Re: [Paddlewise] Electrodynamic hydropurgation devices

From: Peter Treby <ptreby_at_ozemail.com.au>
Date: Mon, 31 Jan 2000 17:19:19 +1100
Bob posted:
>...Laurie Ford ..."As for electric pumps - in the last 20 years there is
only one type that I would recommend, and I have tried out several >others.
The RULE 500 (used to be 400) is the only one that never gives any trouble.
Others have had he  impeller >disintegrate, or the housing develop
leaks...."

Thanks, I knew that the legendary Tasmanian had said this somewhere, it may
also be on the Maatsuyker Canoe Club's website
http://www.tassie.net.au/~lford/. This is worth a look. Plenty to say about
pumps, sails, rudders and a good rave about paddling philosophy.

 >I wonder if twoRule 500 pumps connected to two separate batteries and
switches would be a solid system, despite the weight?
>They would probably be a solid system, but the weight of the batteries in
an otherwise empty or near-empty kayak might begin to affect the trim of the
boat, with resulting differences in weathercocking and such.  In any case,
I'm not sure that  the 2-minute gain would amount to much advantage.  After
all, the hands-free activity of the pump allows the paddler to manage the
boat defensively while it is emptying, and that's the main thing.>

Quite right, one is enough, but if 4 AH batteries are used the weight might
be bearable. At the moment I have a heavy 7 AH battery, too heavy in fact,
overkill. As I usually carry too much even on a day trip, bivvy bag, excess
water, etc., the mass of another Rule 500 and battery would hardly be
noticed on one of my bad boat-stuffing days. My paddling partner was amazed
yesterday when he suggested a stop and coffee on a sand bar, and I was
unable to offer the stove and coffee making equipment! That won't happen
again!
The thought in having a second electric system was backup against failure,
as well as double quick pumping.

 >When using the electric pump, as the water is pumped out a vacuum is
created in the cockpit space causing the spray deck to suck down. I open a
gap in the body tube of the spray skirt to relieve this and keep the pump
going at full capacity. This wouldn't be possible if both hands are on the
paddle working hard. Has anyone tried a small hole in the deck to get over
this?
The hole would be small enough to only let in a few drips, perhaps like the
bulkhead holes described in other posts which relieve pressure variation in
bulkhead compartments and stop rubber VCP hatches bulging.>
| Has this been a serious problem for you?  I'd imagine that a quick "burp",
accomplished by partial lifting of an edge of the spray skirt for a second
or so, would be sufficient to relieve the vacuum.   In most instances, one
wouldn't have a full cockpit and still have the spray skirt on.  I guess the
most likely scenarios for this would be after a re-entry and roll or any
other kind of re-entry (assisted or otherwise) in surf, when the paddler
would need to replace the spray skirt before pumping out.|
 Bob V

Right again, it's not a serious problem, a burp of the spray skirt does fix
it. The pump goes chugging on even with a vacuum to fight, as some air
enters somewhere. But it would be good if that wasn't necessary. Last winter
here, I had exactly the situation you refer to, a capsize, re-entry and roll
in surf which had wiped me out into cold water, leaving me in an unstable
flooded cockpit facing another pummelling and capsize. I've thought about
the many lessons of that day ever since. They include:
1. A reliable roll is a necessity.
2. A good spray deck is also a necessity, and must be able to be fitted
quickly, before the next breaker.
3. A pump system must be hands-free and quick. I haven't yet seen a system
which will empty a cockpit to low stable levels in the time it takes for the
next breaker to arrive, which would be ideal. Of course, the cockpit volume
has to be minimised to help the pump along.
Regards, PT.

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Received on Sun Jan 30 2000 - 22:25:37 PST

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