Fuel consumtion and alternative fuel

[StianM]

Originally Posted by Raggi_Thor

Light weight is of course important at all speeds!
At the same length a lighter boat can have smoother lines and less wetted surface.

Yes, but not as mutch that it will justefy the use off lighter and more exspensive materials.
For pure speed yes, but for fuel comsumtion no.
Why is big oiltankers, cruise ships, ferrys, fishingvesels made off steel or even tug boats and supply vesels?
The fuel has to be even more exspensive then now befour reduction off wetted surface by lighter and more exspensive materials are justefied.
Cat's with SES skirts and hydrofoils might have a bether effect upon total economy than choice off material.

[Raggi_Thor]

Originally Posted by StianM

Yes, but not as mutch that it will justefy the use off lighter and more exspensive materials.
For pure speed yes, but for fuel comsumtion no.
Why is big oiltankers, cruise ships, ferrys, fishingvesels made off steel or even tug boats and supply vesels?
The fuel has to be even more exspensive then now befour reduction off wetted surface by lighter and more exspensive materials are justefied.
Cat's with SES skirts and hydrofoils might have a bether effect upon total economy than choice off material.

For recreational crafts, I mean that you can design a lighter boat and be happy without using expensive materials. I will not continue to stress this, but when I say "lighter boats", I mean smaller boats, say 12x3 meters instead of 16x4 meters.

Large boats (ships) are made of steel because global stiffness is a dimensioning factor while for smaller boats it's local (panel) stiffness that dictates the hull thickness. Smaller fishing vessels are often made of aluminium or grp to save weight and fuel and carry more fish.

Hydrofoils are interesting at higher speeds. Cats will use more fuel than monohulls at slow speed. Travelling in a low cp monohull at "hull speed" will probably be most ecoonomic?

One problem with many boats today is that they are designed for high speed but are run mostly at slow speed.

[StianM]

Stiffnes can be acheved with thicker aluminium plates instead off steel and save weight, but stil they are made off steel.

If you want to build one off a kind smal light boat aluminium would be my choice. If I want to make a series I would go for moulded FRP hulls.

If I'm building a larg displaisment hull steel is what I go for.

More focus on the aerodynamical side off high speed boats would also provide bether economi.

Lower the bow to allow increased airflow ower the hull and lower the stern.
This will create aerodynamical lift with will lift the hull out off the water and reduce water resistance.

The really big chalenge for smaler boats is fuel. Large boats can use cheap HFO, but for the rest off us it's the exspensive petrolium's like diesel and gasoline. Gasificate coal and biomas is something I turn on to with a mixture off biodiesel.

[Raggi_Thor]

Originally Posted by StianM

Stiffnes can be acheved with thicker aluminium plates instead off steel and save weight, but stil they are made off steel....

Listen carefully, I will say this only once (more) :-)
On large ships, the plate thickness is almost the same as on a small cruising boat. BUT you have a lot of longitudinal stiffeners inside. On small boats (up 20 meters?) the whole boat regared as one large beam is ussually more than stiff enough if the skin is stiff enough to take local impact. This is not the case for larger ships. Steel is 3 times as heavy and 3 times as "stiff" as aluminium. So when global stiffness is the dimensional factor (do you say that?) there is no weight saving by switching to aluminium. When boats get smaller (shorter) local (panel) stiffness is more and more important, so for a very small boat wood will be lighter than aluminium.

[StianM]

Good. I would not even listen to you once more.
Maybe I'm impolite, but I have ben polite until now.
It's not 3 times les stiff and it's not 3 more heavy.
The diference in weight/stiffnes is about 5%.
Fuel consumtion and alternative fuel is the name I named this thread and not save fuel by weight. I understand that your desperate to sell your products, but that is not my problem.
I can go and make myself a carbonfiber hull or kevlar hull with sandwitch if I want something with low weight. Or I can weld a steel or aluminium hull if I prefere that.

[Raggi_Thor]

Sorry if I pissed you off, and large hulls is probably out of the question anyway, sorry again, hope you'l get over it :-)

[Arlon]

A diesel panga owner converted his diesel to run on reclaimed cooking oil. He said his last trip of 40 miles cost him about a $1.. Of course that didn't include the cost of the conversion. Not a global solution but it's sure letting one pangaphile go boating for cheap.. He's getting free cooking oil right now but sooner or later as more folks figure this out, the restaurants will start want to be paid for their used french fry oil..

[StianM]

Originally Posted by Arlon

A diesel panga owner converted his diesel to run on reclaimed cooking oil. He said his last trip of 40 miles cost him about a $1.. Of course that didn't include the cost of the conversion. Not a global solution but it's sure letting one pangaphile go boating for cheap.. He's getting free cooking oil right now but sooner or later as more folks figure this out, the restaurants will start want to be paid for their used french fry oil..

Why not go to the local dry dock or car workshop and pick up spil oil?
Both hydraulic, motor and gearoil will burn, but maybe you would nead a preeheater.
I would also recomend a good filterunit.
A few % off diesel mixed into it if it has problems starting.
A 100 years ago this fuel price problem would ben solved, people was more inovative back then.
Rudolf Diesel's first engine runn on coal dust(It blow up)that was injected with compresed air.
Rudolf Diesel disapared on a trip to UK and was found in the british chanel by fishermen drovned. Some conspiracy theories say he was killed by oilcompanys because he was saying he's engine could be runn on vegetabile, fish or animal oil's.