So thoughts on how this happened.

[lemans81]

While on vacation this year we took a trip from our cabin(40 mile marker on Bull Shoals Lake, but there is a large arm that goes up so I know its not truly a 40 miles trip, probably more like 25 miles) to the far dam. As Bull Shoals is a quiet lake, you never know which or how many marina's are going to be open, so we went down slowly at what we thought was about the best fuel economy, around 3700 rpm but planed. It was supposed to be a clear day, so we took our time, got down there ate lunch at the dam, we stopped and filled whenever we could.

Then one of those awesome 0% chance of rain storms blows in, as soon as we saw the clouds we started for home, but it took us about 2.5 hours down, with stops and such. Also you have to understand that there are no easy safe places to just tie up and wait out a storm, most of the lake is corp land, the whole day we passed less than 10 boats. So we start home and then the lightning.....lets just say trip is now a nightmare. Since everyone else was hiding from the stinging rain I made the call to scream home(I promise there was no safe place for us, and because of how the roads are a car coming to help would have been 3-4 hours away). So we went home at just over 5000 rpm and around 40 mph, so cut about 45 minutes off the trip home. The real puzzle though is the face that on the trip home we used several gallons less gas than we did going down. The only thing I can think is that I had it more trimmed up and were better planed but I can't imagine that the full throttle wouldn't overrule any better planing.

I know I am going to take a beating over driving in the storm but options were low, so be gentle.

[MerkFalc]

Maybe the weight was all at back and you had the bow out of the water on the way back? Was the wind at your back?

[ron nh]

Remember back in the 70's "assuming your a certain age" when the speed limit was lowered to 55, The truck drivers were all pissed off so they set out to prove they would save gas by going faster. Im sure someone here will do the math, I think you were going so much faster that your mph made up for the mpg if that makes any sense. I.m really sick right now so I don't think Im smart enough to say what I mean to say. I tried. I'm going back to bed.

[Liquid Asset]

I agree about the wind direction. Which way was the wind blowing ? A head wind on your way there and storm force tail winds heading back could easily make a difference. I know a good head wind can knock a couple mph. off my boat and it surely uses more fuel.

[HandymanHerb]

I think he was going down hill on the way back

[illinoid]

I'm blaming the lifting strakes...they get more of the pontoons out of the water so less resistance...less fuel burned.

Or it is a warp in the fuel usage in Arkansas, I seemed to get about the same mileage in my FIL's pontoon no matter how fast I went on Lake Norfork.

The Double Nickel Challenge failed to prove faster trucks burn less fuel. The theory was the turbos are more efficient at higher speeds and the trucks needed to be in overdrive to get better mileage. Trucks now have more powerful engines that produce higher torque at low rpms with less internal friction in the engine. Wind resistance increases exponentially with speed, twice the speed means 4 times the wind resistance.

http://www.inboundlogistics.com/cms/art ... long-haul/

Herb probably has the best theory!

[lemans81]

The wind was coming in off the bluffs so it was hitting us in the sides, going down the water was smooth, but coming back it was white capping. I know we stopped twice going down for fuel and only once coming back(coming back we knew how much gas we would need).

My personal thoughts are that it must be the lifting strakes must have been more out of the water, its possible we had more people towards the back and they were all covered in blankets and towels, so maybe somewhat less wind resistance. This is also a one time event, let me assure you when I am running high RPM pulling people on the tube that engine just gulps fuel.


Also the trip to the dam became something epic around the cabin, my family started going to Bull Shoals in 1955, they build a cabin down there in 1959. Somewhere in the early 60's they took two ski boats and went to the dam. Now the story of that trip became epic lake saga, and it took them a whole day to go and then they had to camp on a small piece of land with nothing around, and then an entire day back. So since that trip no one even attempted it. Like 15 years ago someone had brought down a terrible 16ft Bayliner that was 25+ years old, for everyone to use and me being 18 was like I can do it. So we took that old boat and went screaming down to the dam, and it wasn't nearly as far or as bad as the epic tale had made it. So I have now made like 6 trips and taken all the nay-sayers who were "uncertain" it was that easy a trip. This last one was for my mom(the last doubter), so with the storm she counts it as a horrible trip(it was, but come on, we tamed the epic tale).

[MerkFalc]

I know my boat is faster in rough seas. You were probably skipping off the top of them rather than riding in them. Could easily account for it I suppose

[ron nh]

Dam, another genius theory blown up.

[Discovery]

I am wondering/thinking you had the bimini up? I always felt I had better speed (fuel savings) when ours was up and in chop and a headwind. This was running with a Merc 40, no strakes, so I always left it to a foil effect that lifted the bow and transom a bit. It was an 11' bimini.

This question is a reason I am getting a fuel meter on the next boat.

Did you get a lot of dam pictures? I will see myself out now.....

[HandymanHerb]

On airplanes with pontoons you can't take off on smooth water, the suction holds them down, so to take off they have to circle and make waves to take off, so it rough water less of the pontoon is affected by suction with the water

[dhsofficer]

When I had my deck boat, I made several trips over to Catalina island. On trips going 20mph, I would burn 1/2 tank of gas. If I could go 25mph, I could make it on 1/4 tank.
It all has to do with how much boat you get out of the water.
It takes more fuel to push a boat through the water than over the water.
Plus 5 gallons an hour for 2 hours is 10 gallons.
4 gallons an hour for 3 hours is 12 gallons.

[lemans81]

Yes we had the top up both directions, and we have a double bimini with a zip in middle piece so it covers front to back entirely.

I suppose I do have some dam pictures...and some from the trip as well.

You can see those clouds starting, this was 5 minutes before we left to go back home.




These next three were at my Grandpa's house, my step-grandma is a clown(she was an engineer before she retired years ago), so she made the kids balloon bow/arrow and Carly a Minnie mouse headband.






This one is the view from the front door of the cabin...really makes going worth while.


We set up kiddie pools on the deck for the monsters to play in, as they were always "bored".....


Another look from the front door of the cabin.


I set up movies on all the kids tablets, and got them cheap headphones so I didn't have to hear their movies or games, just thought Carly looked silly in them so snapped a pic.

[Bryden24shp]

Nice pics! Looks like a great time, even in bad weather, at least you are still floating. I'll take a bad day on the water over a perfect day at the plant stuck working, any time!
My thoughts include cooler air temps in the stormy weather create a tighter air/fuel ratio resulting in better fuel injection trim. My old Etec ran 500 to 750 rpms faster in the spring and fall, compared to hot summer temps. And the Verado on the Premmie runs about 300 to 500 faster in cooler weather. I have to change up a pitch in prop in the early spring to stay off the rev limiter when I push it. And I love to push it when no one else is out.

[NonHyphenAmerican]

I'm not experienced enough to comment too much re: toons, but keep in mind that highway mileage is always better than city mileage on vehicles.

My hypothesis is that there is a "Sweet Spot" for mileage no matter what you're driving.

Too slow in a boat and you're pushing water which would increase fuel consumption.

Too fast and you increase fuel consumption again.

With the electronics they have these days, I discovered that my F150 SuperCrew for example gets it's best mileage with the fold down bed cover closed and cruising at 70 mph I get 19.5 mpg. At 80 mph (Interstate here is 75 and you can 'fudge' 5) the mileage drops from 19.5 to 16.5. At 60mph I get 16.5mpg. So I'd bet the same holds true with a toon. Too slow, you're pushing water and increasing fuel consumption. Too fast and you overcome the water push but increase fuel consumption in order to propel at the higher speed. I'd bet that every boat/motor/prop combination has its own "Sweet Spot" where fuel consumption levels out with speed obtained.