%20Steel%22$%7C~
73712.jpg



Can also use a nylon locking nut;
https://www.fastenal.com/products/details/1170860?term=Nylon+lock+nut

70866.jpg
 
Is there any concern with torque when I put these in? Or do I just crank the living daylights out of them till I can't crank no more?

Started chiseling rivets last night -- got the first 8 out. This is going to be a marathon -- not a sprint. Enjoy the work though -- even if the project turns out not to float, it's fun busting my knuckles with a hammer like the old days.
 
Also, Johnny, I have been studying your transom build tutorial -- which is awesome by the way -- and I wanted to get your thoughts on the glue vs. the fiberglass/resin method. Do you compromise if you choose the glue method? To me it looks much simpler and much cheaper, but I don't want to compromise the strength/integrity of the new transom. I only want to do this once.
 
TiteBond III Ultimate is touted to be waterPROOF.
most certainly you can use glue instead of eboxy resin and cloth.
the only reason I went with the reinforced transom panel is that
I want zero flex in the transom with a 35hp motor.
and - will probably last the life of the boat.
I would not suggest Gorilla Urethane Expanding Glue unless you
have some experience with the way it behaves while curing on large projects.

with any adhesive you choose, don't use clamps around the edges alone
or you will force all the adhesive into the center of the two panels which
may not cure completely - thus causing some issues down the stream.

make the panel oversized and cut to fit after it is all cured.
spread the adhesive evenly on both surfaces with a 1/16" V-toothed trowel.
put a couple of screws on each side just to hold it in place until you get it
on the floor and a few hundred pounds of weight on it - then remove the screws.
let cure undisturbed for a minimum of 24 hours.

as far as the torque of the fasteners - there is no reason to over tighten any of the transom bolts.
"one grunt" is tight enough. there are torque specifications for all types of metal fasteners.



.
 
You'd be still best advised to put thick nylon washers under the heads & nuts of any SS fastener to be applied to the aluminum boat. If for use in saltwater, I take the extra precaution of greasing the body of the bolts with a waterproof marine grease, then sealing the body in adhesive-lined heatshrink. My SS bolts on the tin boats I've personally rebuilt. Oh, and the tin does too! As whereas the SS is the more noble metal, otherwise the aluminum will corrode first by releasing its ions and giving them up to the SS.
 
All great stuff guys -- thanks so much! This boat will primarily be electric powered front and back, so the wood glue option might be enough -- not looking to put a behemoth motor on the transom any time soon. There is an outside chance it could see the Chesapeake one day far into the future, so I may look into saltwater-proofing it.
 
pmshoemaker said:
This boat will primarily be electric powered front and back, so the wood glue option might be enough -- not looking to put a behemoth motor on the transom any time soon.
Maybe ... but it could help the future sale of it!
 
I have breached the transom cover!! There were 42 rivets in all holding the transom "sandwich" in place -- when I finally busted off the last rivet this afternoon I was able to remove the cover on the inside and alas, the wooden transom was completely gone!! If you look at the photo that shows me peeling back the cover, you'll see a little scrap that is all that is left of the original wood at the top left-hand corner -- it's about 8" tall and 3-4" wide -- that's it! The rest is totally gone (you can see it's just a little pile of wood pulp that fell out. The good news is that the outer skin of the hull looks pretty good -- just gross. I don't see any signs of corrosion (yet). Looks like it's time to clean down the inside of the hull and build me a transom! Should I put a wire wheel to it? Or just elbow grease and sandpaper/orbital sander? And should I paint the inside of the hull before I put the new transom in?
 

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Yes, I'd wheel or sand, then wash with white vinegar on a scrubbie pad and would paint it with a zinc-chromate primer before sealing back up again.

If you intend to re-rivet it back together, I have a huge stash of 1/2" and 1-1/4" rivets (3/16" diameter) I can send you in the quantities you need.
 
Man that is SUPER generous of you Dale, but I think I am going to put it back together with nuts, washers and bolts -- I am much more confident in my ability to turn a wrench than I am with rivets that big. Will probably follow your earlier advice with the marine grease and the shrink wrap just in case I get this into some brackish or salt water down on the bay one day.
 

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