What is your 'cruise' speed?

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Megabyte

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For me, 'cruise' is 25.4 kts @ 4200 rpm burning 12 gph. :)

Image-6794FB6F464E11DB.jpg
 
Ok. I'll resist the urge to keep quiet.

I still don't know what exactly "cruise speed" is. And to make matters worse I have actually stated on threads here and THT that my cruise speed is mid to high 20's. I have just used the speed and rpm level that I ususally run at.

How do I calculate my actual cruise speed? And where can I see my GPH on my guages? Or am i missing one?

Signed Sal with a brown bag on his head.
 
No need for the brown bag Sal. :D

"Cruise speed" (for me) is the maximum speed I will run if conditions in the Bay permit it.
That is, the maximum speed that I will typically run while burning a reasonably rate of fuel when the sea state is 1' or less.

We don't get many 'flat days' on the Chesapeake, so my 'normal cruise speed' is typically less than what you see in that photo.
However, when we do get one of those nice days, its nice to be able to 'air her out' a bit. :)

My boat burns between 10 and 14 gph over a fairly wide range of motor speeds, but starts going up greatly as I exceed 4500 rpm.
At WOT (about 5100 rpm) I'm burning about 28 gph according to my Navman 2100. :shock:
BTW - The Navman 2100 fuel computer is the round gauge obscured by my left hand (which is on the wheel) as I shoot the photo with my right. :wink:

4200 to 4300 rpm (for me), is a comfortable speed to spin the motor while still getting a reasonable fuel consumption figure.
In this case, 12 to 13 gph (depending on the sea state).

That is what I call "cruise speed".
Also known as... "how fast can I run comfortably (without pounding), and without breaking the piggy bank?" :D
 
Ahhh thanks Kevin... Cruise sounds somewhat subjective, and can depend on what size tabs you have, and personal preference. I just know I like the way my F250 sounds at about 4200 rpm's, and that I am going between 37 and 40 mph.

With regards to fuel burn, sounds like I don't have a way to measure on my boat; just as well, as I don't make a lot of long trips.....
 
yesterday I was running 29.3mph at 3980 burining 9.8gph with 1/2 fuel and regular load. a shot a wot yeilded 42.0mph on the gps at 5380rpms
 
Your DFI burns less fuel/hr than my EFI Greg. 8)
(and at a lower rpm too)

BTW - Take a look at the GPS coordinates in that photo...
Then, compare the position of my boat on-screen, to the contour of the chart...
Now look at the fish finder...

See that lump and the fish it's holding? :wink:

The contour has changed a little since the area was last surveyed by NOAA, but the lump (and the fish) are still there. :D
 
I typically run about 24 mph @ 4,000 rpm and 9.0-9.5 gph. On a nasty day, I drop to 3,800 rpm for about 21 mph and 8.0-8.5 gph. On a blue-bird day, I up the ante to 4,200-4,300 rpm for about 27 mph and 10.0 gph.
 
Porkchunker":2vxcps1p said:
I typically run about 24 mph @ 4,000 rpm and 9.0-9.5 gph. On a nasty day, I drop to 3,800 rpm for about 21 mph and 8.0-8.5 gph. On a blue-bird day, I up the ante to 4,200-4,300 rpm for about 27 mph and 10.0 gph.

Dave that's pretty amazing. The single F225 on my 2320 DVSC runs almost identical numbers to your twins. You got a modifed vee or deep vee? At WOT (BB Day) I burn between 11 and 12 I think (@ 40-42 MPH).
 
On my 2150 MV with a F225, 4200 rpm will get me around 26-27 mph, 10 gph. WOT 5800 rpm with get around 38 mph will suck almost 20 gph.

I have tweeked it 2.8 to 3 mile per gallon when things are perfect, don't remember the numbers exactly but it was around 3900 rpms doing around 24 mph and burning 8 1/2 gph.

As much as I would love to have the Deep V, I wouldn't want to feed them the gas.

Anthony
 
rangerdog":2gnz277k said:
Porkchunker":2gnz277k said:
I typically run about 24 mph @ 4,000 rpm and 9.0-9.5 gph. On a nasty day, I drop to 3,800 rpm for about 21 mph and 8.0-8.5 gph. On a blue-bird day, I up the ante to 4,200-4,300 rpm for about 27 mph and 10.0 gph.

Dave that's pretty amazing. The single F225 on my 2320 DVSC runs almost identical numbers to your twins. You got a modifed vee or deep vee? At WOT (BB Day) I burn between 11 and 12 I think (@ 40-42 MPH).

She is an MV.

At WOT (5,600) she toys with 40 mph.
 
I get at best 3.0 mpg solo with glass like condition empty bait tank etc. For the most part at 4400 rpm's 28 mph I get 2.7 mpg. With a Yamaha F150 on the back of the boat. Any input from other 2120 dvsc owners would be nice to compare.


06 Parker 2120 DVSC
 
Gotst to get me one of 'dem Navmans, Kevin.

I took yesterday off by the way, got to the boat at about 9am with the intention of purposely burning fuel at an obscene rate, and airing the boat out, which had been sitting for a month. I want to get the fuel tank level down a tad, to minimize vent overflow in storage. Man I wish I could get out more this year; what a crisp, pretty day.

I ran her for 2.5 hours, at various speeds between idle and WOT. At 4200 rpm's, sure enough, she was cruising at 25 mph. At WOT 5900 rpm's we ran at 40mph into a 10 knot north wind. Tabs all the way up. Engine tilted up as much as possible. No porpoising (a 2520 porpoising is not graceful or comfortable to watch; kind of like Rodney Dangerfield doing the breast stroke).
 
Cruise as mentioned is thought of as comfort and available conditions.

"Cruise" is typically the rpm and corresponding planing speed for the setup that gives the best fuel mileage (and is usually in the sweet spot of the engine). Sometimes you may see where it can be an estimate of about 75% of WOT.

Anyway, "cruise" for me is 3600 rpm for a '96 2530 DV with Volvo IO, that gives about 25 mph. Burns 2 mpg at this rpm.

Dana
 
dcunniff":1gua72mh said:
"Cruise" is typically the rpm and corresponding planing speed for the setup that gives the best fuel mileage (and is usually in the sweet spot of the engine).

Dana, That's probably one of the best explanations of 'cruise speed' that I've heard.

Thanks! :D
 
Like Megabyte, my little patch of ocean (western LI sound) is rarely flat. That said, in the typical 1-2ft chop around here I run comfortably at 28mph. Enigine is a 225 Opti, rpms will be right around 4500 and I'm burning about 10 gallons/hr. Usually I've got the engine trimmed up slightly with a little tab thrown in for good measure. Fuel-wise, the average is about 70 gallons in the tank.
 
B-Faithful":3rqx41z4 said:
Here is my cruise speed w 3 on board, full fishing gear, and about half a tank of fuel :p

Too bad the lame-azz photographer didn't get a shot of the tachometer and fuel computer in that shot! :D

35.6 knots is about 3 kts better than me at my best. :wink:
Good job Greg. :)
 
Megabyte":1ad6vfth said:
Too bad the photographer didn't get a shot of the tachometer and fuel computer in that shot! :D

I think it was around 20.3gph and 5350-5400 - not the best speed for efficiency. The run back from Rockhall into a head sea was 26-27 mph burning around 9.3gph at around 3890-3900
 
Megabyte said:
B-Faithful said:
Too bad the lame-azz photographer didn't get a shot of the tachometer and fuel computer in that shot! :D quote]



Yeah, for all we know, that Garmin is set to "DEMO" mode. :wink:
 
There you go Greg... The gauntlet has been thrown!

Time for a drag race!!! :D
 
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