21 September 2009

Further thoughts on water ballast

One thing I experimented with again last weekend was the water ballast. Pumping out takes something under 15 minutes. That still leaves a reasonable amount of water in the rear tank that doesn't pump out. I would estimate 10-15 litres. I am sure that self bailers would help, and might even empty the tanks completely. The main time you might want to empty the tanks is when you are going to do significant motoring, and then self bailers would just do the hard work for you. The front seems to rise higher than the stern, so water should just drain naturally to the back. The whole boat rises 75-100mm out of the water when unballasted. I can't really say I notice any significant improvement in speed without the ballast. Motoring I may have got an extra 0.6kt, so could be worth while for a long drive. Sailing, I couldn't really sense any difference. If you were racing it could help, but for general cruising, I think I would say just keep the tanks full.
When she is unballasted, you can really push her high up a beach if you want to. I would think that if you were aground on a and bank, pumping out fast could get you off before the tide falls much further.

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