Seacock backing plate yes/no?

[bob_77903]

If it's the seacock in the top right of your first op post, that's a Spartan seacock, one of the best ever, and Real Bronze, and yes on the backing plate.

[roverhi]

Originally Posted by Jado27

I know this has been asked before but with backing plate glassed in and seacock bolted to it. wouldn't lifeseal be fine for the seacock and through hull vs 4200 or 5200?

I'd use LifeCaulk, the real stuff, 100% polysulfide. Have been using it forever and it's never let me down. Stays flexible indefinitely and stuck to whatever your trying to seal as long as it's oil free. Peace of mind for a very important fitting. It does require patience when removing, a steady force works best, but it's not like the tenacity of 5200.

Have had a ton of bad experiences with Sillycone and no good ones. Remember Sillycone belongs in breasts, not boats. Lifeseal is a blend of polysulfide and sillycone and I wouldn't trust it.

[Jado27]

Great advice folks. And excellent video thanks. And yes I'm using the Seacock in the pic. Good to hear that it's quality, that's what I was told when I picked it up cheap. And sorry bronze, not brass.
Do you know that west marine doesent carry the step down tool for through hulls? I had to fashion one with a drain installation tool but it only works for 1 size.

[Cheechako]

If you are glassing a glass plate onto the already thick hull....err.... what's the point? you are really just making a thick hull thicker, and the hull is already way overkill thick!
No problem with any good underwater caulk..... but not a good place to save a few bucks.
Kinda interesting with all the bad press about gate valves... and yet here's another example of one that lasted what... 40years? i've seen so many on old boats it's amazing. Not that I'm a proponant really but.....
BTW.... how do you know the Hinckley Seacock is brass not bronze? doesnt sound like something they would do... especially in the old days!

[Jado27]

Yeah the gate valve was shut for years and corroded that way but would have lasted almost forever I'm sure. If I didn't need the through-hull for sewage I would have left it. The valve wouldn't come off the through-hull even with a 3 ft long pipe wrench. Having ripped out the original brass through-hull I am confident it would have lasted another 25yrs.


At this point the backing plate is only to hold the bolts/studs for mounts and appease a buyer. I'm looking for a transatlantic boat in a few years so I'll need to sell this one, and don't want any appraiser giving me **** about not having a plate.

I have no clue whether the Seacock is brass or bronze I'm using. I heard it might be a spartan? Nothing on it is plastic. Should last a long time.

Defiantly lifecaulk for through hull.

[Marksman]

I had a gate valve for the out going mail on the head on my old boat, and a gate valve on the galley sink discharge of my current boat. Both worked flawlessly. Me thinks they are OK as long as they get cycled frequently. If I could snap my fingers and swap for a ball valve seacock I would but for now it is still as good as new and will continue on. My belief is they go bad from neglect or extenuating corrosive circumstances.

[HopCar]

The problem with gate valves is that the stem that move the gate are almost always brass. They live in salt water and the zinc in the brass comes out. In an emergency the stem can twist off right in your hand. I bet I've seen a hundred gate valves with broken stems.

They also have the same miss matched thread problem you have when you screw a ball valve directly onto a thru-hull.

It's just a really bad idea to use gate valves on thru-hulls.

[S/V Alchemy]

Originally Posted by boatpoker

That's too bad, brass is a terrible material for skin fittings or ball valve in salt water.

Yes, that was my point, but it seems to have missed the mark.

[Maine Sail]

Originally Posted by S/V Alchemy

Yes, that was my point, but it seems to have missed the mark.

But that seacock is not "brass" it is 85-5-5-5 bronze... The OP just did not know what it was. It is either a Spartan or Wicox-Crittenden tapered cone. They were only ever made in 85-5-5-5 bronze and will often out last the boat they are installed in....

[Marksman]

The gate valve in my gally drain is a one piece afair just like a proper seacock. I think it is original equipment from 1966. Oddly enough it still works like new. Right next to it was the raw water intake which consisted of a bronze pipe nipple glassed into the hull with a ball valve screwed on the end. That got replaced with a proper groco seacock.

[sailvayu]

you can get the tool from Jametown
Search: thru hull wrench

[S/V Alchemy]

Originally Posted by Maine Sail

But that seacock is not "brass" it is 85-5-5-5 bronze... The OP just did not know what it was. It is either a Spartan or Wicox-Crittenden tapered cone. They were only ever made in 85-5-5-5 bronze and will often out last the boat they are installed in....

All to the good and if I ever seen them (I've seen them and the "Apollos" just once, at a chandlery sell off) for sale, I would score a few. But I was pointing out that if you are unaware that brass is a no-no, the backing plate advice becomes a bit secondary, in my view.

[Maine Sail]

Originally Posted by S/V Alchemy

But I was pointing out that if you are unaware that brass is a no-no, the backing plate advice becomes a bit secondary, in my view.

Absolutely....!

[minaret]

Backing plates on glass boats are not for strength, they are to make a flat spot to land the flange on. Often the hull is quite curved in way of the thru hull and a backing plate is the only way for the flange to make contact all around. Only not needed if its in a fairly flat spot. Even then I'd do it.

[Nicholson58]

Originally Posted by Jado27

Yes the seacock was off an old hinkley or something and is defiantly brass.

vs 4200 or 5200?

Fine distinction you may be missing: Bronze is not brass. What lay people usually refer to as brass and what you get at Home Depot are most often yellow brass with a high zinc content. It is totally unsuitable for salt service. The matrix will quickly de-zincafy and the remaining material will be porous and brittle. Marine bronze has a high copper content and the red color will be especially evident in cut threads. Any GROCO or other purpose built marine fittings will be appropriate bronze. Note however, that the codes in Europe have been reduced to a service life of _____ ? years. I don't remember the number but the mere fact is scary.

Here is another source for fittings and valves you might consider in the appropriate place. I have several above the water line (AC drains) and in the genset and main engine wet exhaust. Extremely easy to repair valves and valves can be furnished with any combination of ends they make.

Banjo Valves and Fittings - Alsco Industrial Products, Inc.