I keep a spare starter onboard my boat as a spare.
The USN used some hydraulic starting systems on some of their vessels and ground power equipment
. The pressure in the hydrostatic starting system bleeds down after some time. If you have ever had the misfortune of having to hand pump the starting reservoir up to pressure (3000 PSI) It can take hours and you need to have a few friends to help or blisters
will prevail. Don't stop at (1800 PSI) and try to start the engine
or you will have to start the pumping process all over again. Sounds good in theory but I wouldn't have one on a bet.