Andy

There are some onerous calculations that can predict how much ballast might be required however in my experience the best method is to simply float the model in the bath and load the ballast until the correct trim is achieved.

Paul

As usual Paul cuts to the bone the vexing subject of ballast.

The bath wins in my opinion. Not only do you get to see how much actual weight you need to get the vessel to the waterline, but also WHERE to put this weight, although a wobble test is v useful for determining stability and so on for which the bath may be a bit small. I know Kimo has one of those Imperial Leather advert baths, you know, the sort you walk into and so he does not have this problem.. hang on, no, I am getting this mixed up with leaked pictures of DM`s new workshop area.

Some leeway needs to be allowed, in my experience, for trim changes when on the move. My little HMS Devastation (I wish I hade built a larger one) has significant nose up static trim, due to the upwards levering forces of the twin props DESPITE that the shafts are almost horizontal, perplexing this. This then gives a nice even keel when moving at battle speeds (or a bit more perhaps).

A recently built model had to have so much ballast added I actually ran of available space available to put the ballast (on its initial bath test) and I had to redesign the interior and ditch some equipment then purchase sheet lead as this would take up less room than my bits of squashed pipe….

Ashley

Like Paul, I favour the KISS method (Keep it simple….) of loading ballast in until the desired trim is achieved. Onerous calculations give me a headache

Peter.

If you have an empty watertight hull then float that empty hull in the bath. Now, using a measuring jug (calibrated in litres/ml) pour water into the hull making an accurate note of the volume of water that you have used to get the hull down to the desired waterline. The density of fresh water is 1 gram per millilitre (cubic centimetre) hence then convert the volume of water that you have just measured to grams. This will be the total displacement of the boat not including the weight of the hull – in other words the total weight of everything in or on the boat must not exceed the weight of the water that you have just measured. Obviously this method is only suitable if you are at the start of construction and the hull is empty. Dry out the hull when the measurement has been completed.

Hey guys this is getting complicated. I'm with Paul

Mark the water line on the boat, chuck it in the bath, throw in what ever weight is to hand until she sits level on her water line. Pull her out, mark the balance point fore and aft, weigh the stuff you chucked in her. Job done

I totally agree with Amy. Keep it simple and you can't go wrong.

Ashley, you need to broaden your horizons and embrace new concepts

Peter.

Mark the boat with a pencil line of the water line / level. Get some lead shot and put it in the small sealable bags. Place in boat in the bath and put sealable bags in your boat to right levels. Some trial and error will happen these bags are in the correct positions. Note you may have to alter the weights if you have to put the superstructure/ cabin back on to the boat. You can then with a little touch of glue attack bags to hull. inside.