Plumbing the outlet of a livebait tank

[steeevooo]

Hi all,

 

I'm guessing this question may have been asked, but keen for some experienced input on the topic.

 

Recently built a livebait tank out of an esky and bilge pump.

Haven't had a chance to test it out on the water yet, but testing it at home it circulates water well.

The plan was to sit it towards the rear of the boat in front of the transom, sitting on top of a frame.

 

Inlet hose from bilge pump coming in higher than outlet hose, which then drains out over the back.

 

However after some handy input from another Fishraider member (cheers Frank), I've come to realise that having the bait tank up high like that won't be ideal as the water will slosh around, (plus I did have possible concerns around the impact of higher centre of gravity).

 

So my question, for installing a bait tank lower down on a runabout, probably removing and replacing one of the rear seats, or perhaps just under it and the seat on top for when its not in use, what advice do people have for the outlet of the tank?

 

My plan was to just have the outlet gravity fed, draining out the back as the outlet was higher than the transom wall. But if the tank sits lower than the wall, how does the water get out?

 

Is it essential to drill a hole?

 

Haha not so keen on drilling extra holes in my boat...

Or maybe having a 2nd bilge pump could be an option to pump water out but seems a bit unnecessary?

 

Or would I be best off mounting something externally to the rear of the boat, where it can then drain out on it's own accord?

 

Keen to hear everyone's thoughts on this

Any advice welcome!

 

Boat is a 15ft Stessl, aluminium runabout.

 

[PaddyT]

Show a picture of the back of your boat-

[steeevooo]

Here are pics of the inside & outside:

 

 

[frankS]

Stevo. Keep in mind if you are talking about having the bait tank under the bait board you have to factor engine at full tilt so you would have to remove tank/bait board before tilting engine for transport on trailer.

If you are talking about having the bait tank where I suggested , port side where seat is now you could simply put a drain hole through side of engine well without too much fuss and have easy drainage. Could fit quiet a large tank in that space.

Frank

[Smobaby]

Externally would be you ideal option but there is nothing to take the weight fixings would be in sheer on an aluminium transom could cause problems. Don’t be afraid to drill holes into your hull done correctly with the right fittings and sika no problems. Keep your bait tank as low as possible this will help with the handling of your boat remember weight distribution is very important your boat looks pretty heavy at the rear already with full fuel and battery. Depending on capacity do a trial with it full and move it to different locations before cutting holes for drainage spend the time it will be worth it cheers David.

[steeevooo]

Thanks for the input folks!

Smobaby, not a bad idea to test weight. A valid point about weight at the rear also. 
I really would prefer the bait tank somewhere near the rear though...

I did consider relocating the battery to the front but was told by someone it's best to have battery not far from the motor for cranking purposes, not sure if this is correct?

If not, perhaps I'll relocate the battery. 
New motor is being installed in a few weeks, so now would be a good time to move it.

The more I think about this, the more I'm considering it may be best to have 2 rear boarding steps welded on, then I can have the bait tank resting on top of one of these.

Could be the best option for both saving space as well as for plumbing the tank. 

[steeevooo]

Hmm reading into it more it sounds like relocating the battery can have other drawbacks. 
Voltage drop over cable length seems to be the reason batteries being kept close to motors, which can be overcome with bigger gauge cable, but potential impact on top speed and fuel consumption if relocated to the front. Plus potentially shortened battery lifespan from banging around in chop.

Maybe I'll leave that until last, and see how it sits on the water and how easily it gets onto plane once new motor is fitted and bait tank running. 
 

[PaddyT]

I think Frank's got the right idea- port side corner- drilling holes in aluminium is no big deal (as long as there above the waterline!!) - this will be offset by the starboard driving position anyway- just think before you drill.

[frankS]

Stevo. In my 14 foot tinnie I have a 100 ltr tank sitting in front of the rear twart seat I have bilge pump filling tank and also have bilge pump emptying tank both are through hull type bilge pumps each has a switch to operate pump, you just have to remember what switch is turned on, both can run at the same time if you just want to refresh water but that's a bit of a waste of battery power. I have the outlet coming out the side of the boat just below the gunwale . most pumps are capable of pushing water uphill to approx. 600mill 1 metre maximum.

So you could have your tank sitting on the floor and still have the outlet going over the gunwale, engine well location ideal for outlet hose to be. 

I would recommend a tank no smaller than 50 ltrs if you intend to venture offshore.

Frank

[frankS]

I made the tank to follow the shape of the floor so it sits really low.

Frank