Re: Voltage puzzle
Unfortunately voltage alone doesn't tell you much - a rough indication at best, esp with no load.
With your shore charger you only "put in" 8 amps, and while motoring only 15 to 20 I'd guess.... So how much charge you got to depends on how run down the battery actually was vs its amphours capacity.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)