Kayak Livewell & Dry Box (Part 2)

In part 1 I covered the basic construction of my dual purpose kayak dry box/livewell.

The were certain features that I wished to have with regards to the livewell, these were as follows:

• Dual water level to cater to different sized bait
• Internal aerator pump to minimise noise
• Dual pump speed
• Easy pump priming when afloat
• On/off switch to be easily reachable
• Quiet overboard draining
• Alternative power source if required
• External battery charging point
• Ability to drain the tank when afloat

That potentially seemed a tall order, some may argue that it’s over-complicated, though it covered my potential needs. Plus it’s what I wanted, I like a challenge. It was potentially going to be challenging, and as it turned out, at times it was just that… and more!.

The basic design has already been covered, though here’s some additional photos that also show the later plastic blanking caps, on/off switch and external charging point.

 

  

On the lower front edge is a drain plug. This allows the livewell to be drained when afloat if required (roughly 2 litres of water will remain) or to be drained when ashore prior to lifting the livewell off the kayak.

The switch was originally going to be positioned on the top of the battery box, though after sitting on the yak I decided it was too much of a stretch. Having it on the forward edge seemed like a good idea, though I had visions of it being accidentally knocked on and off, plus it’d be potentially rather messy routing wiring towards the front. In the end I positioned in on upper rear edge, comfortably within reach.

The switch itself is a three position ON/OFF/ON item, fitted with a waterproof rubber cover. The idea of this three position switch was to allow the unit to have two selectable speeds as well as an off position.

The question was how best to achieve a useable two speed setup. Ideally I wanted full power 12 volt operation for filling the tank quickly, stirring the tank, or just whenever I felt the need. I also wanted a lower second speed for general use and to maximise battery life. The issue was more with the lower speed and what speed did I really need??.

I decided to incorporate and speed regulator circuit, thus allowing me to have the choice on what my lower speed would be.

 

As the speed regulator wasn’t a waterproof unit it had to located in the watertight battery box. Despite a few headaches this was eventually achieved. The main problem was with the circuit wiring, though it all came good in the end. It probably isn’t advisable to change this variable setting once afloat due to the location of the controller, though setting it mid-way will see the pump operating in the 6-8V region.

The photo below shows the wiring loom taking shape.

  

The cut out allows fitment of a either a 12v/7Ah or 6v/12Ah SLA battery. The pump operation can be switched between 12v (Max) and a variable speed (Var) via the three position switch.

I already have a 12V/12Ah fitted to the front of the kayak which powers my GPS, fish finder and stern light. As I expect the majority of the live baiting to take place during daylight hours it seems a shame not to use the existing battery, which would also minimise the all up weight.

To this end I fitted a two pin marine connector to the side of the battery box. This has two main functions, it allows connection of the same charging adapter that I currently use for charging my main kayak battery. The allows me to charge the livewell battery in situ should i feel the need using my existing charging setup.

The second function allows me to connect a jumper lead to the rear light socket which is powered from the main kayak battery. This allows me to operate the livewell without actually having to fit the livewell battery. I could even fit the livewell battery and the jumper lead which would prove a huge amount of battery life, though I cant ever imagine the need to do so.

The photo below show the close proximity of the battery box connection point to the rear light socket. I’ve already proved the principle and I’m currently making a waterproof lead, sadly it’s not quite fully ready at this moment in time.

 

Next I’ll cover the plumbing, now this did also cause some stressful moments!. My initial plan was to have a short length of hose from the pump directly to the tankwell scupper with a non-return valve located within the scupper hole. I knew the pump would require priming and I’d measured that the amount with the pipe work and the pump was approximately 100ml.

I’d originally planned to use a large syringe with a short piece of flexible pipe on the end to inject water into the pump outlet thus backfilling the system. Let’s just say it didn’t work, basically it was badly airlocked due to the non-return valve and that plan was well and truly dead in the water!.

This totally messed up my plans, though with the container already drilled and the pump position low down I was kind of stuck. I decided to use a hand primer, similar to what you’ll find on outboard engines. I rigged this up which ultimately resulted in a large u-bend as the pipe returned to the pump. The hand pump is design for 3/8” pipe yet i was using 3/4” pipe. The pump itself could not move enough water to effectively remove the airlocks within the pipes, basically I was screwed.

Then at 2am (yes I was in the garage scratching my head at that stupid hour) I had a Eureka moment. The hand pump has an internal upper and lower non-return valve fitted internally. Being 3/8” they are also very restrictive on the water flow. I removed the valves and fitted a 3/4” non-return valve to the bottom the the hand pump. However, I positioned the upper (now 3/4”) non-return valve not to the top of the hand pump, but 1/2 way along the pipe between the top of the hand pump and the aerator intake.

In the photo below the hand primer and two non-return valves are visible.

This basically changed everything and allowed the small hand pump to easily push the airlocks through the 3/4” pipe work. The non-return valves also prevent draining of the tank when the aerator pump is switched off. The large diameter of the non-return valves also allows full flow of water through the pipes.

I also made two overflow pipes, one for the higher and one for the low level overflows. You can fit the pipe to suit the level you want and leave the other blanked. The other option is the fit both pipes and to use a 1” bung to block the outlet you don’t want from within the container. This allows you the option of changing the water level when afloat in seconds.

The photo below shows the two overflow pipes and well as the pump feed pipe incorporating the hand primer.

Here’s the pump pipe fitted. All pipes are fitted in seconds.

The overflows were covered with plastic mesh on the outside face to prevent smaller bait such as sandeels escaping from the tank. The reason it was placed on the outer face was to enable the fitment of a rubber bung within the tank as previously mentioned.

The inlet to the lower non-return valve in the pump feed pipe was also fitted with a mesh cover to prevent coarse debris being sucked into the valves and ultimately the pump. There is even mesh on the pump outlet to prevent small fish from entering the pump when it’s switched off.

So, that’s basically the livewell aspects completed, here’s a few more photos to clarify the build and the installation.

Fitted and configured as a Dry Box

Fitted and Configured as a Livewell

 

The hand primer and valve assembly retain water very well with no visible draining with the pump off. However, the hand primer was positioned such as to allow easy operation when seated side saddle. Six to eight pumps are required to prime the system.

The pump intake pipe is effectively almost flush with the hull of the kayak, recessed by only a few millimetres.

The upper overflow pipe drains into the opposite scupper hole, with the lower drain exiting directly onto the floor of the tankwell. The internal pump and direct scupper drains should hopefully all minimise the livewell noise when in operation.

I’ve tried it next to the kitchen sink and it primes easily and works a dream. I’ll probably rig is tomorrow to see how long it will run on a medium setting of around 7 volts.

So there we have it, was it cheap??.. nope. I reckon is cost me about £100, though for a dual purpose container that’s no only durable but should be long lived.