Need to be educated on sea chests.

[lumina]

Hi All,

I just noticed that my stbd sea chest thru-hull looks like its leaking around the outside of the fitting.

I've watched it closely, stopped it up with a rag and It still seems to weep out a bit of water.

Could someone educate me on sea chests.

Another question, should a bilge pump be connected to a sea chest. I wouldn't think so because of the back pressure. I've been taught that a bilge pump requires it's own thru hull. The guy at the yard said it's common and acceptable to go the sea chest route.

Thoughts ???

 

[saltshaker]

Are you saying the thru hull fitting on the exterior is leaking between the fitting and the hull? If so I'd look into that ASAP as I would think water is leaking at the hole in the hull for the fitting. You may not notice it but sea water might be getting into the sea chest through the leaking fitting. Your bilge pumps should dump into the sea chest. That's how my 46C was. There shouldn't be any back pressure as the discharge fitting should be much larger than the pump hose. I have 2 for my ACs. The big AC pumps discharge a lot of water through the sea chest with no issue.

 

[lumina]

Hi All,

Hi Jack, the boat is on the hard. If I look at the stbd sea chest discharge thru-hull which is between the boot stripe and the chine, it appears to be weeping around the back side of the thru-hull, the section below the boot stripe. As you said "the thru hull fitting on the exterior is leaking between the fitting and the hull".

Can you tell me how the sea chest is designed and applied to the hull, and if the thru hull is at the very bottom of it.


I'll try and send an image.

 

[saltshaker]

The thru hull is at the bottom of the sea chest. The sea chest is glassed to the hull from the back side of the hull. Not sure how you would replace the discharge fitting or why it would fail. May need to call Sams on this one and see what they suggest.

 

[MikeP]

The sea chests on our 53 are, as mentioned, glassed-in, roughly rectangular boxes, maybe 8-9" wide by 15" tall, oriented vertically. Two of ours are in the engine rooms, one in each. The chest in the port ER handles the discharge from AC water pump, and the main and standby bilge pumps. The one in the Port handles the water heater pop off and the same bilge pumps in that ER. Other sea chests on the boat accept things like the galley sink/dishwasher output and shower sumps.

They are essentially "structural" and the setup described above is oem on our '80 53MY based on the schematics that came with the boat.

I have had sea chests clog and restrict flow. A year or two ago, a flow restriction in our forward, port chest (there are three on the boat's port side) caused water that was being pumped into the sea chest to back up into other locations. In the specific case, the dishwasher pump would cause water to back up into the shower sump and then the shower sump would activate and cause water to back up from the sea chest into the galley sink. I struggled at trying to figure out how to clean out the chest but a half gallon white vinegar poured into the kitchen sink and allowed to sit for several hours eliminated the problem. Now I routinely do that as a preventive measure for the chests that I cannot access. The ones in the ER have a fitting at the top that can be removed so you can insert a rod/dowel/whatever to break up any clogs but I have never had any in those chests, just the one that serves the galley. I suspect it's related to the food particles that end up flowing through that chest.

The PO revised the plumbing on the aft shower sump, abandoning the original lines from the sump to a sea chest, which were quite long. He installed a separate thru hull just for that shower sump, a run of only a couple of feet. Obviously he had had some sort of difficulty with the oem setup in that case. I suspect it had something to do with the length of the run from the sump to the chest, which was probably 20 feet of hose plus the fact that it was all uphill so the sump probably stayed fairly full which may have caused some odor issues. But I'm just speculating re that.

 

[Pete]

Mike P., question on your white vinegar use. Did you just pour the vinegar down the galley sink with the sea chest overboard drain fitting open or did you block the overboard fitting to trap the vinegar in the sea chest for the half hour?

Pete

 

[MikeP]

I just poured it into the drain, observing that some flowed out of the through hull and left it at that. I can't get to that sea chest drain outlet at our slip so I figured I try just pouring it in and, if that didn't work, I'd turn the boat around in the slip so I could get to the sea chest outlet on the outside of the boat and plug it temporarily. Luckily, I didn't have to do that though there's no doubt in my mind that blocking the outlet/filling the sea chest with vinegar would be better at thoroughly cleaning.