36' Optimum Mileage?

[canuckkb]

Greetings,
I had purchaced a 36' TriFly late last fall, and almost immediately had it shrinkwrapped. I do not know any of the history behind it however I am not new to boating and think that I have a good eye, and it is obvious that it was well taken care of. I have a long trip planned for it in about 2 months. We are planning on splashing then floating from Lake Simcoe to Goderich (on Lake Huron). We have several weeks to do this trip so we plan on taking our time and enjoying some of the sights on the Trent-Severn and in the 30,000 Islands. The trip will probably be at least 500 miles. The boat has twin 400 cu" Chryslers. I was wondering if anybody has done any studies on the fuel mileage of this or similar models of boat. What rpm would give us the best milage giving that we not in a hurry. Would there be a significant difference between running at say 1,000 or 1,200 rpm?
Thank you
Kevin.

[prowlersfish]

Probably not much difference between 1000-1200 , the important thing is to keep it below hull speed . The hull speed on your boat is just under 8 knots (7.6-7.7) when your at hull speed you start pushing water and fuel burn goes up faster then speed .

[todd brinkerhoff]

Looks like the perfect Trawler.

[Away On Busine$$]

Are there specs out there that tell us what is the hull speed for each model, mine is an F32 and I have no idea what the hull speed would be.
Thanks

[canuckkb]

Thank you.
Looks like 7.6 will be it. Not a bad speed in a lot of the area that I will be in.
Kevin

[prowlersfish]

Are there specs out there that tell us what is the hull speed for each model, mine is an F32 and I have no idea what the hull speed would be.
Thanks

Multiply the square root of the LWL by 1.34. This number is the hull speed for your vessel as measured in knots.
or to make it easy
http://www.digiboat.com.au/info/calculators.htm

http://www.anyboat.com/webpages/hull.htm

REMEBER This is water line length NOT boat length . ( Length Water Line = LWL )

Your F32 would be about 7 knots btw

[captainmaniac]

canuck / away.... as Paul says, 1.34 x sqrt (waterline length) is the official formula for hull speed - how fast you can move without 'pushing water'. On an F32 (and I expect the 36' gas engined Trojans) the 'hull speed' is achieved around 1500 RPM. On my F32 with twin 360's, I get an overall consumption at 1500 RPM of about 1.5 mpg (Canadian gallon). A 36 should do a bit better, as its hull speed will be a bit higher than that for a F32.

Your optimum efficiency is usually at hull speed.

For what it's worth, my overall average fuel consumption (whether idle, slow cruise, or on plane 2800-3200 RPM) is about 1.1 mpg (again, Canadian gallons) over the past 15 years.

[canuckkb]

Thank you. This information will be very helpful in planning my trip. Hopefully all goes well.