There will be 3 Phases:
1) Wind 0 to ~4mph - "Wind-Slog-Foiling" (E-assist) even in Wind at 0mph
2) Wind ~4 to ~6mph - "Transition from "E-assist" to "regenerative braking" (if available - optional)
3) Wind 6mph to 10mph - motor auto switch shut down (motor only out of the water).
New Graph:
Going back to the old saying:
"It is the turtle that wins efficiency race at low speed not the hare/rabbit/bunny"
Surprising Aussie Old Innovation, "Old Technology" Discarded, Diminished, Criticized, Labeled "Outdated" - Second look.
For anybody who spent any time on Research on Trolling motors and their efficiency, you probably heard how "Superior" AC Motors are (vs DC Motors that use mechanical brushes). Their Efficiency and Longevity etc, etc. How Superior Electronics Driven ESCs are.
BTW, (ESCs)Electronic Speed Controllers are required in AC Motors to convert DC battery power to AC Motor need) while DC motors to not.
The claim Everywhere is that DC Motors are so less efficient (energy wasting) vs AC Motors that they are pretty much discontinued.
Yes, there is a problem. They mostly have just on/off switch. Some have 2 speed on/off.
Here is a "Practical Reality"
What does Tiny WaterSnake (Aussie Company) T24 (24W 12V * 20A with 24LB Thrust) Do ?
It is tiny and it has tiny only 2 wing propeller.
BUT in Practice:
I could run on this baby my Tandem Oasis Hobie Kayak 96LB/ 42kg (loaded with two people at ~340LB/ 154kg) for 3 hours continuously using just one LiPo4 12V/14V 60AH battery ?!.
This motor is extremely efficient despite being simple commutator / brushed electric motor.
What speed would you expect for such a high load ?
Here is the actual graph when we took it for a spin. So the range is between 2mph and 4mph.
Variable factors:
tail / head wind and weed entanglements. The propeller is not weedless.
Where Motor needs to be mounted ?
Unlike in E-Foils, the motor here needs to be mounted just below the board bottom so as soon as there is enough lift, motor gets out of the water and shuts down automatically. Win-win: less drag safety for the motor so it is not going to burn.
Optional here is that in the wind mid range you could actually use regenerative breaking and charge the battery (if needed)
How Much Cost?
Some time ago the cost was:
Watersnake (T24) 4.85 LB / 2.20 kg - $189.99 on Amazon
LifePO4 w case Bat. 16.80 LB / 7.60 kg - ~$330 (battery) + $50 (Plano Case) = $380 on E-BayTotal ~ $600:
Need to add safety/kill switch and water sensor (auto on/off).
This is now a very Fact Based Concept.
If for entire session the wind only between 0 and 6mph. The motor is on all the time. Watersnake T24 generates apparent wind for you 2-4mph (based on my tandem kayak graph) and you ride the apparent wind. Good for balance.
Battery will last 3h and you do at least 9 miles.
If you add sail pumping (optional) you could do more.
Remember, in my Pumpduro I did pumping (scoop and pull) in no wind for 4.5h gaining 8 miles.
Therefore with sail pumping, you could do 17 miles based on above (if you wanted to).
More details on "Pumpduro" for the reference also here:
groups.io/g/nw-windtalk/message/71543
If you want to pursue "less clattered" options and higher speeds longer distances, it is going to cost ya big $$$.
Here is the Concept on "Dirty Cheap" Budget and using "Aussie Brilliance" Mates, assuming you already have Windfoiling Gear.
And you can make fun of all the hype about Technological Advances and Superiority of AC Motors that "chew my behind" and sent me on a "Wild Goose Chase" with Endless upgrades to more and more expensive & "powerful" ESCs, Motors, Kedean KED380T Jet Fin Drive at supposedly 6k Watts, 4 times Battery pack (4*14V) needed, added weight, etc, etc.
Well, my "pain" is my "knowledge gain" while for You hopefully there it is another "tool" for your "toolbox" or at least some "food for thoughts".
My Personal "Theory of Everything" is that Our "Technical" World of Science is Simple, Beautifull and can be Easily Understood when you see "Patterns in Nature", Ratios, Multipliers. What happens in this specific "Zone". What Forces.
Then you Realize:
"Hydrofoils are like Didgeridoos"
The Aspect Ratio is not that important. It is the surface (or cross section in Didgie) that makes the sound / resonance (lift in foils).
Both Hydrofoils and Didgies have "a sweet spot" optimal maximum performance range or resonance range.
Well,
Here is how Adopted Bloke connects still with Second Motherland Explaining the Didgie. See the correlation with hydrofoil.
Didgeridoo Comparison, Tips, Shortcuts & Secrets Finally Revealed ! - try to learn the easier way! - YouTube
