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Fuel economy

Posted: Tue Oct 27, 2020 10:44 am
by wschneid
I have a 86 32' Flybridge Sedan. In general, what seems to be the most economical speed/RPM to cruise in open water?
Secondly, My engines seem to top out at about 4000 RPM when on the water. I thought they should go to 4600 RPM. Any comments or suggestions?

Re: Fuel economy

Posted: Tue Oct 27, 2020 11:09 am
by Fastjeff
The way to determine the most economical speed/RPM is with a FloScan type fuel monitoring device.

I can tell you from my own experience (with a similar boat) that mine made 1.2 mpg at 2,500 rpm doing around 20 mph. Mine would get slightly better mileage at 2,000 (15 to 16 mph) and slightly less at 2,800. My engines topped out around 3,900 with the 17 x 15 4 blade props.

Jeff

Re: Fuel economy

Posted: Wed Oct 28, 2020 5:23 am
by wschneid
Thanks for the info.

Bill Schneider

Re: Fuel economy

Posted: Wed Oct 28, 2020 3:35 pm
by jralbert
I found tabs aided fuel economy by a small but significant amount.

Re: Fuel economy

Posted: Wed Oct 28, 2020 6:17 pm
by Tuggle
What's that? All kidding aside mine does fairly well cruising around 2400-2600, 16-18 mph, about a mile to the gallon. We recently ran a steady 2000-2200 rpm's for a solid five hours with some higher rpm's from time to time and burned about 50 gallons.

Re: Fuel economy

Posted: Wed Oct 28, 2020 9:04 pm
by GB49
I haven't done it on the 32 yet but on the 28 we took the flame arresters off while running and looking at the carbs you can tell when the secondary valves open. Make note of the RPM and stay below it, you will save fuel.

Re: Fuel economy

Posted: Thu Oct 29, 2020 8:10 am
by bcassedy
GB49....

Great suggestion!!! Coupled with watching and noting the GPH update on a Floscan (if someone has one installed) should be a spot on usage rate, if all things are equal - fuel load, cargo and passengers the same, planing the same.

Can't wait for next year's splash day (what does one call it when the boat stays in the water all year? :lol: )

Bill

Re: Fuel economy

Posted: Thu Oct 29, 2020 9:13 am
by Fastjeff
Trust me: a Floscan unit will pay for itself in a year, maybe less. And (if you're a cheapskate like me) you need only install it one one engine (assuming the boat has twins).

Jeff

PS: Be sure to install it WAY away from the fuel pump to get more accurate readings.

Re: Fuel economy

Posted: Thu Oct 29, 2020 5:53 pm
by TinLizzy
Floscan went out of business a year or two ago, someone bought them up, but they do not reply to any form of communication. I tried to order the twinscan flow meter, but no luck. Lowrance and Garmin have fuel flow sensors to connect to their NEMA 2000 backbones.

Re: Fuel economy

Posted: Thu Oct 29, 2020 7:16 pm
by bcassedy
:cry: Rodney,

Not good news.....

Great quality product and we're left with poor options...
Have to spend $$$$ to get a system and then add fuel sensors.

Bill