by GreenLake » Wed Mar 29, 2023 1:35 am
The bailer is supposed to work based on Bernoulli's principle, that states that water flowing in a restricted pipe (or around an immersed object) speeds up and has lower pressure. And the way the scoop is oriented with the opening facing aft should only make that work even better.
So if you effectively have an "unbailer" then the cause must be that the water pressure is higher outside than inside.
When the boat is stationary, the "unbailing" should stop the minute the water level on the inside is the same as a the water level surrounding the boat. I would expect that level to be at or below the level of the level of the cockpit sole in a DSII, unless the boat is very heavily loaded. If you then start moving the boat, the level should drop. How far it drops would depend on the speed.
However, I could imagine a situation where the boat is so stern heavy that the drop in water level gets to be more than the pressure differential available from the movement of the boat. In such a situation I would expect the water level to drop some, but not all the way.
What I would not expect is the boat filling all the way. There's just too much enclosed air volume under the cockpit for that to happen. (It's probably worth making sure that the boat isn't taking on a lot of water between the hulls, because in that case, you are relying on the air above the cockpit floor - and below the coamings - to keep you afloat.)
Now, if you mount the scoop with the opening forward, you get positive pressure from the water pushing into the opening. Essentially, you turn your bailer into the kind of scoop used by fire fighting aircraft. I think you would know.
In summary, from afar, I have no definite conclusion, but if you observe a steady state: some water comes in but then it stops and the level changes (goes down with increased speed), then the bailer is fundamentally working and I would look at whether your boat is super stern heavy. If the flow doesn't stop, I'd suspect massive amounts of water in the bilge.
One test to perform would be to open the plug on a stationary, but empty boat. That should give you an idea what the level of the surrounding water corresponds to in terms of height above/below cockpit sole on a DSII. (I think it should be below, but it's been a while since I've seen a DSII in the water).
~ green ~ lake ~ ~