Saturday, July 26, 2008

My Adventures In Foot Pumps

*DISCLAIMER*: Impex Kayaks takes no responsibilty for the information contained in this artical and in no way suggests that you modify your Impex Kayak. If you choose to do so it is at your own risk and may void your warranty.

No with that out of the way. Check out this artical submitted by Ward Swann.

Author: Ward Swann


I have wanted a foot pump in my kayak since I first started studying the sea kayak. Derek Hutchinson’s book convinced me. Not having to hold my skirt open and take my hands off my paddle to operate a pump in conditions that had caused me to tip over and blow a roll in the first case just makes sense. While I have had a boat with the chimp pump (deck mounted hand pump in an awkward position), most of my boats were bought with the idea of short term use (2-3 years). That promotes ideas of “oh I better not mess up the resale value,” or “if I knew that I was going to keep this boat for a while I would have ____ to the boat a long time ago” When I bought my Impex, Force 5 I was determined to make it a long term boat. It has the expedition layup and a ridiculously strong keel strip of Line-X armor. Now it is time to put in that long awaited foot pump.


To find out about this project I read old Sea Kayaker Magazine how to’s from the internet ( and posted “have you ever” questions. I also went to the companies that sell pumps and looked for Ideas. There are lots of good battery operated submersible pumps out there. They are even showing up in whitewater canoes now. But really, a person who chooses to think in “worst case scenario” mode will not want to rely on batteries. And let’s face it; nothing says “worst case” like anticipating the use of a pump. I choose to go with the Bosworth company guzzler 450 foot pump ( because it was half the price of the British made Henderson and MUCH easier to get. Plus the Bosworth site linked me to a really cool idea. There’s this company ( that makes various things that strike their interest. One of the things is a metal bracket for a foot pump. This bracket uses the foot peg tracks that are already in the boat to suspend the pump. That way I can do much less fiberglass work in deep dark places to support the pump and the pump will move with the foot pegs should I want to move them. The problem was that the company is in Australia and had no interest in shipping me the bracket. No profit. Fine, I’ll make my own.

Well, my bracket didn’t turn out quite like theirs.

The Order

The guzzler 450 suited my interest because it was supported half way down the side rather than from the base. By being supported as such I could finesse its position relative to my feet better on the tracks. One could modify it at the manufacture in several ways but I followed the standard recommendations, save only that I wanted the duckbill valves for grit tolerance and light weight springs. Since I am one to believe that more is better, I was tempted to keep the mid weight spring or even beef it up to the heavy weight spring. That would have been a massive mistake. The lightweight is plenty strong enough. And given the effort it takes for the light weight spring, I think that I would have to jump up and down on the heavy weight spring to use it. .
It took them about one business week to cobble the thing together and stick it in the mail along with the Pre-Pak. A Pre-Pak includes 10’ hose, 2 end cuffs and 2 SS band clamps. If they really wanted to make it a good Pre-Pak then they would include a through hull, some kind of strum box option and two more end cuffs. As it is the aspiring mad scientist is left to wander the halls of hardware and boating stores to find these items. Or, like a true mad scientist, you can make them yourself. I did both.

I approached this as a piece of interactive art rather than a feat of engineering. That is to say I had a pretty good idea of how it was to look at the end but I was open to better options along the way.

1. I wanted the foot pump to be adjustable fore to aft. At this point I feel the need to point out that the boat is a cone. Like an ice cream cone the distance at one area is different at another. This can be an intuitive understanding for someone with long legs and big feet. In this article the cone shape makes a complication.
2. The button (pump) should to be closer to my left foot for ease of access, but I wanted my right foot to reach it too. Besides, my right foot more often needs room to stretch than my left and the pump might get in the way.
3. It needed to be a natural arc with my left heel at the pivot point. That is to say that the button needed to be higher than the foot peg but not so close to the deck of the kayak that my toes would scrape the deck when used.
4. In emails to the Aussies of the above company I was convinced to put the through hull in the deck of the boat rather than at waterline like the Sea Kayaker article. I’m not sure that it makes a huge difference, but I do like seeing the water surge up.
4. I wanted the intake to be just behind the seat. I know this is the lowest part of the boat because that is the area that has been most scratched on the bottom of my boats save only the last 3 feet of the stern. Since I have size 12 feet there is a corner of the boat I never use. It runs right down the side just under the foot peg tracks. That’s where I put the hose.
5. I wanted unwanted water to easily find its way to the intake and then out the boat. After all, that is the purpose of the whole process.

With these principles in mind I started creating with no diagram at all. None. Zip. Zero.

Well, that’s not entirely true.

Making the frame for the pump

I started my fabrication from the pump outward, to do that I needed to create a template in cardboard. That was transferred to the aluminum sheet that I picked up at the hardware store. After drilling, messaging and cutting I created a foundation. I then positioned the left side with an arm that would not adjust. When I went to the right side the arm had to adjust. Where the arm fit to the foot peg tracks was going to be a slot of one going into the slot of another. On top of this is angled aluminum to prevent twisting/ rocking. Easy and adjustable right?

Amending the pump assembly

Putting the pump in was hard! Reaching in there to hold the pump in place and operate two wrenches had to have qualified me for defusing a bomb in confined spaces while upside down. On top of that, the pump twisted. Not the pump within the frame. The sheet of metal that fit in the slot of the foot peg track (as pictured above) did not fill up the space so the whole thing rocked back and forth. Plan B, get spare foot pegs, drill, cut and shape them to fit the pump assembly. Then slide them in past the foot pegs and mount the assembly to them. This provided a much more solid foundation but it took up more room thereby limiting the adjustability. Tip, if you try this, you must leave the fittings loose on both sides until you get to the right position. The conical nature of a boat will cause you to doubt yourself until it gets in the right area and everything is tightened down. Still, this was MUCH easier.

Installing the through hull

The boat’s not even a season old and yet again I am willfully taking weaponry to the thing. I was eager to get the drilling part of this over. It was inevitable. After taking a length of the hose that came with the pump to the “marina” to get the through hull fitting, I went to the hardware store(again) for a hole saw that would fit it precisely. To site the future hole I used a cheap-o laser to compare where the center of the hole was going to be from one side to the other (that is, a laser’s light was intense enough to see precisely through the hull. This kind of precision is important to be sure that you are not drilling into important things.). After drilling the hole and installing the plastic through hull with a smidge of marine silicone I was ready to connect the pump to the outside world by way of hose.

Making the strum box

To maximize the intake of the hose from the pump to the bottom of the boat you need a strum box. This is a device that puts the opening at the very bottom thereby minimizing how much air will get in the system. The hose I was using was the perfect size for a bottle from bottled water that I am one to have lying around. I cut this to shape, covered it with fiberglass and epoxy’d it. I then marked where I wanted to put it in the boat. And epoxy’d it down to that spot with two coats. The second one was to make it smoother. That way less sand will get into the grid of the Fiberglass. After it was Fiberglassed down I cut horizontal openings at the bottom to let water into the chamber. Then I put the seat back in.

Taking the seat out and modifying

Before I could do that I had to take the seat out. While paddling the boat before I noticed the possibility that water would collect in the seat and not drain out. Not relishing a prolonged wet rump, I decided to drill two little holes in spots that I would not feel them and would allow water to get to the pump area under the seat. The person who puts that foam under there at most manufactures doesn’t think that there might be an advantage to not putting foam all the way across the bottom of the seat. Unless there is a channel from the front of the seat to the back of the seat then it doesn’t matter what kind of pump I put in, water can’t get to it. So I cut into the foam a small channel that will allow water to move under the seat.
I also fiber glassed two loops onto the back of the seat for general principal. Twisted parchment paper holds the loop open while the epoxy cures. These loops may be used for the seat back or to hold something down in the future. It was just easier to do it while the seat was out.


gnarlydog said...

there are commercially available brackets ready to install in Impex kayaks (and others with Werner footrests) from Hybrid Australia.
If however the foot pump seems to complicated there is always the option of the electric bilge pump. Install details at

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