T&T: Fw: Bilge pump sizing

[Larry N. Brown]

> i currently have 4 x 2000 + 1 3600 on my 53 footer... planning on adding 
> at
> least one more 3600.
>
> Pascal
> miami, fl
> 70 hatteras 53MY
> live helm cam @ www.sandbarhopper.com


Pascal has a good layout- multiple pumps with remote alarms on them.

I suggest that any time you are designing or rebuilding systems on a boat 
you go to David Pascoe's website: http://www.yachtsurvey.com/ You can find 
articles from why windows leak and what to do about them to electrolysis. 
Here's his article on bilge pumps: 
http://www.yachtsurvey.com/bilge_pumps.htm

A few weeks ago I detailed Cigano's bilge pump system which was laid out 
using Pascoe's logic. Three Rule 3700's with float switches and alarms in 
the FB, mounted 1 1/2" above the bilge, and one Rule 1100 as a maintenance 
pump mounted in the bilge low point. All are on separate power sources.

Another point that Pascal mentioned but which I don't think he emphasized 
enough is head height. That Rule 3700 quickly turns into something less for 
every inch you push the water uphill.

Another point is illustrated by a fellow listee's boat sinking in his slip 
recently. He had no siphon breaks and the thru-hulls were not very far above 
the WL. Boat was heeled over enough to submerge them. When the boat took on 
some water during a rain storm, the pumps dutifully pumped the bilge dry but 
when the float switch shut them off, water immediately began to siphon back 
in. He still would have been OK but there was a power failure and the 
batteries finally went flat and the boat went down.

Moral: One little workhorse pump with float switch mounted low, lotsa big 
pumps with float switches and remote alarms mounted higher, hoses with 
siphon breaks and through hulls installed well above the WL. Oh, try to have 
as many different power sources as possible.

As for 120vac, big box, basement pumps, there's no savings over a 12 vdc 
bilge pump. I shopped this very idea at Lowe's and to get north of 2500 gph, 
you quickly get over $150. Check out the Rule 3700 for $129.99 here: 
http://www.boatbandit.com/rule-3700-pump-4143.aspx

Regards,

Larry and Teri
M/V Cigano, 47' Prairie Sundeck Cruiser
Lying: Covington, LA
N 30 26.7
W 90 07.1