Bilge pump mounting / Johnson Ultima questions

[jarcher]

Hi All...

I am in the bilge pump market and I was thinking of getting an 800 GPH Johnson Ultima. This pump is supposed to have some technology that uses field effect sensing to decide when to go on or off. Would anyone care to share their experience with it?

Also, the instructions say to glue a 3/4 inch piece of marine plywood to the bottom of the bilge, then mount the pump on that. I suppose there is little other way to mount it, but this would mean that there could always be as much as maybe about 1.25 to 1.5 inches of water in the bilge.

Is there a better system that will result in less water normally?

Thanks...

[scottyt]

i have the ultima switch controlling a rule pump, it so far has been the longest lasting switch i have had, it made it past 2 months. mine bilge has a vertical stringer in it so mounting was easy. when i mounted it i figured out how high by filling the bilge with water, then holding the switch and lowering it in to the water. when the pump started cavitating and would not pump lower i raised the switch slowly till it shut off and used this height. its almost perfect from my testing afterward, pump runs and start cavitating but pumps just a little more then shuts off. i could get maybe another 1/4 to 3/8 inch of water by letting the pump cavitate and slowy pull a little more out, but that gets into the range of the pump still running with an almost dry bilge

[scottyt]

reread your post

i dont like combined switches and pumps, but i would mount it like they say, then mount a smaller pump with a smaller hose with a manual switch to get it much dryer. the bigger pump would be for when you are not there. if you really want redundancy put in a smaller pump with a manual switch and then put another float switch much higher.

this will have the 600 gallon as your main auto dewater pump. then the small pump when you are on board to get it much dryer, but it will act as a back up if the main does not work, even thou it will take much longer to empty the boat

[jarcher]

Thanks Scotty, I has a similar thought. I might also not be able to use the pump with the built in switch, as the manual says you need an inch clearance all around it, and I may not have space for that.

I can use a separate switch though, and mount it where there is more room. I should have room for a second smaller pump.

[jarcher]

I just ran across something interesting...

Rule makes a bilge pumt that turns itself on every 2.5 minutes and checks to see if there is any load on its impeller. If no, it shuts off. If yes, it pumps. This has the advantage of not needing any type of float switch that could fail, but the disadvantages that it uses power and probably makes noise every 2.5 minutes.

Has anyone tried one? Comments?