[C320-list] Electric Bilge Pump Inline Filter - Good Idea?

[Warren Updike]

I can think of two reasons for installing a second bilge pump: 1) as a
backup in case of failure of the primary; 2) to provide a greater capacity
in case of hull breech. Here, I address the case with the (older) shallow
bilge as that is the only configuration with which I am familiar.

As a backup, it might not matter where it is placed. It might even be
accommodated in the space where the primary is located with its own switch.
As a second pump, it would operate in tandem with the primary. I have heard
it said that having the switch located higher would allow the primary to run
alone until the water level were high enough to activate the secondary pump.
I am not addressing the matter of how to direct the outflow of the secondary
pump.

For the second reason, it might not matter where the secondary pump is
located as the purpose is mainly to apply a much greater capacity for
emergency situations. It probably should be located, or at least the input
end of the hose and switch located, at a point where it would be activated
well before a critical point would be reached. For that matter, if
self-priming, the pump motor could be located in the most convenient place
for power and discharge. In this application, the total pumping capacity of
both should be greater than the inflow occasioned by the breech of one
thru-hull, allowing that the priming head were not exceeded.

It seems to me that an emergent situation of flooding has, as does the crew
overboard situation, so many variables in circumstance that to cover all
with a single solution would be daunting to impossible. Consideration must
be given to the situation where people are on board or not, trained to
respond or not, and what is the nature of the cause. 

In summary, know the condition of your boat, and keep thru-hull closed when
not aboard.

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62


-----Original Message-----
From: Ade Bateman [mailto:lists at adrianba.net] 
Sent: Monday, November 16, 2015 9:09 PM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Electric Bilge Pump Inline Filter - Good Idea?

On Friday, November 6, 2015 8:17 AM, Warren Updike wrote:
> Note for the older models: in 1995, the bilge design was changed from
> "shallow" to "deep." As I understand it, the "deep" bilges have the pump
> sited outside of the actual bilge in which case a filter would make some
> sense. Even just some screening secured with a wire tie would suffice. In
> the earlier "shallow" bilge, the pump is in the bilge mounted on the hull.
> Even here some screening around the pump intake could help prevent stuff
> getting to the impeller. That said, we have the "shallow" bilge with no
> screen/filer and have had no problem with the impeller fouling.

Has anybody fitted a secondary bilge pump in a shallow bilge boat? This
thread and some of the other recent bilge pump threads has got me
thinking but I'm not sure where to mount a secondary and where it would
draw from.

Cheers,

Ade.