Offshoreonly.com - fuel use comparson

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Quote:

Originally Posted by cp5899 (Post 3897717)

I'm torn on this subject. When I was looking to buy another boat this past fall I thought about going with a twin big block boat, but I run my boat every weekend and we don't pull up at the sand bar and sit all day. We will stop at 4-6 places on a regular day of boating. That being said, my last boat (Baja 235 force 468bbc) had a 62 gallon tank and I would burn at least 50 gallons on Saturday and 50 on Sunday.

My second dilemma is I always want to modify my engines and if I had two it would be double the cost on cash for builds and I'm sure fuel bill would suffer too. I knew I wanted a blower motor for my second boat. I ended up buying a 280 velocity and pulled the motor to build a 509 blower motor. From what I understand the velocity is pretty fast and efficient hull so I think the faster cruise speed will cut down on the fuel a bit. I just think if I had a twin blown bbc boat I would be hitting the gas station hard with as much as I run. My next boat will be a 35-38 lightning, so at some point I'm going to have to bite the bullet, but I figured I would stay single engine for another year or two.

My offshore fishing boat has a 150 gallon tank and we use 120 of it a day and its not fun spending almost 600 a day for fuel. If I had some buddies to split it with then it wouldn't be so bad, but I got into boats about 4 years ago and haven't had any of my friends show much interest so my wife and I do it alone so I'm stuck with the bill. 3-4 day fishing trips get expensive when you add up bait, tackle, hotel and diesel for the truck. When we got into speed boats two years ago I felt like I was saving money only having a 62 gallon tank and only being 20 minutes from the boat launch.

Saving money and speed boats in the same sentence....funny, but in my case its been true.

The way I boat, I could get by with 50-75 bucks worth of fuel (20 gallons) for the weekend. boating Friday night after work, saturday, and sunday. but we do alot of sitting and partying and short runs to where we are going to be.

Now i have the Twin BB. and if you where running that kind of gas out in a single, your twins are going to EAT your wallet haha. but totally worth it.

Fuel use comparison: most V hull boats 20'-35' with a inboard outboard configuration get around 2 mpg. +/- 1/2 mpg. at 3000 rpm. with 1 or 2 engines. Average cruse ship uses about 200 gal. a nautical mile or about 50 feet a gal. If anyone is getting any different please reply with your boat info. (mpg. size boat and engine info.) Thanks.

There is so many other things to consider when it comes to the cost. especially when you consider weight of people in the boat, gas and speed of travel. I like to consider the other cost that so many look past. Like the fact that twin 350's can run bravo drives with no issue and a single 502 put a lot of stress on the drive with only one. In the end it's extremely cheap to maintain a 350 compared to a 502 when it comes to re-building motors drives and so on.

I personally burn about $250 a weekend with twin 502 and like many have said "What's $50 when spending $600 to fill a tank

Simple solution just get a single 575 and say screw it!

glad i dont spend 250 a weekend in fuel, I would not be able to afford this habbit.

100 -150 bucks will last me all weekend.

My current boat (27' Hallett) has twin Scorpions (377" small blocks) and is really easy on gas. I would say it uses no more and possibly less gas than the same boat would use with a single Big block. I usually cruise at 2600-3100 rpm and burn from 8.5-12 gph. I check it against the hobbs on every fill up.
My 35' Fountain that I used to have had twin 500efi's and it consistently used 22-25 gph. It was much heavier than the Hallett 270T.

We ran from Sturgeon Bay to Fayette Michigan on a day run (most expensive Subway sandwich ever, $455 footlong), I figure that's about 130 miles round trip. Ran a boring 3400rpm max up there to get a sense for fuel burn, used ~3/8ths tank and ran 4000+ the whole way home, the last 35+ miles around 4500rpm. I think we burned 115ish gallons total with the ride home being much faster. Twin 496HOs 26p merc 4 blades 31 Sonic

I try not to figure the costs, but average about $1000 month in season running all over green bay and around door county. Maybe winter isn't so bad:daz: save all winter, spend all summer. I don't run slow to save money, but would slow down to save gas to get to a pump, I run what feels good and that usually is 3800+

As others have said if fuel $ is a concern, it gets much worse the bigger the boat and engines. I also read here on OSO the most true thing about boats ever: It's not how fast you want to go, it's how fast you want to spend!

I know you're talking small blocks, but gives some reference for spend if you not focused only on fuel costs like me. I think I'd still spend almost $800 with small blocks because they'd be near redline everywhere:lolhit:

BTW, it was one of the most memorable days of the summer. I got to share one of the coolest places in reach by water with my wife and had weather that must have been a gift from above, priceless...

Hey deemo, nice to see someone on the forum that boats the same area as we do. If you see a white and yellow donzi on the water say hi!
Do you ever get to Menominee? Maybe I have seen your boat.

Quote:

Originally Posted by mittens (Post 3898024)

glad i dont spend 250 a weekend in fuel, I would not be able to afford this habbit.

100 -150 bucks will last me all weekend.

Mostly because I like to go full throttle everywhere and always have a few people on the boat. I also make a three day weekend out of it. In the general scope of things around this forum $250 is peanuts!

Quote:

Originally Posted by fctyson0 (Post 3876273)

Here is a scenario I'm sure has been beat to deth.two boats same day same water. 100 mile trip 3500 rpm.
Boat one. formula 271,502 completely stock
Boat two. donzi 28 ,twin 350 mag

App how much more fuel would boat 2 use?

It may be irrational considering the cost of performance boating but I am also concerned with Fuel efficiency

If you were to prop the boat for top speed and only run that prop(s) then the twins would burn about 20% more fuel at cruise and 80% more at WOT.

If you run the 502 and have a cruise prop with more blades and maybe a little more pitch....then the fuel difference is much greater. The twins already have enough blade in the water so more blades don't have the same fuel saving results.

You could switch back to a top speed prop to get the last few MPH back when you know you will be at WOT.

At higher HP the BBC needs forced induction and the twins may not. fuel consumption is alot closer.

At the power level you mentioned...maybe consider a more efficient single engine (less weight and less cid than the 502). ILMOR 7.4 LS 580HP. less expensive than twins, less fuel consumption than a single 502, more RPM range to run only one prop all of the time, and faster than both.

If you want a fast boat but still want good mpg get a Eliminator 30 daytona and put a pair of 370hp Yanmars or 350hp Cummins, you will have a 90 mph or close to it boat that gets 4 mpg at 60 mph and close to 3mpg wide open. 1.36 drives and 32 or 34 pitch props should get you there. Doesn't have a huge cabin but there is plenty of room to sleep in there. You won't save any money but you will get great fuel economy!