No worries. I will hand the problem over to a friend who enjoys working out these sorts of unit-of-measure conversion problems. The only trick will be to get him not to answer using a 10 page paper w/lots of squiggly symbols that look so much more at home on a fraternity entrance overhang than they ever do in a simple email response.
I did some quick math and came up with an increase in sea level from all those ships of 5/10,000 of an inch.