SSB antenna and steel boat

[rigormortis]

Hi folks:
This is the first in a blizzard of information-seeking posts that will be flying your way in the next few weeks.
I bought a Passport 41 March 10 and I plan to ship out on May 10 and my feet are to the fire.
First post has to do with SSB and GAM antenna. My boat is steel, love it or hate it. I had insulators on the back stay when I bought it and an Icom M700PRO SSB. The previous owner said reception was great. I decided to replace the backstay due to its age and the rigger suggested the GAM antenna so as to avoid the insulators.
When I was at the sail show in San Francisco yesterday one knowledgeable chap told me that the GAM will not work with a steel boat/backstay combination. The backstay would have to be insulated for the GAM to work. Something about two wires surrounding a third (the backstay) and energizing the whole boat.
Another knowledgeable guy – an electronics retailer and installer—said the combination would be fine. This is the worst possible situation where experts disagree and me, the schmoe, knows nothing.
Anyone out there with experience with GAM and or steel boats?
Help me, boys.
Pete.