Forums Forums Wirral History : Chasing the Past Wirral History APPLEGARTH

I would guess the ballast tanks are to weigh the tug down, the tow ropes are usually high on the ship and would tend to lift the tug (and its propeller) out the water.

Presumably they are pumped out to reduce fuel consumption when not towing or to enable movement in shallow water.

All guesswork.

Ballast on any vessel is for weight and stability, any vessel that needs to be raised from the depths has to be made as light as possible, removing ballast whether fixed or water and replacing with air if possible achieves this, thus putting less strain on any lifting gear. We were shown and its a very simple example, an empty bottle floats, fill it with water and it sinks, fill it with a certain amounts of water and it can be held at whatever level required. DD was correct in what he was saying about added weight for towing and would also bring stability, however no amount of ballast would help if the correct towing angle was not achieved, the tug would simply lift herself out of the water. Water ballast is taken on and discharged in accordance with any cargo a ship may or may not be carrying and what draught is required.
It is just as important not to be to low in the water as to high in the water, pre Plimsoll Line days, many a ship was lost by overloading by greedy captains and shipowners and many a ship was lost by retuning from foreign ports without cargo, hence no ballast, to save time, some captains were reluctant to fill the holds with rocks (time saving) and paid the price in heavy seas.

Thanks Bert. It all makes sense. Full ahead together both !!