When ships started to make long tropical voyages they were
found to be vulnerable to attacks from worms like the teredo and also
to he- fouled by marine growth and barnacles. The earliest treat' ment
against this was to cover the bottom with layers of tar, hair, tallow
and sulphur and hold it in place with a sheathing of thin planking. One
curious old book describes how the mighty floating castles of man,
"breathing fire and smoke could be brought to nought by the work of
tiny worms nibbling away so that the bottom did fall out". And as a
cure advised the mixing of tar and sulphur with powdered glass, whereby
the little rascals would digest the mixture and their entrails thus be
torn asunder!
These efforts however, did not stop the fouling of' ships'
bottoms with weeds and barnacles etc. which greatly reduced their
speed. The first step was to paint the bottom sheathing with white lead
paint and tallow, creamy in appearance when new and with slimy brownish
streaks after immersion.
The Dutch established a white lead industry about 1620 and
after this date white bottoms are fairly common especially in naval
ships. Lead sheathing was applied spasmodically from Roman times
onwards, but full copper sheathing came into fashion about 1783 after
experiments a few years earlier.
Vessels not travelling to tropical seas would not be so
likely to have copper bottoms — it was expensive.
