Using Seacock of bronze and stainless sheet in ocean

[PHK1]

hi - i am about the install a Groco BV seacock in sailboat used on the ocean. The body is bronze, the ball is stainless steel -PTFE seats and seals. Is there any problem or possibility of corrosion because of dissimilar metals ?





tx P

[Manateeman]

You don’t state hull material bu I’m guessing fiberglass. I have an aluminum hull and I’m removing all my Forespar Marelon seacocks because two are frozen open and there are a number of sailors who have had the handles snap off.
I’m replacing the Forespar with Groco stainless adaptor plates and 316 stainless commercial ball valves. The adaptor plates will be isolated from the 1/2” aluminum backing plates which are TIG welded to the hull. I’ll bolt the Groco adaptor plates to the welded plates. Groco adaptor plates let you change the ball valves, or examine them or take them apart without hauling the boat. All you need is a nerf ball . One test I will run is to CeraKote the bore of the ball valve...another, the entire ball...and see if there is any “corrosion” difference vs non coated or simply greased with Tef-Gel.
I have a custom Bruce King cutter I built 40 years ago which has been at anchor for 25+ years, never pulled out. The seacocks are bronze Apollo with stainless balls. They are a bit stiffer than new, but open and close completely. I haven’t seen the need to pull them out or cut them apart.
I find it useful to add a tee above a seacock with a plug facing up. You can clear any obstructions by removing the plug and ramming a stick straight down and out the hull. I only use this for the main engine raw water.
I don’t consider thru hull supported valves true seacocks. This type includes TruDesign and Forespar. To me, a seacock is a valve bolted to the hull not a valve which depends on a thru hull for support.
Commercial 316 stainless ball valves are used to shut off some nasty chemicals.
I find Nickel Teflon tape and Tef-Gel nice for stainless pipe threads.
If you are still concerned about mixing metals, you can CeraKote your pieces or Tef-Gel them but I don’t think it’s needed. I’m only suggesting you use real seacocks not supported ball valves. I’ve been running a DC electric valve on my gen set supply upstream from a seacock and it works well. Simply my opinion? I’m very impressed with Groco products.
Happy trails to you.
Captain Mark and his frightfully spoiled manatee crew.

[HopCar]

You won’t have any trouble with the Groco BV seacock. It will outlast the boat.
The new BV seacocks come with a zerk fitting to allow you to grease the ball. The valve should be open or partially closed. When you pump grease into a closed ball valve you just fill the center of the ball.