Bilge Pump Wiring

Electrical and electronic topics for small boats
jmich001
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Bilge Pump Wiring

Postby jmich001 » Tue Jan 03, 2023 9:15 am

I have a 2021 170 Dauntless with a single battery that I keep on a boat lift. The automatic bilge pump only works with the battery switch in the ON position; the pump is not wired to a constant 12-Volt power source.

Q1: should a bilge pump be wired to the battery via main ON-OFF battery switch?

padrefigure
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Re: Bilge Pump to Battery

Postby padrefigure » Tue Jan 03, 2023 9:36 am

jmich001 wrote:Q1: should a bilge pump be wired to the battery via the main ON-OFF battery switch?
Probably not.

Most would consider connecting the bilge pump to a constant, un-switched 12V power source the correct wiring. In your case, you are on a lift, so maybe you are not concerned with the boat flooding while it is unattended, but windblown rain or some other freak event could flood the bilge and the pump would not clear.

By wiring the bilge pump to the switched circuit, you are protecting the the bilge pump from a false-ON condition, saving the bilge pump. I think I would rather run the risk of draining the battery to prevent the boat from flooding.

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Phil T
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Re: Bilge Pump to Battery

Postby Phil T » Tue Jan 03, 2023 1:16 pm

If you have the boat on a lift then PULL THE PLUG. It's #6 on the figure below.

hulldrains.jpg
Fig. 1. Page 2-7 from the Owner's Manual for the boat under discussion.
hulldrains.jpg (75.96 KiB) Viewed 4227 times


Source: https://www.bostonwhaler.com/content/dam/boston-whaler/technical/owners-manuals/BW-170-DAUNTLESS-2021-OWNERS-MANUAL.pdf

If you rely on the pump and your battery fails, there may be a larger problem.
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jimh
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Re: Bilge Pump Wiring

Postby jimh » Tue Jan 03, 2023 1:22 pm

As PADRE mentions, there are two schools of thought about how to wire a bilge pump with regard to unattended or automatic operation.

If you want to bilge pump to be able to operate at any time, then you have to wire the pump directly (through a fuse) to the boat battery, and avoid the main power switch.

If you want to be certain that the bilge pump will NEVER run when the battery switch in in OFF, then wire the pump as part of the loads that are switched by the main battery switch; that is what you seem to have now.

I assume that the boat on the lift has been rigged so the stern is lower than the bow. This is the preferred arrangement for a boat on a lift. With the stern lower, any rain water that comes into the cockpit or other open areas of the boat will run aft and collect in the cockpit sump. If the sump pump is not able to lift that water overboard, then water will rise in the stern of the boat at a rather rapid rate because the collecting area is probably quite large.

Regarding the risk of the aft cockpit of your boat collecting rain water, that worry can be eliminated by unplugging the sump drains when the boat is on the boat lift and raised out of the water. Of course, then you have the bother of having to put back in place the drain plugs before you use the boat.

Phil T wrote:If you rely on the pump and your battery fails, there may be a larger problem.
As Phil alludes, for a boat with only one battery, coming to the boat for a day of recreation and finding the boat battery has been drained by a bilge pump that ran too much and too long will be quite a disappointment. Generally any lead-acid battery whose state of charge is drained to the minimum will suffer a shorter service life. In my own experience and behavior, any lead-acid battery that is a few years old and has been subjected to a very deep discharge has become a liability. I don't trust batteries like that in any sort of critical use; and I consider being able to start an engine to be a critical use.

One perspective on this question can be found by looking at how the boat came as wired from the factory. The boat is a Boston Whaler boat made just two years ago, so it ought to represent the best thinking from Boston Whaler.

jmich001
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Re: Bilge Pump Wiring

Postby jmich001 » Tue Jan 03, 2023 9:06 pm

I just read the owner's manual. According to the owner's manual the bilge pump should be wired directly to battery by the factory.

A previous owner of this boat stored it in an indoor slip. Maybe he changed the wiring.

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Re: Bilge Pump Wiring

Postby jimh » Wed Jan 04, 2023 8:30 am

jmich001 wrote: According to the owner's manual the bilge pump should be wired directly to battery by the factory.
I see that the owner's manual has a schematic wiring diagram at page 4-8. The wiring diagram shows the circuit that powers the bilge pump is wired directly to the battery.

Also, in order for the boat to have a main ON-OFF battery switch, the diagram indicates the boat must have been ordered with the "Battery Switch CE Option." I believe here that "CE" refers to being qualified to European standard for commercial products. Even with the "Battery Switch CE Option" on the boat, the power for the bilge pump still comes directly from the battery.

Compare at

https://www.bostonwhaler.com/content/da ... MANUAL.pdf

If your boat has the battery switch option, then to revert to the original wiring you would locate conductor 192-14RED and move it back to the "1" terminal on the battery switch from the "C" terminal. See drawing marked Figure 4.9.2 for details. Here I am presuming a previous owner moved the conductor 192 from terminal "I" to terminal "C" on the battery switch to make his unscrupulous modification.

jmich001
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Re: Bilge Pump Wiring

Postby jmich001 » Wed Jan 04, 2023 6:50 pm

Thanks for the help. I will be charging the wiring so the pump circuit is wired directly to battery.

jimh
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Re: Bilge Pump Wiring

Postby jimh » Thu Jan 05, 2023 11:26 am

The Boston Whaler drawing notation of conductor "192-14RED" means there is an identification number attached to the wire that labels it as "192", that the wire insulation color is red, and that the wire gauge is 14-AWG. This should very unambiguously identify that particular conductor for you.

RocketMan
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Re: Bilge Pump Wiring

Postby RocketMan » Sat Jan 07, 2023 12:18 pm

Drains and scuppers can get blocked by leaves or other debris.

Add a solar charger to help keep the battery charged.

Then [unclear, perhaps meant to say "connect"] the pump directly to the battery.

[Something will] help keep it charged,

[You will] not have to use [the pump] unless the drain is blocked.

Jefecinco
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Re: Bilge Pump Wiring

Postby Jefecinco » Sun Jan 08, 2023 10:55 am

The boat under discussion is stored in a boat lift which is very likely powered by AC power from the grid. A solar battery charger would seem an unnecessary expense when a standard AC powered battery maintainer could be used.
Butch