Performance Numbers From GW web site

[Legend]

Does anyone know the answer to this or is it a mistake. The GW perfromance data for a Sailfish with 2 F225 uses 17.57 GPH @4,000RPMs.
The Marlin with 2 F225 uses 14.7 @ 4,000 RPMs. Am I missing somehting. I would think it would use more to push a bigger boat?
Thanks

 

[Tuna Man]

I have compared Grady's numbers on five different Grady's to date in real world condtiions. This was with a total of six different motor setups (one boat was repowered). I every case I was able to achieve their results when the boat was lightly loaded in calm water. That being said, I have paid especially close attention to their tests (as well as Yamaha's tests and various magazines over the years) on all Marlins and late models of the Sailfish. I have noticed that once in a great while the numbers don't add up. I suppose the numbers were entered wrong or perhaps the fact that outboards are 'allowed' to produce as much as ten percent more or less horsepower than they are actually rated at.

In the short time I have spent on my new to me 2006 Marlin with F250's, I have found that on every trip to date I get between 1.5 and 1.6mpg at cruise. This is with at least 150 gallons of fuel and at least three passengers. In rough numbers, I burn between 15 and 23 gph at cruise spinning 19" SWS II props. I think at 4000 I am burning about 19gph at 29mph. Very close to the Grady numbers. I think I may see 1.7mpg if and when I run the fuel tank down below fifty gallons with just two on board. Time will tell.

Lastly I just looked at a magazine article I printed a while back from Boating Magazine Feb. 2004 issue. They tested a Marlin with F225 swinging "17X21 three-bladed props" (no way!) and burned 18.8gph at 26.7mph at 4000. The boat topped out at 5900 doing 40.1gph burning 43.6gph. I think the numbers are about right, but I highly doubt the prop is what they suggested, I would guess a 15" x 17".

 

[wahoo33417]

One would certainly think so. But it could be the difference between how the boats are loaded.

Posted below are Yamaha's numbers from their website. Note that the sailfish gets much more speed and better mpg than the marlin at the same 4,000 rpm.

The yanaha tests give you much more info regarding weight of the boat, fuel load, temperature, props, etc. I have read that air temperature can make up to a 10% difference in how much power an outboard develops.

282; 8600 lbs,

RPM MPH GPH MPG Db
1000 5.6 2.5 2.24 62
2000 9 5.7 1.58 74
3000 19.4 9.6 2.02 82
4000 32.7 15.9 2.06 86
5000 41.8 27.1 1.54 90
5800 48.8 38.2 1.28 92

Marlin 300, 11,300 lbs

RPM MPH GPH MPG Db
1000 5.2 2.1 2.48 59
2000 8.8 5.3 1.66 71
3000 13 9.3 1.40 79
4000 26.2 14.7 1.78 83
5000 35.3 23.1 1.53 85
6100 43.3 41.5 1.04 88

 

[CKJR]

You really have to look at how the boats are propped-the 4 strokes should have max WOT at 6000k, in looking at the earlier sailfish numbers with the f225,S, they were propped with 19" and turned max 5600-5700 perfect conditions. My sailfish propped with 4 blade 17" merc blades burns approx 15GPH at 4k max rpm 6000. MPG's 1.7 to 1.9 roughly, Hope this helps.