Fuel Comsumption

Blase-Jean

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Under Powered; One Advantage?

My boating experience in the Pacific NW has been in 30 to 34ft trawlers at average cruising speeds of 7 knots/hr using i.7 gal/hr.
I recently down-sized to a C-D 25 "trawler" to save slip and haul-out costs.The boat is, in some opinions, under powered with a 2007 Mercury 115hp 4-stroke.
On a 2-week cruise in San Juans, cruising speed, as affected by tidal flows, ranged from 6.6 to 8 knots/hr. Fuel consumption as indicated by FloScan was just under 7 NM/gal. Prop size: 14x13 cup.
Main disadvantage was not being able to achieve full planing speed at cruising load (hoped border would open).
 
That is the lowest HP I have seen on a " modern C Dory 25". The 115 and 130 are on the same block. So it may be possible to get the boat on a plane at sea level with the correct prop.

If you only want displacement speeds, then a 50 would work. I believe that one of the mid 90's Cruise Ship 25's was equipped with a 50 and worked fine for slow speeds.
 
That’s pretty good economy, we get close with our 150 Honda but at a slower speed if I recall correctly. Wait for a good engine to come up and then swap. Lots of demand for used 115’s
 
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