Forgive me for bringing up a subject that has been extensively talked about here. Up until now I'd never had any need to follow the electric pump thread very closely. But with the work progressing on a new kayak it's time to make a decision regarding a foot pump verses an electric. If I go the electric route I was thinking of installing a 500 GPH Rule pump powered by a 1.9 gel battery. Can someone make an informed guess at how long it would take to pump out a small cockpit (114cmX48cm) after a capsize re-entry and roll? I know, I should have paid more attention to those high school math formulas 30 years ago. As I have not got the bulk heads in yet I cannot measure the exact volume of the cock pit. The battery will power the pump for one continuous hour of pumping. Is that enough power? Do gel batteries have a memory? Should they be drained to absolute zero before recharging? And finally does anyone familiar with electric pumps have any battery recommendations they'd like to make? I was taken aback at the weight of some of these gel batteries. Please contact me back channel if you wish. Thanks Gordin Warner *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
>If I go the electric route I was thinking of installing a 500 GPH >Rule pump powered by a 1.9 gel battery. Can someone make an >informed guess at how long it would take to pump out a small cockpit >(114cmX48cm) after a capsize re-entry and roll? It is not the size of the cockpit but the volume of the hull's midsection that (in part) determines the pumping time. The volume can be estimated using the following equation: Volume = 3.14 * width * height * length / 4 You'll then need to convert the units into gallons to order to compute the pumping time: 1 U.S. gallon = 231 cu. inches = 3785 cu. centimeters For many production kayaks you can find the data here (this data is in liters: just divide by 3.785 to convert to gallons): <http://www.havkajakroerne.dk/links/survey.html> From that page, it looks like something around 150 liters (about 40 gallons) is typical. Using this value, pumping time will be around 5 minutes. These calculations neglect several other factors: 1) the kayak's midsection won't be 100% full of water; 2) the kayaker displaces some of the volume; 3) the pump's GPH rate is probably overstated. Brian *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 24 Sep 2003 at 12:48, Warner Family wrote: > If I go the electric route I was thinking of installing a 500 GPH Rule > pump powered by a 1.9 gel battery. Look at the Attwood 625 (or is it 650?) - more pumping capacity with better power demand (only 0.9A vs 1.9A). > Can someone make an informed > guess at how long it would take to pump out a small cockpit > (114cmX48cm) after a capsize re-entry and roll? Brian gave you an estimate, but I'd add that when I do roll and rescue practice, I rarely see the cockpit more than about 1/3 full in relatively calm water. A wave breaking over the empty cockpit could change this, of course. > The battery will power the pump for one > continuous hour of pumping. Is that enough power? You should only need a few minutes at a time. Assuming the regular Rule 500 (not the automatic) model 29-25D, it draws 1.9A. With a 1.9Ah gel cell, that's one hour to a full drain. Note that the Attwood I mentioned abouve draws only 0.9A in my kayak and would last two hours under the same conditions. However... > Do gel batteries have a memory? Should they be drained to absolute > zero before recharging? No memory, but never drain to zero. The gel cells should be deep cycle types, but even that can mean different things between types. The manufacturer should be able to give you the exact discharge characteristics. Yuasa, for example, has the spec sheets for their batteries online in PDF form. In general, if a deep cycle lead acid battery is discharged less than 20%, it should have maximum life. Some of the better batteries can be discharged to 50% repeatedly. Only a few can handle 80% discharge on a regular basis without seriously restricting their life. Best to assume that 50% is the worst case and design accordingly. IOW, if you think you need 1Ah capacity, get a gel cell battery that's 2Ah. For your 1.9Ah, assume a worst case of 0.95Ah available on a regular basis. This means the Rule will run for 1/2 hour and the Attwood for an hour. You will be stressing the battery somewhat, since it's max discharge rate should be a fraction of its capacity. The Attwood at c/2 is still high, but should be ok for occasional use. C/1 with the Rule is high. > And finally does anyone familiar with electric > pumps have any battery recommendations they'd like to make? I was > taken aback at the weight of some of these gel batteries. Consider a pack made up of 12 AA NiMH batteries in series (14.4V total). These can be discharged to 90% repeatedly with no loss of performance for at least 500 cycles. An average AA NiMH today is around 1.8Ah, so it would be even more powerful than the 1.9Ah gel cell after conservative use is considered. NiMH can handle C/1 discharge rates. The important thing about a AA pack is to make sure all 12 batteries are at the same state of charge. Never mix fully charged with partially charged in the same pack. In use, the partially charged will over-discharge and toast the whole pack. I can get 12AA name brand for about C$45. That's comparable to the price of a gel cell. In the US, they're somewhat cheaper. Get a good charger, preferably a "smart" charger that monitors each battery individually. BTW - the Honda Hybrid uses NiMH batteries. I believe that the Toyota does as well. Mike PS - here's a good web site on batteries. http://www.buchmann.ca/faq.asp *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I had a Rule 500 in a Romany for 2 or 3 years. Never measured the volume of the cockpit, but the pump would clear all but the last inch of water from a totally swamped boat in4 minutes. Bob Volin > >If I go the electric route I was thinking of installing a 500 GPH > >Rule pump powered by a 1.9 gel battery. Can someone make an > >informed guess at how long it would take to pump out a small cockpit > >(114cmX48cm) after a capsize re-entry and roll? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Gordin wrote: - >Up until now I'd never had any need to follow >the electric pump thread very closely. G'Day Gordin and Paddlewise, The advice on batteries and pumps and their care sounds good, though I'm suprised that Attwood now has a pump that is faster than the Rule. Just a point of view, its probably worth spending at least as much effort choosing a switch as the pump and battery. The switch is usually the weak link. It should be waterproof to some kind of verifiable standard (eg IP68). All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
[Moderator's Note: Content unaltered. Excessive quoting (i.e. headers/footers/sig lines/extraneous text from previous posts, etc.) have been removed. Please edit quoted material in addition to removing header/trailers when replying to posts.] Gordon, As a ham radio operator, I designed a charger for gel cells about ten years ago. I got all my data from the Powersonic web site (www.powersonic.com). I just checked and they have a technical manual on the site. I never discharged by 12 Volt nominal gel cells to less than 10.5 Volts. Apparently they have improved their technology, but check their manual.. No, don't discharge them before recharging. Mine are still going after 10 years of light use. If you keep it watertight and don't let the voltage go below their recommended minimum (probably several drain cycles), they will last a very long time. Their 2.3 and 5.0 AH gel cells (I had both) seem to be good choices. Regards, Steve Pituch "Warner Family" <hmgwarner_at_shaw.ca> asked: > Do gel batteries have a memory? Should they be drained to absolute zero > before recharging? And finally does anyone familiar with electric pumps > have any battery recommendations they'd like to make? I was taken aback at > the weight of some of these gel batteries. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Warner Family wrote: > Can someone make an informed guess at how > long it would take to pump out a small cockpit (114cmX48cm) after a capsize > re-entry and roll? I know, I should have paid more attention to those > high school math formulas 30 years ago. > I would guess 200 liters at most, to stay on the safe side. If you want to know exactly, try to find a sales brochure or internet description of your boat. With a bit of luck, it will state both the total volume of your boat and the storage room. Total volume - storage = cockpit volume. My own pump uses a lead-acid battery, good for 25 minutes pumping. By the way: TEST this, by installing the pump, filling the cockpit with water, and start pumping while keeping the cockpit about half full. Testing the pump out of the water will give no good indication of the power usage. My own 25 minutes of pumping will help me through 5 self rescues. That should do for a normal trip. Niels. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 25 Sep 2003 at 20:38, Niels Blaauw wrote: > Testing the pump out of the water will give no good indication of the > power usage. BTW - if you do test it (including power draw with a VOM), compare it to the rating for the pump. IIRC, the "standard" for rating is pumping against a three foot head. Since a kayak should have less than a one foot head, this will give you an idea of the rating's accuracy and you can adjust your battery size accordingly. It helps if you have a source (old car battery?) to test with before plunking down the money for the real battery. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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