Replacing the Thru Hull Valve

[Mark Nooney]

I own a 1984 H31. All the valves on the thru hulls are original equipment. I never have been able to confirm they are all the way closed or open. I would like to change these to the handle ball valve type. My question is has anyone changed the valve without removing the thru hull? Is it better to remove the entire assembly and use all new parts? Any idea what this job would cost for 3 valve and thru hull replacements in the Chesapeake sailing area?

 

[seadaddler]

Depends

How do they look and are they working OK and open and close them often is the best this way you making them move and not letting stick open or closed.
you could take the hose off when closed and see if they are leaking or sealing good,do you take the boat out for your winter or not and if so that would be the best time to service or replace,if everything is looking good and no bad condition just lube every year or could change just the value if the thru hull is in good shape but some may change everything depending what condition they are in.
Nick

 

[Steve Dion]

I would replace the thru hull and the backing plates too if you are going to this expense.

Mainesail has some info on his website on doing this process.

 

[Sanfelice]

Sounds as though you have gate valves which were common on your vintage of boat. They should be replaced with marine ball valves. The ones made out of marelon are cheaper than bronze ones but some people don't like them. Do not use the brass ones found in hardware stores since there is a difference in threads than those intended for use in a marine environment. The thru hulls will need to be reseated at best, if not replaced. Marelon ones will work but again, many prefer bronze. When removing the old valves you may break the seal between the hull and thru hull. Cost wise I would figure about 1 hour of labor per valve. Two people should be able to replace a valve and thru hull in a 1/2 hour. You can price the cost of valves and thru hulls from a West Marine catalogue and add some to it for boat yard pricing. Also the cost of pulling the boat if it is being pulled for this purpose itself. In reality this is an easy DYI job if you have the time.

 

[Mike Culik]

Hi Mark, I replaced all the OEM thru hulls and valves below the water line (4) on my H31 just a year ago. Why? The galley gate valve knob stem was corroded off and the valve was in a questionable position. (After getting this assembly out and looking at it, of course it was OPEN!)
Also the engine cooling thru hull had a marelon valve threaded to it and I didn’t trust it.

I started my project with the galley and found it impossible to remove the valve from the thru hull. The easiest way for me to replace these was to carefully grind off the thru hull outer flare (the boat was on the hard) and pull the thru hull/valve assemblies out from inside the hull.

I used all new parts (Groco or Conbraco) from West, Defender or your marina. Your two choices are a thru hull and seacock or thru hull, flange and ball valve for a proper no worry job.

In retrospect, I should have removed the Head discharge valve and glassed over the hole because you can’t “dump” in the Chesapeake Bay. I would have saved the money on the thru hull/ seacock and then later on the money spent on a sanitation “Y” valve which is now locked out and won’t be used!

My opinion is spend the money and do the job right (you can do it yourself) and then you don’t have to worry about it again.

By the way, I also replaced the above water line plastic thru hulls (3) …. Anchor locker, head vent and bilge pump. All three were deteriorated on the outside by the elements