Fuel economy

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wschneid
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Fuel economy

Postby wschneid » Tue Oct 27, 2020 10:44 am

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?

Fastjeff
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Re: Fuel economy

Postby Fastjeff » Tue Oct 27, 2020 11:09 am

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
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

wschneid
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Re: Fuel economy

Postby wschneid » Wed Oct 28, 2020 5:23 am

Thanks for the info.

Bill Schneider

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Re: Fuel economy

Postby jralbert » Wed Oct 28, 2020 3:35 pm

I found tabs aided fuel economy by a small but significant amount.
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD

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Tuggle
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Re: Fuel economy

Postby Tuggle » Wed Oct 28, 2020 6:17 pm

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.
"Deplorable", 1975 32' Express, Twin 318's, Raw Water Cooled, Lake Lanier, Ga.

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GB49
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Re: Fuel economy

Postby GB49 » Wed Oct 28, 2020 9:04 pm

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.
1986 Sedan 32'. Twin Chrysler 360in^3, 275hp, with K&N flame arrestors.
Forum member since 1998, 1262 original forum posts.

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bcassedy
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Re: Fuel economy

Postby bcassedy » Thu Oct 29, 2020 8:10 am

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
Bill & Sharon Cassedy
"Sunset Seeker"
'88 32' Sedan Bridge
Located in Aurora, In.
Twin 318cu in Chrysler
1.5:1 Velvet drive trannies
Fresh water only

Fastjeff
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Re: Fuel economy

Postby Fastjeff » Thu Oct 29, 2020 9:13 am

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.
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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Re: Fuel economy

Postby TinLizzy » Thu Oct 29, 2020 5:53 pm

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.
Rodney
1975 28 Express-Twin 350 Chevy's, Raw Water cooled
Portage Canal Waterway-Upper Peninsula,Lake Superior

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bcassedy
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Re: Fuel economy

Postby bcassedy » Thu Oct 29, 2020 7:16 pm

: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
Bill & Sharon Cassedy
"Sunset Seeker"
'88 32' Sedan Bridge
Located in Aurora, In.
Twin 318cu in Chrysler
1.5:1 Velvet drive trannies
Fresh water only