Fitting Bilge Pump to Delphin 155

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Allan Olesen
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Re: Fitting Bilge Pump to Delphin 155

Post by Allan Olesen » Mon Sep 11, 2017 5:53 am

A new observation which may be a reason for abandoning the idea of a non return valve:

This weekend we trained scoop rescue. I was the last "victim" in row, so when I was rescued and my cockpit was almost completely water filled, I just strapped on my sprayskirt and started paddling with the group, letting the pump do its job. (A very satisfying feeling, by the way!)

While I was paddling, the vacuum in the cockpit became so high that the sprayskirt was sucked almost to the bottom of the kayak. Suddenly, I heard a quite forceful swooshing sound as air was sucked into the cockpit, and the sprayskirt returned to its normal position.

At first I did not realize where the incoming air had come from - I actually thought that the vacuum had been large enough to burst my sprayskirt somewhere - but then it occured to me that it was of course the pump which had stopped pumping and the air was being sucked backwards through the pump outlet.

If I had had a non return valve in my outlet hose, I would have had to vent my cockpit manually by releasing the sprayskirt.

Eventually, the pressure would of course have been slowly normalized through whatever leaks I have may have in the sealing between the sprayskirt and cockpit coaming / drysuit. But that could have taken a very long time, given that the slow pump was able to create the vacuum in the first place. (Again a very satisfying feeling, by the way: It seems that my Snapdragon sprayskirt works!)

seawolf856
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Re: Fitting Bilge Pump to Delphin 155

Post by seawolf856 » Wed Sep 13, 2017 1:32 pm

Haha, good point Allan. I was talking to a couple of old sea dogs on a beach on the Menai straights about my pump install. They both had pumps fitted and strangely enough, warned me about having to 'crack' the sprayskirt to avoid a vacuum in the cockpit. To be honest I found it a little difficult to believe that such a small pump would create a vacuum but when I thought about it, it is pretty obvious that the volume of water being removed from the cockpit is considerable and has to be replaced by air at some point or a vacuum will indeed be formed. Thanks for raising the point, I will hopefully remember to crack my sprayskirt as I paddle away with that satisfied smile on my face.

Phizz4
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Re: Fitting Bilge Pump to Delphin 155

Post by Phizz4 » Sat Oct 07, 2017 8:41 pm

I haven't read all of this thread so apologies if I am covering points already made. I have been using a Yuasa 1.2 amp hour gel battery but, as it sits inactive for quite long periods (due to a rubbish summer) it has come to the end of its life. I have replaced it with a set up from Mark at https://www.mtbbatteries.co.uk/ He happens to be local to me and I was able to collect but he does a pretty rapid mail order service. I got him to link three Panasonic 18650, 3400 mAh together in series to give a 12 volt output. The battery pack, plus a dedicated charger, cost £41. Much lighter than the gel battery, much longer run time and can withstand long periods of non-use so long as they are maintained at about 50% charge. I've now fixed my pump and switch in place with marine adhesive and soon I will pluck up the courage to drill the deck and sort an outlet for the hose like Douglas has done. For the moment my Reed spraydeck has the optional bale hole in it.

seawolf856
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Re: Fitting Bilge Pump to Delphin 155

Post by seawolf856 » Wed Oct 11, 2017 2:17 pm

Hi Phizz4, welcome to the biggest thread you are likely to see. That is for a very good reason. I would recommend you read this from top to bottom and also any associated threads on electric bilge pumps, you will discover a whole world of really helpful tips and advice. You will also discover that there is no one simple solution to fitting an electric bilge pump to a sea kayak.
With regards to batteries, my battery is the most expensive component of my system. I use a Lion 12v 10mAh unit from Tracer and it has been brilliant. I chose a Lion battery for the size and weight advantages. I know Lion batteries need a little bit of looking after but they are small and light and the 10mAh has emptied my boat dozens of times (training days) without having to be recharged. I can also use it to recharge my phone/GPS/head torch etc using a neat 12v accessory plug.

Good luck with the final part of your install. I've posted a couple of photos of my system, including the scary drilling the deck moment. Let us all know how you get on.

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