Let's say I have a boat that I need some help with.

Said boat is ~3000 pounds fully loaded with fuel, supplies, me, and other stuff.

I need the boat to do about 12.5mpg. Consistently.

I was thinking to do this that I would design it like a catamaran. This boat also needs to be ocean worthy, and a cat would be more stable than say, a regular boat.

For the engine, I was thinking a bi-supercharged 350.

I know, you're thinking what the hell, that won't make it economical?

I went with this engine because, my theory is, a bi-supercharged 350 would make the same amount of power and propulsion at 2000rpm than a regular marine engine at 7500rpm.

This would mean extreme power when needed, but also good speed for the fuel.

To recap, I need 12.5mpg, 3000lbs, catamaran, bi-supercharged 350.

Anyone got any ideas?

EDIT:

http://thefutureofthings.com/upload/items_icons/Proteus-Catamaran_large.jpg

Something like this.

Two of these:

http://koti.kapsi.fi/hvartial/oss3/oss3.htm

EDIT:

make them taller, though. 1500lbs on one of those would easily sink.

also, where is the propeller going? or will it use a fan? Also, how do you plan on getting it to the ocean from minneapolis? (Aren't any of the 10,000 lakes big enough?)

I'm pretty dead set on pontoons, not something like that.

It'd be propeller driven. Unless there's a more efficient way. Is there?

I'd get to the ocean from Deluth, it's the world's most inland sea port.

I'm pretty dead set on pontoons, not something like that.

It'd be propeller driven. Unless there's a more efficient way. Is there?

I'd get to the ocean from Deluth, it's the world's most inland sea port.

Great Lakes FTW.

-N-

this is never going to happen.

and dual blowers on a 350 will never ever give you 12.5 mpg.

so fucking unrealistic.

Use a sail. That's the only way you will get 12.5mpg

You ain't getting that kinda milage out of a twin blower SBC.

and the money you spend on the engine, blowers, parts, tuning probably just wouldn't be worth it. something like a mild 383 stroker would probably do just fine. but then again, it won't give you the milage you are looking for.

and I would make it fan powered with a twin turbo 572 BBC and a 300 shot of the spray muahahahahaha

What you need is a crew of pirates who will board other vessels, steal fuel and bring you wenches and booty...Why worry about fuel consumption when it's not costing you anything?!

But cereal...Go with a sail with a motor as back up.

You need to give more specific (quantifiable) constraints if you want real, usable advice & ideas.

Exactly how fast (what range of speeds) are you wanting to travel? How much energy it takes to move something is directly related to how fast you want to move it.

What kind of fuel are you wanting to use? You can do more work with a gallon of diesel than a gallon of 87 octane gasoline.

What's your budget? What's the expected lifetime of the equipment? It could be more economical to use solar &/or wind power.

wait. you do realise that 350's don't hit anywhere near peak power at 2k rpm right?

Don't you realize that I DID give you a pontoon design? Just cover it up on the top.

Also, I'm not an engine expert, but the above posts seem to indicate that your plan won't work. So rethink the engine part. Also, don't boats tend to get shit mileage to start with? I mean, there's a whole hell of a lot more resistance from the water. I recall reading somewhere that big tugboats and the like get ~1 mpg (if they are lucky).

I recall reading somewhere that big tugboats and the like get ~1 mpg (if they are lucky).was that while pushing a load or what?

Just to give everyone something to compare to, This boat (http://www.mainship.com/models/34trawler/34T.html) weighs 20,000lbs (http://www.mainship.com/models/34trawler/34TrawSpecs.html), has a 380HP Cummins diesel, and gets 4 mpg cruising at a speed of 7 knots (http://www.mainship.com/fueleconomy/FuelOverview.html).

It was actually about a shrimp fishing boat, but it got 1 mpg.

i know it has been said but if you are going to be going at any speed that engine is going to be revving higher than 2000rpm's unless you have some sort of gearbox. and with that sort of power you would probably be going at a pretty fast pace. that would make high speed turning difficult as it would not be able to roll. though the idea of a powerful engine on a boat is sweet.

Chance of this happening- 1%.

Diesel? No way. The block in a diesel has to be made of solid steel, so the engines are VERY heavy.

To give more specific details, I'm looking for something to cover 2,500 miles in about 4 to 5 days, so it has to be faster than something that's wind powered.

But, thinking of solar power, maybe, to do the 2,500 miles, I could sleep during the day, so that the batteries could charge, and pilot the craft at night? Come to think of it, this actually might be a good idea. Assuming it stays sunny for the whole trip.

Said craft also needs to be seaworthy. So it needs to be strong enough to withstand large waves. This is another reason that I went with the catamaran design, because I figured this would keep it light and stable at the same time.

And I just realized how stupid it was to think of a SBC for fuel economy. Hell those things can barely get 12.5mpg on land :D.

So a solar-powered electric craft might suit what I want to do, if I sleep during the day and craft it at night, but the cost of the batteries would be VERY high. Of course, I could just jack them from a golf club from their carts...

Also, the solar powered idea would need a full charging system and what not, but it still seems more practical then a gas powered craft.

What does everyone think about a solar powered electric craft, given my new requirements?

What does everyone think about a solar powered electric craft, given my new requirements?Well, not very practical since covering 2500 miles in 4-5 days would require an average speed of 20-26 mph, which is fairly quick for a boat, which means you'd need a lot of power and thus a large area of solar panels considering current solar panels have to be over 6 square meters in area to get just 1 horsepower under ideal conditions.

For the hull, you could use 50 gallon drums welded together and foamed. Each drum ought to be able to support ~ 200 lbs / 90 kg. You could also fabricate something from fiber-glass or aluminum.

Solar power would be cool. How about, instead of sleeping during the day and having a whole bunch of heavy batteries to store a day's worth of electricity, you travel during the day and are constantly drawing power from the panels so that you don't have to store it.

Even if you don't want a sail, you could still use wind power. Install one or more electricity generating vertical wind turbines on the boat. Use the electricity to drive the propeller.

Just in case there's no sun or wind, why not mount a diesel generator on the deck? Sure, you'd get greater efficiency from driving the propeller directly through a gearbox, but, since you're using electric drive already, it seems much simpler to just use a generator.

To cover 2,500 miles in 5 days requires an average speed of 20.83mph. If you were to float the boat on 44/55 gallon drums they would create a lot of drag at that speed. It is impractical. Fibreglass is cheap and not too hard to learn to use.

There aren't that many 3,000lb vessels that are ocean-worthy. That doesn't mean it can't be done.

To put sail boats into perspective: the Sydney to Hobart race covers 727 miles and the fastest time was slightly less than 43 hours. That's an average speed of 17mph. Remember there are restrictions on these boats. An amateur achieving 17mph is possible since there are no restrictions on the technology used on your boat.

The difference in efficiency between a gearbox and diesel-electric is marginal. Not many large ships have gearboxes. The engine drives an alternator and an electric motor drives the prop.

If you want to go that fast on that little fuel then buy a jetski.

solar is a bad idea.

and piloting the craft at night? you don't want to be doing that.

solar is to expensive anyway

You are out of your mind. I have 2 words for you.


Motor Sailer.

he is fifteen, gives this 0 chance of ever happening.

If you're concerned about fuel consumption, why not take a standard engine, and convert it to run on Brown's Gas?

hahahahahaha

You cannot be serious:o