If you plan to use HF on the amateur...

Denny... could well be that he is just interested in using the
conventional hf marine bands.

At any rate... a good news group for this sort of inquiry is the
"rec.boats.electronics" web site:

http://groups.google.com/group/rec.boats.electronics

They have some real knowledgeable guys that hang out there
when it comes to maritime mobile radio issues. Some of the
key posters are... Larry... Bruce in Alaska... Old Chief Lynn
just to mention a few.

Best regards

Bill (N6TGC)