Leak Repair: GluVit, 3M5200, G/Flex650

beckoning

Petty Officer 2nd Class
Joined
Dec 15, 2010
Messages
161
I apologize for posting this here and Tinboats.net. My TinBoats post didn't show up, so I'm hoping to get answers here.

I need replies from those with experience sealing leaks in riveted aluminum 20' boat. My 20' SeaNymph Great Lakes Special sits on a hoist behind our house until I motor out 2 miles at 25mph on Lake Michigan for solo salmon fishing twice a week May-Sept. It winters on a trailer, then I haul it 1/2 mile in Spring and Fall to/from its winter home. Until late 2023, it didn't leak but 1+ qt per 5 hours. With an automatic bilge pump, I was not very aware of leaking. Fall 2023, leaks appeared (2-4 gallons/hr) after a 15 mile trailer ride, and the local marina patched some rivets, seams, and old screw holes in the transom. They used either 3M 4200 or 5200. Again, it was leak free....until Fall 2024 when ti started leaking 2-4 gallons/hr after another 15 mile trek to the marina for motor work. The marina said many bottom rivets were dripping water when they took the boat out of the water after testing the engine work. Come Spring, I need to repair the leaks. I love that boat for big water fishing (heavy aluminum, high freeboard, deep V), and I'm too old (80) to buy another boat+motor. Only a few more years of solo salmon fishing are in me. So, it's try to stop the leaks. I need to hear from those who've used Gluvit, or 3M-5200, or G/Flex650, or Loctite to repair rivet and seam leaks on a big boat that goes 25mph to deep water, then trolls for 5 hours at 2.2mph, then returns home at 25mph, frequently in 2-3' swells. Two problems: 1) Turning the 1,500lb boat over is nearly out of the question. Turning the boat over would involve emptying the 20 gallon gas tank, and removing the 100hp motor. So I need to seal leaks while laying on my back under the boat, from the outside. 2) I replaced the flooring 10 years ago. Between the floor and hull is sprayed in closed cell foam, so the rivets and seams below the waterline are only accessible from the exterior.

PS: Don't just suggest I get a bigger automatic bilge pump. That drains the battery and my kicker doesn't charge the battery, and I'm not going to idle the 100hp for 5 hrs just to keep the batteries charged.

So, which product is best for my application without turning the boat over: Gluvit, 3M 5200, G/Flex 650, or Loctite?. No fast-cure needed. Please give me your opinions based on experience.
 

briangcc

Commander
Joined
Jul 10, 2012
Messages
2,415
You are much braver than I relying on a band-aid in 2-3' chop 2 miles offshore.

IF this were my boat, I'd be tearing the floor out and re-bucking/replacing any leaky rivets. I have this thing about swimming in cold water...it ain't for me.

**If you read the mfg specs, Gluvit is NOT UV stable, it needs to be top coated to protect it. This is why its normally applied to the inside of a boat.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,313
I no longer support 3M products as even their UV stable stuff fails within a year

I agree, pull the floor, rebuck the rivets.
 
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