No need to get terribly scientific about this, but it does help to be cognizant of the numbers involved.
Have a quick look under your kitchen sink. There is your answer :-)! You'll see that the pipe from the sink goes through a 180º bend, rises for a little way and then goes horizontally into the wall. It's called a “P”- trap for obvious reasons.
You ought to have an upside down “P”-trap on your bilge pump :-)! The through-hull should be mounted high enough that when you heel the boat 15º, or so, to the side where it is, the through-hull won't be submerged. This is to preclude “siphoning”.
2000 pump will lift
about 1,300 gallons per hour to a distance of 6 feet. So sez Rule
. Let's assume we believe them :-). So you drive the water up some distance above your waterline, take it over the top of an inverted 180º bend and then down to your through hull
. These pumps have a 2” outlet, so that will be the diameter of the pipe or tube or hose you use.
You will agree that the interior
cross-sectional area of a 2” tube is 3.1416 x (2/2)^2 = 3.1415 square inches and that 6 feet = 72 inches. Therefore the quantity of water than will be in the riser when the pump stops is 72 x 3.1416 cubic inches = 225 cubic inches, or just a tad less than a gallon. Because the pump is a centrifugal, self-priming pump, this water will all fall back into the bilge when your pump stops. Can you live with a bilge that always has a gallon of water in it? I can. If I want ALL the water out, I mop up that residual gallon of water with a sponge.
Now, 1,300 gallons per hour = 1,300/60 = 21 gallons per minute. Short of a catastrophic hull
failure, how are you ever going to get so much water in your bilge that your pump can't dispose of it in under a minute? Bilge pumps are for “tidying up”. Not for “saving the ship” If you get water in you bilge constantly, or even just frequently, the pump is the LAST thing you want to be thinking about. The first thing to think about is where the water is coming from, and when you've determined that, you take whatever remedial action is apposite. When THAT's done you can use the pump for “tidying up” :-)
The float switch is a somewhat separate issue. It should be mounted at a height in the bilge that permits the residual gallon of water to lie there without lifting the switch and activating the pump. But it should also be low enuff to permit
no more that a tad more than a gallon of water in the bilge before it triggers the pump. Mine is mounted on a little platform at the bottom of a strake that attaches to a floor by means of a wing nut. Thus I can easily pull it out for servicing. It is also wired so a "Normally Off" push button on my instrument panels
permits me to bypass the float switch and operate the pump from the navigation
Hope that gives you something to think on :-)
All the best!