Electric motor sailer of the future

[Paul Scott]

Better sketch

 

[Paul Scott]

Light isn't in the cards yet. You need about 20,000 pounds of displacement to have a smallish e-cruiser with decent range. If you had an ULD, you know how little of the interior is actually living space, to save weight. That's good, because electric takes up a lot of space. Think Hans Christian or Baba 40 sunk down about 6 inches below design lines. L/D about 350 for a 40' LOA double ender. This can work today. The propulsion electrical footprint is the size of a medium car, but heavier. The battery compartments require heating and a/c (or forced ventilation in cool climates) to get nameplate life and performance. The chargers will fill a closet. The above will handle a 10kw emotor pretty well for half a day. If the boat comes standard with a 35hp diesel, you will want to up that to 40-45 hp with the electric system so you can charge batteries while motoring. This arrangement can cut the engine hours by 2/3 while cruising. You need an extra $4k of alternators as well. But no need for a night genset - the main bank chargers can load the engine at 1200 rpms with the correct alternators. You can run a/c all night on the batteries.

Propulsion batteries - three strings of eight L16 400Ah 6V lead carbon such as SWE-6 for 1200 Ah at 48 V.
House batteries (12V or 24V) - four L16 400Ah.
Battery box - three feet by nine feet, sealed from occupied spaces, with room for wiring and cooling.
Alternator - twin Balmar high gain
Chargers - one Victron Skylla 48/50 TG, two Victron multibus 48/2 kVA 120, one 48V - 12V(or 24V) DC-DC charger
Battery switches - four Blue Sea 6006.
Relay/contactor - Trombetta Bear 225 Amp (for combining banks, mostly for shore charging 3 banks with the two Multibus 48/2s.)
Fuse blocks - four 100 A

Warm climates may require changing from L16 to a slab type battery footprint because they can be cooled much better. But their lower Ah rating makes it difficult to build efficient battery banks for a 10 kW motor.

The above specs were what I came up with to fit an off-the-shelf Beta Hybrid with 10 kW e-motor and 5 kW built-in charger in the controller.

we went from a nearly dead Yanmar 3gm3 to a Torqeedo 48-5000 2 pack for the 10.0 Cruise saildrive and saved a couple of hundred pounds, may 250. So far, we can average 5 knots in very light winds using current etc with the electric. We used to motor at 5 knots with the Yanmar because even with lead foil lining the engine compartment the diesel was too noisy over that rpm ~2100. 15 gallon tank that we filled twice a summer.
Electric decibels, 50. Yanmar decibels 78. Light skinny boat. Not a Baba. Adding solar in a bit, when we know more about performance. I’d argue that we need to think long and hard about big heavy boats & electric. But you’re right, big heavy boats can carry more weight, kind of like why pickup trucks and Hummers are good candidates for electric battery power.

 

[Squidly-Diddly]

Prius Prime batteries are mostly flat squares that weigh IIRC 300lbs and are selling on Ebay for about $1500 and that probably quite a bargain as far as battery capacity and life cycle. Tilt on side and slide into keel. Streamline ends with lead casing. Haven't heard of any Prime batts blowing up even after a crash.

 

[Rumars]

Your version would be pretty difficult to implement, it would need a heavily reinforced luff tape on the upper part, and I think you wouldn't be able to install battens on the upper part of the sail (they would need to reliably feed into the slot and still allow sail rotation).

I would go old school for this, two versions. On a small sail sliding gunter using big boat batten cars holding up a carbon spar in a sail pocket. Bernd Kohler designed such a thing for his KD 650.
For a big sail, a gaff with yard topsail variation. I would use a wide square top sail instead of a gaff, and for the topsail I would use a winsurf sail, boom included, the heel possibly traveling in a separate track on the mast. On deck, set the windsurf sail for the conditions, and hoist it up. Removing it serves as the first reef, and if desired one can have different size topsails. I think it would require a separate sheet for the topsail, the square top batten is probably to flexible to attach a sheet.

Here is Kohlers modern gunter interpretation, he sells the plans for 25$:

 

[rwatson]

Retracting Rotor

 

[Rumars]

If you want a telescopic flettner rotor you don't have to fuss around with different diameters, just make the top part inflatable. In the center you can have a telescopic guide rod to keep it straight until pressure is up, and a few elastic cords pulling it inside in the middle.

 

[rwatson]

If you want a telescopic flettner rotor you don't have to fuss around with different diameters, just make the top part inflatable. In the center you can have a telescopic guide rod to keep it straight until pressure is up, and a few elastic cords pulling it inside in the middle.

 

[Paul Scott]

Your version would be pretty difficult to implement, it would need a heavily reinforced luff tape on the upper part, and I think you wouldn't be able to install battens on the upper part of the sail (they would need to reliably feed into the slot and still allow sail rotation).

I would go old school for this, two versions. On a small sail sliding gunter using big boat batten cars holding up a carbon spar in a sail pocket. Bernd Kohler designed such a thing for his KD 650.
For a big sail, a gaff with yard topsail variation. I would use a wide square top sail instead of a gaff, and for the topsail I would use a winsurf sail, boom included, the heel possibly traveling in a separate track on the mast. On deck, set the windsurf sail for the conditions, and hoist it up. Removing it serves as the first reef, and if desired one can have different size topsails. I think it would require a separate sheet for the topsail, the square top batten is probably to flexible to attach a sheet.

Here is Kohlers modern gunter interpretation, he sells the plans for 25$:

I wasn’t clear, and I apologize- I was only using the term sliding Gunter to apply to the topmast sliding down to reef, much as a telescoping FR would, lowering CoE as well as center of gravity. As far as Kohler’s Gunter, which I admire, for my rotating wing mast Gunter, I was sailing in mountain lakes, and needed the ability to scandalize the sail quickly because of sudden willawas coming down from mountains onto the lakes, so I had a folding Gunter made, not a slider. Still fiddly though.

 

[Paul Scott]

View attachment 188262

Proa = smaller spiral?

 

[rwatson]

Proa = smaller spiral?

The range of performance is a function of hull size, rotor size, but mostly the arbitrary size of the paper and reproduction of the graphs.
For all intents and purposes, they are v similar.

 

[Paul Scott]

Does a FR have a CE that, on a proa, means that CLR doesn’t need to change after shunting?

(If this has been addressed elsewhere, a link? Thanks)

edit- could a vertical wind generator unit (without the generator part) act as an FR?

I’ve not found the proper question to ask the Internet about wind lift/drag on the central tube ( or the whole of the unit, for that matter) of the second pic above, or around the first pic. It’s tempting to think of a FR that wouldn’t need a motor.

 

[Paul Scott]

Could a large anemometer effectively spin a flettner rotor? Someone must have tried, but I can’t find it.

 

[clmanges]

snip

edit- could a vertical wind generator unit (without the generator part) act as an FR?
snip

I'm going to say no. Vertical turbines have no directionality with respect to incident wind, so when powered, all they'd do is create general turbulence. I doubt if they'd work well even if you modified one to feather its blades for best lift in your desired direction.

Now, a squirrel-cage blower would be a different matter, but it wouldn't need to be vertically oriented. I'm betting it would also be far less effective than an airplane propeller.

 

[Clarkey]

Could a large anemometer effectively spin a flettner rotor? Someone must have tried, but I can’t find it.

Savonius started out on this route around the same time as Flettner and made a boat with his vertical axis rotors that drove using Magnus effect (picture below). There are a couple of limitations with this though. First it is not easy to reverse the direction of rotation of a Savonius rotor without complex mechanisms. Secondly because they are drag devices they will only rotate with the surface moving slower than the apparent wind and this will not get near to the circumferential velocity/windspeed ratios that give the best performance.

Keksijä Sigurd Savonius :: Inkoon-pitaja https://www.inkoo.info/l/keksija-sigurd-savonius/

 

[Paul Scott]

Savonius started out on this route around the same time as Flettner and made a boat with his vertical axis rotors that drove using Magnus effect (picture below). There are a couple of limitations with this though. First it is not easy to reverse the direction of rotation of a Savonius rotor without complex mechanisms. Secondly because they are drag devices they will only rotate with the surface moving slower than the apparent wind and this will not get near to the circumferential velocity/windspeed ratios that give the best performance.

Keksijä Sigurd Savonius :: Inkoon-pitaja https://www.inkoo.info/l/keksija-sigurd-savonius/

Edit- the pic finally decided to upload so I could see the whole thing. Thanks! Maybe Google garbled the translation, but the Architect seems to have tried the idea of using the wind to rotate the column? (Or engine?) by separating the halves of the FR column, and letting them rotate (around what?), which developed more power? Sounds like a anemometer approach with two cups that extended the length of the column? Or did they power a propellor? Try Google translate on the article. If I got it right, Flettner was interested in the idea?