Elec Bilge Pump--Magnetic Reed Switch

I’ve posted on electric bilge pumps before, a year or two back. I installed one in my kayak. The pump was activated by a foot switch mounted on the forward bulkhead. http://www.basspro.com/Big-Foot-Trolling-Motor-Foot-Switch/product/16071/

This worked okay, but was not ideal and I’d like to replace it.

Recalling prior advice, what I should have used was a magnetic reed switch, mounted under the deck, activated by a sliding magnet, atop the deck.

Anybody know where one buys a magnetic reed switch suitable for this purpose? Oh, and I don’t want to buy in lots of 50 or more.

The big box stores sell them, sort of, for alarm systems. The sort of is that they are backwards from what I want. The alarm ones activate the circuit when the magnet is removed. I want one that activates when the magnet is present.


Seems costly
But bluewater has a system. It is possible that you could buy their switch from them and adapt it to what you have.


I haven’t yet found a switch, though I suspect they are out there.


Why not
just use a high-quality switch with a waterproof boot? This would require drilling a small hole in your front deck for the switch to go through but it would be cheaper and simpler.

gnarlydog would be our resident expert
He has done quite a bit with electric pumps and waterproof switches.



– Last Updated: Jan-29-13 12:06 AM EST –

In the process of installing an electric bilge pump. Using a Rule 25D 500gph pump. Some installs use a reed switch with relay. I chose to get a bigger reed switch so no relay needed. I used two for extra reliability in parallel.
Iam also using a Lipo battery as its lightest you can get. Needs special charger but I have several since I use lipos on my radio controlled planes.

The switch I bought is here, rated at 3amps.Incase the switch or switches in epoxy.
I see my direct link didnt work its part
# DRR-129 67-73


For more info on istalling a pump with links to parts used go here.I got alot of good info off this site.

Automatic Pumps?
I am thinking about putting in a powered bilge pump in our kayaks as well.

From reading Gnarlydog’s post (near the bottom)- it looks like Automatic pumps may be easier in the long run (ones that use a sensor to detect resistance by checking every 20 seconds not the ones that use a float) - Don’t have to figure out the whole switch thing and don’t have to drill another hole in the hull for the button/wiring.

Something like this:


Let us know how it goes! Pictures of the process would also be greatly appreciated :slight_smile:

Great find!
That switch is a great find. Tsunami pump is rated at 1.5 amps, so the switch can do the job without a relay. I will order that immediately!

I have to replace my battery, too. What are you using?

Thanks for the link to the switch.


Rule autoswitch
I tested out the Rule-mate 750 in a bucket. The switch-less operation appealed to me. But it took a lot of water in the bucket to get it to turn on, and it turns off with more water in the bucket than I wanted to have in my boat.

The 750 is a different pump than you are talking about. There is a pump that turns itself on periodically, senses whether it is doing any work (lifting water) and turns itself off if not. That might work better, and maybe that is your pump. The 750 has some electronic wizardry that sense water beside the pump through some sort of electronic field sensory device–bad explanation, I know. But, I don’t think it is suitable for kayaking, and it also would not fit behind the seat in my kayak where I wanted to install it. I still have it–let me know if you’d like to buy it half price.

I take my kayak on extend trips, and I didn’t want the one that turns itself on to discover water. I feared it would run down the battery while I was away from recharge capability. Perhaps the power drain is insignificant and my fear was baseless, but that was my reasoning. Also, I don’t have a check valve in my pump outflow, so there is always going to be a tube full of water that runs back into the boat. Would that be enough to make the pump think it needed to pump again, and if so, it would cycle endlessly, because there is always going to be that last tube of water.


I think
FE developed this jet pump that empties a boat in about 1 minute.

Check Valve
Would it be fairly easy to add a check valve? I’m no plumber, but I’ve seen simple versions of various ID/OD.

I bought this battery
I bought this battery


It requires a Lipo charger. I use this one for my planes now, http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11060

I haven’t yet finished my install but from what I found out from others is that some have used as small a 2amp batteries and some as large as 5amp. So I went with a 3.3 amp one. Its a little higher voltage but I know the Blue water system also uses same 4 cell type lipo on there Lipo version so not expecting any trouble with a slightly higher voltage battery.

As far as an auto pump that would annoy the heck out of me with a pump turning on every so often. Plus I want to be able to turn it on when I want. Plus if I do have water in the boat how can I spray fellow kaykers unless I control when it turns on, he he.

The Magnetic Reed switch is a piece of cake to make. I bought some small magnets off of ebay for a few bucks.Glued those into a small plastic cap, drill whole in it to attach to deck rigging. For better instructions look at what I posted above with link to another website were he shows the whole install.

Pump manufacture recommend NO check valve should be used.From what I have found out its not a big deal and some put a loop on the bilge hose to stop any water coming back into kayak. I will use a loop in the hose.

Battery immersion?
Are you putting that battery in a dry box?

One of the other site references in this thread was to a northwest paddlers page with a parts list. It also specified an LI battery pack, albeit beefier. I checked with the manufacturer of that battery (Tenergy Li-Ion 18650) and was told it is not for immersion.

I was using an SLA battery. Maybe water was what killed it. But I use a different SLA battery in my whitewater boat and water hasn’t killed it. I thought the S was for sealed.

I like the idea of a battery that weighs less than a pound! Even in a box it beats the battery I was using, which was 4 - 5 pounds.


I have had poor results with magnets and reed switches. It seemed to take a lot of fiddling in order to get it to work properly every time.

I have made two eletric bilge pumps using toggle switches and a rubber waterproof cover. I purchased the stuff from Radio Shack, but it’s not exclusive to Radio Shack. The toggle switch is similiar to what you would install on a dashboard after drilling the proper sized hole. The rubber cap looks like the rubber part of a medicine dropper. It screws on to the toggle switch. The toggle switch can be mounted anywhere you want, just avoid places where you could hit it by accident. For a battery box, I used a small pellican waterproof box and penlight batteries. This relatively small pump would run for about an hour. As I recall, I used only 6 penlight cells, which provided only 9 volts to the 12 volt pump. It pumped water a lot faster than a hand-pump. I mounted mine behind the seat in my fiberglass kayak and a thru-hull fitting was on the deck just behind the seat.

Where to put a toggle switch?
I am pleased with the toggle switch/boot arrangement in my whitewater canoe. I have it mounted on the front of the saddle, so I can just reach down between my legs to activate the pump. Up is on, down is off, so I don’t turn it on accidentally when I put something down in front of me.

But I can’t imagine a place on the front deck where a toggle switch will not be in the way. Maybe off to one side next to the attachment point for the deck bungees. I imagine hitting it with the paddle. I imagine it being in the way when practicing rescues, emptying others boats, just this thing sticking up on the deck that I think will be irritating.

The magnet will stick up a little, but at least you can move it from one side to the other if it is in the way at one time or another. And it is not a fixed and rather delicate promontory on the deck.

So, where exactly do you mount your toggle and what has your experience been with being annoyed by it being in the way?


my findings on bilge pumps
apart from what I have published I will also say:

  • “waterproof” toggle switches were waterproof for a short time (well it all depends how much I used that kayak) and then they failed on me: torn/deteriorated rubber booth

  • some reed switches are not turning on (latching) well. I test a few to make sure that the one I will use on my kayak works fine. It is what I get for paying pennies for something that should cost more. Cheap, good… pick one

  • I use the smallest SLA 12V battery available locally (1.2Ah) which gives me tons of water pumping, really. I think I would have to empty my flooded cockpit 100 times to flatten the battery. That’s a lot of “falling in” something that even the most klutzy/unskilled person will probably never experience.

  • if my battery was NOT in a waterproof case its life was short, sometimes very short. Flooding of the compartment where the battery sits is a possibility; a waterproof case is cheap insurance.

    -My attempts to position the battery in the cockpit (not day hatch) failed: I could not find a really waterproof case (for the pressure a flooded cockpit in surf experiences) that is also ventilated for battery use.

    Of course YMMV

Yes in Pelican case
Iam mounting the battery inside a Pelican 1039 micro case and the whole thing will be inside my day hatch thats also water tight. But if water should get in day hatch even though none ever has the battery will be in a water tight Pelican micro case. I wouldnt want the battery to get wet. Also my inline fuse will also be in Pelican case which is were I will do all the sodering of wires. Only connections that could get water on them are at the pump itself which I will soder the connections and cover with shrink tubing.

So when battery needs charging I will open Pelican case unplug connections remove and charge. Lipo battery can be balanced charged in about 30 minutes.

Thanks, GD
I think you advised back in '11, to go with the magnetic reed switch. Wish I’d listened.

My day hatch is better now, but used to regularly take on water. Never enough to submerge the battery, but the plug between the battery and the rest of the system probably got wet. And the + and - are only a half inch away in the plug, so I could well have had some current leaking there. This time around, I’ll put the plug with the battery inside the otter box I just ordered. Hopefully, I’ll have better results. Plus, the major leakage into the dry hatch has been addressed, so that is much less of an issue now.

Thanks for the tip about checking out the switch prior to installation.