Question on sealants

Hey guys,

Had a fishing trip cut a day short last week when my livewell pump cracked off of the intake tube and water came pouring in. This all happened at the dock, and I didn’t find out until a few hours had passed and I was going out for some evening walleye, and noticed a lovely 2 ft of water in my boat. Everything got soaked, but luckily no lasting damage.

After I bailed it out and plugged the leak, I took it out of the water and then had to head back home the next day where I took the whole pump assembly out (minus the hose) and picked up a new pump.

Question for y’all who’ve been doing this kinda stuff longer than me; what’s the best kind of sealant to use around the intake tube? I was going back and forth between marine expoxy and marine silicone sealant, but I’m just not sure which one would be better/more durable/longer lasting.

Thanks in advance for any advice, fellas.

Did mine with marine silicone earlier this summer. Seems to work fine. Would think the epoxy might get pretty hard and tough to work with/remove if needed in the future.

Nate, it sounds like you should also think about adding an auto bilge pump to you set up, very lucky it wasn’t worse. For sealing, the 3M marine sealants are an excellent product.

FYI, since this has also happened to me, I’ll share what I learned. If one has the room, a marlon valve should be installed between the intake point and the pump so that in the event the pump fails, water can be shut off from flooding the boat.

Goop brand, marine or sportsman. It sticks really well and stays pliable for years. I use that shiat on everything. It holds the transducer wires to the transom, the break line to the trailer frame. I wish it came in caulking tubes instead of just the smaller tubes.

Do NOT use epoxy! That could make an future repair of the through-hull fitting almost impossible. The rigidity of epoxy could also cause cracking because it cannot flex. Use silicone.

Also, your situation is exactly why I repeat the advice to always use stainless steel hose clamps for all marine applications and ALWAYS double clamp (meaning use two clamps) on each side of all below-waterline fittings.

Honestly, the things I’ve seen used to “clamp” below waterline fittings, it’s surprising that we don’t see boats sinking all the time. Cheap pot metal automotive hose clamps, or my recent favorite, zip ties. A fantastic way to sink your boat.

Grouse

Grouse, I think Nate’s problem was the pump plastic got brittle and cracked. Look for marlon through hull fittings and ball valve, they don’t get brittle like PVC.

I would use an RTV silicon from Permatex… Used to make gaskets, has a strong bond but remains waterproof and flexible. Can be found in the hardware section of any auto store.

SuperDave1959 wrote:

Grouse, I think Nate’s problem was the pump plastic got brittle and cracked. Look for marlon through hull fittings and ball valve, they don’t get brittle like PVC.

Yes, I understand and you’re right. My suggestion for double clamping is just a belt and suspenders approach. My point is that you can’t be too careful with below waterline connections and if a hose clamp rusts and breaks off, you have a real situation on your hands.

Grouse

Goop is the best. Silicone works fine but isn’t as tough/strong. The 3M marine adhesives (5200 or 4200) are generally too strong for anything that might possibly have to be removed from the boat; you have to chip/sand them off to remove and replace the part. My $0.02.

Just note some silicones are rated for above the waterline and some for below the waterline. Meaning the can be used underwater 100% of the time instead of intermittent exposure. Go with the below the waterline rated stuff.

Hey thanks so much for all the input, guys…I really appreciate it! The valve sounds like a good idea, as well as the quality below-water silicone.

I also get to put a new alternator in the truck before I get to go fishin this weekend! The alternator went out on my way home from the lake last weekend and I drained my battery – so I threw the boat battery in and JUST made it into the driveway at home (bout an hour away). When it rains, it pours, right?

Thanks again guys

Boat’s fixed, truck’s fixed! She’s watertight again with the new pump – got er all sealed up well. Couldn’t get any fish to bite yesterday morning when I went out though. Thanks again fellas!

silicone sealants do not perform well when submerged in water . I would use a sealant called Vulkem 116. This is often used in pools and other wet areas.

Dalton Keep wrote:

silicone sealants do not perform well when submerged in water.

Not that I am calling you a liar, but silicone is used in aquarium construction, so I have a hard time believing the statement that it does not perform well when submerged in water.