Ball Valve Specification for Seawater Intake

MARCH IS FIX THE HOUSEBOAT Month here in Iowa. I get to dig into my new (to me) 82 Gibson ’42 Std.

Seacocks. There. I said it. Seacocks. (I feel better now) The water intake for the houseboat does not have Seacocks. I just wanted to say Seacock.

What she DOES have is Gate valves. They suck. One is frozen open!!!

I am going to replace them with Bronze Ball Valves. iBoats.com has Apollo brand for $115. (The price is for a 1 ½” valve that most likely isn’t the right size, but lets pretend it is for now) McMaster Carr has a ball valve for $59. Differences? Both are bronze. Both have unrestricted flow. I wonder if the more expensive valve meets some high pressure steam specifications that I don’t need.

Thanks for your advice!!!

Capt Ron

Hate to be a tool, but a ball valve is not a seacock. Seacock is one piece, flanged, with an incorporated valve and is screwed to a thru hull fitting as well as bolted to the hull on the inside. Only seacocks should be used for below the waterline inlets on thru hulls. OK. Done.
The main difference between the cheaper ones and the Apollo is the handle on the Apollo is stainless, as well as the ball. The cheaper ones usually have zinc plated steel handles and nuts. The ball is sometimes chromed brass. This is probably not a big deal in fresh water, but in salt you gotta pay the big money.
When installing a ball valve, you need two lock nuts on the thru hull. One lock nut is used as one would expect; to hold the fitting in place. The other is used to keep the ball valve from loosening. Remember to double clamp any hose that is attached below the water line. Use AWAB hose clamps from Jamestown Distributors. There is a fine art to installing thru hull fittings. If you ever look inside a brand new Fountain, you'll see how not to do it. If they used gate valves on your Gibson, shame on them.
You may also consider the Marelon ball valves and seacocks. They are all plastic and never corrode. They are slightly weaker than metal valves, but are pretty much install and forget.

I also had to toss out the gate valves that came with mine since one of them froze in the open position. Sound familiar? I used ball valves instead, the screw in kind (like the gate valves). Being anal, I tie-wrap the handles in the open position to be sure the little darlings don't close as I roar down the river.

Jeff

My boat is a 1984 Gibson 50'. The brass gate valve is standard. I had one go out a few years ago. The stem came loose from the gate. It would not open. I replaced it with an exact duplicate and have had no problem since nor with any of the others. I found the replacement at a local "old time" hardware store in Memphis. I have had the boat 22 years. Recognize this boat is a fresh water boat so the application is not as tough as you all see in the salt water boats.

Chuck Hanson

Gibsons must be plumbed by plumbers and not marine riggers.

A lot depends upon exactly what you have and what you will reuse. If you have assembled components - thru hull, valve, hose barb fitting - it makes a lot of sense to swap the gatevalve for a ball valve. The key is to ensure thread type compatibility between new and old. NPT and NPS are not the same and there are rules about which type (on what gender) form an acceptable union. Me I'd ensure they were the same on both ends of every joint.

As far as the differences, the stainless aspects of the marine part are one cost driver - another is the casting's thickness. More metal = more costs. If they are the same (physically) the cost difference is likely only due to that word M A R I N E.

BTW, if your engines burn gasoline, it is highly likely your inlet hose is 1.25" ID which is what the rest of the hardware would be sized at. Bigger is okay but not needed.

Thanks all for the input! I am going to peel back the cover and measure for fitting sizes tonight!