Thru Hull Replacement

[Stormer]

Hello All -

This may be a really stupid question - so please indulge me if it is...

I want to replace some thru hulls. I''ve read some articles, posts, etc. and the best thing to do in my particular situation is to use a dremmel with a cutting tool.

Exactly where I try to cut will depend on the size of the thru hull. If it is a large thru hull, I plan to stick the tool up inside from outside the hull and cut the lip off. If the thru hull is too small, I''ll try and cut the lip from the outside somehow, being careful not to do too much of a number on the hull underneith the protruding thru hull lip.

There are posts that seem to suggest this approach is appropriate.

Questions:

1. Any opinion on this approach in general?

2. Regardless of approach, after seacocks, nuts, etc., have been cut away and you are left with only the thu hull, how do you pry it out, keeping in mind that there is old 5200 type sealent still holding the thru hull in place?

Thanks in advance for your replies.

[e31]

I replaced all of my seacocks and thruhull last fall on my 1979 Ericesion 31I. The old thruhulls were clamped with the thruhull nut, and the seacocks were old "swing gate" styles. When I turned the wrench on the seacock, the thruhulls spun in place.

You may find that your thruhulls do the same. I had no need to cut up the old one, but torque seemed to break the old sealant up easily. For the thruhulls that didn''t spin on seacock removal, I would remove the seacock and thruhull nut, the ups a flat bar on the internal tangs to spin the fitting. After they spun, they were easy to push out of the hull.

Doug

[VIEXILE]

I''ve probably done 20+ through hulls this year on various boats. Large plumber''s wrench inside, small wrecking bar outside (2-person job). Heat can be applied to the valve assembly flange inside if necessary. There are ears inside the exterior portion of the through hull. Once apart, take a small cold chisle and cut four notches on the lip of the through hull. From there, the bronze bends back pretty easy. No matter what you do, you''ll need to clean up around the hole, sand or grind and level it with thickened West System. On valves that wouldn''t budge, and, actually, on the last few I did just because it''s quick and easy, I just did the cold chisle thing, knocked back the flange and drove the whole assembly inward. I can now do one in minutes that way, but if you want to re-use the valve, you still have to get things apart. There''s a touch to not damaging the surrounding glass. KW

[Stormer]

4 notches around the opening on the outside on the lip? Then just pry the lip outward (not leveraging on the fiberglass) till I can knock the whole assembly inward? What about the sealant? When you pry does the sealant pretty much come undone? Thx.

Matt

[VIEXILE]

There''s usually no need to "pry" against the hull. 4 opposed notches on exterior flange (or more) and you''ll find the bronze pretty cooperative when you try to knock it in toward the center. 3M5200 may take some laminate with it - or at least gelcoat - which is unavoidable even if you could unscrew the assembly on the inside. If it''s spinning anyway, then no problem. Try to avoid prying and crushing the laminate. I started by unscrewing and trying to pound these things out years ago. By notching with a cold chisel, I can get some of them out in under a minute. Just did half a dozen on my sailboat. A few required some minor repairs with West System before new thru hulls and valves (and a transducer) were installed. Measure twice, cut once, and just sit and stare at things for a few minutes before you start whacking with a hammer. Toasted my stern tube and had to rebuild due to too much aggression when trying to knock out an old cutless bearing. KW