Reworking Bilge Pumps

[Turbo Dog]

I have a 35 ' monohull that I want to install a new bilge pump system in .I'm thinking about installing 2 Rule 3700gph pumps with new hoses etc. Is this the size that would be recommended ? What type of bilge hose is recommended ? Should the hose for each pump make it's own exit out of the transom for best performance ? Should each pump be on a seperate battery ? What back up pump systems are recommended ?
Thanks so much for the advice !!

[S/V Alchemy]

I have a 41' steel full keeler with a Rule 3700 as the main bilge pump in a largish sort of well just aft of the engine. Upon reflection, I like the idea of a two-stage pump installation in which a very small 400-500 gph pump of this type is installed at the bottom of the bilge and the Rule 3700 is installed above it. This means stuffing box drips or occasional spills from rainwater down the mast sheaves or random condensation is dealt with at little cost in amps by an appropriately sized and hosed pump, whereas the Rule would only activate in a more serious ingress situation.



Don Casey explains this logic at the bottom of this article.

Installing a Bilge Pump by Don Casey

The use of check valves to eliminate backflow is somewhat contentious; I would solicit opinions if I were you.

[osirissail]

- - I use the two tier bilge pump system. A small automatic 500 or less pump in the bottom of the bilge or sump area. And then a larger high capacity pump mounted higher up. Should the little pump not be able to handle the quantity then the bigger pump kicks in.
- - Bilge Pumps are notorious for over-stating what they will put out. Also they are notorious for poor contruction. Non-tinned wires, steel motor shaft to the impeller and sticky auto-on/off switches. I had a small bilge pump go bad in the Bahamas and when the water got to the large capacity pump - nothing happened. Luckily I carry a duplicate/alternate pump in storage for every installed bilge pump. The high capacity pump had never been used as the little pump worked fine. When I disassembled the high capacity pump the motor shaft to impeller was rusted through and jammed. I switch brands.
- - Using the little pump is great as they are relatively cheaper and when they quit the replacement is easy. Always carry spares!
- - Also spare water level sensors. They are also notorious for failing at the worst moment. So much stuff, oil, hair, nuts and bolts and strange sealife always manages to somehow get into the bilges and clog the pump or disable the on/off level switch.
- - For hoses I use the cheap white vinyl smooth wall. Never use corrugated hose - too much resistance to water flow. Also avoid translucent or transparent hoses. The sealife will growth wonderfully in those hoses clogging them up.

[GordMay]

Originally Posted by osirissail

- - For hoses I use the cheap white vinyl smooth wall. Never use corrugated hose - too much resistance to water flow. Also avoid translucent or transparent hoses. The sealife will growth wonderfully in those hoses clogging them up.

Indeed!

[Pete7]

What have you got at the moment? we put a jabsco waste pump into one of our manual bilge pump lines. Pumps 19 litres per minute so not huge amounts but it is a diaphragm pump so will cope with solids in addition to water. However the big advantage is that it was the same size pipe as the manual pump so fitted in series using existing fittings. Both manual and diaphragm have one way valves and either can be used without the other even in series.

50890-1000 Self-priming diaphragm waste pump 12 volt d.c. > Toilet Waste Pumps > JabscoShop - Jabsco & Rule Pumps and more - from the experts

We also have a small low profile auto pump in the engine bay which for us I think is the most likely area to have water enter the boat via the engine cooling hoses or stern gland.

We plan fit one more big pump for piece of mind but location is the problem, we only have 4" of bilge height being a twin keeler. Good idea on seperate circuits and different batteries switches etc.

[Tropic Cat]

Originally Posted by osirissail

......I had a small bilge pump go bad in the Bahamas and when the water got to the large capacity pump - nothing happened. Luckily I carry a duplicate/alternate pump in storage for every installed bilge pump. ....

Interesting. I had the same small Rule auto bilge pumps for years. 2 years ago they were blown out by a lightning strike. I replaced them with the same make and model Rule pump. Two engine compartments, and two pumps. Bought at different stores, at different times. Since then, I've had to replace them twice. They just stop working.

Has anyone noticed a deterioration of quality in bilge pumps recently?

[Pete7]

Sorry work pc won't let me edit a post.

One pump exits through the hull at deck level just forward of the mast having looped upwards to prevent back filling. Engine space pump drains into the cockpit so we can see instantly if it is running whilst sitting topside. If we are motor sailing I need to know if an engine hose has split. Final pump to be fitted will probably exit out the transom to avoid the lift to deck level.

Are you sure the Rule 3700 pumps 3700 gph? always an interesting question converting between US, imperial gallons and litres, but yes lots of nice big pumps, all separate incase it goes pear shaped and you are short handed.

Pete

[osirissail]

- - Again the real capacity of the bilge pump is not what is quoted on the pump - that is open circuit, zero rise, full electrical voltage/amps available. In real life I find the pumps put out about half of what they claim. For the manual pumps substitute "young bronzed well developed muscles 20 y.o." for the volt/amps.
- - I have found the "little" first level pumps fail reasonably often due to the odd junk and stuff that they suck in from the bilge. Then the motor jams and burns out. But they are relatively inexpensive and I carry 3 or 4 spares. I would rather jam/burn-out a $30 pump than a $200 larger pump. Plus the little pumps with their smaller hoses are easier to lift and clean than the bigger pumps.
- - Before a passage now, I crack open the lid on a sea-strainer and flood the bilge to see if the higher up bigger high capacity bilge pump will operate correctly. Live and learn . . .