Logic behind fuel efficiency?

[sailorboy1]

Originally Posted by Cotemar

For cruisers its not really about the speed or even the fuel cost.

Its all about the distance you can go without stopping for fuel.

I'm with you on that. Crossing the Gulfstream yesterday the math said it needed to get the backup 5-gals out and put in the map tank! And that was the special expensive Bahama diesel

[ranger58sb]

Originally Posted by jsc7

I don't really understand the interest in fuel efficiency for larger ships (above 50 feet).

I don't really get this. For someone spending up to $3 million on a ship, why would they care about a few thousand in fuel costs? Heck, I would expect they spend more on food than on fuel. It's a trivial cost in the grand scheme of things. What is the rationale?

Folks are making good points...

Another might be about how many people buy $3M boats. Maybe not so many here... although that's just a guess.

I'd expect more likely folks buy the boat that suits their needs, often pre-owned, for way (WAY!) less than that... and then they operate it within their budget.

Fuel efficiency comparisons might come up in that case, but maybe more so when comparing two or thirty different vessels that meet the buyers basic requirements. Boat A is otherwise suitable and it'll cost $X to run it. Boat B is otherwise suitable and it'll cost $10X to run it. All else being equal, Boat A might have just found a new owner. (Another version of the same comparison is about operating speeds. 7 knots on Boat C costs $Y/year; 20 knots on Boat C costs $3Y/year. Owner often goes slow and saves.)

But that comparison also works for $3M boats. Most folks I've met who could afford that -- can afford it because they don't just throw money away. Yes maybe "a few thousand" here or there is chump change, but after several years of spending that kind of money every week... even chump change adds up to real money.

-Chris

[spearfish3]

One important factor that many could be missing with the range equation is that engines do not like to be continuously underloaded. That is why you will see a large Nordhavn with comparably small engines. If you were to take a high HP sportfish and idle everywhere, you would see issues over time. All boats are trade off, whether it is sail or power, but it is best to at least have a boat that is equipped for it's intended purpose.

[TrentePieds]

A million here, a million there - it all adds up :-)!

TP

[a64pilot]

You know, I see all the time 50 and 60 million dollar "business" jets buying fuel at Miami International etc. where its a few thousand dollars cheaper just down the road, 10 min flight away.
I think at that level a few thou is chump change.

[30West]

Originally Posted by a64pilot

You know, I see all the time 50 and 60 million dollar "business" jets buying fuel at Miami International etc. where its a few thousand dollars cheaper just down the road, 10 min flight away.
I think at that level a few thou is chump change.

They get charged landing fees if they don't buy fuel there. Plus it isn't cheap to gin up two ten-minute flights, and pilots can run out of duty day and the plane is stuck there.

[Pete7]

Originally Posted by jsc7

That makes sense. A semi-displacement cruiser will max out in the hundreds of miles, not enough to get across an ocean, so it is fine if you want to go up down a coast, but when you want to go to Iceland, then the sailor has to plan on throttling down to hull speed. Of course, if the boat is long enough, that speed can creep up. For example, the FPB 115 in construction is estimated to have a cruising speed of 14 knots.

I have heard that there is a radically new design with knife blade prows that cut through waves and allow the possibility of breaking the hull speed barrier. Of course, if you are knifing through 30 foot swells, I hope your bridge is watertight, because you are going to be a submarine at that point.

Something like this British motorboat:

https://www.youtube.com/watch?v=6MFX3ldg9mQ

[jsc7]

Yes, but in that video the water is perfectly calm.

We need to see what the boat looks like when it is operating in 15-foot swells.

[Pete7]

Originally Posted by jsc7

Yes, but in that video the water is perfectly calm.

We need to see what the boat looks like when it is operating in 15-foot swells.

Well if you want to play in 4m swells and have fuel efficiency then how about this:

https://www.youtube.com/watch?v=1m7GxAnWbVM

[Lepke]

If you're interested in the specs for the FPB64, I found a pdf here: http://www.berthon.co.uk/yacht-for-s...-64-fpb-64.pdf
PDF is probably bigger than allowed to upload to Cruisers.

Not that impressive. I have a 83x17 boat designed about 1940, about twice the tonnage, with twins designed in the 1930s (Detroit 671) not known for economy, and come close to their NM per gallon when I do the math at my economic speed (that I almost never run).
Much nicer interior, better interior design than I have, but almost no deck space. If you spend all your time inside, why have a boat? But I'm an old guy and don't like the new look of yachts.

[tuffr2]

How about cruise ships and freighters. They have that bulbous keel to affect the wave the ship makes. That is one ugly look but for running boats as much as they do, they really like the tiny percent of added fuel economy...cha-ching.

[Suijin]

The FPB boats are at their core expedition vessels. That expands the range conversation; it's not just about being able to cross an ocean, it's also about being able to operate for extended periods in remote areas where fuel is not available. That's obviously a significant criteria in a motor yacht that has no other means of locomotion.

For cruisers, in general, the trade off is clear and has little to do with the price of fuel. You can only carry so much, and the more of it you carry the less you can carry of everything else. Loading up on a ton of it so you can go a few knots faster is not an attractive value proposition even when you ignore the cost factor.