Live Bait Tank.

Decided to build a live bait tank for the new tinny… but wanted to do it on a budget of 300 bucks and also wanted to make it fairly easy to remove if not needed.

Electronics and Computers is my game so this one is a little different.

In the past, pumps I have used to my mind have been too fast even at 360 gph which seems to be the smallest available. I have long thought about 100gph would be ideal so devised a way to slow the pump down without losing the grunt of the pump at slower speeds.

The plan was all drawn out on paper and the biggest problem I could foresee was how to get the water out of the live bait tank without building some sort of pedestal for it to sit on so as to use gravity to out flow water into the outboard well . To do so would mean I couldn’t then use my bait board with rod holders and another idea came to mind.

Plan now was going to use two equal size pumps (600gph) with 2 amp draw on each and use a single 10 amp speed controller to adjust the speed of both simultaneously and therefore, flow of water to achieve the desired 100gph in and out..

This should also preserve battery power at the slower speeds…

I also decided I wanted the out- board pump to be able to be used for a wash down pump to clean up at the end of the day..

Time to get all the gear together…  one 600gph aerator pump to fit to the swim step attached to the transom to pump water into the tank and also for the wash down unit… hose 19mm and s/s clips for each end of the two metre hose .. one 19mm switchable ball valve

one hansen 19mm T junction for inlet on tank .. one double threaded through tank fitting to fit all the inlet gear and allow aerated water to flow into the tank..

The wash-down hose will be connected to this outlet once procured..

Turn the tap to run the wash down hose or to run the livie tank..

 Now for the outlet side..  in the past I have used 1.25inch for a gravity fed outlet as its desirable to have the outlet bigger than the inlet but because the water flow was going to come in and out pumped at the same speed , I once again used 19mm hose and fittings ..  one 600gph bilge pump for inside the tank..

one threaded elbow with hose fitting on other end .. one 19mm threaded unit to go through the tank wall and a short piece of 19mm hose and two s/s clips to hold the pipes on.

On the outside of the tank is a 5 foot length of pipe connected to the through fitting at one end and then to the back of the boat connected to a through hull fitting with another s/s clip to hold it in place.

Now if you connected both pumps to your battery it should, in theory , pump water into the tank and out of the tank simultaneously but at a great rate of knots, changing the total 55 litre water content in about 73 odd secs..  Now to slow all this down.  drastically.

Attached / bolted to the front of the tank are two water proof boxes to house the electronics and batteries (fused) .. On the front of the battery box is a s/s boat connector which is attached directly to the battery terminals  and will allow easy exterior charging of the batteries and also have the ability to connect another battery to power the livie tank for an extended period of time. The positive and negative wires run from the battery box to the controller box and is connected to the speed controller..

The speed controller is mounted inside its housing and both pumps positive (switched) and negative are connecter to the speed controller output.

(This pic was taken before the two pump switches were added   will update when I take a new photo}

A switch on the front of the controller box simply turns the system on and off  and a second switch turns the pump inside the tank off  allowing the tank to fill from the transom mounted aerator pump. When the tank is full to the desired level ,this switch is turned on and allows both pumps to work simultaneously again..  the third switch turns the inlet pump off allowing you to empty the tank when you need to head home..

Now the pump speed can be controlled by the variable potentiometer also mounted on the face of the controller box..

It is capable of a simple trickle of water to 600gph or to the desired 100gph.. about 7-8 mins to change the water out..

This can be simply switched on or off to aerate and change the water as you desire…  I am yet to test this unit out on the boat and did not consider a scoop under the boat as there is no way to expel the water unless the inlet pump is turned off just leaving the tank pump to do that job..  It could be done by just adjusting the outlet flow equal to the water collected by the scoop unit and marked at a certain boat speed for quick setting so incoming and outgoing flow are the same.. Maybe at a later date.. but as it stands, the housed batteries should last about 3ish hours continuously running so periodically turning it off and on will extend that time.

Add an external battery to the cables and no problems for a full day running..

Some parts were obtained from the “Will use one day box” and a second hand 55 litre tank was procured from a fishnet member…  Most connections were “Hansen”  and the hose, s/s clips, through hull fittings , pump were obtained from Torpedo 7 at one of their sales.  Trademe was another outlet for some parts esp the aerator pump..

I’m at 272 dollars and still have to procure a coiled hose and hand-piece to fit to the tank tap for the wash down hose

BTW…  Any livies left at the end of the day are returned to the water as they have earned their right to swim freely again.