Another Try at an Electric Catamaran

[Motivator-1]

Hello Boat Design Members,
I would like to introduce myself as this is my first attempt to post here, though I have read many. After you read this, if you can suggest a better thread to post to, please instruct me to do so.
I have been designing and building Pedal power, Electric power, and small Power boats for the last 25 years. I am a "Hands-on" type of Engineer with experience in a number of fields. I am also a Master Machinist, a Heliarc Welder, and my ventures have taught me to understand electrical and mechanical design and Fiberglass techniques of Plug & Mold design and construction. These capabilities have allowed me to design and fabricate every aspect of my past projects that include a Tandem, Pedal Powered Catamaran, a Solo Semi-recumbent Pedal Powered Catamaran, an Electric Powered Catamaran fishing boat, and lastly a Hybrid Gas/Electric design that I labeled the Stealth Cat that unfortunately did not get further than first sea trials with an outboard motor.
What I am looking to do next is revisit my Electric catamaran to try to push the limits of speed and performance using today's better technologies. Mostly, I'm hoping to get help with the Cat Hull design to see if some rules can be broken. The crafts mentioned earlier all worked well beyond my expectations, and I believe I pushed the envelope a bit even then. I would be glad to share with you the things I have learned. The design criteria that I usually follow does not always incorporate all of the top suggested things, but a compromise that allows the Boat to be a Boat. By this I mean that you should be able to move about on the craft, Fish comfortably from it, and be able to navigate the Shallow waters here in South Florida or anywhere else.
I am not sure how to and what size attachements I can add, but I'll try to show you what I have done in the past. Some of these, I believe look quite professionally built.
I am finding it hard to size my pictures properly to get them to load here. Can someone help.
John Vitsur

[Squidly-Diddly]

that is the only way I found to get my SolidWorks Student Edition CAD pics into a postable format.

Seems to 'size' nicely as well.

[Motivator-1]

Thanks Squidly,
I actually scanned my photos, but the size of each one is huge. I'm not sure that I understand the Re-size function in my Photo editing softwares, but I'll try again.
John

[Squidly-Diddly]

using any Photo Editing Software.

[Motivator-1]

I hope I just figured it out. If so, I'll upload more on a following post. These are shots of my first build of the Pedalcat.
John

[Motivator-1]

Now their too small!! I'll try again.
John

[Motivator-1]

I think I got it, but I have ruined the files of the previous pictures. What I had to do was to first save them as jpegs from bitmaps, then resize. By resizing first in bitmap and then saving as jpegs, the images got way too small. Lets see if these are better.
John

[Motivator-1]

I give up....Help!!!!!
John

[Fanie]

Dear John

Imo there are no worth while advances on electric motors that will make them worth while to put in a boat other than hobby type use.

You can just as well buy a trolling motor, fit a couple of big batteries and keep a good battery charger.

[Squidly-Diddly]

that looks like it allows the drive to pivot?

Have you peddled it "dry" to gauge any power loss?

nice looking boat and pedal-drive.

[Motivator-1]

Squidly,
I'll give you a little background on the boat. The Outdrive unit on this first attempt is a Right-angle drive with small Helical gears in the lower unit that allow it to be only 1 1/2" in diameter and it is filled with Synthetic oil for lubrication. This matches nicely to the Inboard style propeller that I used. I felt that having a lot less Hub on an outdrive was key, and that utilized more of the prop blade around the center. The cords you are referring to are the Steering Cables that rotate the drive. The drive, as you can see, also tilts up when striking bottom or hitting something. There is also a lever to raise the drive unit while powering up to a point where the prop splashes at the surface allowing you to creep over water depths as small as 6" or so. This raising feature also allows you to clear a fowled prop of weeds without having to use your hands. If you hit bottom, simply jumping off the boat raises it enough to push the craft over as little as 3" to 4" of water. There is also an adjustable Bungee cord that runs forward to hold the drive down with enough tension to allow for Reverse operation. There is a bicycle Derailler inside the cowling that allows a choice of 6 different final drive speeds. The later drive units got even better. I'm not sure what loss you are talking about, but in 6th gear, which is a final ratio of 1 to 12 RPMs, the unit turns very freely. I, in fact, had to open up the tension of the Oil Seal Lip that bears on the output shaft quite a bit, and that made everything run quite effortlessly. That turned out to be the biggest friction loss. I'll give you more on the efficiency later.
John

[Motivator-1]

Thanks for your input. I can agree with you on this, and I had very good success using only a 45lb thrust trolling Motor on my Electricat fishing boat. Because of the extremly narrow hulls (Beam to Length Ratio), the boat moved very easily through the water until encountering the Wave-Making drag forces. Even still, I was able to top out at 5 1/2 MPH and with 2 - 105 Amp-Hour batteries, I could get over a 30 mile range if I kept the throttle down to the trolling speeds using a Pulse-Modulated control. It was really quite a surprise what could be done with this boat and 2 passengers aboard. I often took trips with our small children aboard and were cruising for 5 to 6 hours.
What I hope to do next one is to go drastically to twin motors at 107lb thrust (more than 4 timesw the power), likely one motor in each hull, and see what I can gain with 20' hulls (1st were 18') and some better hull shaping, as I feel this is where the real challenge is. The new design will probably have a 36 volt system and 6 batteries. Steering will be by twin throttles or a Joystick. I have a lot of other ideas that I would also like to incorporate. I'm looking for anybody with some hull designing experience in Catamaran type hulls, specifically a discussion as to whether to have slightly submerged transoms or not? I have several designs that I am contiplating based on what my past observations have been. By the way, believe it or not, my Pedalcat could move faster than the Electricat with 2 persons aboard for extended periods, and with only the front rider, about the same as the Electricat, and the Pedalcat was a heavy 275lb boat rugged enough for offshore use.
I have had years of fun and adventure playing with these marvelous toys and hope to make them even better.
John

[thetragichippy]

That is some nice work........

Good Luck

[Motivator-1]

You can probably comprehend the effort that went into this One-Off Project. Thanks again for your appreciation.
John

[Guest625101138]

John
I made some comments on the dory thread.

You may have seen the photos of my pedal boats there. These are the basis of my research and development that is eventually aimed at a solar powered boat. I have done some limited testing of electric drives on boats and have a couple of Mars PMSM for use on the eventual solar boat.

I have built a couple of cats but now use the stabilised monohull configuration.

I stated on the other thread but it is worth stating again. With any selected design speed and displacement you will find that a monohull will require about 40% less power than a catamaran if there is no length constraint. This will translate to a speed difference of about 12%.

Once you apply a length constraint the catamaran is not so disadvantaged.

Anyhow it may be worth doing the comparison and testing how particular design objectives and constraints interact.