Repair two small holes from old transducer

[Lukey27]

Hi guys,

First time posting here. I recently acquired an old 14' Alumacraft from my father-in-law. It needs a lot of work but I have all fall/winter to get it ready for spring walleyes. I removed the old transducer from a previous fish locator by drilling through the rivets. It popped out easy but now I have two holes and it's only the thickness of the boat. I've been reading and want your opinion if I have the right stuff or not. JB Weld Steelstik (Steel reinforced epoxy putty)???? I want something I can smooth out because I would like to refinish/paint the exterior in the coming months. Is this the right stuff? Is there something better? Someone at a store (won't mention what store) said to put bolts through them with marine goop and a rubber washer. I thought about it but that won't make it flush looking, it might be a temp fix but I want a permanent fix.

I'll be curious what you guys recommend.

Thanks,
Lukey27

 

[borntofish]

I followed the advice here on the forum and used SS screws, washers and nylon locknuts. I sealed around the holes first with 3M 5200 Marine sealant. Once cured, this stuff is tough. I think you could paint it. I didn't so I don't know for sure. No leaks at all.

 

[lckstckn2smknbrls]

If the holes are below the waterline I would install new rivets sealed with 3M5200.

 

[bobberboy]

This was recommended to me by a welding shop specifically to do what you're trying to do. It sands well and seems very durable. I have used it both above and below the waterline on my current project. One important thing to note, my current project, although four years in the making, has yet to be on the water... I have only used it on a few minor holes such as you're dealing with below the water line. I have used it to fill about four dozen holes above from pinholes to 1/4" holes. I am so far down the road with the stuff that I can only hope my confidence proves correct! I very carefully prepared all the holes before filling. I made sure there was nothing in the hole but the hole - no silicone from past attempts, no gunk of any kind. If you use it let me know before I head to the boat ramp! :mrgreen:

 

[El_Guapo]

You could take it to a shop and have them weld the holes up, or get some smallish pieces of aluminum flat strap and braze them on (from the backside) yourself, then just finish up the exterior with body filler. The Bernzomatic aluminum rods that Home Depot and Lowe's sell are really easy to use with a typical propane torch and make a strong, long lasting repair.

The Steelstik will work, but you'll have to leave a lump on either side.

 

[Lukey27]

Wow! awesome advice guys - Thank you! I think I'm going to try the rivets with sealant. The guy at the store gave me Marine goop?? Will that work the same as 3M5200??? Seems like the easiest, most waterproof plan. Plus later when I remove all the interior of my boat I'm going to use 1/16'' aluminum angled rods for the framing to keep the weight down & use the rivets there too.

 

[lckstckn2smknbrls]

Lukey27 » Sat Jul 26, 2014 6:40 am[/url]"]Wow! awesome advice guys - Thank you! I think I'm going to try the rivets with sealant. The guy at the store gave me Marine goop?? Will that work the same as 3M5200??? Seems like the easiest, most waterproof plan. Plus later when I remove all the interior of my boat I'm going to use 1/16'' aluminum angled rods for the framing to keep the weight down & use the rivets there too.

If it's silicone based you don't want too use it. You can get 3M5200 at Home depot.

 

[onthewater102]

Aluminum isn't the easiest of materials to match to adhesives. I uses a marine epoxy which was designed to be used on aluminum to seal around where my transducer shaft passes through the bottom of the hull - but when using an agent be sure to sand off any paint in the area so the sealant can contact the aluminum directly.

 

[El_Guapo]

Loctite sells a Fixmaster putty that is specifically for aluminum. It is expensive as hell (something like $70 for a 1 pound kit), but is about as close to building up with aluminum rod as you can get, without fear of warping. We've built up aluminum parts with this stuff and remachined them with 100% success.

 

[fishjunky]

In a hurry and planning on it being temporary, I used the three holes from the old transducer and screwed thru the hull into a block of pvc trim sealed with Goop. I then screwed my transducer into the PVC. It's been a few months and still fine. This should get you by for a while if you want to get on the water asap.

 

[Timtactical]

I goob the holes up with silicone and set a new rivet in place on my boat. I then later drilled out one of the rivets and installed a plastic transducer plate in the same location so I can safely mount a transducer without fear of leaks.

 

[onthewater102]

over time silicone separates from aluminum

 

[Timtactical]

How does it work if it is sandwiched under a rivet like a gasket? It is used around all kinds of petroleum products. I just figure if it seals a rear end diff cover, or an intake manifold it would seal a rivet.

 

[El_Guapo]

Timtactical » 28 Jul 2014, 14:56[/url]"]How does it work if it is sandwiched under a rivet like a gasket? It is used around all kinds of petroleum products. I just figure if it seals a rear end diff cover, or an intake manifold it would seal a rivet.

There are silicones that work well with aluminum, but most don't work so well. A polyurethane based sealant like the 3M 5200 is going to offer superior adhesion in the long run.

One of the problems with silicone is that aluminum is such a reactive metal that the chemical released by most RTV silicones (acetic acid) causes almost instantaneous oxidation on the surface. The oxidation layer is going to break free from the parent metal over time, and your leak is right back.

 

[onthewater102]

El_Guapo » 28 Jul 2014, 19:29[/url]"]

Timtactical » 28 Jul 2014, 14:56[/url]"]How does it work if it is sandwiched under a rivet like a gasket? It is used around all kinds of petroleum products. I just figure if it seals a rear end diff cover, or an intake manifold it would seal a rivet.

...One of the problems with silicone is that aluminum is such a reactive metal that the chemical released by most RTV silicones (acetic acid) causes almost instantaneous oxidation on the surface. The oxidation layer is going to break free from the parent metal over time, and your leak is right back.

+1

It would actually work better if you made a gasket out of it by spreading it like icing on a cake, let it set, then sandwich it with a rivet.

 

[onthewater102]

5200 is recommended to be installed on metals using a primer first. 3M's material specifications recommend:

Scotch-WeldTM Structural Adhesive Primer EC-
1945 B/A

https://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSufSevTsZxtU48_eoYtvevUqevTSevTSevTSeSSSSSS--

This is why I stick with epoxy based adhesives when making repairs.

 

[Timtactical]

good info, thanks guys.

 

[Robert Hunt]

My son and his buddy put 2 holes through bottom of their aluminum boat with hatchet chopping out ice 4 years ago . They sealed it up with JB Weld. Both holes were about two inch long they dollied metal flat the ran zip cut disc up slit to permit weld to bond to both sides . Still holding fine

 

[onthewater102]

JB weld is epoxy - good stuff - it's only problem on aluminum is that it's rigid, while the aluminum isn't, but if they had a generous enough amount on there it's not going anywhere.