From F. G. Grisley
Barry, Glamorgan
Tam Dalyell writes that he is concerned to prevent air pollution by ships
(Thistle Diary, 14 September, p 50).
One way to do this would be to discharge exhaust gases underwater. Although
this might not be desirable in confined waters, in the open sea the pollution
would be diluted beyond trace.
If the gases were discharged from many small orifices spread over the hull
surface, their absorption by seawater would be enhanced.
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Other benefits might accrue. A film of gas bubbles over the hull would reduce
the wetted area, and its compressible nature might dampen turbulence like the
skin of a dolphin; both effects would reduce hydrodynamic drag.
Also, marine organisms which have fouled the hull in dock might find the
environment sufficiently noxious to drop off again, reducing drag still
further.
Has this idea been tried and, if so, with what result?
