Bilge switches and sizing

[stormalong]

Originally Posted by Skipper Lee

Also,
I hate the thought of putting 3-4 screws each into the hull to fix the them and the switches in place, Is it ok to short screw into the hull? The PO just left the 500 GPH holding on by the hose no screws! I wont be replicating that scenario but thought about gluing a pad in place to screw it to with 5200 or similar.

My bilge pump and float switch are on a pywood plank that is screwed into one of the floor beams (called floors) - well above any water. To service the pump and float switch the plank is unscrewed from the floor and the whole assembly is lifted. No screws in fiberglass. My boat has a deep sump so even trying to reach it would be impossible. The boat came that way from the builder. After about 25 years the plywood was deteriorating so I replaced it with a piece of King Starboard.

[moseriw]

Warning: most of the swim switches are SCRAP!! even the 60 USD ones!
A way to live with them is to use cheap automotive relays

Otherwise a Ru... Switch which is rated 20 Amps will burn on an 6 Amps bilge pump.
Happened! Cutted it in half and mentioned that the contacts were cheap scrap iron and not really plated as the good old automotive contacts.

[Scubaseas]

How big a bilge pump depends on how big a hole you are putting in the boat. Bigger is better if you have the wiring and room for it. I have replaced many foot type/submersible mechanical Rule switches. I still am using for many years now and without any issue Water Witch 101 and 230 switches. Practical Sailor liked them also. Size the switch and wiring to the pump. Size the pump to your seacock size.

[foufou]

For mounting I use a fiberglass rod 1/4" diameter just longer than the depth of my bilge so can jam it under the floor. I attach the rod to the pump with a hose clamp and the pump and switch on a piece of thin G 10. I can then pull the entire assembly up if necessary as my bilge is deeper than I can reach. No glue, no screws, easy access. This has worked well for over a decade.

[moseriw]

OK my setup:
Front Bilge 120 GPH
Engine Bilge (Bigger) 240 GPH


Big Boy - Emergency 4000 GPH - higher up

Depending on your bilge but a pump that pumps out 1/3 of the bilge in a minute is OK for general use. As I said depending it can be a 60 GPH pump. The cheaper the better - think oof replacement when you buy :-))

[sail sfbay]

The article below proposes total pumping capacity for a 25 to 32 feet boat to be 4,000 gph. You can accomplish that with two Rule 2000 gph bilge pumps with Rule-A-Matic Plus series 40A pump float switch (this switch has a 5 year warranty).

Good plan to install a second bilge at as higher level as proposed by the article below. That is the way my Hunter 46 is set up.

https://www.boatingmag.com/choosing-right-bilge-pump/

[Madehn]

my pumps are set up with a float switch on a small pump- next is a 4000 GPH pump that is stepped up about 2 inches, then a third pump that comes on about 2 inches below the opening in the engine oil fill tube. The 4000 GPH pump is attached to a switch that is encased in a clear plastic tube and is strapped to the tank- i cant remember the name of the switch- they are not cheap( $100 ) or so but they come highly recommended- the third pump self priming and is controlled by an air switch- all that is in the water is a bell housing that has an air tube that leads up to the switch which is high and dry. highly recommend that switch- i think it is an ARS 5 but not sure-- all this is probably overkill but i like my boat. one last thing- when the first pump goes off, an alarm sounds at the helm- when the second goes off an alarm SCREAMS in the main salon. the alarms are cheap - few bucks at at an electronics store and easy to wire in-- this way i don't find out about the problem by water splashing on the floorboards when i get up at night ( actually happened to a friend- if he had not had to get up in the middle of the night to take a whiz he would have lost the boat. Don't skimp on your setup -- one last point if you dont have the battery capacity to run the pumps for a signifigant time and your boat spends time on a mooring you may be wasting you time with too much redundancy-- all the pumps in the workd wont help if there is no electrical power to run them.

[Madehn]

forgot to mention- both of the pumps located in the bilge are mounted on a stepped piece of starboard-- i dont like holes in the hull either