Shamrock Electric Sailboat Conversion Part 5 - Maiden Trip under Solar, Across the Georgia Straight 

in this case it's a whataboat

It worked reasonably well but in the end I've since removed them due to how much they got on the way when actually sailing and blocking the view. For the shorter trips we tend to do the 500 watts of solar on the back is more than enough.

@@GrinTechnologies ahh that’s unfortunate, perhaps one could hang them lower about level with the deck so not to intrude as much in your vision.

Ah nice, that is a petty clean and simple approach for supporting the extra solar panel

That's a question that hasn't had much consideration! The boat has a grounding system connected to the mast, while the motor drive electronics and battery are fully isolated so hopefully this will be good enough to steer any discharge in a path that doesn't damage the motor drive electronics. Lightning is quite rare in this part of the world but it'd be a good idea for us to have it in consideration. We always have one or two backup motor controllers on the boat in any case since that's an easy insurance against any kind of electrical failure.

More coming this summer for sure!

Can I suggest a bigger boat, bigger array and bigger battery as a proof of concept prototype to a new companies offering! Most of us can't afford the multi million pound catamaran offerings from Silent Yachts and Co!@@GrinTechnologies

20 knots is planing speed, so you a very different kind of boat platform to achieve that. I'd consider it unlikely unless you have quite a lightweight boat, since normally planing requires on the order of 10's of kW.

We were motoring between 9-10 kph, sometimes with the tide and sometimes against it, using 2-3 kW of motor power. The CA said 258 wh/km, but there was marine growth around the water speed sensor of the CA so that was under reporting the speed and total distance (84 km on CA vs 91 kph according to GPS). So actual consumption was about 239 wh/km.

"Robust enough" is key! Wind can be pretty unforgiving to large thin surfaces but if the individual cells were spaced out with gaps so that the air can flow through them perhaps it might be easier to pull off. I do love the idea of having a 'solar sail' that you move around and orient to the sun on calm days just like a normal sail gets trimmed to the wind. And no doubt you'd get way more than enough watts to match sailing speeds without dipping into the battery reserve. We have 1800 pieces of bare Maxeon Sunpower cells on hand to toy with like this kind of stuff, but some other companies seem pretty far along in that exact product development, like www.solarclothsystem.com/home

@@GrinTechnologies PLEASE pursue this because I think a lot of people would be very interested in it. There's no scientific reason why it wouldn't work, just implementation challenges. You could even start with a sail of the same flexible panels that you are currently using and develop further from there.

The bearing on this motor is a deep groove ball bearing (35mm ID, 55mm OD), and the manufacturer of the bearing assured us that the thrust forces we're dealing with here, ~200lb or so max, are no problem for a conventional radial groove ball bearing of this size. We did purchase some angular contact bearings that are even better at thrust loads too if this did become an issue, but they don't have the same waterproof seal on them. Our main concern is in reversing the motor, all the backwards thrust is pulling on the side plate and small side plate bolts, so I have the reverse motor power limited to about 500 watts untill we come on with a better solution for this.

These are boost mode MPPT charge controllers that we have for ebikes. So there are two constraints: 1) The total voltage of the panels has to be less than the voltage of the battery pack, and 2) The total voltage into the MPPT has to be less than the rated voltage of the MPPT. With all the panels in series it would fry it. This would work all in series with a buck mode MPPT, but then we wouldn't have the flexibility of disconnecting and running just a subset of the panels since a buck mode MPPT would require that the panel voltage is always higher than the battery voltage. There is a 72V to 12V DC-DC for doing the house pack. We don't have any electronics on the boat that need 110V AC, but it would be simple enough to add an inverter if we wanted that. The next accessory we're thinking of doing is on-demand hot water, but we'd wire up our own heating element to run natively off the 72V pack without any voltage conversion.

Take your empirically measured Wh/km at your preferred cruising speed, multiply that by your required trip distance, and that determines how many watt-hours are needed. You can achieve that 100% with batteries by having at least that many watt-hours of battery capacity, or you can count on portion of it coming from solar by estimating that on average you'll get 4 times your nominal installed solar watts in watt-hours each day. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-15HHLY4BfA4.html&ab_channel=GrinTechnologies has more details as it applies to ebikes. Boats are no different, just a heck of a lot more power hungy.

We concur. If Shamrock ever gets winds up in an unfortunate demasting incident, you can be pretty sure that would be her future life too! It would be a nice way to bring value to salvage/scrap sailboats that are missing all their rigging too but otherwise have a sound hull.

Yes that it is indeed!

It was supposed to say Vancouver -> Sidney. Seattle would be a longer multi-day trip we'd like to do next summer, and Vancouver->Sydney would be an entire summer long trip by someone much more brave than me!

So how many miles did they travel?

It does regen just fine, but with the winds we have here it tops out at about 100-120 watts at the point of maximum power recovery. So it doesn't even come close to what we get from the solar panels even in the best of days. This regen maximum point is fully related to propeller diameter and geometry. If the sailboat was on land with a tracked wheel then we'd be able to get many kW of regen power from the same sail thrust, but what you can get dragging a prop through water is a lot more limiting.

@@GrinTechnologies it's just the reverse air foil shape of the prop blades, and any reduction losses that drops the potential.....every one knows a prop is less efficient in reverse because you can feel it....but it's not reverse either, it's just the air foil shape is the wrong way for re-gen......but still.....i you get into the programming, you can get more power out of it than your thinking...

@@GrinTechnologies the other thing to remember is: you can get symmetrical airfoil props.....you just have more shopping work to do, when getting a symmetrical airfoil prop for re-gen.

@@GrinTechnologies in reverse, the airfoil is backwards, AND on the wrong side.....but re-gen, it's just typically on the wrong side. though it is difficult to find symmetrical airfoil props, they do exist....and that has more to do with it than propeller dimensions, once your into the programming.

@@GrinTechnologies once you get it right...then the only reason you will have left, for all those solar panels, is extended motor sailing.. if you load the prop too hard, you get more drag than power.....if you don't load it hard enough, it will just spin and produce little power..... but if you get it right, you will understand why i size systems for direct drive, and why i recommend finding a symmetrical airfoil prop.. and the only way i have found to get around the need for a reduction, is the newer Axial Flux motors.