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Boat Leaks


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I have a 1966 16' deep v Lone Star. It has leaked since I bought it 30 years ago. Oddly enough the name on the boat is the BARELY FLOATIN. I've tried rivets, caulking and 2 part epoxy to no avail. I was thinking about using Rhino Lining like on the bed of pick-up trucks.Has anyone seen or heard of using this product to slow down the leaks.




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Do you actually know where the leak is? Could be in a hose and none of that stuff would stop a leak in a hose. First priority would be finding the leak  (or telling us where/what is leaking) and then we can better help with a repair.

Edited by FishingFool34
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1 hour ago, BARELY FLOATIN said:

The seams in the hull is where it's leaking. I've tried using a wire brush down to the bare aluminum and put JB Weld on the seams. That worked for a while.Everything I do is temporary.

 Have you tried 3M 5200? That stuff is basically permanent after you apply it.

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I own a '94 Princecraft 196 SuperPro. Over 15 years ago while the boat was on the trailer after a heavy rain I noticed water leaking near the Transom but dripping out the Keel.

I called a couple of Boat Repair Shops in London, ON to see what they would suggest using to stop the leak. Their recommendation was Sikaflex-291. I found that most Marine Sales Stores carry it $10-$15CDN for a 10oz Cartridge.

To be safe I sealed both sides of the Keel for the whole length of the boat. Here all these years later it has never leaked. A fantastic sealer for my purpose and the Price.


Sikaflex ® -291 is a 1-component marine grade polyurethane elastomeric adhesive and sealant. Used by many boat builders, its fast cure time makes it ideal for applications where speed is important.

Areas of Application:


  • General all-purpose sealant
  • May be used for light duty bonding


  • Use above and below water line
  • Resists salt water
  • Fast strength build-up
  • Stable
  • Paintable
  • Versatile packaging
  • Excellent bond
  • Fast tack-free time
  • High solids content
  • Sandable
  • May be squeezed or brushed into place
  • Excellent adhesion to gelcoat, fiberglass, metal and wood

Sika Sikaflex 291 Polyurethane Marine Sealant White is a one component, moisture curing, elastic adhesive and sealant that is used for bonding boat building materials such as fiberglass, wood, metal, and gel coat. It is fast curing, stable, high solid, NSF approved for potable water, USDA approved for food contact, and used above or below water. It is resistant to salt water, fresh water, diluted acids, limewater, and caustic solutions. It can be applied by painting, squeezing, or brushing methods. 10.3 oz Cartridge. Black or White.

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I have a 1976 starcraft that was leaking pretty bad. This past spring I completely gutted everything, floor, flotation foam etc. I sanded the entire inside of the boat to bare aluminum. I re-set a few rivets that appeard a little loose, and used some JB Weld on one that was missing a head. I used 2 coats of gluvit on all the seams and rivets on the inside. Then put all new floor etc back in. I sealed all bolts in the transom with 5200 so that wasnt suspect either. Afterwords it's great. Barely leaks. The bilge barely sucks up any water after a 6 hour trip. I moored it for a week this summer and only pumped the bilge once. Not too shabby for a '76.


Have you looked at gluvit? Checked the rivets to see if any look loose or twisted or anything? I layed for hours under my boat on the trailer going rivet by rivet. What does the transom look like as far as old bolts etc going through?

Edited by sstout
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Here's a couple pics of the prep for gluvit and then the actual gluvit on the seams. It's the yellowish looking stuff on the seams and rivets in the second pic. I took the stringers out for sanding and then re revetted them back in. Year 1 was great. We will see how long the gluvit holds for



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I have had experience with 2 aluminum boats that leaked 1 mine ,1 a friends . 


First priority was to find out where leaks was . We filled the boats with water in the driveway .  


Mine had 2 rivets ,I tightened then I  put some sealer  over them and it stopped it . 


My friends was leaking where the transom bottom.met the hull by the keel about a foot left and right . He wound up having someone weld it and it stopped . 

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Chances are if your boat has leaked for that amount of time your foam will be water logged. Does it have a hard time getting on plane? tow heavy? just feel heavy in general? That would be my first look. Because if it is waterlogged then theres no point in trying to just fix it on the outside. I would look at gutting it like @sstout I too have done 3 boats. 2 of which were water logged. Couldnt even get the boat on plane. it was sooooo heavy! After you gut it. I would take PRO FORM urethane. They use it to install windshields on vehicles. So you know its uv resistant. I would do every rivet and seam on the inside of the boat. Then create a tunnel for water to flow. with either pipe or ridged foam (not white) and then pour in foam. From the outside I have done the same. Sandblast around the seams and rivets. Be sure not to blast the glue out of the seams where the aluminum overlaps. Then again i would use the urethane. nice beads. smooth out. and paint. I think the Rhino liner is a good idea. I've thought of it. was just never in the budget. 


And most importantly! cleanliness is key!!! Make sure everything is perfectly clean before you apply any type of glue, sealer, paint ect. you can buy the best stuff on the market and it wont hold if it isnt clean 





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That's a great point. My foam was so waterlogged. Especially in the center of the boat where the water sat. And I found the suprise that the foam had been chewed by mice. Must have been from the previous owner since I know I didnt have any mice in the past years I have owned it. I left a channel under the new foam for water to flow if need be and used the pink insulation foam from home depot. Its closed cell so shouldn't soak up any water. In the end it was alot of work to gut it, but totally worth it. It's all new from the aluminum up, and should last a long long time. And I could address the leaks from both the inside and the outside.





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Thanks for the info. I do have foam board under the floor but it will not absorb the water. I've tried sealing the seams from the inside using various waterproofing products. Overtime, the water pressure from the under the boat will still find a way into the boat.Bottom line is I need to stop the water from the outside the bottom of the boat. I've tried caulk,paint and JR Weld. The water pressure from running the boat peels the material. I need some type of bottom paint is what I need.

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Nice choice. One word of advice on the gluvit: it takes two or 3 coats. When I ordered mine I didnt read that, put one coat on and figured out I had to do another couple more. Then realized I didnt have enough gluvit, so had to wait a couple days to get more. 

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3 hours ago, BARELY FLOATIN said:

I believe the jury is in: I will be using GLUVIT on the interior and Sikaflex 291 on the exterior seams and a fresh coat of paint. I goes without saying the areas will be cleaned to the metal.


Thanks everyone for your input.


Good choice using the Sikaflex 291 on your exterior seams.  You won't be disappointed and hope you get your boat leak problems solved.


Per my above Reply Post when I used it for sealing my Keel, on a fishing excursion a few years ago out of Erieau, ON my Bilge was taking a long time to pump out rainwater.  After lifting the Viny Skirt to the Transom area we find several gallons of water and taking in sum more at the top Port Side corner below the motorwell.  We were about 2 miles out of Port and headed right back to the Marina.  After tying up to the Dock with no more water coming in but still the Bilge wasn't pumping any.  After feeling around the Bilge I found a part of a lure paper packaging that was stopping most of the Bilge suction.  That problem solved.  We headed back out into the Lake but kept an eye on the water that was coming in at the Transom corner which wasn't large amounts to be concerned about.  After our day's fishing and checking out where water might be coming in you couldn't define what the problem was.  The Princecraft Super Pros have a downward angled Gunwale to the Transom. All I did was Sikaflex the whole angled Gunwale outside lip hoping to stop the leak which it did.  I imagine when the Boat was Manufactured there would of been some type of seal installed between the wide Gunwale and side of the boat and it failed.  To be safe in case the Starboard side failed I also Sikaflexed it.  No more water problems since.  


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I realize that this topic " Boat Leaks" is concerned with caulking and sealant .


However I would like to share my experience. We almost lost our boat due to aerator failure. The aerator being plastic developed a small crack which shattered over time (years) underneath the rubber piping. I suspect the pipe was over tightened at the factory and vibration from daily boat use did the rest. We just caught it in time!  You can never fully trust plastic.


Hope you all have a great New Year!

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There are many products on the market that will work but  first and foremost is preparation. Dirty metal or too smooth nothing will adhere to it and will fail over time.  If possible clan out the inside of the boar and fill it with water  go under the boat and mark every place you see water dripping out. Rivets can be tapped tighter  but that is hit or miss. I you find a seam that is leaking you will have to clean the seam with a pressure washer to remove the dirt etc. scuffing the metal with wire wheel or sand paper  then wiping with acetone will prep the surface to bond any of the above items. Cabelas sells a green stick looks like plastic you use a propane torch on the area heat it and the stick  wipe it over the rivet or crack and it will last years. There is another product on Ebay Ultrafuse Aluminum Repair 25 rods which will solder the leaks. Please keep in mind if you shortcut prep  no matter what people tell you work al will fail. 


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