thundercamel
10 kW
Uma was my first thought when I saw this thread. Thanks for digging up that data!
Shamrock, 25 foot sailboat electric conversion with an ebike hub motor
- Thread starter justin_le
- Start date
nicobie
100 MW
Justin, nice to see your post. It's been awhile.
New boat
New wife
New baby
Good fun!
As I'm sure big moose would say, "enjoy the journey "
Nick
PS thanks for footing the bill for this joint.
New boat
New wife
New baby
Good fun!
As I'm sure big moose would say, "enjoy the journey "
Nick
PS thanks for footing the bill for this joint.
Hillhater
100 TW
Justin,
This variable servoprop would seem to be the ultimate trick solution to both hitting the optimum drive efficiency/speed/W/km settings...
...And maximising the regen when needed..!
https://oceanvolt.com/solutions/systems/servoprop-sail-drive/
They also say they will do a folding version !
Sadly, it looks like it would need a tricky special propshaft ...and quite a few $$$$s
This variable servoprop would seem to be the ultimate trick solution to both hitting the optimum drive efficiency/speed/W/km settings...
...And maximising the regen when needed..!
https://oceanvolt.com/solutions/systems/servoprop-sail-drive/
They also say they will do a folding version !
Sadly, it looks like it would need a tricky special propshaft ...and quite a few $$$$s
Hillhater said:Meanwhile i came across this (whilst burrowing down a YouTube “rabbit hole”) .. which i found interesting.
Its the test data from a “OceanVolt 8” electric saildrive fitted to a 36’ Pearson sail boat, ( The “Sailing UMA” series on UT, .. which you may have seen ?)
Thank you for digging that up! Indeed I stumbled on the Sailing UMA videos about a week before I started posting this and damn they do an amazing job of detailing life on an electric sailboat. They had a great discussion they had with several other couples all about first hand experiences with electric drives:
[youtube]rNG6LRDyC4E[/youtube]
But I didn't see the actual test result graph you posted here which is golden. It does indeed look like about double the watts as I was seeing for a given water speed, and that seems about right considering the size difference of our boats (36ft vs 25ft).
Regarding the sail-drive with variable prop pitch etc, that is a feat of engineering for sure but I'm kindof hoping we can see meaningful gains just with a simple fixed blade. I was lamenting the cost of buying new propellers for testing out pitches and diameters that could be better optimized for electric propulsion, and then remembered that we have a CNC milling machine and could just make our own on that!
At least for 2 blade propellers that should be a perfectly viable approach. We could mill prototypes from bars of aluminum stock easily enough which would let us test and characterize the real world efficiency gains (or losses, who knows) at our sweet spot cruising speed, and then if the improvements are high enough then machine a lasting model from Stainless.
nicobie said:
Hee thanks, it's fun to be back for a bit and see some good old faces around and plenty of new ones too. The journey never stops, and there are so many dimensions of EV's to unfold even as lots of it is now happily in the mainstream.
DogDipstick
100 kW
So the controller went thermal at a 80* motor temp and limited the 2900w to 2000W~...the 92Km trip, 159Wh/, that is alot of consumption for such a little motor.
Thats alot of consumption. Wonder how much she weighs. Thanks for the log. That section is even higher, 210Wh/.
For some reason that number just blows me away. I cannot "fathom" it. ( pardon the pun, pls. ) Lol.
We rebuilt our Yanmar four times. Rings and bore.
The exhaust kept on filling up with soot.
Thats alot of consumption. Wonder how much she weighs. Thanks for the log. That section is even higher, 210Wh/.
For some reason that number just blows me away. I cannot "fathom" it. ( pardon the pun, pls. ) Lol.
justin_le said:
We rebuilt our Yanmar four times. Rings and bore.
The exhaust kept on filling up with soot.
goatman
10 MW
im looking at your m4040 r ta
https://ebikes.ca/shop/electric-bicycle-parts/motors/m4040r-ta.html
do you know what nm you get at 1140 rpm if you do the delta wye switch with relays "on the fly" like in this video?
https://www.youtube.com/watch?v=sm9STU4sIKE
this shows the switch on the fly
https://www.youtube.com/watch?v=_aLrTRaEMOE
all that does is switch up to 19 rpm/v right?
https://ebikes.ca/shop/electric-bicycle-parts/motors/m4040r-ta.html
do you know what nm you get at 1140 rpm if you do the delta wye switch with relays "on the fly" like in this video?
https://www.youtube.com/watch?v=sm9STU4sIKE
this shows the switch on the fly
https://www.youtube.com/watch?v=_aLrTRaEMOE
all that does is switch up to 19 rpm/v right?
cpcanoesailor
100 µW
- Joined
- Nov 24, 2020
- Messages
- 8
Justin, I've really enjoyed this thread. It makes me wish I'd studied electric motors more. Hope to meet you on the water some time (need another boat first). :thumb:
DogDipstick said:
It's about the same as an electric car, except that an electric car moves at like 50-80 kph, while this boat is doing 9.5. So yeah boating through the water is not an energy efficient way to get around that's for sure. Our 2 person sliding seat rowboat would do the same 9.5 kph speed using more like 250 -300 watts, or 25-30 Wh/km. That's not as crazy, but still way worse than a tandem ebike moving at at slow of a speed which is like 3-4 wh/km.
goatman said:
If you converted it to a Delta the motor would be about 17 rpm/V and so you'd have no problem getting 1140 rpm with a 72V or higher battery pack. I don't actually have the H40 motors modelled on the simulator yet to know exactly how much additional torque output you could sustain, I've only got the slightly narrow H35's. But using that and extrapolating I'd estimate you could probably do about 30-34 Nm continuously with Statorade in the hub.
Stealth_Chopper
1 kW
- Joined
- Aug 30, 2019
- Messages
- 320
Very interesting reading, and full of detail about motor powered vehicles, Thanks !
I'm a boater and am wondering about optimizing the propeller design for an electric vessel.
What if: 25' boat;
~4' ? Large prop has variable pitch bouyant hollow titanium blades turning relatively slow.
Mike
I'm a boater and am wondering about optimizing the propeller design for an electric vessel.
What if: 25' boat;
~4' ? Large prop has variable pitch bouyant hollow titanium blades turning relatively slow.
Mike
Voltron
1 MW
During our electrified Catalina testing, we called it watt-knots as verbal shorthand for the power consumption at different speeds 
Re prop selection, a lot of it is influenced by your target cruise speed, and in a sailboat, figuring out the drag under sail, and maybe reverse handling depending on the size of the boat vs pure efficiency.
For going all out, with a platform that holds the props at a pretty steady angle and height to the water, it's hard to beat the Turanor Planet Solar approach of surface piercing slow rpm carbon props.
Re prop selection, a lot of it is influenced by your target cruise speed, and in a sailboat, figuring out the drag under sail, and maybe reverse handling depending on the size of the boat vs pure efficiency.
For going all out, with a platform that holds the props at a pretty steady angle and height to the water, it's hard to beat the Turanor Planet Solar approach of surface piercing slow rpm carbon props.
thundercamel
10 kW
Half the prop above the water. That is bizarre...
Voltron
1 MW
It shows up in high speed surface drives also, for off shore race boats.
I think the part of the benefit without the whole prop in the water is it's not twisting the prop outflow into an underwater vortex, and any losses from the above water blades is made up in the vortex reduction, and not having the prop hub and shaft in the water flow as much. Lots of evolution towards the "chopper prop" style also instead of traditional shapes.
Another low speed version....
I think the part of the benefit without the whole prop in the water is it's not twisting the prop outflow into an underwater vortex, and any losses from the above water blades is made up in the vortex reduction, and not having the prop hub and shaft in the water flow as much. Lots of evolution towards the "chopper prop" style also instead of traditional shapes.
Another low speed version....
Voltron
1 MW
For those that aren't eboat nuts, Turanor PlanetSolar did an around the world trip just on solar.
Alex W
10 W
Justin: This is really cool, thanks for sharing. I'm another sailor/ev/bike nerd and have been interested in electric inboard options for my sailboat one day. There isn't a lot of real data out there so it is great that you have figured out ways to gather so much data, especially the strain gauge for the thrust so that you can measure losses at two key places (in the motor and in the prop). Please keep sharing what you learn.
I would suggest that you be more open minded to folding props and maybe consider making your own if they are out of your budget. A folding or feathering prop makes a huge difference to sailing efficiency and can be the difference between needing to motor or being able to sail when cruising in wind of 4-8 knots. As you know the Salish Sea is generally a light wind region (maybe not this last few days) and so that matters.
I don't know where to find one, but the Albin Vega (a similar sized boat) came with a variable pitch feathering prop which strikes me as being pretty great for an EV sailboat. It would allow you to find an optimal pitch for cruising range, fully feather for maximum sailing performance or reverse the blade pitch to use the motor as a hydrogenerator when there is plenty of wind.
I would suggest that you be more open minded to folding props and maybe consider making your own if they are out of your budget. A folding or feathering prop makes a huge difference to sailing efficiency and can be the difference between needing to motor or being able to sail when cruising in wind of 4-8 knots. As you know the Salish Sea is generally a light wind region (maybe not this last few days) and so that matters.
I don't know where to find one, but the Albin Vega (a similar sized boat) came with a variable pitch feathering prop which strikes me as being pretty great for an EV sailboat. It would allow you to find an optimal pitch for cruising range, fully feather for maximum sailing performance or reverse the blade pitch to use the motor as a hydrogenerator when there is plenty of wind.
Hillhater
100 TW
Alex W said:
I posted this link earlier in the thread..
https://oceanvolt.com/solutions/systems ... ail-drive/
They also say they will do a folding version !
Grantmac
10 kW
You could probably use the electric freewheel option in some controllers to negate the prop drag.
If you wanted to get really clever you could write code to start fading it out then applying regenerative braking as the boat hit hull speed.
If you wanted to get really clever you could write code to start fading it out then applying regenerative braking as the boat hit hull speed.
Why not use a Rim Driven Propeller...may be a little while before they are commonly available but here is a short introductory video and IMO they are nothing more than a Direct Drive motor with fins :lol: : https://www.youtube.com/watch?v=Te_xejpriFM
Stealth_Chopper said:
Yeah it's a great thing to wonder about. Part of the later phase optimizations was going to be seeing how much we could change this wh/km vs speed curve with different propellers, and using a CNC mill to machine prototype aluminum props that would at least last long enough in the salt water for some meaningful sea trial tests.
Most installed boat propellers are already well optimized to balance the tradeoffs matter to a boater, which pits things like vibration (more blades better than less), vulnerability and clearance (preferring small diameter) against propulsion efficiency (fewer blades, large dia). The pitch and blade area are other variables are also tailored for running at close to max continuous engine power at the boat's hull speed which is the norm when running on fuel. In an electric drive I imagine most of the time people be running at like 1/3 - 1/2 that power level because of the diminishing returns going to hull speed.
I think with electric the weighting of those tradeoffs can shift a little more in the direction favoring propulsion efficiency, but not at the complete expense of everything else. A 25 foot boat with a 4 foot diameter prop is a funny proposition for sure. But even if it ranks better wh/km I don't think a 25 foot boat owner would be happy about having blades that big sweeping though the water. Going from a 12" blade up to say 14" or 16" could be realistic though.
Voltron
1 MW
Honestly, most sailors are going to want a folding or feathering prop, much less a 4' one
I just bought a Catalina 27 with a dead engine to do a conversion with... Electric sailboats are a pretty unbeatable pleasure machine for humans to enjoy life on.
I just bought a Catalina 27 with a dead engine to do a conversion with... Electric sailboats are a pretty unbeatable pleasure machine for humans to enjoy life on.
Stealth_Chopper
1 kW
- Joined
- Aug 30, 2019
- Messages
- 320
I see from the pictures of the solar cruising yacht my rough guess of a 4' prop was about right.
The surface piercing props are the 'racer's edge' winning at super speed or slow motion.
:wink: Anything But Sails
I learned,
( spending time & $,$$$ ),
that wind does not blow hard to push any vessel I've owned or sailed
on my day off.
The surface piercing props are the 'racer's edge' winning at super speed or slow motion.
:wink: Anything But Sails
I learned,
( spending time & $,$$$ ),
that wind does not blow hard to push any vessel I've owned or sailed
on my day off.
Voltron
1 MW
Not even these?
The new Americas Cup 75' boats... They're hitting 30-40 knots steady with 40-50 knots bursts, and doing triple the windspeed at times!
[youtube]59f40bT51r4[/youtube]
I had one of these hydrofoil trimarans, that was the first boat that was so fast I thought to myself, maybe I should be wearing a helmet!
Then one big wave day I went so far underwater it was getting dark, and the boat never even slowed down as it launched out of the back of the wave back into sunlight..epic!
P.s. I think those Plant Solar props are 10' diameter!
The new Americas Cup 75' boats... They're hitting 30-40 knots steady with 40-50 knots bursts, and doing triple the windspeed at times!
[youtube]59f40bT51r4[/youtube]
I had one of these hydrofoil trimarans, that was the first boat that was so fast I thought to myself, maybe I should be wearing a helmet!
Then one big wave day I went so far underwater it was getting dark, and the boat never even slowed down as it launched out of the back of the wave back into sunlight..epic!
P.s. I think those Plant Solar props are 10' diameter!
tai626
1 mW
Love your sailing stories!
Regarding to propeller, folding/feathering would be less of drag. But since we have a motor/generator, probably the best choice is the variable pitch so it can be more efficient to generate energy once wind pick up:
https://oceanvolt.com/oceanvolt-blog/introducing-oceanvolt-servoprop-variable-pitch-saildrive/
Tai
Regarding to propeller, folding/feathering would be less of drag. But since we have a motor/generator, probably the best choice is the variable pitch so it can be more efficient to generate energy once wind pick up:
https://oceanvolt.com/oceanvolt-blog/introducing-oceanvolt-servoprop-variable-pitch-saildrive/
Tai
cheapcookie
100 W
- Joined
- Aug 2, 2014
- Messages
- 277
Hello Justin cool project! Can you talk about the implications of removing the sail or doing such a conversion on a motor only boat. How many kwh can you store and how many days can the boat be sailed on motor power ?
Voltron said:
Wow, I can't believe I didn't come across this project yet! That is a mighty purpose build solar boat of there ever was one. But it's surprising to see that in spite of that and with so much solar and what should be such a fast cat hull it looks like it was still only averaging 4-5 knots.
I played with surface piercing props in a different earlier project (~250-500 watt system for rowboats and kayaks) but found it made a crazy splashing mess, though that was with an off the shelf airplane prop so maybe the blade design needs to be quite a bit more specialized. The concept of surface piecing is great.
cheapcookie said:
I mean the math is pretty straightforward with the number's I've published earlier.
If there wasn't a sail and then no need for a weighted keel either then the boat would be lighter and have a lower power requirement for a given speed. This sailboat has about a 5000lb displacement of which just 175lb (3.5%) is batteries, and those 175lb of battery give me a 90km range at 5knots, or a 140km at 4 knots. If instead I put in 500 lb of batteries (ie 10% of the boat weight), it would have a 260km range at 5 knots and over 400km at 4 knots.
It becomes more of a budget question than anything, you could very easily put enough batteries to go 1000+ km on a charge at displacement speeds in a regular boat hull if you have enough $$ for all that lithium!
