Intro to Shamrock, Justin's first electric sailboat conversion

Please read this forum thread for more detailed information and updates!
endless-sphere...
(If you want to avoid the trappings of youtube's autosuggestion hole, click on Part 2 here • Shamrock Electric Sail... once this clip is done!)
This summer Justin completed what had been a long sought dream replace the inboard diesel engine of his 25 foot sailboat with a pure electric drive. After crunching some numbers and looking at the mechanical clearances, he realized that he could pull this off using a direct drive electric bicycle hub motor attached to the prop shaft with no transmission at all.
This video shows an overview of the motor installation and captures the very first sea trial as we powered the boat over to the dry docks for a needed cleaning and overhaul.

[@dastardlyman]

this is a great fit as you can use the batteries as ballast and put them where needed and with solar panels on the boat you are able to go anywhere

[@iankrausz7690]

Nice !! I have a 36' sailboat. After 2 years i finally got the diesel running perfectly. If it ever dies I'll definitely go all-electric.

[@mskogly]

Super interesting solution. Really curious to hear how the project progressed!

[@solosailorsv8065]

Day sailing race yachts will LOVE this !!!! ( and they spend crazy $$ to be lighter/faster !! )

[@WorstUsernameInDaWeb]

I live in a mountain and youtube algorithm recommend me this channel, great, now my head and browser history is filled with boat plans

[@peterthornton2912]

Wow, I can't believe my eyes! Longtime fan of grin technology and now this! One problem with yacht propellers are they are always too small because of the desire to reduce drag when sailing. Bigger prop can run at lower shaft speed and be much more efficient.Less friction on shaft bearings. Potential to run a system like your Gmac electrically rotating the shaft at slow speed so blades are screwing through the water with no "slip' electronic freewheeling.of course folding props can do this but the cost and complexity is huge. Once its blowing hard enough and boat speed gets up regen becomes viable. I wonder how much energy would be needed for the "electronic freewheeling prop? I'm sure you can measure that with your various torque and load cell sensors. Keep up the great work!

[@GrinTechnologies]

Exactly! I'll be posting both test details and thoughts on this front on the endless-sphere thread as time allows. With this setup I was able to get about 120 watts of regen when sailing in ~15 knot winds, but if you flip that the other way and put in like 120 watts of power then I presume it would be effectively like free slipping through the water. Unfortunately I don't have the thrust load cell hooked up in the current arrangement, but once we DO then it will be so easy to see what's going on there. Any drag will be reflected by negative thrust on the shaft, any propulsion from the prop will be a positive thrust, and the sweet spot to emulate freewheeling is when the thrust is zero. We'll be able to identify this point with precision.

[@sunlightconversions828]

Only takes a few watts to freewheel since the blade wants to spin anyway. Anytime the boat goes faster, like surfing down a wave, the motor automatically becomes an generator.

[@sausage6984]

I think a few years ago, I had seen a propeller which folds it's blades when engine wasn't running.

[@thatdudethatsezshiz7706]

Can't wait to see the 5000w motor in it 🥳🥳 totally awesome 😎

[@ixxolos]

Innovation at it's finest here 💯

[@grindz145]

Hell yeah! I've long been into sailing! Ripe for innovation!

[@robkaOK]

Brilliant. Simply.Brilliant. Well done!

[@michaelrowave]

I am so stoked on this.

[@frankstocker5475]

Brilliant you have the torque it's all down to the right propellor.

[@johnlewis6880]

Justin this is great video that opens the door to a lot of possibilities. Ocean going sailboats spend most of their time under sail. The ability to use regen power to charge batteries would be a tremendous advantage. Even a larger boat with a diesel engine could still get a lot of benefit from using such a motor to generate electrictiy while under sail and letting the prop freewheel. While sailing around the world I met a guy, in an electronics store in Opua New Sealand, who was looking for a relay to deactivate his homebrew regen system. It charged his batteries really fast and he needed to be able to turn it off. He said he had rewound an automotive alternator to get it to generate electricity at the relavively slow speed of the free wheeling prop. Sailboats in the trades are usually charging along at their hull speed so the drag of a regen system would be irrelevent. There are lots of coulombs to be harvested that way. He mounted a large sheave on his prop shaft and coupled it to his alternator with a belt. Doing the same thing with a gates belt seems like a really good idea. If it would be possible to add a direct drive ebike motor to the drive train so that the belt would be unnecessary. There is not so much space for the belt drive arrangement if you have an engine in the boat. If you could design a clutch that grabbed the shaft when regen was desired but let the diesel drive the boat with the shaft freewheelin through the motor, when serious propulsion was needed, it would be a very attractive product for a lot of sailors

[@GrinTechnologies]

Hey there and thanks for sharing that firsthand info. It's a bit tricky to mount the direct drive motor on the shaft and have the shaft still go through the motor to couple to a diesel engine on the other side. It's doable but requires a motor with larger ID ball bearings than we are using here. The drag of a well designed motor is so low that you don't really need a clutch to disengage it when you don't want regen. There is less resistance from the motor than your typical stuffing box, and definitely a lot less resistance compared to turning over the engine clutch itself. When we had the 8hp yanmar on the boat the propeller would only spin the shaft when we reached about 4 knots of sailing speed, below that there was too much drag with the stuffing box and engine clutch for it to turn over. With the electric drive and the dripless shaft seal, the propeller now starts to turn on it's own when the boat is moving as slow as 1 knot. It's pretty impressive.

[@Philbuiltit]

Nice work Justin! I also happen to be working on an electric propulsion system powered by ebike batteries. I went the outboard route and have an upcoming video on quantifying different pitch and size props for the given craft that the boat is attached to. Best part is I can 3d print props and experiment to my hearts desire!

[@GrinTechnologies]

Oh sweet! I had no idea you were doing this Phil. Just watched your Part1 and will be keen to follow part2 and see some quantified data. And rad job with the bike trailerable Hobie. For anyone reading this comment have a watch here: kzbin.info/www/bejne/ioirdJ-CqZhjeNk (PS, and if anyone blows a controller mosfet testing an eboat drive, Phil has you covered there too ;-) kzbin.info/www/bejne/ooXWpHakar6sitk )

[@bradarmstrong1656]

Yay for electric boats! And, bikes, airplanes, cars, motorcycles and all kinds of electric propulsion. (and unicycles, too;-) It is a clean setup Justin made to measure propeller efficiency (thrust per torque) independent of motor efficiency which he measures all the time. Such a clean and simple arrangement is the marking of an excellent brilliant engineering mind. Go Justin Go! Good going! :-)

[@GrinTechnologies]

Ha thanks Brad. I'm hoping that with a bit of data collection like this we'll be able to really contribute more to the optimization of e-drives for boats and if we can make it easy for people to see and collect that data then more people can contribute. It could also be a nice tool to see quantitatively the effects of things like marine growth or a bit of rope wrapped around the propeller. Certainly I got way more velocity from 1000 watts after the boat went back in the water with a cleaned hull and barnacle free propeller.

[@disproman]

I had the same ideas / issues re: propellers , until I found Dave Gerr's book - Propeller Handbook published in 1989 - pre-PDF days when you had to get paper books. It is a bit of a "read" but he does a fabulous job explaining how to calculate what prop might be the "best" for your boat. The main focus is for boats that are displacement hulls. Another reference that I have used extensively for hull issues is Weston Farmer's book - "From My Old Boat Shop" - really good stuff in that one. Your work in documenting the performance of the e-motor conversion is one of he best ! Thank you

[@GrinTechnologies]

Happy to hear you find this interesting and thanks for the book suggestions. The propeller handbook has been on my shelf for a while but there's still quite a bit to digest there. The Farmer book I have just added to the summer read list :-)

[@jeffpowell1616]

What a brilliant project. I love R & D stuff like this. I can't wait to see what the MKII looks like. Hopefully a bit quicker than the MKI?

[@GrinTechnologies]

We're up to 10.3 kph ish at 3000 watts with the 72V battery pack in place! And with the cleaned off bottom and propeller we are doing more like 7.5 kph at 1000 watts. She's a bit quicker now for sure. It'll need an upgrade to a 12 fet controller to test out in the 4-5 kW range.

[@marklong8608]

Brilliant. I'm so glad you are working on the problem. Propeller design is an mysterious art and it seems that most standard props are very far from good much less optimal. Your setup will already give you more data than most. You might reach out to the founders of EP Carry and PureWatercraft, who are both working on electric outboards near Seattle.

[@GrinTechnologies]

Hi Mark and thanks for the feedback. I've actually met the founder of EP at the port townsend boat show a couple times and they've done a great job at using high efficiency (large diameter, 2 blade) model airplane propellers in their setup. Unfortunately with a lot of the sailboat inboard drives there just isn't the room to have a larger diameter prop due to clearance with the bottom of the hull. I've got a 12" and could probably fit a 14", but much larger than that and I think the tips of the blade would be too close to the hull and result in heavy vibrations. I'll check out PureWatercraft! seems like a very well designed outboard system.

[@markthomasson5077]

As I understand, a large as possible, low speed, two blade prop is as efficient as you can get. Ideally an adjustable pitch prop. That would make generation more efficient. Then engineer in so it folds back / feathers - both to reduce resistance and to reduce chance of snagging floating lines etc. But of course these are sailing boats, so going all out for motor efficiency is perhaps not worth it.

[@tabottietjen3186]

So cool, this is awesome! I would love to see how this project progesses

[@GrinTechnologies]

Sure thing, we will try to keep updates coming both in video format and on the endless-sphere thread linked in the description. We've now clocked about 300km on it with zero issues so far. It's gonna be an ongoing project for the next year or two so should be lots to look forward to.

[@arthurfleck1554]

The barnacles are his killing his gains!

[@BStudioT]

Crazy! Right before the last pictures i thought: is he yet planning an electrified childs bicycle? And then a short second with the nice little electrified boat! Great!

[@GrinTechnologies]

This one was courtesy of Colin Angus angusrowboats.com/pages/bumblebee-sailboat It's a genius kids boat design powered by a bilge pump (which we powered from a LiGo battery and DC-DC converter). Our daughter hasn't quite figured the tiller yet, but my 3 year old nephew rides around in it like he's the boss :-)

[@ettrickdoo7287]

We have a fleet of sailboats itching for eConversion over here in Whitby Ontario (adjacent to Lake Ontario). This use case is so intriguing with wind vanes, trolling rechargers, reverse props, solar panels you could stay on the water for extended periods versus diesel options ... not to mention reduced maintenance. With energy recapture options now available, a net positive energy balance must be seen ... cost is only issue.

[@GrinTechnologies]

Yeah, cost is an issue but it's not all that different from the cost of a new diesel engine installation. Without batteries the electric motor is WAY cheaper, and if you can do the installation with surplus lithium batteries (eg pulled from wrecked electric or hybrid cars) then you can do quite a bit on the same budget as a new IC engine.

[@jcreedy20]

Just anchor up on a river or strong tidal area and let regen do the charging!! Free energy :)

[@groundcontrolgainesville4841]

EPIC! love your videos and ideas

[@PilliBisiklet]

Cool! 3000w hub motor can give a pretty decent performance on that boat

[@GrinTechnologies]

With our sea tests so far we've been doing about 10.1 kph at 3000 watts, compared to 9.4 kph at 2000 watts. I'll need a larger motor controller in order to test at more than 3000 watts since the phaserunner goes into thermal rollback after a couple minutes. It definitely starts to hit fast diminishing returns for each extra watt of power.

[@El_Croc]

@@GrinTechnologies Hull speed is a brick wall though. Mine is about 8 knots when de-barnacled, try to get faster and you need to thrash the engine against the drag factor. There is a huge market out there for a cheap and simple solution to electrify or hybridise sailboats. A simple pulley on the propshaft when the engine's gearbox is in neutral is pretty simple with a slim motor like yours.

[@Vectorebike]

Great idea! Can't wait to see this boat at 10kw, and water cooled motor

[@GrinTechnologies]

From my testing so far I think that would make a very large wake and like an extra 1 kph more speed than at 2kW. But that won't discourage us from trying!

[@Vectorebike]

@@GrinTechnologies Hello! Any news on this water boat project? Very interested to hear continuation :)

[@KING_OF_FARTS]

Amazing 👏 i would like to try it with 2 motors & props.

[@TheHuntercamper]

Just a suggestion, you could go to a gear box and with the right ratio double/triple your speed all the while taking the torque off the motor and reducing your Amperage usage ....all in all great job.....

[@GrinTechnologies]

This would actually reduce the motor efficiency. Even though the phase current would decrease by half or 1/3rd and the copper losses would go down, the eddie current losses from spinning the motor that much faster (which increase at the square of motor RPM) would increase by more than the copper losses decreased. If you follow this link on my ES post I show how at the ~2kW operating point the direct 1:1 transmission is at peak efficiency, gearing it up or down from there only makes the performance worse. endless-sphere.com/forums/viewtopic.php?f=39&t=108411#p1586635

[@Doctorbasss]

Justin that is awsome. Is there any possibility in the future that the Cycle Analyst could do some math and multiply two value together to get the mecanical power for exemple? If we could use one of the input as a load cell torque information as well as the actual speed, we could get the instantanous mecanical power and also use the nice cycle Analyst into a dynamometer display doing the multiplication in real time and also compare with the Power in and get real time efficiency value. for people like me who like DIY DYNO =) Thanks.

[@groundcontrolgainesville4841]

OH SHIT ITS DOCTORBASS!!!!

[@grindz145]

@@groundcontrolgainesville4841 the legend himself!

[@GrinTechnologies]

Hey Doctorbass, yeah you and me do think alike ;-) The CA3 already does this for showing the human watts, and since I have the hall sensor speed of the motor hooked up to the PAS RPM input line of the CA3 instead of the normal speed input, then all I need to do is hook up the torque sensor of the motor mount to the pedal torque sensor input on the CA3 and it will show the mechanical motor power right there in the human watts field. With the custom views option you can choose to show human watts on the 1st display screen too, so then have both motor mechanical watts and electrical watts in the same screen. All that's missing is to do the division to show this as %efficiency. As long as there's an audience of more than 2-3 people, I think we can do this.

[@michelcote]

@@GrinTechnologies I am in too

[@Deqster]

That's so cool!

[@nobrakes7247]

Mad You guys so Smart

[@bluewanderer9903]

Beautiful. Sailboat with e propulsion, doesnt get much better than that.

[@ChrisBGramz4u]

Thank you! Been looking to find a small electric motor, with some torque.. Knew there had to be some out there, on some product. Hadn't thought of electric Hubs.. Lol, didn't know these types of hubs had been invented, yet...Wonder how well it would work, if used as a wind turbine...

[@GrinTechnologies]

Many people have used ebike hub motors in DIY wind turbine applications too. They are quite versatile and efficient motors/generators for applications that need to operate in a lower RPM range than conventional electric drives.

[@ArcticSeaCamel]

The dirtiness of the hull really seemed to affect a lot. In my boat (27 footer) 1000w gives almost 4 knots of speed. If I remember correctly (check my video) 100w gives 1 knot, 300w 2kn, 700w 3kn, and 4kn it goes to over 1kw. Then the consumption raises rapidly with max speed of 5,2kn with full 3,3kw.

[@ArcticSeaCamel]

But that torque and force metering is brilliant!

[@GrinTechnologies]

Hey thanks for the references and yeah, the 3 years of marine growth had played it's roll. Have a look at the latest Part2 video for the consumption vs speed numbers after a sanding and fresh coat of bottom paint, it's quite similar to that: kzbin.info/www/bejne/apykpJd_nqlrmpY

[@fredio54]

I don't see how mythical "hull speed" can help you know the power output of the prop, however between the load cell and the boat's speed-through-water you could get close (depends on shaft angle), which would be really sweet to see side by side with the other data you have there. Unpausing to find out soon :-)

[@fredio54]

Oh god, when you said "hull speed" you didn't mean it at all, you meant speed through water. You fucking land lubber, ha ha, get your shit together! :-D

[@GrinTechnologies]

Yeah exactly, I caught that flub too and cringed on hearing me say it in the rewatch when I meant to say "hull speed through the water". Good eye on you for spotting it and realizing what was meant too. Guilty as charged as a land lubber still getting his feet wet.

[@fredio54]

@@GrinTechnologies Ha ha, all good man, I've had my feet wet since birth and that was a hell of a long time ago. Hull speed isn't even real, so you're doing better in my interpretation :-D

[@doraexplora9046]

So now you can see by looking along the waterline of the boat you can see you need to put weight aft of the boat to get the stern down. Might be a good place to store more batteries?

[@GrinTechnologies]

Yeah, have a look at the more recent videos when we got 22 kWh in there, the trim is getting closer but we'll need to have a full 30 kWh to match the weight of the diesel engine that came out.

[@thisradguy1969]

This amazing. I am in the process of moving my 27ft Cheoy Lee with a Yanmar SB8 over to shelter island in Richmond to do a refit, including an electric conversion. Perhaps we could do some kind of collaboration. I definitely would love to chat with you further and have a look at what you are coming up with. So great you are local in Vancouver.

[@GrinTechnologies]

Hey Dusty, for sure. Send us an email as we'll be looking to do a small pilot production run or Marine motors this summer and will be wanting to have locals in on the beta phase. Shelter Island is one of my favorite marinas to walk around, so much eye candy.

[@normellow]

Temperature is critical to efficiency

[@nfineon]

Would love you to add a few more electric motors to the setup! There are a lot of 5kw single electric motors but if you wanted to stick with just eBike motors how about 5 through axle electric motors connected through a common shaft :)

[@GrinTechnologies]

You could do that, but it would then be putting up to 20 kW of power into a boat that reaches hull speed at about 5-6kW, so not a very good use of battery power for this boat! Have a read here for the actual power consumption vs speed graph: endless-sphere.com/forums/viewtopic.php?f=39&t=108411#p1586012

[@machinesandthings7121]

Two matted together would be interesting.

[@GrinTechnologies]

You mean double motors for double the torque and power? I think that this size of hub motor (27mm wide stator) will be OK for sailboats up to about 27-28 feet, but anything larger and we'd want to have a wider stator assembly for sure. There's a CAD model on my computer for a marine motor like this with a 45mm stator on it, and that's a lot easier to do and more efficient than trying to stack two narrower ones.

[@jhnoakez]

Wow! This is great stuff! Have you guys considered putting a fast wound GRIN motor on an old outboard?

[@GrinTechnologies]

Do you know the RPM that most outboard engines run at? As long as it's less than about 2000 rpm then it could be made to work, though mounting a hub motor in a retrofitted outboard I suspect will be trickier than this inboard job.

[@jasonwoods3711]

That's loud !! 2 to 1 belt set up would be quieter I'm sure ...

[@Diycanada560]

May I know how much the boat weight? Which motor model are you using thanks

[@michiganengineer8621]

Just stumbled onto this video while looking at electric outboards LOL Took a look at your thread over in the endless-sphere forum and saw something that give me a bit of concern. Your battery packs. Are the 21700 batteries still prone to the short circuit thermal runaway issues that have plagued the 18650's? As you probably know, sea water is EXTREMELY conductive so I hope your packs and connections aren't just insulated but SEALED! Hopefully at some point in the future you'll be able to replace those LiPos with LiFePo4 such as are used in off-grid homes. They DON'T overheat to an ignition point when shorted which has happened with the other battery chemistries.

[@GrinTechnologies]

Hey John, we deal extensively with 18650 and 21700 cells in the ebike industry and can say that things have come a long long way in terms of robustness and safety, and cell failures (when using Panasonic, Sony, LG, Samsung etc) are exceedingly rare. However, any time you have a large stash of lithium batteries around you should always be a little bit on edge and know what you are doing. These packs all have single port BMS circuits so any one battery that detects a cell issue will effectively be able to disconnect itself from the parallel array.

[@jasonbrand5762]

Rock On !

[@FearTheTaswegian]

Would be interesting to see regen performance with suitable prop. How much speed lost under typical sailing conditions vs rate of charge.

[@DannyBokma]

Absolutely! All forces in the other direction, hopefully the axial loadcell can sense pulling forces.

[@GrinTechnologies]

Once we get a nice collection of data on this front I'll share the link to the endless-sphere post here. So far we've only had one day with wind for regen and I didn't have the logger hooked up, but with sailing winds that had us moving at about 10.5 kph we were getting a max of 120 watts with the propeller spinning at about 300 rpm. The regen power was less if we let the prop spin faster, and less if it was torqued to spin slower too. With no regen at all the propeller would free spin at about 600 rpm.

[@CPTCleoTorris]

Very interesting... Subbed

[@peterkacandes5905]

Um, there’s a good reason why boat propellers don’t spin that fast. It’s called cavitation. You might want to look it up. It basically invalidates your entire premise from the beginning. Once you get beyond 5k rpm, you’ll just be making bubbles, let alone 11k.

[@GrinTechnologies]

For sure, I think you might have heard an extra zero in there. The top speed of this hub at 72V will be about 1400 rpm. I've just posted the measured plot of hull speed vs propeller RPM and motor power here if you are curious: endless-sphere.com/forums/viewtopic.php?f=39&t=108411&p=1586012#p1586012

[@vijaykorvekar1009]

Do you have 5kw peak power 60v bldc motor kit for my ebike build

[@lnewbyliveca]

Put on a flex fold prop and you might get a bit of regen.......

[@fossilfool]

Sweet project! Is weight reduction an important goal for that boat? With my bike sailing system on my channel weight is crucial because I bike to the water (now with a GMAC equipped folding bike). So far I've done with out a motor on my dinghy but have thought of doing one at some point and possibly using ebike parts. Would be fun to see how your boat moves under sail.

[@GrinTechnologies]

I've recently posted a lot of test results on the ES thread endless-sphere.com/forums/viewtopic.php?f=39&t=108411#p1585615 Weight reduction wasn't a critical goal when the boat is already like 5000lb, but I was really curious just how much range you'd get if you replace pound for pound the diesel setup with a compact electric drive and lithium batteries, and the answer to that looks to be about 180km which serves my needs just fine! For your setup then for sure weight is everything, and you'll be super impressed at what you can do with like 100-200 watts of power and a well chosen RC airplane propeller and just a lightweight lithium battery. Look at the flexible shaft drives that are used in efficient pedal powered boats for inspiration. Generally you'd be looking at a shaft speed of like 400-800 rpm depending on pitch. Lovely looking skin on frame boat build too btw!

[@fossilfool]

​@@GrinTechnologies Thx for the tip. 100-200W is a lot less than the rating of the Torqeedo outboards I was researching. For now I'm sticking with oars but I appreciate your innovation and curiosity. Have you checked out @PauliJuppi on KZbin?

[@visionontv]

Intresting project, we are looking at supplementing our lifeboat with electric for #boatingeurope life. Do you have issues with over heating at full power?

[@GrinTechnologies]

RIght now what happens is that the motor controller overheats and goes into thermal rollback before the motor itself gest more than about 90 degrees celcius. When we install a higher power motor controller and run the motor at more like 4KW continuous instead of 2KW then we're expecting to see the motor core reach close to 130 degrees or so. We can set the thermal rollback to kick in wherever we want and for this project we'll likely set that at 140 C.

[@ken2633]

Good. Next video no background music please.

[@zeroandplanb4life]

Your genius

[@zeroandplanb4life]

Use solar panels to recharge battery sail when you don't care about either so cool

[@JohnBraman413]

do you have this whole setup as a kit to buy?

[@GrinTechnologies]

Not yet, but we're dialing in the details on this particular project so that we can make it into a commercialized kit before the end of the year!

[@spartaeus]

Way underpowered! You'd get into big trouble trying to power through a strong current or a storm.

[@GrinTechnologies]

Have a look at the follow-up videos. This was just a first test run, with the larger controller and higher voltage battery pack the motor goes up to 5000 watts and gets the boat up to 6 knots just fine, so it's about the same as the original diesel inboard: kzbin.info/www/bejne/hnOlln-Mg8yUaNU&ab_channel=GrinTechnologies

[@mayamachine]

Useful data.. yup. I'm wondering, conversion to solar electric, and sky sail.

[@fun_ghoul]

Hey look, it's Mikowa Millions! A plane, a sailboat...you got a Corvette too? Maybe a few homes? lol omg

[@kurtrakeman9319]

Wearing a lifevest inside the marina...

[@zoranpocrnja2646]

Bravo I try to do as well it's better to get worm gears geared engine us well to get more powerful engine you can use the same engine just

[@GrinTechnologies]

Have a look at this post here to see details on the engine power and efficiency, it's almost perfectly mated as is with no gearbox. Either gearing it up or down would actually decrease the motor efficiency endless-sphere.com/forums/viewtopic.php?f=39&t=108411#p1586635

[@DallasAya]

All your test are a joke with that bottom. Need to put a racing bottom on that boat , bring it up to it's PHRF rating. Then and only then will the math be right.

[@sunshine5349]

get rid of that 1000 lbs of ballast on the bottom, should accelerate a lot faster, you dont' need the sail anyway, lol.