Throttle For Best MPG?

[eyepatrol]

Just curious what throttle position would give my dad's boat the best mpg for some of the longer boat trips we like to take while on vaca. A little info on his rig....he's got a 1987 16' Crestliner Angler, dual console with 1996 75hp Mariner on the back.

I've always guessed at what the best throttle position would be (no gauges) for getting the greatest fuel efficiency, and my guess has always been around that 1/2 - 3/4 throttle range. Have I been guessing right? Also, I've always wondered if we'd get better gas mileage if we go 1/2 - 3/4 throttle, but trim the motor up a little to get the nose up a little higher out of the water. I know it reduces drag, but it also increases speed a little along with rpms.

Any thoughts from anyone?

Thanks.

[Cliff Wagenbach]

You are right about trimming your motor to the point that you gain a little speed, ( that means that you have reduced drag) thus better MPG.

Most dealers reccomend that you open up your throttle to full speed,trim the motor, and throttle back just to the point that you can hear the motors RPM's drop and not lose to much speed. That will give you your best MPG and also it is much easier on your motor over the long haul.

Cliff

[Surface Tension]

By all means trim up after you get on plane.

As far as the throttle it depends on the rig to get to that best cruising speed. Say your close to the max HP rating for the boat and your top speed is 40 mph but you throttle back to 30 mph. Now the same boat but with a smaller outboard with a top speed of 30 mph. The boat with the bigger outboard throttled down to 30 will get better mileage then the boat running full throttle at 30 mph. If the boat with the smaller outboard wasn't trying to squeeze the last couple mph at WOT and throttled back to 3/4 there'd be a big savings.

[PerchJerker]

I've always heard that the most fuel efficient speed is basically the slowest speed that will keep your boat up and plane. Get up on plane, trim out your motor, ease your throttle back until you get to the point where your rpms drop but your boat easily stays on plane.

I have SmartCraft gauges for my Opti, and one of the things it does is monitor fuel consumption in gallons per hour. Best crusing for me is around 3000 to 3500 rpms. Fuel consumption increases pretty quickly as the rpms go up from there.

My boat is a Ranger Reata with a 175 Optimax. WOT is 5500 rpms, 53 mph, and I burn 16.5 to 17 gallons per hour. When cruising at 3000 to 3500 rpms I get around 30 mph and burn 5.5 to 6 gph. Big, big difference in fuel consumption.

[eyepatrol]

Thanks for the info fellas. That's close to what I've been doing, but I'll take your advice and run it that way.

Not that I'm really trying to penny-pinch here, just that my dad has 2-6gal tanks in his boat, I'm bringing my 2-5gal spare gas cans, and want to get the best consumption efficiency to travel a little further out on the lake than if I were to "blaze" out there WOT.