Thru hull replacement

[dnimigon]

I'm soon going to be pulling our 79 Catalina 30 out for some major refitting. One item is to replace all the thru hulls that are mostly original with the new Marleon type. Question is what is the best method for sealing these to the hull. I realize to have a good ply backing inside but what type of caulking sealant should I use. Do these Marleon thru hulls need to be glassed in on the exterior to prevent leakage or will the sealant suffice. Don't want to have issues once back in the water.

[dohenyboy]

Forespar recommends 5200, Sikaflex or Boatlife. I used Boatlife and all was well.


Sent from an undisclosed location on the high seas or from the lounge chair by the pool, you decide.

[Dave852]

I used 5200 on the exterior, heavy duty Teflon tape of the threads. I used G4 backing plates epoxied to the hull. Buy carbide tipped hole saw blades for the G4, (hard stuff).


Sent from my iPhone using Cruisers Sailing Forum

[deblen]

Suggest chamfering the hole a bit,on the outside.It allows the sealant to form an "o-ring" around stem of thru-hull.

[Cheechako]

Be sure to buy the Marelon type that don't have the "handles break off issue"... type 93...?
Is your Catalina gate valves?

[DeepFrz]

If you use plywood backing plates make sure you build in epoxy annulus (s) so the bolts don't compress the plywood over time.

[dnimigon]

The cat now has Bronze ball valves but they are corroding up. Still work but thought if the boats coming out I'll change them all. Was going to use epoxied ply plates on the inside. also was going to chamfer the holes slightly. Just needed to know thoughts on best sealant. It seems the 5200 is the route. Problem may be getting it on a plane. We live in alberta. Boat is in Mexico PVR. Had issues before trying to take some PL Premium through the checked baggage. Customs didn't like it too much till I explained what it was. 5200 may be the same.

[delmarrey]

Originally Posted by dnimigon

The cat now has Bronze ball valves but they are corroding up. Still work but thought if the boats coming out I'll change them all.

You do have to remember to keep thru hulls lubricated/greased, even the Marelon types.

[kentobin]

Load Testing A 3/4" Marelon Ball Valve & Thru-Hull Fitting courtesy of Compass Marine Inc.

https://www.youtube.com/watch?v=l5ajZ3nfzzQ