"Monohulls are what 90 per cent of the sport does and knows. Therefore there'll be more spectator interest, there'll be more media interest, in turn there'll be more sponsor interest, which will lead to more teams."
As a high ranking official in the GGYC and advisor to Oracle boss Larry Ellison, Ehman was involved with the bold decision to go with a catamaran for the 34th America's Cup in San Francisco.
"I was a big proponent of the multihulls when we moved to it in 2013 ... but as we saw in San Francisco [in 2013] there were only four teams [including the defender], as we saw in Bermuda this year there were only six teams, three of which were Ellison teams, so really you only had four independent teams.
"But go back in history and how many teams were there in Newport Rhode Island in 1983 when the Aussies won it? There were 10. In Australia in 1987, there were 17 teams.
"Every other match - think about Auckland in 2000 and 2003, there were more than 10 teams. That's because other sailors, other clubs get behind what they know, which is monohulls."
The return of monohulls has also received a tick from America's Cup icon Bruno Trouble.
The veteran French sailing figure has backed the view of top yachting analyst Mark Orams, that the excitement generated by the foiling catamarans in Bermuda will be repeated in the 2021 Auckland regatta.
Trouble said this week's revelation that foiling monohulls would replace the cats was "nothing new", the Team New Zealand decision being a fait accompli once Luna Rossa was confirmed as the challenger of record.
"They will be fast, amazing, impressive - maybe they will sail at 24 knots instead of 40 but on television it won't make much difference," he said from Monaco.
"All the boats will be very spectacular. I'm pretty sure if we invest the money which was put in last year, those boats will be very, very impressive.
"Again, this is not big news, but we don't know other details. Now we kneed to know more about the event...where, when. "
Trouble suggested a change to monohulls would give Italy an advantage though.
"They are very good in monohulls - I've heard two or three teams from Italy getting prepared. It is good for the future of the America's Cup," he said.