Water as additional ballast

[Mike Waterhouse 1Participant @mikewaterhouse1]

Whilst testing the bow thruster for leaks yeaterday I realised I need a huge amount of extra ballast to bring this years project down to the water line. I've got 2 X 900 motors, 2 X 12 V 7 AH batteries and a 6 V 5 Ah battery for the bow thruster, so adding more lead will just make the boat too difficult to handle saftely out of the water.

I'm thinking of adding some sort of water tank arangement to fill via a hole in the bottom of the boat with a vent pipe on top to go above the water line. Put the boat in the water, push down until the tanks are full and plug the vent pipe to stop the water escaping back into the lake.

How would you inventive chaps seal the vent pipe or does anyone have a better idea from a tryed and tested method?

As usual all replies gratefully received.

Regards

Mike.

[Mike Waterhouse 1Participant @mikewaterhouse1]

[Trevor HollowayParticipant @trevorholloway99134]

My barge is free filling and draining, as long as the vent pipe is well above the waterline you do not need to seal it off.

Would be sensible to have the tank baffled to stop the water sloshing about. However if the tank is completely full there would not be any sloshing !

[Paul TParticipant @pault84577]

Mike

There are three different methods of water ballasting

The first is as Trevor describes where the tanks are free flooding with an open vent pipe, this isn't strictly ballasting as the model is effectively subject to a controlled sinking and the water level in the tanks changes if the model rolls or pitches in the water but providing the vent pipe is well above the water line the system can be very effective.

The second is as you postulated where the free flooding system has a sealable vent which, when closed uses external air pressure to maintain the water level in the ballast tanks, there are plenty of domestic plumbing fittings that can be used to create the pipework and sealable vent for this system.

The third is to pump fill the ballast tanks after the model is launched (and pump empty before recovery) this is my favoured system as I can use clean tap water as ballast as opposed to lake water. I take a few containers of tap water with me and fill the tanks from these and after use the ballast tanks can either be pumped empty into the lake of back into the containers.

I hope this helps answer you question but if you need any further details on the plumbing materials required to construct the sealable vent system please ask.

Paul

Edited By Paul T on 24/09/2013 07:16:59

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