[PUP] Fuel consumption Was: The right boat

[Arild Jensen]

> -----Original Message-----
> On a personal note, while I will be making a journey as Arild describes
> (mostly within 50 miles of a coastline) I hope to take on fuel
> infrequently.
> It seems to me reducing the number of times you take on fuel reduces your
> exposure to contaminated supply.  However, the case could then be
> made that adopting this practice would result in a huge load of bad fuel,
> rather than a smaller sample your filters may be able to deal with.  My
perception is
> I'd rather find out quickly the supply was bad and return (within distance
> of the wing engine supply?) to the source and address the issue.
>
> Great points Arild, and as you suggest people investing in boats should
> consider these variables as they apply them to their voyaging goals.
>
> Scott Bulger,



REPLY
Scott, you have touched on a key point.
FUEL MANAGEMENT and tankage arrangement should be one of the key design
elements when considering a vessel design.
Having one or two large tanks may prove a handicap in dealing with a large
quantity of bad or questionable fuel.
Several smaller tanks may be a better bet despite the increased cost of
additional piping and valves.

Vessel trim with full and empty tanks is also something that needs
consideration. We have seen plenty of posts from Krogen owners discussing
the heeling characteristics as tanks are burned empty and the fuel is
shifted side to side.

What happens if you have a bad load of fuel and need to filter and pump all
the fuel over to the other tank.
AS a minimum a third tank with at least 48 hours fuel burn capacity is
required. This now becomes the CLEAN FUEL reservoir and  is never
compromised by filling directly from shore. It only gets filled from the
fuel polishing system.

Second issue.

Scott, you rightly point out the distinction between a coastal passage maker
and a blue water passage maker.
However the reality is you may buy a trans-oceanic vessel but will not get
around to making such a passage for a long time.
Meanwhile, what to do while coastal cruising in short hops? Do you still
want to drag around a couple of tons extra fuel when you know you are near
reliable fuel sources? A number of posts have been made regarding empty
tanks and condensation.
Having several smaller tanks means you can run a few tanks full and cap off
the unused tanks. If this is a longer term situation, it might even make
sense to fill the tank with Nitrogen. This will prevent the expansion
/contraction breathing which is the biggest source of dragging in moist air
that causes condensation.


Now that I am working full time in a naval architect design office, I find
myself spending a great deal of time considering all these issues. <Grin>
Then I get to put concept to paper and eventually see it built. <VBG>
Working full time with four other naval architects has proven to be quite
the education.

cheers
Arild