Solar Electric Catamaran Model

[KnightSailor]

Many years ago I was considering building a Solar and Wind powered sailboat. The concept was a flat horizontal Wind Turbine on top, with Solar Panels on the roof above that and elsewhere on the boat. Those would charge batteries and power electric motors. My initial design was a Catamaran. I moved before finishing the model and sort of never got back to the design.
Last year I got out that unfinished model and decided it was a poor design. I started looking at Solar/Wind boats and saw that technology had advanced dramatically in the last 40 years and there were quite a few Solar/Wind boats out there. I decided to work on designing a Solar powered Catamaran, so I started work on a new model
Now I have an electric Catamaran model that is 44” long and 24” wide. The hulls are one of a kind fiberglass with a ⅛” plywood deck and superstructure. It has electric motors in each hull driving 1½” props. I have ordered a Differential Controller. I will power it with batteries until I determine the power required.
I added a few things such as air scoops to direct cooling air to the electric motors and a mast with model radar and running lights. When the ice on the ponds melt, I will take it out and make some videos. If the model performs well, I plan to make a full scale Solar Catamaran. Here are some photos.

[Chotu]

I want to see the horizon wind turbine

[KnightSailor]

Originally Posted by Chotu

I want to see the horizon wind turbine

I never built a working model of that turbine. The design was a squirrel cage turbine, as wide as the superstructure and ¼ 1/3 as tall, covered by a flat roof. That would have been very low profile. After looking at the new horizontal and vertical wind turbines, I decided that no one would want that 10ft wide monstrosity spinning over their heads.
This is one of my original drawings from 40 years ago.

[BillKny]

How do you expect the power usage to scale up?

It is going to be very non-linear with length or weight. You'll be operating at a Reynold's Number different by probably 2 orders of magnitude...

It's always the challenge... how do you generate enough electricity to move a boat of useful weight at useful speeds against wind and current...

[KnightSailor]

Originally Posted by BillKny

How do you expect the power usage to scale up? It is going to be very non-linear with length or weight. You'll be operating at a Reynold's Number different by probably 2 orders of magnitude...

My model is fairly large for the electric motors I am using. I am hoping I will be able to get some ballpark ideas of how that works. For instance, the motors worked great on a monohull ¼ this size, and close together, turning it is a tight circle. I want to see how they work on a Catamran, much further apart, and twin hull. The purpose of a model is to test various things before building a boat. I have a lot to learn.

Originally Posted by BillKny

It's always the challenge... how do you generate enough electricity to move a boat of useful weight at useful speeds against wind and current...

I don’t have that answer, yet. I suggest you ask those who have built full scale solar powered electric monohull and catamarans. There are lots of them out there, and some very large and very expensive. Some have additional wind generators, and some are solar power only. I was surprised to see how many different solar craft there were.

[Dsanduril]

Here's a minor critique: you've built a model with a generous, flat coachroof ideal for the placement of solar panels, and then you've gone traditional and put a mast on it, creating shadows and wreaking havoc on your electrical production. Find a way to get rid of, move, or otherwise change the mast so that you're not casting shadows on your solar facility.

[BillKny]

I like the addition of a large vertical turbine.

Once you get the boat moving, the apparent wind should generate enough power to keep you going upwind forever.

[KnightSailor]

Originally Posted by Dsanduril

Here's a minor critique: you've built a model with a generous, flat coachroof ideal for the placement of solar panels, and then you've gone traditional and put a mast on it, creating shadows and wreaking havoc on your electrical production. Find a way to get rid of, move, or otherwise change the mast so that you're not casting shadows on your solar facility.

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.

[KnightSailor]

Originally Posted by BillKny

I like the addition of a large vertical turbine.

Once you get the boat moving, the apparent wind should generate enough power to keep you going upwind forever.

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.

[harlem24]

There is technology available that doesn't really care about beeing partly shaded.
But why did you put up those scoopes? If you look at Silent Yachts or OV systems, you'll see that the motors don't need huge cooling.

[Redreuben]

Sails are wind powered what’s the problem ? Too much manual Labour ?

[moseriw]

As backup a would bunker a few AAA lithium cells.

[KnightSailor]

Originally Posted by harlem24

There is technology available that doesn't really care about beeing partly shaded.
But why did you put up those scoopes? If you look at Silent Yachts or OV systems, you'll see that the motors don't need huge cooling.

The motors I used in this model are motors I took from a model speedboat. They were mounted in an open area in the speedboat and attached to large heat sinks because they get hot. In order to mount them in the hulls of the Catamaran, I had to remove the heat sinks. The air scoops are to cool the motors in the confined area in the narrow hulls.

[KnightSailor]

Originally Posted by Redreuben

Sails are wind powered what’s the problem ? Too much manual Labour ?

Not at all. I sailed my Phoenix 18 and many Hobie 16 Cats and loved it. The issues I was addressing with the turbine/solar combo was twofold.
First, with both solar and wind charging batteries, the Solar Wind could sail day or night, calm or windy, without having an engine or fuel.
The second was the ability to sail directly into the wind, a shorter route than tacking, or easily sail around in circles, or even be able to very quickly turn back to rescue someone, regardless of the weather.

[KnightSailor]

Originally Posted by moseriw

As backup a would bunker a few AAA lithium cells.

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.