Originally Posted by TrueBlue
I can see SD's point of not wanting an overly wet bilge, especially since he dosen't have a keel - just a roundish torpedo tube along the centerline, flanked by two outriggers
. The vertical distance from his boat's bilge bottom to the above waterline through-hull, must be relatively short.
LOL... my bilge is all of 3" deep... what do you expect on a boat with a centerboard up draft of 15" or so.
On my boat however . . . and I suppose on most keel boats, it's nearly impossible to pump all standing bilge water out of the keel bilge. This is due to the fact that my draft is 5'-2" and all water left in the drain hose will fall back into the bilge, once the helm switch, or float switch, disconnects power.
I've also never seen a float switch that didn't require at least a inch of water or so to function. A layer of water an inch deep over the entire bottom of the bilge is a lot of water for you to get rid of via evaporation... and if your boat doesn't have A/C, you're going have a dank, sticky, musty boat until it goes away.
There also seems to always be some trace amounts of oil residue at the bottom of this dank cavity - and as everyone knows, oil floats on water - but the pump draws from the bottom. I use one of those giant bilge tampons, but even still - some oil always seems to stay there.
There is that risk of dumping some oil from an unclean bilge into the water... and that can lead to nasty fines...
Therefore, unless you've scrubbed the keel bilge upon haulout, I would avoid deliberately raising the bilge water level whenever possible.
Even then, I see absolutely no point in putting water where it don't belong on a well-found ship. Standing water in the bilge, even fresh water, helps contribute to higher humidity, possibly hull osmosis, mold and mildew, and corrosion of equipment. I've seen no arguments as to why draining the fresh water tanks into the bilge makes any sense.
Boasun's point about work boats, which have very high capacity pumps and very, very large tanks, makes sense to do so, but on most sailboats, what is a good reason?
T37Chef might be used to a dank, wet, slimy bilge, but that isn't the case for many of us. RickBowman also doesn't give any valid reasons for the practice.
Getting back to how we discharge our 140 gal water tank - I use our PAR belt-driven diaphram pumps by turning on a galley sink tap. Those Jabsco PAR pumps do a very efficient job of quickly pumping water to onboard sinks - which is then drained by gravity through a below waterline (but above ground when on the hard) through-hull.
Makes sense to use the pump the way it was meant to be used...