I'm considering replacing my thru-hulls, seems cheap enough, has anyone replaced them before and if so, do I caulk them, what with and where? Thanks for your comment. M.C.
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Dan McGuire
Not an Expert
I have replaced several. I use a high quality silicon cauking on both sides, inside and outside of the hull, of the thru-hulls. I usually apply liberally and then let it squeeze out as I tighten them. I then wipe off the excess. What I just wrote appears simple, but it is not difficult.
I have replaced several. I use a high quality silicon cauking on both sides, inside and outside of the hull, of the thru-hulls. I usually apply liberally and then let it squeeze out as I tighten them. I then wipe off the excess. What I just wrote appears simple, but it is not difficult.
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Greg
Not an expert either...
You didn't say what kind of boat or thru-hull you presently have. If its a Catalina with their plastic thru-hulls, its very advisable to replace them. I've heard many folks say that the plastic factory thru-hulls are down right dangerous. When I replaced mine I was warned not to mix bronze thru-hulls with brass valves or fittings and vise versa, has something to do with dissimilar metal corrosion. Also, the caulk I used was Life Caulk (I think). It was what was recommended by the folks at the marina. A word of advise about the caulk, put enough on both sides of the hull like Dan recommended below, enough that it squishes out when you tighten the thru-hull but don't try to clean the excess. Let it harden and cut it off with a razor blade. Good luck! --Greg
You didn't say what kind of boat or thru-hull you presently have. If its a Catalina with their plastic thru-hulls, its very advisable to replace them. I've heard many folks say that the plastic factory thru-hulls are down right dangerous. When I replaced mine I was warned not to mix bronze thru-hulls with brass valves or fittings and vise versa, has something to do with dissimilar metal corrosion. Also, the caulk I used was Life Caulk (I think). It was what was recommended by the folks at the marina. A word of advise about the caulk, put enough on both sides of the hull like Dan recommended below, enough that it squishes out when you tighten the thru-hull but don't try to clean the excess. Let it harden and cut it off with a razor blade. Good luck! --Greg
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Tom S
Greg, that is untrue about "plastic" thru-hulls on
Catalina's. The thru-hulls, at least the ones that I know of that Catalina puts in their boats are made of Marelon and not plastic. Very different materials, Marelon® plumbing components are U.L. marine listed (MQ1151R) and exceed A.B.Y.C. (H-27) (American Boat & Yacht Council) standards. http://www.forespar.com/resources/tips/MarelonGen.htm This topic has been discussed ad nauseum, just do a search of the word "Marelon" in the archives. There are a few qualities that are superior to marine bronze, such never having to worry about the thru hull failing due to electrolysis. In fact there are many very high quality metal boats sailing the seas with marelon thru-hulls due to the concern of mixing disimilar metals. Speaking of disimilar metals, brass should NEVER be used on a boat especially below the waterline. Only use high quality marine bronze. The brass has a very high zinc level and will quickly deteriorate and fail in a marine environment. As for caulking I use 3M 4200. Its pretty tenacious stuff, but not as much so as 5200. I have heard of other people even using 5200 because they don't want that thru-hull seal ever failing. I figure that thru hull I installed will be there the life of the boat anyway, so I shouldn't have to replace it and I have heard of people able to remove a thru-hull even after sealing it with 5200. Just took a bit of work, thats all.
Catalina's. The thru-hulls, at least the ones that I know of that Catalina puts in their boats are made of Marelon and not plastic. Very different materials, Marelon® plumbing components are U.L. marine listed (MQ1151R) and exceed A.B.Y.C. (H-27) (American Boat & Yacht Council) standards. http://www.forespar.com/resources/tips/MarelonGen.htm This topic has been discussed ad nauseum, just do a search of the word "Marelon" in the archives. There are a few qualities that are superior to marine bronze, such never having to worry about the thru hull failing due to electrolysis. In fact there are many very high quality metal boats sailing the seas with marelon thru-hulls due to the concern of mixing disimilar metals. Speaking of disimilar metals, brass should NEVER be used on a boat especially below the waterline. Only use high quality marine bronze. The brass has a very high zinc level and will quickly deteriorate and fail in a marine environment. As for caulking I use 3M 4200. Its pretty tenacious stuff, but not as much so as 5200. I have heard of other people even using 5200 because they don't want that thru-hull seal ever failing. I figure that thru hull I installed will be there the life of the boat anyway, so I shouldn't have to replace it and I have heard of people able to remove a thru-hull even after sealing it with 5200. Just took a bit of work, thats all.
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VIEXILE
Marelon is fine, but I use 5200
This is one of the applications (if below the waterline) where 5200 is appropriate. I have installed bronze throughout with Groco ball valves mounted on West Systemed plywood plates (inside). I took out a couple that I'd 5200'd in 10 years ago. To take out the old bronze, rather than hammering form inside, I cut four slices in the outside flange and chisled back the ears until I could tap the thing out. The old 5200 takes a little gelcoat and glass with it, so I grind out a little around the hold, add 1.5 oz mat where necessary and (all with West System) fair with west system and what . . . hmm . . . 406 filler? back to the original shape. Sometimes this isn't necessary. I don't think there's anything wrong with Marelon through hulls, but the plastic ones can break off from impact and they do get sold in boat stores. The old bronze through hulls were amazingly brittle and I was glad I took the time to replace all. Instead of drilling through the baseplate of the ball valve and installing bolts, adding more holes to the hull, my recent installations were done with a large amount of 5200 on the inside behind the backing plates on the hull. No inadvertent rotation there. That'll last 15 years, and I can remove the valves if I need to.
This is one of the applications (if below the waterline) where 5200 is appropriate. I have installed bronze throughout with Groco ball valves mounted on West Systemed plywood plates (inside). I took out a couple that I'd 5200'd in 10 years ago. To take out the old bronze, rather than hammering form inside, I cut four slices in the outside flange and chisled back the ears until I could tap the thing out. The old 5200 takes a little gelcoat and glass with it, so I grind out a little around the hold, add 1.5 oz mat where necessary and (all with West System) fair with west system and what . . . hmm . . . 406 filler? back to the original shape. Sometimes this isn't necessary. I don't think there's anything wrong with Marelon through hulls, but the plastic ones can break off from impact and they do get sold in boat stores. The old bronze through hulls were amazingly brittle and I was glad I took the time to replace all. Instead of drilling through the baseplate of the ball valve and installing bolts, adding more holes to the hull, my recent installations were done with a large amount of 5200 on the inside behind the backing plates on the hull. No inadvertent rotation there. That'll last 15 years, and I can remove the valves if I need to.
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Greg
Marelon thru-hulls
I know that my valves are marelon but I thought the thru-hulls were plastic. The valves are black, the thru-hulls are white. Even saw a post here referring to the thru-hulls as "volcanos" as the fiberglass on the inside on the hull around the thru-hull is built up and resembles a volcano. Whatever the thru-hulls were made of, I didn't like it because when I would actuate the valves I could actually see the threaded portion of the thru-hull flex under the force of turning the valve handle. The link below was from the forum a few years ago. The first reply gives great instructions for replacing these thru-hulls.
I know that my valves are marelon but I thought the thru-hulls were plastic. The valves are black, the thru-hulls are white. Even saw a post here referring to the thru-hulls as "volcanos" as the fiberglass on the inside on the hull around the thru-hull is built up and resembles a volcano. Whatever the thru-hulls were made of, I didn't like it because when I would actuate the valves I could actually see the threaded portion of the thru-hull flex under the force of turning the valve handle. The link below was from the forum a few years ago. The first reply gives great instructions for replacing these thru-hulls.
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Tom S
Ya know Greg I can't be 100% sure
I would call Catalina and ask them directly. Either way you are correct, I'm not sure I'd want a Volcano Thru-hull either. I would prefer proper thru hulls and seacocks. I know thats what Catalina does now. What year is your boat?
I would call Catalina and ask them directly. Either way you are correct, I'm not sure I'd want a Volcano Thru-hull either. I would prefer proper thru hulls and seacocks. I know thats what Catalina does now. What year is your boat?
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Greg
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Tom S
That makes more sense
I do recall hearing that 20 years ago they did glass in thru-hulls on some boats. I would call to see if they are Marelon. Its very **scary** to think they they might be regular plastic !!
I do recall hearing that 20 years ago they did glass in thru-hulls on some boats. I would call to see if they are Marelon. Its very **scary** to think they they might be regular plastic !!
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