The Electric Boat Thread

[FeralDog]

I think we're used to very different waterways!

Yep! Like floating thru the looking glass. Our local US system is so much more like a huge crowded highway, and similar to navigate.
http://upload.wikimedia.org/wikipedia/commons/8/80/Mississippi_watershed_map_1.jpg
& http://en.wikipedia.org/wiki/Inland_waterways_of_the_United_States
Thanks for the thread link to the prop build. Reminded me a little bit of the Gossamer Albatross's tapered prop.
I'm curious as to why you didn't use brass blades for your initial prop trials?

On our river system, you need sudden power to get out of the way of these ...

I currently am enjoying Jake's blog (http://www.portagetoportage.com/) . I have seen folks from all over the world in the weirdest craft: aluminum canoes stretched long and one welded on top of the other, 2 stroke mini-surf boards, hippy-yachts , large racing hovercrafts, etc but hardly any E-boats on my local rivers.
thank for posting your e-boat efforts!
Cheers to ya'.

[Jeremy Harris]

Thanks for the links, we are definitely in different environments! My nearest canal on the network is the Kennet and Avon. Here are some photo's to give you an idea of what it looks like. It's a pretty standard British canal, virtually the whole network of around 2,200 miles looks much the same, with most of it running through open countryside.



This a general view of a typical bit of the canal. The towpath on the right was originally to take the horses that pulled the canal barges along. Nowadays a lot of the towpaths have been turned into cycle paths, as they are pretty flat and make ideal routes for bikes, avoiding busy roads.



This gives a better idea of the width. Generally, most of the bridges are just big enough to get one narrow boat through, so will often have an opening of only around 7 or 8 feet wide.



Where the canal has to go over a valley (they are generally cut to follow the contour lines around hills) the engineers had to build aqueducts. This one is around 150 years old, built during the latter part of the canal building boom, when the railways were already threatening to take away the business.



Where the canal had to go up and down hills, there are flights of locks like this one. As England is generally less than flat, most canals have quite a few of these and you can expect to do several each day when cruising. There is a fairly big flight of locks near me, at Caen Hill:



It's the best part of a days work to get up or down this flight when the canal is busy.

One of the nice things about the network is that, as it was designed for commercial use there are lots of pubs alongside. When cruising it's pretty easy to have lunch at one pub, cruise on and spend the night within an easy walk of another pub.

Hope you enjoy the insight into our way of using the local waterways!

Jeremy

[Lock]

Tks for the pics Jeremy... I got to cruise the Fens and the Broads twice... as a young Canadian guy it was living a fairytale...
Lock

[Jeremy Harris]

Glad they brought back good memories, Lock.

I had a sailing holiday on the Broads a few years ago, on the George Thetford, a Broads yacht with a Lynch motor for auxiliary propulsion.


The George Thetford under sail

It was very capable propulsion system, as we had to cruise under power pretty much all the way up the Bure on the way out (a couple of days of electric powered cruising) and only needed to charge the batteries once during a weeks cruising, up at the top of Hickling Broad.

Jeremy

[Lock]

Very nice...

seems like a good time to throw the good people at The Solar Boat Company Ltd. into this thread:
http://solarboat.co.uk/

Hard to believe their 69 foot long EV "Unity" is still for sale:
http://apolloduck.net/127806

Lock

[Jeremy Harris]

That's a nice boat, and it's only a few miles away from me at the moment. I think the reason she may not be that easy to sell is her beam, at 13ft 6in she's too wide for most of our canal network. She'd make a nice liveaboard, though.

The majority of UK canals can only accept narrowboats, up to 70ft long by 6ft 10in beam, set by the size of the locks and the width of the bridges. Only the newer canals, those built from around the mid 1800s onwards, are broad enough to take boats of Unity's beam. Much of the most scenic part of the canal and river network here was built in the 100 years or so before then, to the narrower width.

Electric power is gradually catching on here as a viable propulsion method for inland waterways boats. There are a few companies, like Solar Boat, who are quietly developing and selling electric boats. The curious thing is that, back in the late Victorian, early Edwardian, period, electric river launches were quite popular. With the development of the infernal combustion engine their popularity waned, and with it a lot of the style and efficient hull design that typifies some of these old boats.

My hope is to play a tiny part in trying to promote the use of electric power as a practical way to cruise our rivers and canals, in the hope that more may become interested in the idea.

Jermey

[Malcolm]

The Kennet and Avon is a lovely stretch of water. I spent a very relaxing week in a narrowboat on the canal with the family when my eldest son was just a toddler. My most vivid memory is from about halfway through the holiday when we turned a bend and were confronted by a motorway flyover. The noise and the smell and the starkness of the concrete came as a real shock after a few days of settling into the pace of the canal and watching herons and otter.

I also made the mistake of strapping my son's trike to the top of the boat. Some of those bridges are very low...
... but luckily there was a large hammer on board so I managed to straighten up the mangled trike after a fashion. It always listed to one side after that though.

[Jeremy Harris]

I had a similar culture-shock moment years ago when cruising on the canals through Birmingham with some friends. Even in the middle of the city we were still in relative peace and quiet on the canal, and very definitely in "4 mph mode". We tied up in Gas Street Basin (which hadn't yet been developed as a tourist attraction) and decided to venture out on foot for a meal. We opened a wooden door and found ourselves instantly in the inner city mayhem of Broad Street - the overwhelming temptation was to just close the door and flee back to the quiet of the boat!

Jeremy

[jag]

It's the best part of a days work to get up or down this flight when the canal is busy.

Here's where it's nice that your boat is lightweight. Bring a foldable canoe cart and use the path on the right. B.t.w. how do you pay for lock use and maintenance of the canals? Taxes or per use? In Sweden there's usually a 1-way fee for all the locks to go up or down a canal system. It is only for the locks though, so a canoe carried around the locks is free.

I tried to cycle the canal paths of southern England about 1990. At that time many were poorly maintained, and there was no cycling map. We started in Kensington (where my friend was living at the Imperial college student housing -- quite a contrast to the luxury mansions nerarby), and tried to make it out of London on the canal paths, but encountered barbed wire fences in industrial areas, sections were the path was not maintained and completely overgrown with bushes. Getting out and in of London was a nightmare. Cycling in the countryside was nice and pleasant. Still remember the ubitiquous Wetabix tomato and sausage breakfast in the hostels. Maybe I'll try again in some years when my kid can cycle along.

[Jeremy Harris]

I've already been thinking along the lines of making a canoe-style portage trolley, as it would make a big difference at locks.

Over here, we pay an annual licence fee to British Waterways which covers as much waterway use as you wish for the period of the licence. You can either buy a short term licence (for a day, week or month) or a long term licence (for 3 months, 6 months or 12 months). If the boat is portable, then there is a 50% discount on the fee, and there is a 25% discount for electric power.

The towpaths on quite a lot of the canals are now pretty good; there's been a fair bit of work done in recent years to make them cycle friendly. Some of the less well used canals still have towpaths that are a bit rough, but their generally passable.

Jeremy

[Lock]

March 1, 2010
World's Mightiest Solar Boat Unveiled
The PlanetSolar catamaran will circumnavigate the globe in 120 days running on nothing but the sun's energy
By Christopher Mims

Nearly 500 years after Juan Sebastián Elcano completed the first circumnavigation of the globe using nothing but renewable power, Swiss engineer Raphael Domjan and French sailor Gerard D'Abouville are preparing to repeat Elcano's journey in an all-electric boat powered by the energy gathered by 470 square meters of solar panels.

Unveiled for the first time in a ceremony at a shipyard in Kiel, Germany, last week, their vessel is a catamaran made entirely out of the same kind of carbon-fiber composites that make modern airplane wings strong yet light. On its 40,000-kilometer journey, the 30-meter long and 15.2-meter wide boat, known as PlanetSolar, will have to withstand high winds, stormy seas and days without sunshine. On board, the world's largest lithium-ion battery, a 13-tonne monster capable of storing 1,300 kilowatt-hours of energy when fully charged, will allow the boat to slice through the water at an average speed of 13 kilometers per hour for three days straight in complete darkness before its charge is completely exhausted.

The ship can fully recharge its battery in the span of a little more than two days of full sunshine if it's not drawing power at the same time, such as when it's docked in a marina, according to Domjan, a paramedic turned engineer who is the visionary behind PlanetSolar as well as its co-captain. The ship is designed, however, to operate at sea indefinitely, and under normal conditions its 38,000 solar cells average enough power production to muster the 20 kilowatts of power needed to keep the boat cruising along at its average speed. The maximum electrical output of all the cells together on a sunny day is about 100 kilowatts.

Full article here:
http://www.scientificamerican.com/article.cfm?id=worlds-mightiest-solar-boat


Thought this was interesting:
"...PlanetSolar's propeller design—both propellers sit at the water line, half in the water and half out. This kind of prop, known as a "surface-piercing" propeller, can be much more efficient than traditional propellers, because it prevents the blades of the propeller from interfering with one another as they push through the water, Morehouse says. The blades of a surface-piercing propeller also experience almost no drag during the time spent out of the water."

Surface_Prop.jpg

(35.41 KiB) Downloaded 253 times

also this bit about solar cell efficiency:
"PlanetSolar also uses the highest efficiency mass-produced solar cells. Manufactured by SunPower Corp. for installation on the rooftops of homes and commercial buildings, these cells can convert 22 percent of the sun's energy into electricity, says Joern Juergens, director of components at SunPower. After installation on the ship, however, the cells' efficiency is reduced to 19 percent, because they must be covered in layers of plastic and transparent composites in order to make them immune to the corrosive effects of seawater and variable temperatures."

Planet Solar site here:
http://www.planetsolar.org/

tks
Lock

[Jeremy Harris]

Time for a long-overdue update. Apart from playing about with ways to get a more efficient drive unit, I've also ordered a custom built hull. I've just got the first pictures from the builder and have to say that it's looking pretty good. Here's a sneak preview of the super lightweight (4mm marine ply) hull, minus the deck and transom:





The motor drive has evolved so that I no longer need the noisy and expensive right angle drive reduction gearbox. Instead I'm using a belt reduction drive coupled to a double universal joint. This is extremely smooth and absorbs less power than the gearbox, plus it's a lot cheaper. Here's a photo of a prototype 100 degree angled drive using this method:



I made a composite housing by laying up some epoxy/glass over that alloy mandrel in the photo, then I split the moulding in two with a Dremel to get a housing that locates the two bearing housings. The output shaft housing includes a seal and the input shaft will be bonded into the drive leg. When finished, the whole sealed lower leg will be filled with light oil. I've opted to use a slightly bigger angle for the final version, of 120 degrees, because it fits the transom profile of the boat better when lifted up (the motor shaft fits through a centreboard-like case in the stern compartment of the boat, so will be invisible normally from outside the boat).

The next job is to make a fairing to go around the leg, so that it's nice a low drag. Total power losses at maximum speed on the prototype motor, controller, belt drive, bearings, seals and universal joint are 12 watts. At cruise power the losses should be around 8 watts. This means I'm probably on track for my target of no more than 100 watts to cruise at 4 mph, making solar power augmented cruising viable.

Jeremy

[liveforphysics]

Very cool Jeremy! I always enjoy seeing your great projects.

That center section of the driveline will have continous rotational speed changes twice every rotation based on the amount of angularity at each joint. Running the second joint 180 out of phase counters the shaft deltaV for the remainder of the shaft/prop, but the section between the two will be a continous source of some of that 12w inefficiency, and getting as light as possible on that mid-shaft section reduces this loss. At your low speed range though, it may be trivial.

[Jeremy Harris]

You're right, Luke, the short centre section between the two UJs does have a fair variation in rotational velocity with each rev. You can just feel this as a sort of very slight pulsing if you hold the casing whilst it's spinning. I haven't measured the UJ losses alone, but the lower unit losses, which includes the bearings and the shaft seal are 5 watts at maximum rpm and around 3 watts at cruise rpm. Most of the loss comes from the shaft seal, which I know soaks up around 2 to 3 watts at full speed. From this I would guess that the UJ and bearings absorb around 2 to 3 watts, which is tiny enough not to worry about.

Jeremy

[BMI]

For all those who are in Australia and interested in electric boating I hope you can make it to the Sanctuary Cove International Boat Show which is on next week from 20th May until the 23rd May. This is one of the largest boat shows in the world.

I will be at the Torqeedo motor stand and will have various LiFeTech batteries on display including our 48V 45Ah battery which will be supplied to Sanctuary Cove for their electric patrol boats which should be starting construction soon. I will be demonstrating the battery/computer interface for monitoring/diagnostics so feel free to drop by and say hi.
Hope to see you there!

http://www.sanctuarycoveboatshow.com.au ... 0-show.php

[John in CR]

Very cool Jeremy! I always enjoy seeing your great projects.

That center section of the driveline will have continous rotational speed changes twice every rotation based on the amount of angularity at each joint. Running the second joint 180 out of phase counters the shaft deltaV for the remainder of the shaft/prop, but the section between the two will be a continous source of some of that 12w inefficiency, and getting as light as possible on that mid-shaft section reduces this loss. At your low speed range though, it may be trivial.

So a double U-joint results in constant velocity of the output shaft? I've gotta do a shaft drive now. I don't think I showed you the big brushed motor I have. It's too long to reasonably mount with the drive shaft parallel to the wheel axle, so that's been on hold pending a good right angle gearbox solution.

[Jeremy Harris]

So a double U-joint results in constant velocity of the output shaft? I've gotta do a shaft drive now. I don't think I showed you the big brushed motor I have. It's too long to reasonably mount with the drive shaft parallel to the wheel axle, so that's been on hold pending a good right angle gearbox solution.

That's right, John, using a double joint like this does give you a CV joint. The joints are pretty nicely made, too and run very smoothly. The one I'm using was made by a company called Lenze (http://www.techdrives.co.uk/html/universal_joints.html) and cost around £30 (~$45). My power and torque requirements are modest, so the joint I'm using is only 22mm in diameter, but they make much bigger ones, capable of handling pretty high torque levels and higher rotational speeds.

Jeremy

[FeralDog]

Jeremy : great job.
Your engineering concept of that "double u-joint" encased in the composite housing is interesting.
Just my opinion, from practical decades of u-jointed power-shaft boat usage: It may have some "wear" problems if that is the end to be submerged.

Traditionally, propulsion units that use a U-joint to shift direction get a bit of "wobble" on the joint. Your light oil filling of the inner housing can leak out pretty quick.
This was the case of "J" tubed cable-shafted electric boat motors from before WW1. The heat and cooling causes expansion & contraction, and if the lower seal is left in the water, well the seal often leaked.
May I suggest you use screw-on caps with "O" ring seals at each end of your housing (use of Oilite bronze bearings in the center of the caps)? Put zerk fitting on the housing casing , then use marine grease instead of oil. The pressure/viscosity of the grease keeps the U-joint better lubed, and wont weep/leak out so easily.

Oh, I am curious. Since you may extend the angle to 120 degrees, why not stick the whole shaft/joint into a bent piece of pipe with appropriate inner diameter?

[Jeremy Harris]

Thanks for those tips, I'd love to know more about the old J tubed electric drives, I'm thinking that these may have looked a bit like a bent tube strimmer drive (weed whacker in US-speak), would that be right?

I did try to get away with feeding the shafts and UJ down inside a tube, but couldn't find a way to do it. Whatever way I tried I needed to get the lower end of the UJ out the end to connect the prop drive shaft, and the geometry just didn't seem to work to allow this to happen.

I'm running at low power (around 100 watts), so I'm hoping that wear won't be a big issue. The boat won't be kept in the water, either, it's not much bigger or heavier than a canoe, so the plan is to keep it at home and trailer it to the rivers and canals nearby.

The output shaft is supported by two ball races, with a seal on the outer end. Similarly, the long input shaft is supported by a single ball race at the lower end and a pair of races at the upper end (to take the side load from the driven pulley). The UJ is therefore pretty well supported, as the UJ outer ends are butting up against the inner races of the bearings on each shaft.

The other factor that makes me hopeful that this will last, is the relatively low operating rpm. Maximum prop rpm is just over 700 rpm, cruise will be around 500 to 600 rpm.

I'm off now to Google up on J tube drives!

Jeremy

[FeralDog]

Jeremy: The drive J tube is similar to weed wackers.
It worked , it still does.
The earliest I have seen for either a "J tube" or straight shaft using an inner cable (flexible shaft)to prop was a W. S. Salisbury electric motor from 1892.

The reason for a cable (or coiled wire) drive was to keep the power-head above the water, give good steering geometry, and make manufacturing simple.
The cable was great if kept lubed, took some good shock absorption from prop strikes, and worked better if the "bend" in the housing wasn't too tight.
The cable fell out of favor somewhat in USA 1940's when oil seals got better so that the whole electric power-head was submerged for better motor cooling and steering control on some boats(submerged power heads were used since 1899 in USA).
I think the practical difference between a J Tube cable to prop, and a U-joint (or bevel gear) is really just your motor (power-head balance), steering geometry, and RPM's.
In short, a cable in tube "J drive" might work for you too.

(In general , we don't use many submerged ball , or roller bearing support parts versus a simple plain bearing. Around water, the plain bearing is much more forgiving.)

[Jeremy Harris]

The interesting thing about this J drive is that I did toy with the idea of doing something similar. I bought a flexible shaft, intended for use with a drill. The thing that stopped me going any further with it was that this particular flexible shaft wouldn't take a reverse drive, plus it was marginal at handling the torque from my big propeller.

One of my first drives used a plain bearing on the output shaft, but the frictional losses were very high. Similarly, the gearbox came filled with grease, but I found that the grease alone absorbed about 5 watts, way too much for what I'm looking at. For every watt absorbed in the drive train, I need to generate about 1.5 watts from the solar panels. My total power target is 100 watts maximum for cruise power, I'm actually hoping that I can get away with less power.

Most of the ideas I'm using have come from the leading human powered boat developers, people like Rick Willoughby. They also have a limited power budget, pretty similar to my target, so their techniques tend to work OK for my application. The pedal boat version of the hull I'm using uses ball bearings throughout and the drive train has been very reliable after three or four years use.

Jeremy

[Jeremy Harris]

An update on this rather long drawn out project. I made a 9 hours round trip today, to the far West of Wales, to collect the hull for my project boat. Here are a few photos (although please bear in mind that the hull is only painted in primer and the woodwork hasn't been oiled yet).







The next step is to fit the propulsion system, give the boat a coat of paint, then go and do some trials on the water to see if the performance matches expectations.

Jeremy

[regmeister]

deleted

[MrKang]

What a beauty Jeremy! a friend of us took us with his little boat (normal gasoline powered) for a trip. For me it was the first time.
It looked so peacefull and quit on those little water creeks/canals. And when i saw your snapshots ....wow...must be very relaxing.

Are you going to use some solar storage in the future?

[liveforphysics]

Beautiful boat my friend!