Fuel Quantity for Blue Water Cruising

[zboss]

Originally Posted by StuM

Going a bit OT, but it's sort of relevant:

I've never researched W&S hydrogenerators before, but they sound promising, so I took a look at Cruising hydro generator

120w at 5knots. So less than 10 amps. And it looks like about 200w at JazzO's 6 knots or maybe 15 amps.

And they only work when you are underway on a passage - not at anchor.

They look like a good option under certain conditions, but they don't appear to be the answer for most cruisers.

You could make the same argument for any of the alternative energy options. Solar is only good when you have sun or when you can put enough on the boat, wind is only good when its blowing but not when sailing downwind, etc..

Most boat have higher energy consumption on a passage or when moving... autopilot, etc. this is a perfect time to have a hydrogenerator.

With that said - we have not seriously considered a hydrogenerator because of price. If you had the money then a combination of wind, solar, and hydro should provide more energy than you need under the vast majority of conditions. If you have to run a diesel engine for an hour a day and burn a half gallon 365 days a year then you are more than easily paying for the hydrogenerator over two years.

The OP question was how much fuel does one need and it certain is dependent on a lot of factors, including the combination of alternative energy options available to them. We opted for solar and will be adding a wind generator at some point but thats because I really don't like running the engine unless we have to.

At anchor we do not need to run our engine at all unless it is seriously overcast for a day or two but I could easily see where the hydrogenerator may be able to play a role in certain inshore areas that have high currents twice a day. For example... St. Augustine's Municipal Marina current is about 3 knots because its near an inlet.

[Wandering]

We use a duogen towed charger. They are made in the UK. It makes a lot of current. It drops behind on a pole not a rope. It converts to wind power when stationary. It made most of out power on the last Atlantic crossing. The solar topped it up so we never needed to run the engine for charging. We used an electrics autopilot, refrigerator, radar etc and showered every day with water from the watermaker. check duogen out on the net

[Talbot]

Originally Posted by Wandering

We use a duogen towed charger. They are made in the UK. It makes a lot of current. It drops behind on a pole not a rope. It converts to wind power when stationary. It made most of out power on the last Atlantic crossing. The solar topped it up so we never needed to run the engine for charging. We used an electrics autopilot, refrigerator, radar etc and showered every day with water from the watermaker. check duogen out on the net

Know them very well. They feature very high on fits for the ARC, but the D400 is preferred when the boat is at anchor. I am hoping that I have enough solar to not need to use anything extra very often, but recognise I may need to top up occasionally - that is what the year in the Med will prove. My query was more aimed at fuel for motoring.

[Wandering]

I agree that the D400 is a high quality bit of kit. If I needed just a wind turbine I would go for one of those. In reality, we rarely need a wind turbine. We use most power on the move. we have 320w of solar that provides what we need at anchor so the wind turbine isn't used much. It is always there if we need it but the output of the duogen in water mode at 7knots is circa 12amps@12v. You need a lot of solar to match that or wind over 20knots. The new sail-gen looks good as well. I might have been tempted to go for one of those if I was starting again.
We make water with a genset and 240v powered watermaker. We can charge batteries at the same time as a back up so we will never have a problem but I really don't like burning diesel to charge batteries

[Jeannius]

Originally Posted by Talbot

My tankage is double the normal (two additional 90 ltr tanks in the forward lockers) hence the total. I dont have the locker space you do, but reckon 4 jerry cans diesel and one petrol (for the outboard) is possible.

What did you use as the lines for Panama - what size/length

We were part of the World ARC so all the lines were arranged for us. The lines were a good 50 m each with a light weight line with a monkey's fist in the end thrown first and then heavier lines fed out. Heavy lines were maybe 3cm diameter.

[goboatingnow]

Originally Posted by Nicholson58

I hear they make great lures for very large fish Lots of tales of nothing left but the cable at dawn.

Towed one twice across the Atlantic. whale had a look at it once , that was about it. , generated about 50-80Ah per 24 hours.

Dave


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[zboss]

Originally Posted by goboatingnow

Towed one twice across the Atlantic. whale had a look at it once , that was about it. , generated about 50-80Ah per 24 hours.

Dave


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Thats too funny. Sorry!

[svseachange]

Originally Posted by goboatingnow

Towed one twice across the Atlantic. whale had a look at it once , that was about it. , generated about 50-80Ah per 24 hours.

That's good practical info. Would you have preferred to have a wind turbine, or was it one of those transformer types that doubled as a wind turbine?

[JazzyO]

Originally Posted by svseachange

That's good practical info.

For the sake of clarity: The more traditional "lure" type hydrogenerators like Ampair generate the amount that Dave mentions. They cost about $1000 or so. The WattAndSea costs about $6k but generates around 3 times as much energy. People say they are expensive but to generate the same amount of energy from wind and solar, you need some dough as well, and it will not be much cheaper. A Superwind costs $3k including mounting.

I agree with a previous poster that they are not a total solution for every cruiser, but no single source of power is. Our cruising grounds (for now, the Med) will have marinas in the vicinity 99% of the time. We can survive without power generation (at anchor) for at least 5 days if we don't run the laptop, and then we can start the engine to charge if we want. Or we go for a daysail and use the hydrogen. But much more likely we will have taken in a marina for a night inbetween. I've thought up all sorts of scenarios but I can't imagine we would ever run out of power, without adding wind or solar. Nevertheless, we are still considering adding a solar panel to top it up at anchor.

If you are staying at anchor for more than 7 days, then you need solar and/or wind. But we are not likely to do that.

However, if you have only solar or wind you can struggle to keep your batteries full during a crossing. I think that is where a W&S hydrogen comes into its own.


Onno

[Neptune's Gear]

My 2c. I have once had to motor 1300nm - no wind at all. Could have just sat and waited though I guess. I have wind and Solar, run an electric fridge and freezer. All lights are LED, and I run a PC and radar a lot of the time, and an AP. No genset, no watermaker. Sometimes I have to run the engine to charge, but not often. Solar and Wind is enough for us. Windgen of choice is a silentwind, which is why I sell them!!

[Polux]

Originally Posted by zboss

...

Most boat have higher energy consumption on a passage or when moving... autopilot, etc. this is a perfect time to have a hydrogenerator.

With that said - we have not seriously considered a hydrogenerator because of price. If you had the money then a combination of wind, solar, and hydro should provide more energy than you need under the vast majority of conditions. If you have to run a diesel engine for an hour a day and burn a half gallon 365 days a year then you are more than easily paying for the hydrogenerator over two years.

The OP question was how much fuel does one need and it certain is dependent on a lot of factors, including the combination of alternative energy options available to them. We opted for solar and will be adding a wind generator at some point but thats because I really don't like running the engine unless we have to.
...

Yes I agree, also on the efficacy of the batteries and the charging set-up, how good the boat is sailing with light winds and the life style.

Some years ago I remember on a similar discussion a guy saying that he only had needed half a deposit on a J120 to go from the US to Australia and that boat has a very small tankage. Putting in general terms the question is meaningless: It could go from 90L to 3000L depending on the boat, life style and climate.

[Jim Cate]

FWIW,

On our previous boat we used a home brew trolling generator. Used a surplus 32 volt perm mag DC motor, some 1/2 inch double braid and a three foot s/s shaft with a used Johnson 6 hp prop. Towed it for thousands of miles. Put out around 4 amps at 5 knots, 10 at 6 knots, lots more at 7, but jumped out of the water frequently and tangled up the torque rope.

It was brilliant when in use, but a PITA to retrieve under way. Tried all sorts of clever (?) schemes suggested by experts... none worked consistently. Eventually just hove to briefly (< 1 minute) while we hauled it in... even when sailing DDW with a poled out genoa. Must have looked ugly from a distance, bt it worked well!

I'd like to have that old rig back!

Cheers,

Jim

[cll2]

Regarding carrying extra fuel, I often see people mentioning using many jerry cans to supplement their tanks. I'm curious though if it's common to use collapsible fuel bladders instead of plastic jerry cans? It seems like it would be much easier to store an empty bladder rather than 5-10 empty cans that take up the same space whether full or empty. Of course this assumes having enough deck space or a suitably sized vented locker to accommodate the bladder while it's full. The 50 gallon FueLocker listed on this page seems like it could be a good choice for Atlantic or Pacific crossings at 30"x30"x14". I've seen 25 gallon versions from other suppliers too, though they tend to be the flatter pillow style with a bigger footprint. One negative is certainly cost compared to plastic cans, and having 10 containers instead of 1 gives you lots of redundancy in the event of leak compared with having it all in one bladder. Just curious what others think about this.

http://www.atlinc.com/rangeextender.htm

[Nicholson58]

Empty, easy to carry cans are useful for schlepping fuel to the boat. Especially where the dock cost is ridiculous or the fuel untrustworthy.