When is a boat most fuel efficient?

[drrnjnr]

Me, being quite new to boats and the ins and outs of, have probably a silly question......

My boat is a Campion Explorer 542 with a Yam 150 FAET motor, it goes like stink. Accelerating HARD at 40mph, I dare not take it above 60mph. The boat really is a pleasure to "drive" on tick over at 8MPH, love it......

Now, when I accelerate to 14mph the boat rises out of the water to plane, This too is a very pleasant speed to travel.

If I accelerate to 40mph the boat leans or lists a little to the left under acceleration, but is OK if I'm alone to counterweight the tilt with my 210lbs:facepalm:........ I think it comes from the torque of the prop.....above 30mph she straightens up again. I would only do WOT on mirror like water because I have seen the result of speed on water, it aint pretty.

So guys, - What's your opinion of the most efficient way to go? 1000rpm and 10mph or 1400rpm and just in plane at 14/15mph or 25Mph at about 40% of the motor capacity??

 

[fhhuber]

The only way to know is to do some experiments holding steady speed and then calculating mpg.

Your boat it might be in the "hull speed" range or it might be while on plane. It won't be wide open throttle...

 

[Scott Danforth]

you need a fuel flow meter to determine where your motor with your prop trimed at x condition on your boat with your gear in the waters you boat with the conditions you boat in are most efficient.

generally, at idle, just putting along and at cruise (about 3000 RPM give or take)

 

[Leardriver]

No Title

Somewhere there is a fuel flow chart for your motor. In this example from a stern drive Sea Ray 240 SD, the most efficient rpm from a mpg standpoint is 3400 to 3700-ish rpm. Your motor will obviously be different.

 

[redneck joe]

Mine is best when sitting on the trailer, in storage....

 

[jbcurt00]

Mine is best when sitting on the trailer, in storage....

Hmm, thats wierd, mine get the most MPG while on the trailer being towed, zero fuel consumption at a tick over 70mph

To accurately assess fuel consumption, you'll need the fuel meter, and lots of test data. Which would mean taking copious notes, in lots of conditions, and sounds like a lot of work to be generally accurate at best. Not to mention burning fuel simply to get test data....

Channel, river or off-shore current, head/tail wind, boat load and several other factors could easily change fuel economy slightly, which over the course of an 8hr+ day on the water, could mean a fairly large overall change....

 

[redneck joe]

true...

the way I view boats and fuel economy is it ain't gonna matter much unless you are into the 4 barrels to WOT. And of course not plowing nose to the sky.

 

[Scott Danforth]

if you want fuel economy in a boat, get one with oars or a sail.

 

[wrvond]

As long as I have enough fuel to make it to the next pump, I'm golden!

 

[CV16]

All of my boats tend to be best getting on plane and cut the gas just enough to stay on plane. Might not be the absolute best, but it's close.

 

[drrnjnr]

All of my boats tend to be best getting on plane and cut the gas just enough to stay on plane. Might not be the absolute best, but it's close.

Now thats what I was thinking..........

if you want fuel economy in a boat, get one with oars or a sail.

That too, hahaha.

 

[wrvond]

if you want fuel economy in a boat, get one with oars or a sail.

Did that once, but I wasn't satisfied, so I re-oared it. Installed oars with longer shafts and much larger blades. In fact, I over oared it so much that the oars broke both oarlocks, and I was stranded in the river for days. Nearly starved to death waiting for rescue! :rofl:

 

[drrpm]

To get the absolutely spot on number takes care and a fuel meter to figure out. The answer that is accurate enough for general use is the most efficient speed overall is just above idle and the most efficient cruise speed is a few MPH above minimum plane. These may vary a little depending on the boat's design but the difference is negligible in practice.

 

[garbageguy]

Me, being quite new to boats and the ins and outs of, have probably a silly question......

My boat is a Campion Explorer 542 with a Yam 150 FAET motor, it goes like stink. Accelerating HARD at 40mph, I dare not take it above 60mph. The boat really is a pleasure to "drive" on tick over at 8MPH, love it......

Now, when I accelerate to 14mph the boat rises out of the water to plane, This too is a very pleasant speed to travel.

If I accelerate to 40mph the boat leans or lists a little to the left under acceleration, but is OK if I'm alone to counterweight the tilt with my 210lbs:facepalm:........ I think it comes from the torque of the prop.....above 30mph she straightens up again. I would only do WOT on mirror like water because I have seen the result of speed on water, it aint pretty.

So guys, - What's your opinion of the most efficient way to go? 1000rpm and 10mph or 1400rpm and just in plane at 14/15mph or 25Mph at about 40% of the motor capacity??

The only silly questions are those that are not asked.

Nive boat - got any pics?

Your description of acceleration, speed, etc is a bit confusing - at 40 mph it leans, but above 30 it straightens up again? How do you know your speed? Boat speedometers are usually pretty inaccurate.

Are you looking for fuel efficiency with respect to time, or distance covered? If time, probably just barely moving. If distance, probably just on plane, trimmed just right.

 

[drrnjnr]

The only silly questions are those that are not asked.

Nive boat - got any pics?

Your description of acceleration, speed, etc is a bit confusing - at 40 mph it leans, but above 30 it straightens up again? How do you know your speed? Boat speedometers are usually pretty inaccurate.

Are you looking for fuel efficiency with respect to time, or distance covered? If time, probably just barely moving. If distance, probably just on plane, trimmed just right.

It leans from about 30 up to 40 under accelleration and then straightens up again when accelleration is over.
Pictures are on the thread 'New guy saying hello' in the Dockside chat, here's a link, hope it works.......I must say the boat is bullet proof(Almost)
http://forums.iboats.com/forum/other/dockside-chat/10282526-new-guy-wants-to-say-hello

 

[drrnjnr]

Did that once, but I wasn't satisfied, so I re-oared it. Installed oars with longer shafts and much larger blades. In fact, I over oared it so much that the oars broke both oarlocks, and I was stranded in the river for days. Nearly starved to death waiting for rescue! :rofl:

You poor man...Did you have enough water, or did you use a straw??:lol:

 

[JoLin]

In my experience, every boat and motor has a sweet spot. It's that combination of speed and engine rpm where everything just feels right. The motor sounds happy and the boat rides well. In my case, that's about 3500 rpm and 24 mph. Beyond that, I just don't pay much attention to fuel usage.

Here's an observation. I recently made a 10-day, multi-stop voyage of 245 (statute) miles. Starting with a full tank, I filled the boat 4 times along the way (topping off each time), and logged average speed and distance for each leg via my gps. Here's what I got...

Leg 1 - 69.8 miles - 65.4 gals - avg SOG 12.1 - GPH 11.9 - MPG 1.06
Leg 2 - 61.7 miles - 59.7 gals - avg SOG 13.1 - GPH 9.9 - MPG 1.03
Leg 3 - 51.0 miles - 49.1 gals - avg SOG 19.6 - GPH 15.1 - MPG 1.04
Leg 4 - 62.0 miles - 57.1 gals - avg SOG 15.6 - GPH 10.4 - MPG 1.09

Logging all this stuff was valuable from the standpoint that it confirmed what I already thought from informal observation over the previous 2 seasons. Definitely handy for trip planning purposes, but otherwise doesn't mean much to me. I go where I go and use the fuel I use..

My .02

 

[bruceb58]

My fuel flow meter is integrated into the GPS so it displays instantaneous MPG. My sweet spot is 3500 RPM but every boat and motor combo will be different.