I am a ham, but have not installed any radios on my boat. I have a 2 sq ft steel plate for a mag mount...VHF-UHF.
I even bought the antenna for an HF, but health has really stopped almost all my plans.
There is a business in Alameda I think..sorry, can't remember for sure. They seem to know quite a bit about installing them.
I was going out for a couple of weeks, so I thought I would bring my Yaseu 890A and Hustler
antennas. 20-40-75 meters. And a Broad Band
Bazooka for 40 meters. I was prepared to have a good time down in the Bay Area, but health issues stopped that one too.
If you go to the main forum you will find several hams who can be more help. I have been on Morphine and some strong pain meds for a couple of years now, so my memory is only a rumor.
Most 440 repeaters are off the air right now due to PAVE PAWS up at Marysville. DOD says the 440 band is interferring with the new anti-missile system..and since they are primary in this part of the freq. spectrum, we had no choice.
There is a forum...uh...sorry, can't remember the name...38th Latitude? Look it up, they have a classified section that usually has a Marine HF on it for good prices.
Good luck with it...Dave N6TTG