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Old 10-03-2013, 04:04   #16
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Re: Longest time/distance you've had to motor?

anybody in springfield? i might need some fuel rods in 25 years or so

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Old 10-03-2013, 05:30   #17
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Re: Longest time/distance you've had to motor?

Aargau,

the efficiency of Diesel engines is around 35 to 40%, with larger ones up to 50%. Source: Car-technolgy, valuable informations, simulation, questions, tasks.

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Old 10-03-2013, 15:33   #18
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Re: Longest time/distance you've had to motor?

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Originally Posted by Aargau View Post
Feel free to correct below...

With combustion engine efficiency around 12% of its energy density, diesel is about 1.5K Wh/kg when measured engine to propulsion.

The not-ready-for-production Lithium seawater systems on a 25% efficient electric motor are 375Wh/kg for propulsive force.

Not there yet. However, batteries do have the advantage of being rechargeable by solar over time. No diesel dumps between Marquesas and Johnston atoll.
Pretty much exactly what I said - you'll be waiting a LONG time for batteries to get anywhere near diesel power for energy density.

Yes, you can recharge batteries by solar, but is it realistic? A 2 kw solar array is very big for a boat, yet will provide very little power in propulsion terms. Like around 3 horsepower for maybe 8 hours per day. It's not going to get you far.
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Old 11-03-2013, 00:16   #19
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Re: Longest time/distance you've had to motor?

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I feel like solar/battery/brushless electric propulsion will be the wave of the future once battery energy density gets within 15% of diesel, but right now it's not.

However, the longest I've had to motor was 2 days, and that wasn't strictly necessary, light winds between Tonga and Fiji. It was a pretty slow but sturdy monohull, and we had a flight schedule. Same boat had to motor 4 days between Galapagos and Marquesas, but that was also due to some urgency with supplies and repairs.

So I'm interested in real life examples of necessary long motors, such that if an electric/battery motor can't meet that range, it's not ready. I would be doing another trans-pac and possible round the world trip, so anywhere that requires sustained motoring is interesting.
There's a logical inconsistency. The point of motoring a sailboat on passage is convenience of predictability, not necessity. A very well stocked sailboat on a well-planned course well captained would almost never "need" to motor.

It's interesting to note that, in your example, you "needed" to make a flight. One could argue that you were not sailing, but were rather out on a motor boat which had a secondary function as a sailboat, and that when you were out of sailing time, you motored it to port so you could make your flight.

Or one could argue that the motor gave you a convenience of predictability that you could not have achieved by sail alone. Your "need" to motor was based on a "need" to get on a flight which was predicated by your "need" to be somewhere OTHER than on that sailboat.

If you had never left the area of your harbor, you would not have "needed" to motor at all, except perhaps to get in and out of harbor.

On the extreme, it could be argued that a sailboat never "needs" to be motored unless someone's life or health is at risk in an unexpected or unplanned way.

That risk can be reduced by choosing a longer, faster boat with more effective sailing systems, and by stocking for the possibility of weeks or months at sea, even on very short crossing, and by avoiding areas of known doldrums - although such avoidance may add hundreds of miles to a journey.

So I think a more reasoned question is "What is the most you would WANT to motor on a crossing, and to what extents would you be willing to go to achieve that?" - and I think the answer to that would better lead into the secondary topic of electric drive systems.
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Old 11-03-2013, 07:50   #20
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Re: Longest time/distance you've had to motor?

5 (or 6 days, I forget!) and 750(?) nms from Salalah, Oman into the Red Sea in 2010 in a convoy. No wind and motored the whole way. Not bad for a Beneteau with a 38 gallon tank! Ok we had 13 Gerry cans of diesel too!

Most interesting thing is of the 26 boats in the convoy only TWO boats stopped their engines at all, ever during the convoy to check oil etc.
fatty Goodlander on Wild Card and I both stopped our engines at about 9 am each day... The convoy didnt stop so there was GREAT motivation to do the fastest oil check in known human history! I was in the last packet anyway, so we were about level with the last boats by the time I had finished, but Wild Card was in the first packet and he needed to do an extra check (forgotten what) and the whole convoy would pass him by and he would pop out the back. When he would finish his checks he and Caroline would have the wind right up them and m otor flat out to get back into position. Nothing like a little piracy threat to make you hit the throttle!

Of the 26 boats only a few had engine problems. Had to stop the convoy twice, if I remember correctly, for an hour or so while work was done on one boat. Scary time sitting like sitting ducks. And one small catamaran had two new 15 or 20 hp outboards... They both broke down and he needed to be towed for 3 days.

It was one of the biggest confidence boosters to know my engine will do more than what you could reasonably ask it when necessary. My Yanmar just keeps on chugging along and and I love it!
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Old 12-03-2013, 21:57   #21
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Re: Longest time/distance you've had to motor?

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Originally Posted by 44'cruisingcat View Post
Pretty much exactly what I said - you'll be waiting a LONG time for batteries to get anywhere near diesel power for energy density.

Yes, you can recharge batteries by solar, but is it realistic? A 2 kw solar array is very big for a boat, yet will provide very little power in propulsion terms. Like around 3 horsepower for maybe 8 hours per day. It's not going to get you far.
I agree that diesel's energy density and efficiency are an order of magnitude higher than battery/catalyzed fuel cell/ultracapacitor, but we shouldn't see any marked improvement from diesel's current metrics.

Batteries will keep improving. The most promising research I'm personally aware of is via graphene protected cathode/anodes for several of the battery chemistries (LiS, Li-Air) which are hoped will increase energy densities by a factor of 3 and by a factor of 10-100 in recharge cycles. This research is being invested in heavily from both military (UAV) and the ground transport industry. However, like the solar industry, 1000 press releases using the words "promising" and "could potentially improve" average out to maybe 2 or 3 real advances

There are some other solid fuel cell chemical and nanotech structure approaches that have 40% of the energy density of diesel but feed directly into fuel cell generation of electricity.

I don't have much hope for marked improvements in solar panels.

So I think electric motors in general are probably going to benefit from some of the energy storage technologies down the road, and if one can measure ones current desires and find them close to adequate, electric would work for them. Personally I'm still on the fence, as my tolerance for risk may be a bit lower than some others.
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Old 12-03-2013, 22:19   #22
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Re: Longest time/distance you've had to motor?

pretty much all the way from Anacortes to Alaska and pretty much from the Panama Canal to L.A.
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Old 12-03-2013, 22:20   #23
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Re: Longest time/distance you've had to motor?

OH HELL! I forgot about L.A. to Seattle!
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Old 06-04-2013, 15:53   #24
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Cool Re: Longest time/distance you've had to motor?

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Is there any energy storage technology that can even get within 50% of diesel? I would love to go electric, but I don't see it viable for anything other than day sailing, and it would take immensely disruptive technology to make it a good choice for the offshore sailor. Hybrid sailing, maybe, but without some kind of fossel fuel generation, I don't see it. I have spent many many hours contemplating this.

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gasoline
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Old 06-04-2013, 16:15   #25
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Re: Longest time/distance you've had to motor?

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gasoline
Ok. How about:

Wood
Turpentine
Alcohol
Jet Fuel
...


I am sure you knew I meant electrical storage technology.

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Old 06-04-2013, 16:23   #26
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Re: Longest time/distance you've had to motor?

The only other thing I can think of that's different then the list's above, is a set of sweeps, (oar's) or maybe a single sculling sweep (oar) that would really be Green !!!
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Old 06-04-2013, 17:05   #27
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Re: Longest time/distance you've had to motor?

Actually i didn't know that was what you meant. I was tryng to be supportive of your claim. Fossil fuels, despite their numerous drawbacks, have more btu's per lb than any other commonly available fuel. When cost per btu is factored in, nothing else is close. The examples you quoted do not have the energy potential-- btu/ lb--- of either gas or diesel. Really, just trying to participate.
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Old 06-04-2013, 18:46   #28
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Re: Longest time/distance you've had to motor?

John is right there is a lot of energy packed into a gallon of gas. That's why I use it to quickly charge up my electric propulsion system on occasion with the Honda 2000. But, it's not the only thing I can use to provide fuel for propulsion. There is solar, wind and regen too. Not as fast but, they do add up and keep things topped up when at anchor. Mark mentioned about motoring in a convoy but, having to stop and rush to check the engine in order to not fall to far behind. With electric propulsion you never have to stop as the batteries keep you moving while you check the generator and even refuel it. I have done that a number of times:
OUT OF FUEL IN HELL GATE - YouTube
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Old 06-04-2013, 19:48   #29
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Re: Longest time/distance you've had to motor?

Anyone know why the hybrid engine on the Lagoons was such a disaster? I love the hybrid systems on Toyota, and it seemed like Lagoon had created a similar system..


Would love to have a boat with hybrid propulsion. MBianka, I'd really like to know more about your experience with this - how you're using it, range, fequency to run the generator, etc.

If the Lagoon 420 hybrid could be "fixed" of whatever problem it had, I'd put it high up on my 'to buy" list.
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Old 06-04-2013, 23:13   #30
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Re: Longest time/distance you've had to motor?

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John is right there is a lot of energy packed into a gallon of gas. That's why I use it to quickly charge up my electric propulsion system on occasion with the Honda 2000. But, it's not the only thing I can use to provide fuel for propulsion. There is solar, wind and regen too. Not as fast but, they do add up and keep things topped up when at anchor. Mark mentioned about motoring in a convoy but, having to stop and rush to check the engine in order to not fall to far behind. With electric propulsion you never have to stop as the batteries keep you moving while you check the generator and even refuel it. I have done that a number of times:
OUT OF FUEL IN HELL GATE - YouTube
A Honda 2000 produces 2kW. That's about 3 horsepower. A decent sized cruising boat won't manage much motoring speed from that. But use any more power than that, for any length of time, and your batteries will go flat.

You need a generator which at least matches your motor's power output if you're going to motor for any distance.
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