Hunter 306 salt water in the bilge but only when sailing

[Arbee]

Hi,

I intend to take a scientific process of elimination to this problem but thought I'd ask here in case anyone already has the most likely answer.

After a typical day out, our 2004 Hunter 306 has about a half cup of salt water in the bilge. At the dock she stays bone dry, especially after we installed the PSS last year. We also had all new seacocks fitted two years ago when we bought her. Nothing under the engine. Nothing apparent trailing from the log/depth fittings in the forward bilge area. It all seems to concentrate around the central bilge section where all the "action" is (where the bilge pump, refrig hose, head floor drain etc all meet).

I'm wondering if the bilge discharge outlet might be slowly siphoning water back into the bilge (given there is no seacock) when we're moving, but not sure how feasible that is.

Thanks as always for any insight!

Cheers, Robert

Charisma H306
Westernport Marina
Victoria, Australia

 

[RoyS]

We get sea water entering from the rudder packing on a different boat. Worth a look on yours.

 

[Ralph Johnstone]

I intend to take a scientific process of elimination to this problem

A most unusual process when you see some of the hair-brained processes occassionally presented.

I'm wondering if the bilge discharge outlet might be slowly siphoning water back into the bilge

If you insist on being logical about this, try disconnecting the hose and plug it before heading out on a sail to see if that eliminates the water ingress.

 

[Capt Robbie]

Question?
do you have a loop in the bilge hose near the hull discharge and do you have a check valve just after the bilge pump. If not then you could be back filling if the discharge fitting goes under water when the boat heals. If you have a check valve installed then perhaps it is starting to fail.

 

[Arbee]

Thanks for the replies, I'll start from the bilge pump to the discharge and explore that route as @Capt Robbie suggests. If nothing there I might need to look at the rudder, but I have noted that the entire channel running down the middle of the hull under the cockpit behind the engine is bone dry.

 

[RoyS]

Arbee, If the entire channel behind the engine is bone dry, there is no need to look at the rudder.

 

[senang]

Put the bilge pump slightly above the bilge and cover it in kitchen wipe paper. After a sail you will see if the water came from the bilge outlet or somewhere else.

 

[Rick486]

I had this problem on my P39 years ago. Turned out to be a cockpit drain hose had a tiny leak and would only leak on port tack.

 

[Will Gilmore]

Heeling is likely the difference between, at the dock, and out for a sail, but moving water can also change the pressure on hoses, thru-hulls and cb trunks. Have you checked for moisture on the inside of the hull above the waterline on either side of the water in the bilge? Chain plates, engine exhaust, ...

What is that on the stem, just above the waterline? Is that an anchor locker drain?

-Will

 

[Parsons]

I'm with @Will Gilmore (although he does not know that the pointy end is not called the stern), the difference is probably from healing. I'd check first any through-hulls near the waterline that get submerged occasionally. I had the cockpit drain hose that Rick mentioned, where they saved a dollar by putting in a cheaper mushroom fitting that sheared off after only two decades, I guess because it was typically above water.

On the thought of check-valves on the bilge - I would do a search on this and see that it is not recommended nor ABYC standard - there is a reason. If the valve fails in the closed position, you no longer have a bilge pump. There is no amount of nuisance water that would accumulate to make me take that risk, but it's your boat .... The siphon-breaking loop above water line is fine to eliminate backflow, but typically a difficult thing to place as there are probably no vertical runs near your bilge pump in which to place said loop.

 

[Will Gilmore]

although he does not know that the pointy end is not called the stern

Ha ha ha. I thought spell check was getting mischievous again, but I wrote 'stem', not 'stern'. In type, the difference between those two words is only half a millimeter.


-Will

 

[jaysweet]

Hi,

I intend to take a scientific process of elimination to this problem but thought I'd ask here in case anyone already has the most likely answer.

After a typical day out, our 2004 Hunter 306 has about a half cup of salt water in the bilge. At the dock she stays bone dry, especially after we installed the PSS last year. We also had all new seacocks fitted two years ago when we bought her. Nothing under the engine. Nothing apparent trailing from the log/depth fittings in the forward bilge area. It all seems to concentrate around the central bilge section where all the "action" is (where the bilge pump, refrig hose, head floor drain etc all meet).

I'm wondering if the bilge discharge outlet might be slowly siphoning water back into the bilge (given there is no seacock) when we're moving, but not sure how feasible that is.

Thanks as always for any insight!

Cheers, Robert

Charisma H306
Westernport Marina
Victoria, Australia

Robert,

First, I'd ask how wet it is right behind the engine, underneath the stuffing box. Two sources of water in the aft end of the 306 are the stuffing box, and the aft rub-rail, which squats underwater when you're under power. I pulled the rub rail off in 2020 and recaulked with 4200, which almost eliminated the leaks back there. Of course, both of these things (stuffing box and rub rail) are best done when hauled out.

Water in the main bilge in my boat, though, seems to come from rub-rail leaks on the beam or from the fixed port lights. Or from the anchor locker (see my post in "ask all sailors"). It's pretty perplexing: the bilge can be dry for 2 months and then... not.