Pearson Yachts Forum
Pearson Boats - Common Systems => Plumbing and Galley Systems => Topic started by: selene on October 17, 2011, 04:10:19 PM
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I currently have a single Rule2000 bilge pump, not automatic, which joins the cockpit drain on the port side (after it's venting loop). I am looking to add a second pump, with a float switch, bit higher than the first, as backup.
The question is - where to I route the outlet?
My current ideas are:
(1) out with the shower sump - stbd side. Only problem is that the outlet is a smaller bore than the pump (~3/4"? vs. 1-1/8")'; it would be a pain to change the through-hull.
2) Run it to the transom - the manual bilge outlet is on the stbd side, there is a covered-over hole in the same position on the port side. Put a new marelon through-hull there. Longer run - not sure where I would put the venting loop; it would have to be high enough so the water would go downhill to the thru-hull.
Any suggestions?
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Would appreciate any comments on how your bilge pump is configured....
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I recommend a completely separate discharge, above the waterline.
On Dolce Vita, the Whale Gusher manual pump, and the automatic Rule pump
both have dedicated hose runs to independent thru-hulls on the transom.
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Thanks, Ed! Incidentally, where is your venting loop for the Rule? I was thinking of epoxying a wooden plate to attach the loop right next to the manual/whale pump. Should be high enough. Then out the transom.
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With the discharge above the waterline, no vent loop is required, as a siphon can't start.
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Appreciate the feedback, Ed; I'll give it further thought. I read on another site:
"Even if the outlet is normally above the waterline, water may siphon into a heeled or well-laden boat, as mentioned previously. It may he driven up by following seas; or, in an otherwise calm anchorage, be forced up the pipe by repeated wakes from passing boats or water-skiers. This phenomenon is known as water hammer. I heard of an interesting case of this recently in which waves, deflected off a seawall, repeatedly hit the stern of a boat, eventually sinking it."
Of course this is not a problem with the valves in the Whale Gusher; probably not with the Rule routed out on the transom, either....just wondering what other folk do!
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I read on another site:
"Even if the outlet is normally above the waterline, water may siphon into a heeled or well-laden boat, as mentioned previously.
True, but that's why mine is on the stern, and high enough that it never goes under.
It may he driven up by following seas; or, in an otherwise calm anchorage, be forced up the pipe by repeated wakes from passing boats or water-skiers. This phenomenon is known as water hammer."
Quite true, but an anti-siphon valve won't help with this. Anti-siphon valves break open under suction, to stop the siphon. They close under 0 or positive pressure.
The check valves in the whale gusher would prevent this, but the bilge pump lacks any kind of valve, and would benifit from a check valve.