Question re sump

[denpooch]

Hey mates,
When I was filling the fresh water tank on my 2005 Mariner I noticed water coming out of one of the thru hulls on the starboard side of the boat. I checked the boat diagram and it labeled the thru hull as 'SUMP'.
Can anyone explain what the might be? I could not hear the sound of any pump working.
Thanks,
Dennis

[g36]

The sump refers to the gray water from galley or head sinks and ac condensate sometimes. Its generally a white square box with float switch and small pump. First I would think that there is a leak in the top of your water tank or the vent hose. So as you were filling your water tank it overfilled into the bilge and I would think the bilge pumps would have pumped this overboard first. Maybe the diagram you looked at is wrong or a bilge pump outlet is. The sumps generally would be higher since the bilge pumps would be at the lowest point however if water flowed into the sump from whatever point including the lid it would pump that out too. Have you looked to see where the hose in the boat from that outlet goes too? To verify. Maybe its a water tank vent hose?

[denpooch]

Hey there. Thanks for your response. I need to take another look at the diagram. Perhaps there is a fill overflow that feeds the sump pump. The flow was not from the bilge as that was dry.
I appreciate your thoughts.

[Midnightsun]

If the bilge is dry I can only think of the vent line for the potable water tank which as you probably know, also acts as an indicator allowing water to flow out when the tank is full . Was there quite a bit of water coming out or just a bit? Is the thru hull located close to the water line or higher up?

Another possibility is a shower sump was just on the edge of going off and was coincidentally triggered.

[denpooch]

Hey there Hans.
It was a substantial flow. Even when I shut off the water filling the tank there was still flow.
The shower sump was near empty. The previous day I had run the shower water to confirm the sump was functioning properly.
On reflection, the only thing that comes to mind is that there is an over flow for the fresh water fill connected somewhere to the sump. However I must first confirm that indeed the thru hull in question is in fact connected to the shower sump.
I have had experienced a 'mislabeling' by Carver in another instance.
I will run the shower and confirm that indeed the flow is from the shower sump. I think that must be the first step.
I will post the result of my 'look-see'.
Thanks.

[Midnightsun]

the only thing that comes to mind is that there is an over flow for the fresh water fill connected somewhere to the sump. However I must first confirm that indeed the thru hull in question is in fact connected to the shower sump.

This sounds very probable.

[Cooler]

There should be an overflow vent on the water tank, but there is no water pump connected to it. Explains why you did not hear any pump noise. The water will just flow out. Maybe the water tank overflow line hose is connected into the sump pump line outflow. Strange, but strange things happen. Curious issue. er

[denpooch]

Hey there mates. As a follow up to my previous post, I was able to confirm a couple of items and believe that I understand what happened.
First of all, the diagram provided by Carver is totally mislabeled. ( I would post the image but cannot figure out how to do that!). On the starboard side there is a group of 4 thru hulls.Three of four are labeled incorrectly. I tested the sump, followed the lines, etc and determined that the overflow was coming from the Fresh Water Tank Vent Thru Hull.
So that's that. I got my answer.
Thanks for your help with this.