Boat use determines the system requiements. If you are on a lake or bay and mostly day sail and mostly use your engine for docking and a short motor to open water a very simple electric motor would work. But in bigger water or cruising the requirements probably make electric not cost effective or practical. But for someone with a Catalina 22 used for day sailing a large trolling motor and a couple extra batteries would suffice.
electric engine in sailboat
- Thread starter Franklin
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The problem is that the range on most electric motors is fairly limited. As Moonsailer said, if you're just using it for docking and leaving the slip, it should work. But if you're planning on doing any longer cruising, the electric motor becomes a major liability, since it doesn't have the ability to be easily "re-fueled".
Fuel cell.. Probably going to be a conversion cell that catalytically turns hydrocarbon into usable clean hydrogen, and then electricity.. You'd carry propane or butane to run it and generate electricity.. Hydrogen is very bulky to store and is not easily liquified so the same number of BTU's requires a bunch more space.. propane liquid requires around 200 PSI containment and hydrogen gas storage is more like 5000 psi..Expensive to run a compressor to get to those kinds of pressures.. Much more high tech (expensive) and still does not match the propane for energy density.. MUCH easier to find propane or butane to fill your tank than it is to find hydrogen..
One other thing, those batteries are like laptop batteries (lithium-ion). Given the number of recalls of laptop battery packs due to fire hazard, I don't think I'd want them in that quantity on my boat.
I think a combination small diesel generator with an electric propulsion MOTOR would work; tugs and locomotives have been diesel/electric for years, and the size of the engine could be scaled back because unlike tugs and trains, a sailboat only has to move itself and not tons of other vessels/cargo. The generator could charge a battery bank for house loads and minor propulsion duty, then the small diesel could run for longer periods. This way you only have one engine, instead of two, and by using AC power on the boat, you could reduce weight cause of the higher voltage of the AC. I think it has merit.
Like this? I think Sail had an article about this boat about a year ago.
http://www.catamarans.com/news/lagoon/420/index.asp
http://www.catamarans.com/news/lagoon/420/index.asp
There was an article (Cruising World?) where a group of boats on a trans Atlantic crossing had wind/water generators (i.e. raise the pole up in the air it generated using wind, dip it into the water to use the water). When these boats were sailing and dipping their generators in the water they generated so much electricity they has to turn stuff on to avoid over charging the batteries.
The company was duogen[FONT="] (http://www.duogen.co.uk/). From their website it is a normal micro turbine, suitable for mounting on a yacht, may intercept 7 - 10 square feet of air stream, the sails of a typical cruising yacht will intercept many times that figure. DuoGen in water mode produces a steady 8 amps at 6 knots, 11 amps at 7 knots, 16 amps at 8 knots.[/FONT]
The company was duogen[FONT="] (http://www.duogen.co.uk/). From their website it is a normal micro turbine, suitable for mounting on a yacht, may intercept 7 - 10 square feet of air stream, the sails of a typical cruising yacht will intercept many times that figure. DuoGen in water mode produces a steady 8 amps at 6 knots, 11 amps at 7 knots, 16 amps at 8 knots.[/FONT]
I figure for my boat to get up to 6 knots, I need about 12 knots apparent wind or more. Fourwinds says theirs will put out about 7 amps at 12 knots of wind and it doesn't create drag, so I'm not all that impressed.
http://www.fourwinds-ii.com/v2/?c=library&i=windGenComp
Now I do think those who use the prop to re-charge can get a lot of power from it without creating drag that isn't already there.
There remains a basic energy balance to be satisfied.. If you deplete the battery AND want to continue motoring, ya have to have the same horsepower to drive the boat plus the horsepower to charge the battery .. so if you are using 10 horsepower to drive the boat, ya have to have that in a small diesel plus the efficiency loss so now ya need 12-15 hp.. Now ya need to charge the battery in a reasonable amount of time.. (with a very high voltage generator/alternator) .. Using the Telsa battery again, a charge of 8 hours would require about 12-15 hp to drive the powermaker that hard.. HEY.. that is a 24-30 hp diesel.. which already is on the boat ! This only applies if you are going to motor over 50 miles..(in the case of the Telsa battery again) which doesn't happen often, but I don't want a boat that CAN'T do that.. and costs a bunch more from the start. The reason the technology works well in cars is that they aren't typically run at constant power levels and can usefully employ regenerative braking which charges the battery. I do believe that Catamarans are a place where diesel/electric can work well since you can have one diesel and two electric motors and no gearboxes. Fuel cells can be throttled pretty well but ya still going to need a pretty big one to do what the humble diesel does so well.
kloudie1:
you are right. It all comes down to storage of energy. Right now batteries just can't come anywhere close to energy storage as diesel fuel can per size/weight. Diesel fuel can't compare to Nukes but because nuke material can be so deadly, most don't want to buy into it.
Hopefully one day some really smart guy will discover a better way to store energy. Hopefully it will be like a battery that can be re-charged by the prop while sailing but still hold 2 days of motor sailing on it's own. Some day. Having a quiet engine that it's energy source can be re-supplied while at sea is a sailors dream.
you are right. It all comes down to storage of energy. Right now batteries just can't come anywhere close to energy storage as diesel fuel can per size/weight. Diesel fuel can't compare to Nukes but because nuke material can be so deadly, most don't want to buy into it.
Hopefully one day some really smart guy will discover a better way to store energy. Hopefully it will be like a battery that can be re-charged by the prop while sailing but still hold 2 days of motor sailing on it's own. Some day. Having a quiet engine that it's energy source can be re-supplied while at sea is a sailors dream.
In calm water a 38ft boat needs about 5kw for 6 knots and 10kw for 7.2 knots. (http://www.proboat-digital.com/proboat/20070607/). In rough water its about 15kw and 20kw. How important is it to be able to plow into gales at 7+ knots? If you can accept the performance of a 10kw system and have a 5kw generator and a 5kwh battery then you can go for 1 hour at 7.2 knots and 6 knots until the fuel runs out. The total system weight would be about the same. Much quieter during normal usage (i.e day use). Probably longer range for the same fuel load, but what does it mean to motor for days on end?
Don't forget that the system actually weighs a whole lot more, reducing your ability to carry other things, like beer, food, crew, boat bunnies.... etc.
Kloudie's point about cars being able to take advantage of hybrids is a good one. The typical five passenger sedan, weighing 4000 lbs, only requires 5-10 HP for 95% time it is being used—yet most cars have engines that put out well in excess of 150 HP. Why? Because, that other 5% of the time, they need all the horsepower to do things like accelerate onto a busy highway... Boats tend to run at much higher power levels consistently, since water resistance is so much greater. If you shut the engine down on a boat moving at hull speed, time how quickly it stops—do the same thing for a truck that has the same mass as the boat on level ground... one is going go a good deal further.
Kloudie's point about cars being able to take advantage of hybrids is a good one. The typical five passenger sedan, weighing 4000 lbs, only requires 5-10 HP for 95% time it is being used—yet most cars have engines that put out well in excess of 150 HP. Why? Because, that other 5% of the time, they need all the horsepower to do things like accelerate onto a busy highway... Boats tend to run at much higher power levels consistently, since water resistance is so much greater. If you shut the engine down on a boat moving at hull speed, time how quickly it stops—do the same thing for a truck that has the same mass as the boat on level ground... one is going go a good deal further.
Not to start a bruha here but I don't want a boat that can't do that.. I have motored for 3-4 continuous days a few times..Once in calm water.. Once to get out of a nasty storm; water was far from calm... Again, for many folks it will fit the way that their boat is used; that is great.. current technology (little pun there) does not fit me. Don't forget the inefficiencies.. the generator will be about 90% efficient and the motor about 95% so now, the 5 kw at the motor shaft needs about 8 HP of diesel power to make it go.. getting close.. Then there is the loss in the wiring and the loss in the motor controller .. The gearbox is already in the original equation, and it is about 96%, or more efficient.. Yes, the diesel is noisy and stinky.. Battery storage is not a propulsion option for me..
Most automobile driving is at a speed of 45 MPH or less.. I'll bet most people’s cars can go faster than that and they wouldn't buy a car that would only go 50 MPH..??
Most automobile driving is at a speed of 45 MPH or less.. I'll bet most people’s cars can go faster than that and they wouldn't buy a car that would only go 50 MPH..??
[Kloudie wrote Quote]
Most automobile driving is at a speed of 45 MPH or less.. I'll bet most people’s cars can go faster than that and they wouldn't buy a car that would only go 50 MPH..??[/quote]
The only reason to have a fast car is to avoid being a hazard on the highway. You have to be able to keep up. In 1960 I drove an old Chevy from Bangor to Gulfport at 45 mph. I didn't dare to take a chance on the engine running faster than that. With a boat, speed is a personal thing, there is enough room out there to be avoided.
Most automobile driving is at a speed of 45 MPH or less.. I'll bet most people’s cars can go faster than that and they wouldn't buy a car that would only go 50 MPH..??[/quote]
The only reason to have a fast car is to avoid being a hazard on the highway. You have to be able to keep up. In 1960 I drove an old Chevy from Bangor to Gulfport at 45 mph. I didn't dare to take a chance on the engine running faster than that. With a boat, speed is a personal thing, there is enough room out there to be avoided.
Electirc motor use
I was of the impression that I would not have to use the motor for propulsion if the wind was blowing.
With that said, I don't see where I would need a huge motor during a storm. Could I not just reduce sail and continue to harvest the free wind energy to move my boat and charge my batteries?
Seems to me that a motor would be great if I'm becalmed in the doldrums and have to motor for a day or two to get out but when else would you need it except for pulling into the slip.
BTW the marina makes me use the motor to pull into the slip, I'm not convinced that even that is necessary.
I was of the impression that I would not have to use the motor for propulsion if the wind was blowing.
With that said, I don't see where I would need a huge motor during a storm. Could I not just reduce sail and continue to harvest the free wind energy to move my boat and charge my batteries?
Seems to me that a motor would be great if I'm becalmed in the doldrums and have to motor for a day or two to get out but when else would you need it except for pulling into the slip.
BTW the marina makes me use the motor to pull into the slip, I'm not convinced that even that is necessary.
Lagoon 42 with Hybrid setup -
"Built on Leroy Somer's Motor Technology, the new motors offer strong savings in carbon dioxide emissions and engine maintenance.
All Lagoon 420s coming out of the Lagoon Factory will be standardized on the new propulsions system, which typically require only one simple bearing change per 20,000 hours.
Complete installation comprises of two electric motors connected to propellers by straight shaft transmissions, one generator and two set of 6 batteries. When batteries are 100 % charged, the boat will be able to function with both motors for approximately two hours (depending on speed).
When batteries are 80% charged, the generator will automatically start and charge the batteries in order to provide electricity for the motors. When sailing, propellers will recharge the batteries."
These boats probably require less power to move them along when compared to our average 35 ft mono hull. As you can see you need a LOT of battery reserve to move it along for a prolonged period of time without the aid of a generator to recharge the battery bank/s.
A large battery bank is going to be a larger load on smaller boat as a percentage of the overall weight of the vessel. Until some new proven battery technology, these systems are not very practical.
"Built on Leroy Somer's Motor Technology, the new motors offer strong savings in carbon dioxide emissions and engine maintenance.
All Lagoon 420s coming out of the Lagoon Factory will be standardized on the new propulsions system, which typically require only one simple bearing change per 20,000 hours.
When batteries are 80% charged, the generator will automatically start and charge the batteries in order to provide electricity for the motors. When sailing, propellers will recharge the batteries."
These boats probably require less power to move them along when compared to our average 35 ft mono hull. As you can see you need a LOT of battery reserve to move it along for a prolonged period of time without the aid of a generator to recharge the battery bank/s.
A large battery bank is going to be a larger load on smaller boat as a percentage of the overall weight of the vessel. Until some new proven battery technology, these systems are not very practical.
So you mean to tell me that when my 36 hp yanmar went out on me, instead of spending 10K on a new 40 hp yanmar, I could have spent $400 on a 5KW DC motor and ran my 3.5 kw generator and could have motored at 5+ knots? On top of the 200% savings, I could go 200% more miles on a tank of diesel? Add a few batteries and 90% of my motoring is dead quiet. I feel like an idiot now.
Franklin, don't forget to factor in the cost of replacing batteries. I don't see this as a cost saving solution for many years to come.
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