Yanmar Roulette
David, I have a 1999 h380 which is pretty much the same boat as your's. I have spent in excess of $500.00USD trying to resolve the very same problem you are experiencing. I've talked to Hunter, they claim they've never heard of such a problem. I've talked with Yanmar, they too claim that they have never heard of such a problem. I replaced my starter, solenoid and starting battery and it still would not start after even a short sail. So then I started thinking that it is was a cable issue, so I disconnected the "one size fits all" harness that Yanmar uses at the back of the engine and cut out the big plug with the three wires and put butt connectors on each wire. I then went to the other end of the harness at the key switch and did the same thing, cut out the big plug and put butt connectors on the three wires. This seemed to help for a short time but once again the start/no start problem returned. I use my boat a lot so I've had plenty of time to evaluate this problem. One observation I've had is that if my refrigerator is running when I turn on the starting battery and immediately try to start the engine, it won't start. Same thing if I've been sailing a long time with the running lights on. If I shut off the fridge and wait one minute, it starts first try. This holds true with the running lights. Once in a while I even have to shut off everything, instruments, running lights, and fridge. By the way, having do take these steps while you are in harms way compounds the potential for a serious accident. And so here's my conclusion, the starting battery needs to be larger than a group 27, the wiring harness from Yanmar needs to have larger diameter wires to decrease resistance(ohms), Hunter needs to address this problem with a massive recall before somebody gets seriously injured and/or killed and Yanmar need to step up and admit that they are working on the "cheap" when it comes to cable aquisition. The only positive thing that's come out of this is that now I can dock a 38' under sail! The comment from my local dealer was "what do you think you bought, a Swan", nice.