Older jon boat repair questions... From a newbie

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FLguy81

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I've recently acquired a 1976 Lowe Line 14 foot jon boat. Now I'm trying to figure out exactly what I've gotten myself into. The boat has been sort of fixed and repaired over the years and I'd like to make sure it's done right, even of it means removing old fixes and reworking it.

Many of the rivets in the bottom have some sort of sealant gooped over them and there are a few small tears or holes in the bottom that have been somewhat fixed. The interesting part about those boat is that the stringers, I think that's the proper word, are made of fiberglass and not aluminum. Is that normal for this age of boat? Will it affect how the rivets are sealed or replaced? One of these stringers is cracked right in the center of the boat, I'm not sure how to fix that one yet.

The other oddity is that some previous owner redid the transom and it seems to be made of 1/2 inch thick polyethylene that's been bolted together sandwiching the aluminum transom. With an additional layer of it where the motor mounts. It seems quite solid so far.

So I wanted to see what you guys think, any suggestions as well are always appreciated. Thank you!
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The white stuff on the bottom os more than likely 3m 5200 sealant. Once cured the stuff is pretty serious. Alot of people use it to fix leaking rivets, small pin holes, etc. What you have "gotten yourself into" is a project, and from the pictures it looks like its gonna' be a fun one. Lol. Ive been around boats and bodies of water my whole life and ive never personally seen an aluminum jon with fiberglass bracing like that. With that said, what are your plans for this thing? Did you buy it? If i were you, what i would do is put on your pfd, put it in the water somewhere in a calm spot, take an oar and float around for a little bit in the shallows. Assess the situation. If its full of "springers", get it off the water. If you have a couple of slow leaks, take a wax marker and try to mark them. Once you assess the true condition of the hull, you can go from there. Are you sure its a Lowe brand boat?
 
The plans are to fix it up as best I can and take my kid fishing on it hehe. The bracing is definitely fiberglass, i even sanded it down on the crack to make sure. It has a Lowe Line emblem on the side next to the transom.

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Take a picture of the emblem and post it. I'd be interested to know if it is a lowe boat. Do you have a motor for it? If so what size is it? Is it a flat bottom or a mod v?
 
I've got an 8hp mercury 4-stroke. It's an interestingly hull shape. Almost all of it is flat except the first few feet of bow which is v shaped.

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Thats a mod v. Thats a good thing. What kind of rivets are securing the braces in the floor? Are they bucked rivets, or are they pop rivets? Bucked will be smooth on the head and pop will have a hole in the middle of the head.
 
Actually upon further review of your pictures it looks like you have a v bottom, but its hard to tell
 
https://www.tinboats.net/forum/viewtopic.php?f=21&t=34018&start=30 looks like they exist 8)
 
That's the one! I'll take more pics soon. I like what they gentleman did with his but I don't think I'll get that extreme. First check for leaks then look into repairing the one brace that's cracked right in the middle. There's also a section on the bottom right in the center, just after the bow transitions to the flat bottom where it looks like the hull scraped hard and there possibly a gash in it. The previous owner filled that section on the inside with sealant and what looks like that flex seal stuff sprayed on the outside.


Kingbryce said:
https://www.tinboats.net/forum/viewtopic.php?f=21&t=34018&start=30 looks like they exist 8)


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I don't have a marine repair background so there may be better ways but I would repair the the ribs (usually ribs give shape and stringers tie the skin and ribs together) using a fiberglass and epoxy overlay repair. I would extend the length of the repair six to eight inches on both sides of the crack. You could vacuum bag the layup but it probably wouldn't be required. Use enough layers of fiberglass to give equal or greater thickness of the rib.
You would have to drill the rivets out and re-drill and drive new rivets after the repair cured. If any rivet holes are larger than the rivet diameter you may have to move up to the next size diameter rivet. I would drive all rivets wet with sealant.

There are sealed pop style rivets that could be used instead of solid rivets, they are aircraft rivets and are a little expensive. I have joined fiberglass bonded to aluminum by putting the rivet head on the aluminum side and putting​ a small washer over the rivet shank before pulling or driving the rivet. This gives a wider grip surface on the bucked side of the rivet and prevents the rivet from tearing into the fiberglass.

Cracks in fiberglass can be repaired with a fiberglass/epoxy doubler and cracks in aluminum can be repaired with a riveted aluminum doubler with sealant between the two pieces.

You can restore structural soundness with these type of repairs but someone may have experience with a different method that you would prefer.
 
Are you saying those cross bracing ribs are made out of fiberglass? I wonder why they would do that, doesn't sound very cost effective to me for an aluminum boat manufacturer.
 
surfman said:
Are you saying those cross bracing ribs are made out of fiberglass? I wonder why they would do that, doesn't sound very cost effective to me for an aluminum boat manufacturer.
I know right? It's definitely fiberglass. The crack in the middle made suspicious so I took a dremel with a sanding bit to it and exposed the fibers. My first reaction was whhhyyy?? And then how do I fix this. I think it'll be like the previous guy mentioned just reinforce the hell out of it with more fiberglass on top.
 

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