Bilge Pump wiring

[PaulGooch]

I think I read what you wrote carefully enough. The figure of 15000 is an approximation based on the manufacturers figures for flow and draw with a 4' head, and assuming I could draw about 80AH out of the battery before it was dead - all reasonable enough assumptions (although it assumes that battery started off well charged).

You might quibble with the figures - but they aren't going to be that far out. Anyway, IIRC 1000 gallons of water would weigh 5 tons so whether you would find 15000 gallons, or 5000 gallons is rather academic, 5000 would be more than enough to sink most boats.

In fact on my boat I have the bilge pump connected directly through to the engine start battery (as it is usually fully charged). It is wired through a dedicated CB bypassing all the isolation switches and fuse panel. When the boat was on a swinging mooring I used to have a small solar cell on board that I reckoned would go a long way to replenishing the drain from the pump, and the self-discharge

The OP asked if it was the norm to have the auto bilge pump wired AFTER the isolator switches. I replied that in many cases it was the norm, i didn't say it was a wise or desirable way of doing it, that wasn't his question.

Is it pick a post apart day and i missed it ?

 

[omega2]

All this "theory" i.e. pumps output, battery drain, and the like are good for rain water and maybe a drip on the shaft glands, but if you are on a swinger and the boat does not come round with the tide due to a fouling, then all the pumps in the world are not going to stop you sinking as the water comes in through the scuppers and then over transom.

 

[rafiki_]

With my previous mobo, US built, the master switch turned off the bilge pump. After a couple of weeks, on returning to the boat, she was sat very low in the water. Took some pumping, but no real damage. Water was seeping in through the speed log pitot fitting. Easy repair. But could have been worse if we had left the boat a few weeks!!

Rafiki's bilge pump is wired off the dom battery, not through the master switch. Will need to be a major drama to flatten the battery!

I am happier with Rafiki's set-up.