Installation of Thru Hull Fitting
TonyG13
Member Posts: 1,335 ✭✭✭✭
After re-using an existing hole for my new bilge pump installation, I needed another hole for my cockpit sink drain. Here is my step-by-step process for an above-the-waterline thru-hull fitting...
1. Mark new hole location at least 4" on-center from any other nearby hole - and paying attention to make sure there are no obstructions inside of hull to prevent access.
2. Cut hole.
3. De-burr and clean up hole and test fit the fitting.
4. Tape fitting in place. I use a contrasting color tape.
5. Score through both layers of tape with razor knife.
6. Remove fitting and layers of tape that were previously scored, leaving an area for caulk to adhere. Scuff up this area with some sandpaper then wipe clean.
7. Apply caulk or butyl tape to the underside of the fitting. I chose clear caulk.
8. Insert fitting into hole until caulk begins to squeeze out and then cover with tape to hold in place.
9. Go inside boat and install backing nut and tighten. Some fittings come with a rubber gasket. Some do not. If using a gasket I don't think it 100% necessary to caulk inside since it's a mechanical fitting above the waterline - and it makes it much easier to change/maintain if needed. But if you feel like caulking inside, go for it. I would not use 3M 5200 or any permanent adhesive. Always use something that can be removed.
10. Back outside, remove top layer of tape and wipe caulk off surrounding area.
11. If everything looks good, carefully remove all the other tape and you should have a nice clean, mess-free installation.
12. Attach your hose to the fitting and you're done!
1. Mark new hole location at least 4" on-center from any other nearby hole - and paying attention to make sure there are no obstructions inside of hull to prevent access.
2. Cut hole.
3. De-burr and clean up hole and test fit the fitting.
4. Tape fitting in place. I use a contrasting color tape.
5. Score through both layers of tape with razor knife.
6. Remove fitting and layers of tape that were previously scored, leaving an area for caulk to adhere. Scuff up this area with some sandpaper then wipe clean.
7. Apply caulk or butyl tape to the underside of the fitting. I chose clear caulk.
8. Insert fitting into hole until caulk begins to squeeze out and then cover with tape to hold in place.
9. Go inside boat and install backing nut and tighten. Some fittings come with a rubber gasket. Some do not. If using a gasket I don't think it 100% necessary to caulk inside since it's a mechanical fitting above the waterline - and it makes it much easier to change/maintain if needed. But if you feel like caulking inside, go for it. I would not use 3M 5200 or any permanent adhesive. Always use something that can be removed.
10. Back outside, remove top layer of tape and wipe caulk off surrounding area.
11. If everything looks good, carefully remove all the other tape and you should have a nice clean, mess-free installation.
12. Attach your hose to the fitting and you're done!
Comments
I prefer to change out those factory installed sink drain hoses. Always seems quality is lacking from factory. Had one dry out & split when it got bumped.