Mileage economy

[Joe Yochem]

I have a 2005 280 Sundancer - twin Merc Bravos. Can anyone advise the most optimum speed/rpm settings to achieve best mpg (not gph)?

 

[andy k]

which engines do you have? do you have any idea of what pitch you have for your props? how many people/weight you you usually plan on have aboard? will you usually be doing short cruisers or long cruises?
if you have the 5.0s here is what you should expect, got to love boattest.com

 

[Presentation]

http://www.boattest.com/boats/Boat_video.aspx?ID=174

Looks like you now need to pay to see the data.

From memory, MPG varied almost nothing from about 28 MPH thru 35 MPH.

Anywhere in that range, change was insignificant.

Not filling your water tank with water you will not use on that trip would make a bigger difference then the difference you would get anywhere in that 28-35 MPH window.

BTW…..all total, three years of records, checking distance traveled vs gallons purchased I average 1.37 MPG.

I do run heavy / loaded and we do sports like skiing and tubing plus we have a fair amount of no-wake zones in our area, too may in my opinion.

If you run light and don’t pull people you may get better fuel economy. Oh, we also have a generator and that gets 0MPH, so it lowers our average.
So consider 1.37 MPH on the low end.

Anyone that says they are averaging 2MPG with this boat / engine / drive setup is full of shi………being towed by another boat or drifting. So there is your window of economy in this boat.

 

[Presentation]

edit - data now posted by andy k

Thanks!

 

[Sundancer]

Most of these charts start at 1,000 rpm. Why is that? I would guess that your BEST mpg is at the lowest idle possible. BUT, that takes forever to get anywhere, is annoying to other folks if you are in a channel, can lead to overheating if your impellars are marginal, isn't always the best for your engine and more importantly is about as much fun as watching paint dry! Fuel is a SMALL expense when you look at all of the costs associated with boating. The average northern USA boater, does something like 40 - 60 hours a year. That's about $2,100 in fuel costs for your engines at 14 gph and 50 hours. If you idled, you could cut that to approximately $480. How much is insurance, maintenance, moorage, trailerage, storage, etc.,?

So to answer your question, to get the best mileage IDLE!! To optimize your fun and reduce time in transit, run about 3,300 rpm!

 

[88dancer300]

Sundancer, What is your cruising speed and RPM ? Also wide open throttle RPM and speed? This will be my first season with my 300 sundancer, and not sure what to expect. Usually the engines will tell me where they like to be. I am hoping to be able to cruise at 3000 RPMs or so? speed is not a big concern, I just want to run the boat without beating it up. Shes a old girl. I have the 5.7s, 16X16 props, AC, Gennie, usually carry 1/2 tank of fuel, always have a full water tank, carry a rolled up dingy and a 3.3 Merc outboard, usually 60 lbs of Ice, four 30 packs of adult refreshments, and food for the weekend. Sorry for the long winded post. OH BTW, thanx for turning me on to this site! Very informative and a great group of people. Dave

 

[Summer Fun II]

I have the 5.7s, 16X16 props,

I have 15x15 props on my tug and can max out at 51.9mph. :thumbsup:
I don't have all the other crap on the boat as you do.

 

[Sundancer]

88D300:

You have a lot of stuff that I don't have!! Regardless, we usually run with under 1/2 tanks, full water and gear for the four of us and the two furry dogs. We typically run about 3,100 to 3,300 as optimal cruise which is 26 to 29 mph. Sometimes a little slower depending on the weight and weather. That just seems to be where it trims out fairly level and I can optimize by tweaking the drives and tabs while watching the speed on the gps. Top speed with my props is around 40 mph and 4,600 rpm. I'm running 15 x 19 or 15 x 17's. I can't remember, but I think it's the 19's. Wide open is only hit once early in the season and again late in the season to confirm everything is still in working order.

This is a great site and I think you'll find a lot of great information here!

 

[88dancer300]

Thanx Sundancer. I should be fairly close, its only myself and my fiance, and no big furry pooches. I will find out soon enough. Dave

 

[Sundancer]

Those numbers are taken at 2,200 feet above sea level too! When we're in the San Juans, the boat has a WHOLE lot of power!

 

[370Dancer]

Of course, economy, mileage and Sea Ray are oxymorons.
Fun is a direct correlation.
Do the math.