I think you will find that the old artificer branches of different specialist no longer exist, indeed I would not be surprised to hear that the Artificer as a whole will shortly become defunct. So it is difficult to repair at sea, plus more importantly most things bought and fitted to ships as well as in the home cannot be repaired onboard if they can it is with laptops loaded with specialist software, operated by specially trained people, Caterpillar engines are a prime example where ships engineers cannot repair them themselves. It is the world we live in and the way it is going, everything is now diagnosed by computers with special software, look at modern cars, I dare say Shipmate 60 can expand more on this subject as a qualified marine engineer and a good car mechanic he is well versed in this area.
By the way I found out we still have 45 Admirals, a larger number of Commodores, and several hundred Commanders, infact there is enough officers to man the fleet, with people spare with out having to use any rank and file.