Getting to the bottom of blacking
AIs it correct that the bottom of a narrowboat is not painted when routinely blacking below the waterline?
There are mixed views on this. People who apply the two-part blackings that are far tougher than tar or bitumen based blackings advocate blacking the bottom. Some people also black the bottom with tar or bitumen-based products. However, access to the baseplate can be difficult. You also have to make provision to jack up or move the boat on the supports so you can black the parts that were sitting on the supports.
It’s said that there is far less oxygen in the water at baseplate level so corrosion is greatly reduced, making blacking unnecessary and that blacking will just get scraped off, but I am not so sure. On a modern boat with a 10mm + baseplate, it would take very many years for an un-blacked baseplate to corrode sufficiently to cause concern unless the steel is of very poor quality or you have mains on board without sufficient protection.
Perhaps the best answer is to black the baseplate if you can or if you can afford to, but remember that the smallest puncture might tend to concentrate any electrical corrosion into a small area.