As stated previously it is illegal, but after several years of cruising I believe in redundency. Are you looking to have emergency access to Marine HF or VHF or both.
In the case of Icom my Marine HF m700, died after 20 years of use,and 802 (current) are marine certified SSB that can tx on the ham bands. The 700/710 have one power setting 150 watts. They work, but are not as user friendly and flexible as a dedicated ham radio.
Many cruisers have the Yeasu 650 series which has HF and VHF which can be programmed for Marine HF & VHF, but is illegal to use except in an emergency. It is not very handy to use for those not familar with the radio, especially in an emergency. Marine VHF's are pretty simple, turn to the channel and hit the button.
I would recommend having two radios or at the very least the marine cert radio. Otherwise a USCG inspection could be an expensive problem.
I am currently preparing to add an icom 7000 to Makai for ham use as the 802 works but it is a pain on some ham freq's.