Solar Electric Catamaran Model

[Ifitsworthdoing]

In the full scale boat the motors should be pods which are cooled by immersion in the surrounding water. I am currently finalising commission plans for a 34ft/5 ton a olar electric cruiser cat and that’s going to have twin 10kW pod motors and around 20 square meters of solar estate as well as 2 vertical wind turbines at the aft end of the hulls. I plan on using a 20 square meter kite sail in suitable following winds and possibly 2 (coupled) adapted windsurf or dinghy sails on the forward end of the hulls. Ideally the boat would operate as a motor sailer most of the time.

[seandepagnier]

If you use 4x larger diameter propellers and gear 1:16 you will use less than half the same power at a cruising speed. Get the largest propellers possible until the two propellers almost touch each other from each hull


Please consider the terrible efficiency of tiny propellers.

[KnightSailor]

Originally Posted by Ifitsworthdoing

In the full scale boat the motors should be pods which are cooled by immersion in the surrounding water. I am currently finalising commission plans for a 34ft/5 ton a olar electric cruiser cat and that’s going to have twin 10kW pod motors and around 20 square meters of solar estate as well as 2 vertical wind turbines at the aft end of the hulls. I plan on using a 20 square meter kite sail in suitable following winds and possibly 2 (coupled) adapted windsurf or dinghy sails on the forward end of the hulls. Ideally the boat would operate as a motor sailer most of the time.

I assume that the pods will be steerable. That would make maneuvering in tight spaces easy. Why not go all way and add bow thrusters?
Thanks for the information. Pods are a great idea. They are probably a little pricey.

[Ifitsworthdoing]

The pod motors (either a new larger Evo pod model just being introduced by ePropulsion or Vetus' new rim driven thruster E-Pod model) are around £7k each as fixed installations but either not available or much more expensive on swivels. With the twin motors of a catamaran you usually don't need a bow thruster.

[joelhemington]

Originally Posted by KnightSailor

Definitely. When I get the solar panels, I will use them to charge batteries and power the motors. That will be the same on the full size cat.
Some of the solar powered boats I have seen are also Hybrids, with a small motor to keep them going and recharge the batteries if there is no sunshine and the batteries are discharged.

While a lot of people are intrigued by the idea of electric motors (myself included) the technology is not quite there yet. The motors are radically expensive and the regeneration systems are not performing as advertised (just ask Jimmy Cornell). The current Ocean Volt system for a mid sized catamaran runs about 100K with the regen system which I could almost stomach if the regen system actually worked. With about 2.4k of solar (six large panels) and a 2,000 amp hour LIFPo4 battery bank. You could easily provide the electrical power for a well equipped catamaran (just not the engines for any extended run) For now, I'm planning on twin Yanmar 20hp engines with a 8k backup genset and a couple of pod style Watt and Sea hydro generators to keep the banks topped off. These only work under sail but that's the only time you'd be using radar, auto pilot and other cruising electronics. On the hook, the solar should keep the boat functioning - if not, I'll just crank up the genset for awhile. When electric motors finally become viable, I'll be the first in line and convert my fuel tank to fresh water - sell the Yanmars and genny and get diesel off the boat completely.

[BillKny]

Originally Posted by KnightSailor

Perhaps. The original concept was to have a “sail boat” that could sail directly into the wind. I got the idea from a boat in Australia that had a tall tower with a three blade turbine that was mechanically connected with gears to a large water screw. It could “sail” in circles. That got me thinking about a better way to do that.

Oh wow... I see the joke went right over your head.

Like everybody else I see who proposes a "solar powered boat" you haven't a clue.

A wind turbine always will consume more energy in drag than it generates (thanks to the 2nd law of thermodynamics). There is NO WAY to sail directly into the wind. If you actually manage it, you'll win a Nobel prize for proving 400 years of science wrong and inventing a perpetual motion machine.

But have fun trying, and keep us updated on it. These days we always need a good laugh.

[KnightSailor]

Originally Posted by joelhemington

While a lot of people are intrigued by the idea of electric motors (myself included) the technology is not quite there yet. The motors are radically expensive and the regeneration systems are not performing as advertised (just ask Jimmy Cornell). The current Ocean Volt system for a mid sized catamaran runs about 100K with the regen system which I could almost stomach if the regen system actually worked. With about 2.4k of solar (six large panels) and a 2,000 amp hour LIFPo4 battery bank. You could easily provide the electrical power for a well equipped catamaran (just not the engines for any extended run) For now, I'm planning on twin Yanmar 20hp engines with a 8k backup genset and a couple of pod style Watt and Sea hydro generators to keep the banks topped off. These only work under sail but that's the only time you'd be using radar, auto pilot and other cruising electronics. On the hook, the solar should keep the boat functioning - if not, I'll just crank up the genset for awhile. When electric motors finally become viable, I'll be the first in line and convert my fuel tank to fresh water - sell the Yanmars and genny and get diesel off the boat completely.

For many years I have been looking into electric systems for vehicles, including a car, a motorcycle, and a 4 wheeler. I have the rolling frame for the 4 wheeler, and two of my three Ford Broncos don’t run and I could convert one of them. For a vehicle, I found kits from $6000 to $8000. Those should power the Cat. At one time I could have bought a compact used electric car at a local dealer for $400. I think I could put an entire electric drive system into a 25’ Cat for about $20,000 - $25,000. That would be internal motors, without pods.
I have an amazing inventory of parts, building supplies, metal etc. and I love doing fiberglass construction and repair. I constantly shop at the local scrap yard for aluminum and other parts. Example, last year I bought an intact 32’ mast from a boat, complete with all the stainless rigging and the boom, for $65. I found one like it on the internet for $850 used.

[KnightSailor]

Originally Posted by BillKny

Oh wow... I see the joke went right over your head.

No, I ignored your so-called joke.

Originally Posted by BillKny

Like everybody else I see who proposes a "solar powered boat" you haven't a clue.

There is always someone like you on a forum that ridicules people they don’t know in a vain attempt to insinuate their own superior knowledge. BTW, there are dozens and dozens of solar powered boats cruising right now.

Originally Posted by BillKny

A wind turbine always will consume more energy in drag than it generates (thanks to the 2nd law of thermodynamics). There is NO WAY to sail directly into the wind. If you actually manage it, you'll win a Nobel prize for proving 400 years of science wrong and inventing a perpetual motion machine.

Clearly you missed the obvious. You might want to rethink your comment before commenting again. Hint: By “sail”, I obviously meant move under power. That was probably obvious to everyone else since my proposed design includes solar power, batteries, and electric motors.

Originally Posted by BillKny

But have fun trying, and keep us updated on it. These days we always need a good laugh.

Great. You yuck it up while the rest of us create.
Meanwhile here is a little “light” reading for you. Enjoy.
https://robbreport.com/motors/marine...es-1234576202/
https://www.powerandmotoryacht.com/b...nlimited-range

https://www.treehugger.com/awesome-s...st-see-4857671
https://www.engadget.com/2016-09-24-...red-ships.html

[Ifitsworthdoing]

Actually BillKny there have been prototype catamarans mechanically powered by a large mast mounted horizontal wind turbine capable of beating up against the wind operating both in the UK and Australia. Granted this concept has never been adopted commercially but it does work and there are YouTube clips showing it.

FWIW my understanding of the solar powered cruiser concept is that we are currently roughly where the Model T Ford stands in the history of car development. The concept has been proven by the Koehler couple sailing SolarWave across oceans in the early 2010s but until battery tech improves further - which will not be a long wait - doing so necessitates very slow speeds. Wind turbines and hydrogenerators can help a little, but by far the greater part of charging depends on solar panels, and their efficiency will soon increase from the current 20 percent to at least 30 ... What remains out of reach is fast pure electric power boating over any significant distances - speedboating (other than short distance coursing) remains intrinsically linked to burning fossil fuels and thus will become tarnished over time like tobacco has.

[KnightSailor]

Originally Posted by Ifitsworthdoing

What remains out of reach is fast pure electric power boating over any significant distances - speedboating (other than short distance coursing) remains intrinsically linked to burning fossil fuels and thus will become tarnished over time like tobacco has.

That technology is being advanced aggressively by auto racing. The new FIA Formula E race cars are fast and becoming more efficient all the time. Now, due to improved battery technology, they don’t even have to change cars in the middle of the race.
https://www.keithprowse.co.uk/news-a...and-formula-1/

[Redreuben]

I don't understand this need to sail directly into the wind, it is the most uncomfortable angle of them all, even a power boat skipper steers at an angle crossing the waves, its the quickest way to damage your boat and your person.

[KnightSailor]

Originally Posted by Redreuben

I don't understand this need to sail directly into the wind, it is the most uncomfortable angle of them all, even a power boat skipper steers at an angle crossing the waves, its the quickest way to damage your boat and your person.

Hmmmm…. I never said it was a need, merely one of the options not available to conventional sailboats. I loved tacking as close to the wind as possible. That is sailing.
Having said that, I also know first hand the advantage in some (not all) conditions to cutting straight into the waves. Of course that depends upon many different factors. As stated, the point of having the Solar Powered Electric Driven Cat is the number of options. I still love conventional sailing, but at my age I believe I have earned a little laid back luxury.

[BillKny]

Originally Posted by KnightSailor

Great. You yuck it up while the rest of us create.
Meanwhile here is a little “light” reading for you. Enjoy.

I HAVE a wind powered boat. It's been around the world. TWICE.

I looked at all the links you sent me. Very rich on "concept" boats, and very lean any that have actually been built and tested.

I look forward to your Nobel prize. I am following closely.

[KnightSailor]

Originally Posted by BillKny

I HAVE a wind powered boat. It's been around the world. TWICE.
I looked at all the links you sent me. Very rich on "concept" boats, and very lean any that have actually been built and tested.

Those were proof of concept, something you seem a little light on. (pun intended) I don’t know the actual number, but there are probably well over 100 practical, functional, and operational Solar Powered Boats that have been built and are out cruising. There may be many more than that. The various links don’t really address that.

Originally Posted by BillKny

I look forward to your Nobel prize. I am following closely.

So you are falling back on your absurd comment, even though it has been explained to you. I don’t have the statistics on a Horizontal Turbine to Generator to Motor to Propeller drive, but the boat in Australia with the Wind Turbine on a tall mast driving a huge water screw by direct drive did in fact sail (power) straight into the wind.
I shouldn’t do this, here is another hint, in physics this time:
Wind Turbine Blades use aerodynamic lift to power them, just as cloth sails use aerodynamic lift to pull the boat forward. Have fun learning practical application physics.

[stark]

Originally Posted by KnightSailor

Thank you for your concern.
After looking at hundreds of photos of powered Catamarans, the mast is far from common or traditional. Most didn’t have one. Even so, I put it on the model mostly for show, although a version of it may end up on the full size Cat.
I did the calculations and the largest shadow that mast could cast is 2.4% of the surface of the deck. Depending on the angle of the Sun, that would amount overall to perhaps 1% of the surface overall. Therefore the shadow is not an issue.

The issue is that a solar panel will not produce much electricity if even a small part of it is shaded. It has to do with the way the cells in the panel. are tied together. The mast shadow might be 2%, but the output of the whole panel might drop 90%. Maybe they'll figure this out in the future, but you'll probably just have more electricity overall by dropping the wind gen part