I have 2 HV30's and loved them. Well I had two.
Today one of them died, it got a " Remove The Cassette " message.
So I tried to remove the cassette and it would not spit it out.
Finally I coerced the tape out - battery out - power down - hold tape eject button - insert AC power adapter - tape came out.
Unit would not accept another tape.
We suspect this was a moisture/humidity issue.
I bring this up because you mention going to sea and using it.
GOOGLE --> HV30 Cassette Removal
You will see too many mentions of this error on the HV20/HV30
Some have had to use " Reset " to clear it, that did not work for me.
I suspect "Reset" works in the case of a bad tape and not humidity.
I returned THAT unit, because I was able to. Still have one.
Now looking for another solution as I many times am in areas of high humidity.
I saw mention of this on the HV20 HV30 and one of the GL models.