Tuesday, November 16, 2010

Kokomo's Performance Data According to Honda

Some have asked about our boat's power configuration and what it translates to in terms of power reserves and fuel consumption. I had the same questions before we bought the boat, of course. After all, the twin BF150 4-stroke engines represent the maximum horsepower recommended by the factory and I wondered about the fuel efficiency (of major concern to us) with these two large engines. We had spent years anticipating ownership of an inboard diesel and, though the other advantages were clear (space onboard, accessibility for maintenance and repairs, the reliability of Honda and Yamaha outboards, the ability to raise the engines out of the water, etc.), our concerns regarding trawler-speed cruising at low fuel burns remained.

Happily, some time before I purchased Kokomo, Honda technicians performed a test (on my boat) to determine what the real performance specifications with twin Honda BF150's were. I was able to review this before I bought the boat and have confirmed it's accuracy in some 80 hours of cruising since. I'm delighted to note that, at trawler speeds, I'm getting at least the efficiency that a Cummins QR150 diesel would get in my boat - maybe better - and, of course, the high-speed capability that a diesel would not be capable of (30 knots, or 35.6 mph at W.O.T.).

I've included a link (in the links section, below right) to the Honda page where my boat is featured for your review. Note the fuel burn at trawler speeds (6-7 knots) and again in the 14 mpg range (another strength of the Rosborough hull). I'm very pleased with the overall performance of the boat. In a recent trip to San Francisco Bay, I ran Kokomo for four days and returned with 1/5th of a tank of fuel (per the digital fuel management system). We ran at WOT for about 5-7 minutes per day (engine maintenance) and at trawler speeds about 70% of the time and cruising speeds (14-20 knots) the rest of the time. NOTE: I estimate that we're burning about 15% more fuel with twins than if we'd had a single-engine powered boat, and the wear on the two engines is greatly reduced at higher speeds. Also, I've found that the boat's agility with twins is very valuable. I can literally 'turn on a dime' (no forward or backward motion) by engaging both engines in opposing directions, which makes getting into and out of tight spaces a breeze.              * The boat features counter-rotating propellers.

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San Quentin Prison

San Quentin Prison
One of the more 'captivating' sites along the Corte Madera channel . Rowers from Corte Madera are practicing in the foreground.