Now I know what it means!
No seriously, ‘unshipping’ means to load, unload a ship or the sailors progressed rapidly with the task of unshipping the packages and caged animals. “Unshipping the wheels” meanings Larboard battery, unship your rear wheels from the cannons to raise the angle of fire.
Think in this case it’s not to get an angle of attack, more like to prevent theft of boat and trailer from the sailing club yard.
Taken last March, on my Leica M4-2, Summicron 35mm f/2 ASPH and taken on Ilford HP5 plus film.