Can a Sailboat carry to much Fuel?

[Jman]

Originally Posted by DryRot

Interesting read considering I am looking at a Ketch with a 3200 gal fuel tank. I had not considered the low sulfur "bug" problem. I will be living aboard and cruising but it will take a long time to get through that much fuel. Hmm, back to more research.

3,200 gallons! That has to be misprint, unless the boat is enormous. 3,200 gallons would be nearly 25,000 pounds!

Not to mention at $3 a gallon, it would cost nearly $10,000 to fill up!


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[DryRot]

Originally Posted by Jman

3,200 gallons! That has to be misprint, unless the boat is enormous. 3,200 gallons would be nearly 25,000 pounds!

Not to mention at $3 a gallon, it would cost nearly $10,000 to fill up!


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Not a misprint. The steel ketch is 94' and displaces nearly 70 tons. And yes I figure that fillup will hurt the pocketbook.

[SkiprJohn]

I had 80 gallons on my 35 foot ketch and used 40 from Hanalei to Bremerton. That was mostly used in the Straits where I could have ducked in to buy more fuel if I needed to. I think 50 is just right and anything over 80 is overkill.

[markpierce]

I have, as a motorboat, nearly twice that fuel tankage, providing a minimum of 1000-mile range. If you need/want to motor a lot, as some sailboats do, it isn't a bad thing. Regardless, the boat needs to sail on its lines.

[barnakiel]

Imagine the longest non-stop motor ride, add a margin and that's that.

If you believe you need plenty of fuel then perhaps get a power boat instead.

b.

[Boatin]

The only time you are carrying too much fuel is if you are on fire !

[UNCIVILIZED]

My apoligies for the ramble, they're an ad hoc stream of consciousness of concerns/things to think on.

The concerns about proper baffels in the tanks has already been mentioned, but... how can you really inspect them to ensure;
- There are enough of them?
- They're stout enough?
- They're properly designed?
- They're properly affixed to the tank's walls, bottom, & top? And that those welds are up to spec.

Also, you'd likely need to consult with an engineer on this. But what are the appropriate scantlings for a tank such as that, & how do you determine if it was built to such spec's?
And, ah, was proper NDT done on all of it's seams & joints when it was being built? Plus, how do you know that no materials used when building it, it's bearers, or it's tie down points, were up to spec?

Then there's the "fun" part. Is it well enough secured for heavy seas, or in the event of a roll over? To what, inside of the boat? And according to whom?
As a load like that would probably necessitate extra laminate in the hull to support it under normal loads, & especially for roll over ones, & the same for the tie down points.

What is it resting on? Has that system been both properly engineered, & built? How does one check as much, without pulling the tank? As you'd want to have a surveyor inspect those structures, at a minimum.
That, & you'd realistically want an engineer to run the numbers on their design & construction after measuring them. Plus do some NDT to make sure that they're up for handling that kind of weight slamming up & down on them, at a couple of G's per wave cycle, when going to weather.

Plus, that much mass, even if the tank's only half full has got to do some crazy things to both the boat's trim, & it's handling. As the difference between when it's full, & when it's empty is more than even 2 full barrels of chain.
And is the boat's original construction up for handling such a concentration of weight, long term? Also, has any unseen, or microscopic damage been done to the boat's laminate already?

I'd say, that there are too many safety type, structural unknowns. Let alone, practical ones. With any Pro's being heavily outweighed by the Con's.
- PASS

[SeaSon]

The only time you'll worry about having a lot of fuel, is when the boat's on fire.

[zboss]

Originally Posted by Jman

If you do the math right it is more ��

185 gallons / 0.7 is about 264 hours of fuel. 264 hours @ 6 knots is a range of 1,585 miles.

Not enough to cross an ocean, but most of the seven seas.




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oops sorry you are correct! My brain was looking at that as I was typing and I blanked. Oh well.

Anyhow... my point is that its a lot of fuel!

IMO - You want at least as much fuel as you need to get half way across the longest expanse you are likely to cross plus 10-20% - kind of like a scuba tank of air. So, for most people that's about 2500 miles between the west coast of mex/south America and the Marquesas - about 1375 to 1500 miles of range. Which he has and that is great!

[mbuckner]

Originally Posted by UNCIVILIZED

My apoligies for the ramble, they're an ad hoc stream of consciousness of concerns/things to think on.

The concerns about proper baffels in the tanks has already been mentioned, but... how can you really inspect them to ensure;
- There are enough of them?
- They're stout enough?
- They're properly designed?
- They're properly affixed to the tank's walls, bottom, & top? And that those welds are up to spec.

Also, you'd likely need to consult with an engineer on this. But what are the appropriate scantlings for a tank such as that, & how do you determine if it was built to such spec's?
And, ah, was proper NDT done on all of it's seams & joints when it was being built? Plus, how do you know that no materials used when building it, it's bearers, or it's tie down points, were up to spec?

Then there's the "fun" part. Is it well enough secured for heavy seas, or in the event of a roll over? To what, inside of the boat? And according to whom?
As a load like that would probably necessitate extra laminate in the hull to support it under normal loads, & especially for roll over ones, & the same for the tie down points.

What is it resting on? Has that system been both properly engineered, & built? How does one check as much, without pulling the tank? As you'd want to have a surveyor inspect those structures, at a minimum.
That, & you'd realistically want an engineer to run the numbers on their design & construction after measuring them. Plus do some NDT to make sure that they're up for handling that kind of weight slamming up & down on them, at a couple of G's per wave cycle, when going to weather.

Plus, that much mass, even if the tank's only half full has got to do some crazy things to both the boat's trim, & it's handling. As the difference between when it's full, & when it's empty is more than even 2 full barrels of chain.
And is the boat's original construction up for handling such a concentration of weight, long term? Also, has any unseen, or microscopic damage been done to the boat's laminate already?

I'd say, that there are too many safety type, structural unknowns. Let alone, practical ones. With any Pro's being heavily outweighed by the Con's.
- PASS

A concern that came up to me was this a DIY project? Or did a engineer come up with a design to impelement the change? If so, how close was it followed?

The question of baffles did enter my mind if it is a single tank. Does the tank have access hole(s) for inspection and/or cleaning?

I think that you would not let the boat sit without the tank being topped off to keep moisture in the fuel at a mimium.

Best regards,

Mike

[FamilyVan]

I haven't read all the posts here, but in the first couple of pages I read several opinions that a 35 couldn't handle that kind of tankage.

I have a 35' sailboat. With factory tankage.

125 gallons of diesel and 250 gallons of fresh water.

So its definitely possible.

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[Jon Eisberg]

Originally Posted by FamilyVan

I haven't read all the posts here, but in the first couple of pages I read several opinions that a 35 couldn't handle that kind of tankage.

I have a 35' sailboat. With factory tankage.

125 gallons of diesel and 250 gallons of fresh water.

So its definitely possible.

As always, It Depends...

Have a look at the line drawings of the Cal 35, note the relatively shallow underbody and modest displacement...

CAL 35 (1979) sailboat specifications and details on sailboatdata.com

Do you really think such a massive increase in tankage over Lapworth's original design could be added without seriously compromising its performance and possibly her stability as well, not to mention drastically impinging on what is likely to be such a boat's minimal to modest storage space to begin with?

Sure, it now has an astonishing range under power... But what good is that if you've eliminated much of the space to stow all the gear and provisions to support such a style of cruising on that thing? As someone else noted previously, we're talking about something on the order of OVER 20 CUBIC FEET of potential storage space sacrificed with such a modification...

I'd certainly be curious to see this boat, or to hear what her water tankage is, in addition... But based upon what's been posted so far, this has to rate as one of the most ridiculous 'upgrades' to a perfectly good boat from a renowned designer that I've heard of in quite some time...

;-)

[a64pilot]

Originally Posted by DryRot

Not a misprint. The steel ketch is 94' and displaces nearly 70 tons. And yes I figure that fillup will hurt the pocketbook.

Well, that pretty much fits my definition of Enormous, Do you have any pictures?

[FamilyVan]

Originally Posted by Jon Eisberg

As always, It Depends...

Have a look at the line drawings of the Cal 35, note the relatively shallow underbody and modest displacement...

CAL 35 (1979) sailboat specifications and details on sailboatdata.com

Do you really think such a massive increase in tankage over Lapworth's original design could be added without seriously compromising its performance and possibly her stability as well, not to mention drastically impinging on what is likely to be such a boat's minimal to modest storage space to begin with?

Sure, it now has an astonishing range under power... But what good does that do if you'e eliminated much of the space to stow all the gear and provisions to support such a style of cruising on that thing?

;-)

I'd certainly be curious to see this boat, or to hear what her water tankage is, in addition... But based upon what's been posted so far, this has to rate as one of the most ridiculous 'upgrades' to a perfectly good boat from a renowned designer that I've heard of in quite some time...

Jon, I agree, not all 35's are suited to this kind of load carrying, but a blanket statement saying a 35' boat can't handle that kind of tankage is a little bit inaccurate. I have a friend with a Cal around that size (I think hers is a 34), so I'm somewhat familiar with the design.

Agreed, a lot of weight for the boat.

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[DryRot]

Originally Posted by a64pilot

Well, that pretty much fits my definition of Enormous, Do you have any pictures?

She was originally a private yacht built in New Zealand and then used for research for many years.