serious trouble with the SP12

[RW Sailor]

Hello again everyone,
I had a thread open about 5 days ago with my Yanmar SP12 not doing anything any more. Now it turned out the starter was dead - got it changed for quite a few bucks - hard to find, since nobody seems to have spares for old Yanmars any more (really old ones anyway)
well, the starter worked, I headed on further away from Annapolis and on to Maine when in the Dellaware bay I found a leak on the shaft (on the hose behind the stuffing box) - shock first, pulled into a Marina in Cape may second and got it fixed: Engine not alligned with the shaft, needs to be sorted an of course the hose changed which involved pulling the boat out of the water - shock again and then nodding and paying...
So after that incident, running short on time and storms comming up I turned around back towards Chesapeak and motored through the C&D Canal back to Chesapeak bay, where I just motored out of the canal heading into some rough-ish waves when the engine died (definitely enough oil, clean fuel, aligned, ....) so I figured it must be the waves, started again, ran for 2 minutes died again and then also my starter died again...
So right now the frustration about the engine is huge and I'm about to tear iat a[art with bare hands...
Any input? There must be some electrical issue with the starter if it keeps dying right? or just bad luck?
Any suggestions on who to get to have a look at it in Annapolis?
Or do the big step forward and instead of investing another 5000 Dollars in 5-800 buck-steps just do it once and get an electric engine and loads of batteries?
Any experiences with that as well?
Thanks for all your input already... Really out of ideas at the moment...

[Cheechako]

Dont crank the engine for more than maybe 15 seconds with the starter. let it cool for at least that long and then try again. If you crank incessantly, you may have burned up the starter again.
Engine dying once running is almost always a fuel issue... you may have dirty tanks clogging up the works when you get into rougher water... a very typical problem in older boats.

[RW Sailor]

I didn't crank for more than say 5 seconds (if at all) - the engien fired right up, just... died again after few minutes... just don't understand...
And I ran out of fuel before because of bad fuel and back then it did make a few blobbing noises before dying off completely, this time is seems to have stopped from one turn to the next - no slowly running out or anything, just from running to off right away...