View Full Version : Pump not at lowest part of bilge. Problem?
03-08-2006, 01:51 PM
The lowest part of my bilge is directly under the coupling where the transmission and the shaft meet. There is about 3" between the bottom of that and the bilge.
Because of this, the automatic bilge pump is set to one side - which means that it does not sit at the lowest point, but about an inch or more higher. This means, of course, that there is always some water sitting in the bilge - both the 1" - 1.5" which is below the pump and whatever flows back down the line when the pump shuts off (minimal, but....)
So I guess I could fix this in one of two ways:
1) Find a pump with a remote pickup which could then sit at that lowest point
2) Build up the bilge in that area so that the 'lowest' point was now where a pump can actually be mounted.
3rd option, I guess, is to just ignore the problem as being "not very important".
Thoughts? Suggestions? Comments? Questions?
03-08-2006, 01:59 PM
Many boats when going at any speed above an idle, all the water runs to the stern, put another automatic pump there.
03-08-2006, 02:06 PM
Bilge pumps are a problem.
I do mostly speedboats. Generally the deepest place in the boat is under the forward seat. In those boats the bilge water collects in a pool two or three feet in diameter. Others are relatively flat aft; it seems like a gallon of water will cover the entire rear end of the boat. The water then keeps that part of the boat wet. Problem is that the water is 1/2" deep and the typical Rule pump stops pumping at 3/4" and they lose prime if they suck air. Once I put a diaphram pump in a boat. These pumps can pump through a suction hose and they will suck air with no problem. They are, however, suspectible to fouling the diaphram with as little as a hair.
If anyone has any bright ideas let me know.
03-08-2006, 02:30 PM
The book "This Old Boat" has a possible solution. It involves using a large bilge pump for sucking up most of the water and a small bilge pump for getting most of the rest. The small pump has a correspondingly small hose so less water runs back down when it shuts off. Plus this would add a bit of redundancy.
03-08-2006, 02:45 PM
Gary E - boy, I wish I could get this fast enough to have the water flow aft. This is a 33' slow cruiser - displacement hull. You're probably right that this is no problem, I don't see any damage in that area (boat is 13 years old...). But, still...sure would be nice to have it dry once in a while.
willmarsh - this IS the small pump, a Rule 500. There is a larger pump mounted higher already. The problem is the constant 1.5" - 2" of water pooling there - which is there because you cannot physically get the small pump down to the lowest point.
03-08-2006, 04:17 PM
Ok... try this...
Make a basket of wire screen about 1/2 to 3/4 inch deep amd as large an area as will fit in a frame space...
Frame is 10 in front to back and there is 2 inches of water in there. Take a pc of plywood 10 x 10 and form the screen over it then nail the screen on so there is aprox 1/4 inch between the screen and the board ... This gives you a nice filtered area from which to draw water when it's sitting just off the boats bottom. Now you gona have to alter the pump so that the intake is sitting right on that plywood and the hole to the screened side and is sealed to the wood allowing only water from the screened area to get to the pumps impeller. This should draw the water and pump it lower. Mounting of the float switch on an adjustable mount should let this work.
Might have to use a piece of plastic tube to go through the hole in the plywood and glue it to the hole in the pump, so there is no air allowed in from anywhere except below the plywood.
In order to make sure the screen stays 1/4 in from the plywood, Use some nails with big heads and drive them in leaving them 1/4 high. A 1/4 thick steel washer or nut can be slotted to use as a stop when nailing.
[ 03-08-2006, 04:56 PM: Message edited by: Gary E ]
03-08-2006, 06:30 PM
Get a jabsco diaphram pump on ebay (not neccessarily a bilge pump, but one of the external motor, belt driven units. bigger is better). Get a raw water basket type filter with a fine screen (At a farm and ranch store, cheap, plastic, removable stainless basket). Get a Water Witch electronic switch ($50, 7 year warranty). Install the pump up high, outa the bilge. plumb it to pull thru the raw water filter and secure the raw water inlet hose about 1/8 inch above the hull. if you have a large enough flat area you can get a basement pump hose attachment device. Build a bracket and put the switch on the hull as low as possible, but barely above the water pickup. The best way is to have a very small sump lower than anything else, but that is not always possible. I usually put a check valve on the outgoing side of the pump (these are low volume pressure type pumps). This is not considered a safety device, but is an attempt to remove as much water as possible. It works for me.
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