Venting a Smelly Raw Water Line

I have a raw water deckwash pump, the outlet for which is a long way from the intake point. It is not used often but when it is, the raw (sea) water is incredibly smelly....methane I suppose, from rotting sea life in the long length of hose.

Can I put a vented loop somewhere along the line between the pump & outlet tap that will let this line vent? Suggestions for how...or for other solutions...much appreciated.

You could always put a vented loop right after the pump...but you will have to put in a ball valve to drain the rest of the hose.... You could route that drain line to a sump or directly overboard.

Can you briefly switch to fresh water and flush the line out every few days?
How about just use it more often so the stuff doesn't get a chance to rot?

A vented loop would need to be higher than the outlet to drain the hose.
The outlet would also need to be the lowest point after the vent or water would pool in the low points.

Use the pump more often.

Putting a filter (screen) as close to the seacock as possible will catch much of the "stuff" that's causing the odor. I did that for my raw water flush head and it was a help. It didn't stop the odor completely but it cut it way down.

Ron: i have a strainer just after the seacock now. It has a relatively coarse stainless screen. A really fine screen would need to be cleaned frequently and might inhibit the pump.

Aquabelle said:

Ron: i have a strainer just after the seacock now. It has a relatively coarse stainless screen. A really fine screen would need to be cleaned frequently and might inhibit the pump.

Click to expand...

Well, my next suggestion is to let the water from the washdown run overboard for a minute or two before using it to wash the boat.

You could, of course, rig up valves to drain the plumbing between uses but it seems like a lot of trouble to cure a small problem. You have to open both ends of the plumbing for it to drain.

Ron's suggestion is the best fix IMHO. The stuff that's living (and dying) in there is microscopic, so a screen won't stop it, although it might improve it. All those other ideas are just adding things to fail into the system. If it's that big a deal, plumb it into your FW system.

The CL police will be screaming but if the system already exists and it seems that it does the easy fix is. Cut a bit off of one of the swimming pool tablets, stick it in the strainer basket, let is set for 15 or 20 minutes. Run the system, close the through hull. Take out the sea strainer basket and the remainder of the tablet.

Another way would be make an adaptor with a garden hose end on it from Lowe's or HD that replaces the cap on the sea strainer. When you are done using the system, close the TH, replace the top of the strainer with the plastic piece from HD, attach a garden hose, flush the system with fresh water, replace the top of the sea strainer. This could wait until you are back at the dock.