In article ,
says...

On Tue, 18 Mar 2014 06:52:15 -0500, Boating All Out
wrote:

Here's a power cat that will get 29 mpg at 5 knots.
19 mpg at 8 knots.
http://www.multihulldesigns.com/desi...ock/38tri.html
You can accept or reject that mpg figure.

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Those numbers are wildly optimistic in my experience. Basically you
are talking about the same hull as a lightweight 38 foot sailboat,
typically burning between .5 and 1 gallon per hour depending on speed,
wind and seas, while doing 6 to 7 knots. Even the most optimistic
ends of that range only gets you to about 14 mpg. That might be
attainable if very lightly loaded in perfectly flat, dead calm
conditions. More typical would be 6 or 7 mpg.

This boat is about 80% lighter than your typical mono cruiser.
And maybe 60-75% lighter the most "light sailboats" of the same LOA.
Weight: 4,125 lb
Displacement: 5,278 lb (2.394 kg)
That's according to the designer. YMMV.
Though estimated ranges may be optimistic, I don't think "wildly".
I suppose at full power 2 15hp Hondas can only burn so much fuel.
The question is at what speed.
Haven't seen any "real experience" reports with the boat.