Electric boat research

[Jay64]

Ok, I have seen a few threads about e boats lately and I am looking into building one now.
I am looking at two different options. Either a small speed type boat, or a jet ski. These have two different propulsion systems, so it looks like coupling in an electric would be a different task for each style. Does anyone have any experience or information on attaching an electric motor to an outboard setup or onto a jet system?
While looking around I also found a shuttlecraft, which seems to be a mix of both. From a boat perspective, I guess it might be kinda lame. But from a PWC perspective it is pretty cool. Lets you have the performance of a PWC, but then if you have more people that you want to take out with you, you can just dock up and have an expansion. You can also undock once out on the water to go play with the PWC, and your passengers can have a floating platform to enjoy out on the water rather then waiting on the beach. I was thinking it would be cool to have the PWC set up for pure performance and have an aux pack on the shuttlecraft for longer time out on the water.

[Jay64]

From some of the stuff I have found so far, it looks like 4k-5k rpm would be good, and I found a number of 80 ICE hp for an older 3 person PWC.

[Jeremy Harris]

I've done a fair bit of work on electric boats over the past year or so. One thing I've worked out is that a planing hull with electric power is going to have a very short endurance. If you add more batteries to get better endurance then you increase the power needed to plane, which in turn reduces the length of time those batteries will last.

The other thing I've learned is that small diameter, high speed, propellers (or water jet pumps) are horribly inefficient. A PWC pump jet will be maybe 60% efficient at best, so a lot of the battery capacity will be wasted. A good propeller can be as much as 85% efficient, if the diameter, blade chord and pitch is a good match for the motor and reduction drive.

If you're only looking for half an hour of whizzing about, followed by an hour or two of charging, then a fast electric boat is practical. I'd go for something like a very light hydroplane type hull (as light as you can possibly make it), an array of HXT 80-100 motors, driving big diameter, narrow chord, props, via reduction drives and as much LiPo on board as you can afford. If you can make the boat light enough and sufficiently low drag (look at using prone seating, like the old plywood hydroplanes) then you're in with a chance of building a fun boat.

Jeremy

[Evoforce]

I like your choice of using a shuttlecraft for all the reasons you stated. Want to know how it all turns out. I have a speed boat with upper outdrive gone and want to mount electric motor to it! good luck on your project.

[Jay64]

Jeremy, Do you have any suggestions on how to attach an electric motor to a prop? I was thinking of getting a dead outboard and taking the ICE parts out and connecting an electric at the top. Do you have any ideas of a better way to do this? I am definately open to suggestions.

[Jay64]

So something like this would work?

[Jeremy Harris]

Jeremy, Do you have any suggestions on how to attach an electric motor to a prop? I was thinking of getting a dead outboard and taking the ICE parts out and connecting an electric at the top. Do you have any ideas of a better way to do this? I am definately open to suggestions.

I've ended up trying loads of different ways to do it, with varying degrees of success. I found that outboard legs have a lot of friction, which saps power. I tried using lighter gearboxes, one from a right angled power dril attachment (which worked well, but was very noisy) and an expensive one imported from a firm called Mitrpak.

Here's a pic of the cheap drill gearbox leg:



And here's one using the Mitrpak gearbox (with my custom built stainless prop):



The Mitrpak gearbox was really nicely made, but again absorbed a fair bit of power and made a bit of noise. I also tried running a narrow chain drive down inside a stainless tube. This was very low loss, but a complete pig to assemble. Here's a pic or two of it:





I was going to fair the leg to make it more streamlined, but decided not to use it.

I'm now finishing off a leg that uses a double universal joint to turn the drive through an angle, driven by a belt drive unit in a sealed box. Here's some pics to give an idea of what it looks like:







I'm in the process of fairing the universal joint leg and fitting it to the reduction drive box via a length of stainless tube. One option you might want to look at is using a long tail drive, like the ones on Thai river boats, or maybe a different take on the same idea like this system: http://www.boatdesign.net/forums/diy-ma ... post266241

Jeremy

[Jeremy Harris]

So something like this would work?

If it's nice and light I reckon you could have some fun with that! It'd need lots of power, and endurance might be a bit limited, but hydroplanes like that went pretty quickly with only fairly small engines, so would be a good choice.

Jeremy

[Jay64]

Thanks for sharing pics of your work. I know you have posted a lot of it here (if not all of it) before, but sometimes its easier to have it brought back up in newer threads. I also really appreciate the advice.
Here is the underside with prop for that hydro plane. Seems kinda like they sort of used a bit of that thai long tail drive, but started it up at the front of the boat so it doesn't stick way out the back. Looks like it might be a straight drive hook up. I'm going to go look at it tomorrow. I'll let you guys know if I pick it up.

[Harold in CR]

Why would a trolling motor not be the most efficient ?? They are designed to run all day long, use 12 or 24 volts. Might even overvolt them to 36 ??

Water cooled direct drive ?? Already have the steering and downtube.

I took one, made a LONG (10') tube, bent on a 90°, and used it to blow sand away that was covering sunken logs we were salvaging. It was a 12V junker, so I used 24 volts on it, and it did a great job.

[Jeremy Harris]

Jay, that hull looks like it has some potential, if it's nice and light. For something like this the lighter you can get it the better, as it'll get up to speed with less power.

Harold, trolling motors are OK for their intended purpose, pushing heavy boats along slowly, but they aren't efficient, they are built right down to a price that fishermen will pay. Their prop efficiency is down around 40% to 50%, plus, being direct drive they run at high current in order to deliver power at low rpm (about 1200rpm) so they have fairly high copper losses in the motor. One or two people have experimented with fitting better props to trolling motors with some success. I know of one chap who fitted a model aircraft prop to one and got a significant efficiency improvement, around 20% or so, but the motor losses were still relatively high.

Jeremy

[Jay64]

I actually got two. They are both real light. I got the one pictured above.

hydro_shopwall.jpg

(62.9 KiB) Downloaded 510 times

It is also is missing the rudder system, so I have to try to build one of those.

The second one is a HydromiteT or something like that. That one also came with a 2 stroke motor that wasn't installed. Might have to figure some things out with that setup if I want to try to and play with it on the ICE for a while. I was thinking it might be cool to be able to experience what it was like with the ICE and then see how it compares with the EV.

hydraMiteT1.jpg

(76.07 KiB) Downloaded 510 times

hydraMiteT2.jpg

(73.35 KiB) Downloaded 510 times

[Jay64]

How would something like this work on one of these boats?
http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=5142&Product_Name=Turnigy_80-100-B_130Kv_Brushless_Outrunner_(eq:_70-55)

[BMI]

Why would a trolling motor not be the most efficient ?? They are designed to run all day long, use 12 or 24 volts. Might even overvolt them to 36 ??

Trolling motors are some of the least efficient electric boat motor you can buy. Most have an effective efficiency (delivered at the prop) of barely 10%. Torqeedo are the most efficient presently on the market with some of their motors exceeding 50% efficiency at the prop. However these are very high thrust motors for displacement vessels and not for planning boats.
There are efficiency curves for many of the commonly available trolling motors on the Torqeedo website

I am involved with several electric boat projects at the present time including two electric patrol boats we are building and you might be interested to know there is an electric outboard from Austria which might be suitable for your application. These will push an inflatable along at around 20 knots and on the video there is even a water skier being towed behind the inflatable. These are manufactured by Aquawatt and the link to the motors is here- http://www.aquawatt.at/en/electric-outboards.php

[Jay64]

What the hell? I thought I was loosing my mind. I was looking all over the place for my thread. I KNEW I had put it in Electric Vehicle General Discussion, but for the life of me I could not find it. I kept looking and looking. Ha ha ha.

[Miles]

What the hell? I thought I was loosing my mind. I was looking all over the place for my thread. I KNEW I had put it in Electric Vehicle General Discussion, but for the life of me I could not find it. I kept looking and looking. Ha ha ha.

Sorry Jay I guess I should have left a shadow topic there... Anyway, I hope you approve of the new forum...

[Lock]

Hehe... I lose stuff here all the time but there's a "View Your Posts" option that comes in handy sometimes.

[Jay64]

No problem Miles, I just wasn't paying attention to the bottom of the list. I'm not that big into boats yet, but yeah, I think this subsection is cool. Hopefully this will help me to get up to speed on the boats.

Lock, yeah, that is how I finally found it. But I just wasn't using it because I KNEW where I had put it. Ha ha. I guess that's what I get for being so hard headed. I just figured I was looking right at it and just somehow not registering that was it.

[PedalingBiped]

Found this site. Has some motors that are interesting.

http://www.technipowersystems.com/marin ... cts/motors

[Jay64]

Too bad I don't live in the UK or Dubai. Tried finding a local dealer and there are none in the US. I tried finding a price on their website. Didn't find any so I went to the UK dealer website to try to find how much these cost and I couldn't even find the product there.

[Lock]

Found this site. Has some motors that are interesting.
http://www.technipowersystems.com/marin ... cts/motors

Hey! That's Solomon! Now yer talking eboat "Cadillac" motors

If ya find those interesting, fun thread from 2002 with David Tether of Solomon/Technipower here:
http://www.boatdesign.net/forums/hybrid/solomon-technologies-electric-wheel-electric-motor-propulsion-systems-676.html

loCK

[Fizban]

I have read about these adaptors for outboards but I don't know how small they are made.
http://www.fishingmag.co.nz/boats-woolr ... t-boat.htm
there is a good cutaway drawing here showing how they work.
http://www.sschapterpsa.com/ramblings/o ... enance.htm
Found this too
http://www.outboardjets.com/index.php
wonder how an electric conversion to one of the listed outboards would go. Especially with one of these
http://svensons.com/boat/?p=MechanixIll ... d/Aquarail

[Bazaki]

Any news ? Jay or someone else ?

[Gordo]

couple of things;

http://groups.yahoo.com/group/electricb ... =206608459

Large E-boat racing assn in the PACIFIC NORTHWEST, been going for 20 years. http://www.seattleoutboard.org/electric.html

Longtail boats are the most efficient. Arneson Drives http://www.arneson-industries.com/

A little dose of insanity........ http://www.boghogmudmotors.com/longtail.php Complete Ubuild Longtail Kit $1000.

http://www.boghogmudmotors.com/shorttail.php

Go look through the pictures of running in mud with no water.

http://www.youtube.com/watch?v=dIQKq65V ... ure=fvwrel

[Bazaki]

Nice !