fuel economy question

[rburlington]

I am new to power boating.  My boat is a 1981 Aquasport 246, either express fisherman or family fisherman (I'm not sure which, if either, is correct--has a cabin and cabin can be walked around on the outside deck).  It is powered by a 1986 Yamaha 220 hp o/b.  My question is this: What makes the most fuel economy sense for a long ride (say from Peoria, IL to the Southeast coast of Texas)?  Some have suggested that fuel economy is best on the plane, others at crusing speed and other still at 12 to 14,000 rpm (equals about 5 to 7 mph depending on wind and current).  How long it takes to make the trip is not a factor for me, so if going slow really saves fuel, I'm more than happy to go slow.  Any suggestions and advice are very welcome.
Thank you,
Robert Burlington

[warthog5]

The best suggestion I can give you is buy a fuel management guage.

This will help you deturmine the best speed to fuel milage for your boat and will be money well spent.

It will help you with adjusting RPM, trim on the motor and tab adjustment's to get the peak fuel milage out of your boat.

[GoneFission]

The Aquasport hulls seem to be most efficient at about 25 MPH.  Here is a mileage chart I did when I tested a hydrofoil on my rig:

RPM---Gal/Hr--MPH---MPG--G/H w/Fin-- MPH w/fin--MPG w/fin
3000----8.3-------24----2.9------8.4----------17------------1.7
3500----8.5-------26----3.1------9.2----------23------------2.5
4000----9.5-------28----2.9------10-----------26------------2.5
4500----11--------30----2.7------12-----------31------------2.6
5000----15--------37----2.5------16-----------37------------2.3
5500*---18--------40----2.2------20-----------39------------2.0

*note the boat would only make 5300 RPM with the fin, not 5500.

I have a 22-2CCP, but I would think a 246 would be similar.  Note the best fuel economy is at 3500RPM and 26MPH.  Each hull/engine setup is different, but other AS owners I have talked with seem to have similar results - best mileage comes at around 25MPH.  

Good luck and see ya on the water!

[John Jones]

I'll second the 25 mph Cap'n John.

When my Navman fuel gauge decides to work I get the best mpg around 25-26 mph.

Got caught in a storm Tuesday night and had to plow home at <15mph due to the waves and low visibility.  Fuel usage was nearly double.

[rburlington]

I am very grateful for the inputs from all of you and especially for the chart; that's definitely something to work from.  I may add the fuel management guage suggested.  Any ideas on the one to get would be appreciated.

Thanks to those who worked to put this forum together!
Robert Burlington

[John Jones]

Floscan has the best reputation and of course is the highest cost.
http://www.floscan.com/html/blue/recreationalmarine.php

Navman (I have F2100) is relatively inexpensive but is noted for sensor failure.
http://www.navman.com/Navman/Templates/ ... 39311.aspx

Lowrance has just introduced one but I have not heard anything about it.
http://www.lowrance.com/Marine/Products/LMF-200.asp

I have had my F2100 for about 15 months and have had 2 sensor failures.  They replace it with no problem but they are slow about it (6 weeks).  If you search other forums like the Florida Sportsman Fishing Forum www.floridasportsman.com you can find quite a few people with the same gripe.  When it works, it is accurate.  Last week it said I used 34.6 gallons on a trip.  It took 34 gallons of fuel plus appropriate oil to top off.

If I had the $500 to blow I would buy the Floscan 9500 series.
http://www.floscan.com/html/blue/seriesdetail.php?sid=5