Stuck seacock question

[Allowishish]

We have a boat that is kept a 15 hour drive away from us.
We do have someone that looks after it while we are away. He recently reported that the seacock for the forward head is stuck. Before leaving the boat we flush the holding tank pretty well. So my thought is to remove the discharge house spray some penetrating lube on the seacock and work it loose.
However my concern is that we will not be back down to the boat ourselves to do this for a while.
Will this freeze the seacock if put off for a few months?
should I bite the bullet and have someone do it for me since I can’t get down to do it myself for months?

 

[kappykaplan]

should I bite the bullet and have someone do it for me since I can’t get down to do it myself for months?

It can't hurt to have someone do this for you now as waiting could result (worst case) in having to remove/replace the seacock.

 

[dlochner]

I'm confused. Which seacock? The overboard discharge for the head, after the Y-valve? or is this a direct discharge from the toilet.

Are you in an area where direct discharge is allowed?

 

[jssailem]

He recently reported that the seacock for the forward head is stuck

Couple of queries...

• What type of seacock is it, Marelon or bronze?
• Is the seacock frozen closed or open?
• Is the boat in a marina of fresh or salt water?
• Is there corrosion showing around the base of the seacock?
• When was the seacock last changed?

I ask because I live 4.5 hours from my boat on a good traffic day. I averted a sinking. I had not replaced the seacock on my raw water system. I was nervous and felt it was a good preventive action to take. I had the boat hauled for an over night hold in the slings so I could replace the through hull. I thought the valve was still good. I went to remove the seacock and due to the internal corrosion the valve split apart in my hand.

I thought it looked good and it had worked smoothly since I bought the boat.



When I went to remove the valve to replace the through hull it broke in to two pieces.


Consider your boat and valve condition. If it is a concern I would haul the boat and replace the valve. If you know it is newish and in good shape then your approach might work. You may have something stuck in the valve that is causing the problem.

 

[dlochner]

John's seacocks show evidence of pinking, which happens when zinc in the bronze leaches out resulting in very brittle metal. Galvanic action causes pinking and is the result of improper bonding or an unisolated ground wire on the shore power connection or exhausted sacrificial anodes. If the problem is pinking, all of the underwater metals will need to be evaluated.

Adding a lubricant to the sea cock probably won't loosen it. Whether the seacock is a traditional cone type or ball valve also matters. Since the seacock is in the sanitary system the most likely candidate for obstruction is the build up calcium from the reaction of seawater with urine. The cure is acid which will break down the calcified material. A second culprit may be some critter that took up residence.

Given the age of your boat and John's experience I would be hesitant to apply too much force while the boat is in the water. Apply too much pressure and the fitting fails and there is 1.5" hole in the boat.

 

[Allowishish]

Thanks for the advise.
The last time we were down it was stuck as well. I was able to slowly move it back and forth gaining a mm or two of movement at a time till it was able to be opened and closed smoothly.

the salt/water urine calcification is a good point. That said, we flush it after pump out pretty thoroughly (adding vinegar), but I guess there is always some reaction still happening.
We do have the bottom dived on and cleaned monthly (salt water marina) so I am hopeful that it is not externally fouled.
No corrosion was noted at the base internally.
The brute force technique of a hired hand definitely concerns me.

Unfortunately, we do not know the age of the seacock as it is a new to us boat.

Luckily, it is in the closed position and we do have a second head.

 

[jviss]

When messing with seacocks with the boat in the water, have a selection of wooden emergency bungs/plugs and a mallet next to you.

Next time you're there, carefully examine the seacock, to identify it as well as possible, including type, material, size, and make/model, if possible. You may have to replace it. If you can locate the replacement, you can do a short haul as John did to put a new one in (or have the yard do it).

 

[FastOlson]

Unfortunately, we do not know the age of the seacock as it is a new to us boat.

Unless there is some evidence that it is newer, assume that the builder installed it. While our OEM seacocks were working OK, we replaced them, decades ago, with the newer ForeSpar actual seacock designs that are since then integral with the frp hull. I note that ForeSpar now has competition from another maker of composite seacocks, so that is a further good thing. If the old one looks like bronze, it might be... or might not.
Be cautious and consider that after 40 years or so, the OEM parts no longer "owe" you anything. And, they do have to 100% keep the water out.

 

[jviss]

This thread wouldn't be complete without a reference to @Maine Sail 's excellent website. Here's the section on plumbing:

MarineHowTo - plumbing

Here's the article Seacocks and Thru Hull Primer, a good place to start.