We occasionally experienced trouble starting our engine once in a while. Usually it was when it was hot, like at a fuel dock, or a quarantine dock - places you don't want to get stuck. Motors and switches were replaced and the problem persisted.
At a Mack Boring seminar I asked the instructor if this issue was a starter issue with Yanmars. He did confirm the problem and said Yanmar now installs starter relays to activate the solenoid. Interestingly, several others in the audience shared the same problem.
I've now installed a Yanmar relay, part number 129100-77910, and will report back if our issue is truly resolved.
Sam - PSC34 - s/v Grace