How Much Diesel is Enough?

[secrabtree]

Originally Posted by Jim Cate

Sam, that high burn rate is if you were running the engine flat out, generating the full 48 HP. You likely are not doing that at your .67 g/h usage. Doesn't take much power to drive a slippery hull at speeds less than ~80% of hull speed, goes up very quickly for those last few knots.

Jim

Jim - I was making an attempt to be sarcastic, but I guess I was too subtle. The quoted post gave diesel consumption per horsepower without defining whether it was rated engine horsepower or actual horsepower at the prop at a specified speed, or whatever. Since the average sailor has the power curves somewhere in his literature on the engine, if at all, I felt and still feel that it's a sort of useless statement to the average sailor to expect him/her to not understand that blanket statement to mean "fuel consumption per engine horsepower" as advertised and not as calculated from figures not understood if even available.

[Jon Eisberg]

Is it too soon for a snarky reminder of the particular brand being considered by the OP?

Based upon what I've repeatedly observed up and down the East coast, perhaps that 57 gallons could be cutting it a bit fine for his world tour...

;-))

[a64pilot]

Originally Posted by hpeer

I think the bigger underlying issue is..."What is your schedule?"

I think this is your answer really. We rarely HAVE to motor, but based on schedule, we choose to. Cruising will be on a different schedule and I see leaving based on winds, not on what day of the week it is.
I have an IP 38, it burns 1 gph at 2,000 RPM at 6.5 kts, it did that with a three blade fixed prop that was way over propped, and it does that now with a three blade autoprop that is correctly propped, but the auto prop does exceptionally well at part throttle.
My plan is to see the South Pacific, if I get to do that, I'll probably go with fuel bladders on deck, because I don't want to worry about fuel. Once empty of course roll them up and store them in the Lazarette.

My opinion is that fuel capacity is so easy to add, don't pick a boat based on it.

[blackcrow]

Originally Posted by Kenomac

Mark,

'Curious... then why does my Yanmar 100hp turbo diesel only consume 1 gallon per hour at 1800-2000rpms? Enough to drive our 25 ton boat at 6 knots in relatively calm seas <15 knot winds.

What am I doing wrong?

Try WOT sometimes.

[Sandero]

I carried enough fuel with a bunch of jerrr cans to do 1,000 nm and once had to or wait for wind. Problem with waiting is water and provisions. If you have enough... wait for the wind.

Island hoping I did not use jerry cans because fuel was available. Perhaps you need to do some research before you make a passage.

[a64pilot]

Jon,
At 25,000 lbs empty weight and 40 HP an IP 38 isn't particularly overpowered, with what looks like the winds are in the picture you posted, I can sail faster than I can motor, I can't imagine why they aren't sailing, but who knows?
IP's are not known to be good light wind boats, but in 10 kts I do fine, and at 15 kts, I'm as fast as any boat my size it seems.
I currently have a much better than the stock main sail, and will be getting a new Genoa and staysail this winter, I'm going to a 125% Genoa as opposed to the stock 110%, that will hopefully help light wind performance some.
But IP's are not race boats, although sometimes they do well, just like a Westsail will / has done well in conditions that favor the design.

[SeaSon]

Just a note on bladders on deck for those that have not used them. I have.

The issue I found is the sloshing of the fuel within the bladder.

Bladder must be completely full - very little to no air inside and bulging with fuel, and then lashed to the very strongest supports possible, or better yet in a deck box equally secured with stuffing to immobilize the fuel.

Other wise you will find you have a walrus on deck furiously fighting to break free, which it may eventually do, when the storms are raging.

I suggest bladders small enough that you can pump or drain the entire contents completely into a partially empty tank in one shot.


Sent from my SAMSUNG-SGH-I537 using Cruisers Sailing Forum mobile app

[Crom]

Electric motor with a big battery bank plus solar and a wind generator is my choice.

[a64pilot]

Originally Posted by SeaSon

Other wise you will find you have a walrus on deck furiously fighting to break free, which it may eventually do, when the storms are raging.

Sent from my SAMSUNG-SGH-I537 using Cruisers Sailing Forum mobile app

I think that is probably one of the best written examples of an explanation that I have ever read, I understand exactly what you mean, and a great point really.
Diesel is about 7 lbs per gl. so if it was a half full 100 gl bladder, then you would have a 350 lb Walrus straining to break free.

[hellosailor]

A bladder (blivet) can also be kept empty in a locker or lazarette, with adequate chafing protection, and then just filled when it is anticipated to be needed, i.e. for a long crossing. To avoid sloshing problems, run off your main tank, and when that gets low, use a transfer pump to empty the entire bladder into it. So the bladder is either full or empty, and the walrus less of a problem.


The bigger problem will probably be where to put the thing, empty or full, given limited spaces and weight balance.

[a64pilot]

Bladders I don't think are like Blivets if you mean the military ones. I think they are much thinner and are capable of being rolled up and stored.
My intent is to be able to have excess fuel the once or twice that I think I would like that, without having to have excessively large fuel tankage for the rest of my life so to speak.
In my case I'm thinking a 50 gl one or at most two of them, running the main close to empty and re-filling, I'm real sure a siphon would be easy to establish.
But then I used to put dual 60 blue plastic drums full of fuel to go out to the middle grounds on a Sport fishermen on the swim platform too, so I'm sort of used to the idea.
Drums originally contained some kind of fruit juice and were plentiful and easy to come by.

[hellosailor]

A "blivet" is just military jargon for a bladder that's on steroids, designed to hold 10,000 gallons instead of fifty.


Are they the same thing? I don't know, isn't a hawser the same thing as "string" ? (G)

[Jim Cate]

Originally Posted by secrabtree

Jim - I was making an attempt to be sarcastic, but I guess I was too subtle. The quoted post gave diesel consumption per horsepower without defining whether it was rated engine horsepower or actual horsepower at the prop at a specified speed, or whatever. Since the average sailor has the power curves somewhere in his literature on the engine, if at all, I felt and still feel that it's a sort of useless statement to the average sailor to expect him/her to not understand that blanket statement to mean "fuel consumption per engine horsepower" as advertised and not as calculated from figures not understood if even available.

Oops.... sorry Sam, I should have known better. My apologies!

Jim

[a64pilot]

This is what we called a blivet, big 500 gl roll looking thing so thick it kept it's shape even when empty
https://upload.wikimedia.org/wikiped...-YW808-026.jpg


You aren't folding this thing, not at all, they would roll if on a little hill when released and let me tell you they would knock down trees and not damage themsleves