Ballast is fitted into the shell directly onto the bottom plate. It is good practice to lay the canal boat ballast
on top of a non absorbent layer to separate it from the steel of the hull. Traditional non absorbant material would be roofing felt. If an air space can be incorporated between the canal boat ballast
& the bottom plate, even better & this can be achieved by laying the canal boat ballast
onto a non reactive spacer material such as large plastic tile spacers.
Treat the bottom plate with a thick layer of bilge paint or similar which further protects the steel from any condensation water or future leaks. It is worth it at this stage. Once the canal boat ballast
is in, it will be a very long time, if at all, until the inside of the plate is exposed so treat it now & forget about it!
Information on types of ballast available and also how to calculate how much ballast is required on your canal boat can be found in the Integral Parts