They build shit, dig holes, they're never on ships and they hate the marines they always have to work with because they don't get the same treatment(read: respect) working together that corpsmen do if my old RDC's bitching and moaning was any indicator.
Have to hope they get lucky on the outside and don't hop into a an economy on the downturn looking for steady handiman or public works types jobs.
There are only a few jobs in the good old USN that'll keep you off a ship, and if for some reason you decided to join the Navy while not being on one, this is probably your best bet. MA and HM are pretty good ratings for that too.