New Member with questions after sea trial

[danstanford]

I have a question for you experienced Guys with respect to fuel consumption. It seems that hull speed cruising at 1500 RPMS should be way more fuel efficient than getting her up on plane, is this correct? Everything I read says 1 US gallon of fuel per mile is about what to expect when running about 20 knots, is this about right? What would the comparable mileage be putting along at hull speed? Based on the forgoing 1 mpg estimate, I think I am about correct calculating about a $ 1,000.00 to do a 260 mile round trip on Lake Ontario? This particular F32 has twin Chrysler 360's.

Thanks in advance for your feedback, I know that real world examples are better than estimates from somebody trying to sell their boat!

[todd brinkerhoff]

Your efficiency on step (on plane) depends on the boat, weight, hull design, motors and tuning, cleanliness of bottom, etc. Hard to give a definitive answer, as its different for every boat, even boats of the same design. If you are running a 10 Meter, or 10.8 Meter, at 20 knots, you are probably looking at .6 to .7 mph. An F-series with a flatter hull will be more efficient, maybe up to 1 mpg, although that would be very good. As for hull speed, it is based on your waterline length. As long as you run at or below that speed, you will save considerably on fuel consumption. Anything while on step (on plane) will be based more on the boat design and speed at a given rpm. For me, my LWL is 35 feet, with my hull speed at about 7 mph. I can reach that speed at 1400 rpms. If I go even 1 mph over my hull speed, at say 1700 rpms, my mileage plummits. My fuel mileage at 1400-1500 rpms is about double that of my plane speed of 20 (about 3100 rpms).

The only definitive way to figure out your actual numbers for your actual boat would be fuel flow meters with a gps for speed tracking.

[gitchisum]

My F32 has Crusader 270's, and not sure how they compare to Chryslers. At 3000 rpm I am running 21 mph and getting .88 mpg. I think you could use that as ballpark for your needs. ( Gas in my neck of the woods is $3.00 / gallon, so a little over 800 to do 260 miles )

I don't ever run at hull speed because I am in a hurry to get fishing! Maybe when I retire

[danstanford]

So I can figure 1300 rpm's to get around hull speed and then approximate the .8 mpg number to about double that when cruising at this speed. This trip would then cost approximately $ 800.00-$1000.00 at planing speed and about half that if I just bumped along at hull speed taking about three times as long to make the trip?

All number rough but giving me some idea.

Any other input?

[K4282]

I do many many trips including 95% of my time in and out of the channel on one motor rather than waste gas running both, my regular swimming hole is about 10 miles away, I do it constantly on one motor for 10 to 15 gallons round trip figuring docking, checking batteries, running power inverters, ive been doing this for 5 years as many of my fellow boaters also do it

[captainmaniac]

My '79 has Chrysler 360s. I get about 1.1 mpg at cruise (at the planning 'sweet spot', 2800-3200 rpm, 16-20 knots depending on wind and wave conditions). For hull speed, I run 1500rpm and do 6-8 knots, roughly 1.5 mpg. The mpg figures are based on trip miles reported on my GPS. Also, calculations are based on a Canadian gallon. The US gallon is smaller, but in my experience with my car, I get the same mpg on both US and Cdn fuel so don't know if the US fuel packs more of a punch?

As usual, 'your mileage may vary'.