Better things are electric........

[Julian Swindell]

All I did was google sculling and yuloh! I have never sculled sucesfully in my life. (I earn my living lecturing convincingly on subjects I know next to nothing about.)

[Craic]

... I have never sculled sucesfully in my life. (I earn my living lecturing convincingly on subjects I know next to nothing about.)

Is this confessions time?
If so, I better confess too: Both above points, come to think of it. And not convincingly mostly. 

[Tony]

Rowing the Four Sisters is handy at times but nothing you would want to do for fun in a wind or tide. Sculling over the stern – useful in a confined space where you cant get the oars out – is even less fun per  kJ of energy expended. 
Had to row her 5 miles back to port in the Ionian this summer. Engine dead (again) and no wind to speak of – and getting dark.
It was not fun.
It was not even Healthy Exercise.
It was hard graft of the bone-grinding, blister-tearing, sweat-blinding variety ....and if  thats what you like, well, good luck – but pass me the ignition keys, ta very much.
Attempts to go electric next spring have ground to a temporary halt. Can't find anything available to replace a small petrol outboard at a realistic price. Bellmann, Sillette and a couple of other firms have viable systems available - but aimed at larger boats than mine and intended as built-in, permanent fixtures.
Just what you dont want as a trailer-sailor.
The Electric Lugger is still on the cards for next year, if only as a backup for the Yamaha. The saltwater Flover seems the best buy of the trolling type motors but I don't fancy gluing it to the rudder - lose a knot at least when sailing. Some kind of out-rigger is the most likely option as I dont fancy lugging the Yamaha about either, especially not when in a situation dire enough to need back-up power ASAP.   Biggest expenditure will probably be batteries and charger. Even a 100ah battery will not give me more than 10 miles range so I think that, like Grannys smalls,  we will need one on, one off and one in the wash.  i.e. back on shore being charged. This means expensive Lithium cells to prevent the onset of a double hernia. Either that or a small petrol generator - but then I'm back to putting my trust in untrustworthy technology, using up valuable cabin space and generally making myself unpopular in an otherwise peaceful anchorage.

[Julian Swindell]

What is to stop the Sillette saildrive electric unit being used as an outboard, fitted on a hinged plate? I have just been looking at the sizes on their website:
http://www.sillette.co.uk/elect_saildrives.pdf
The total unit looks no bigger and not much heavier than my current outboard and I have a great big hole in the bottom of the boat for it to go through. It doesn't weigh much more than the outboard. Batteries are always a problem, but the BayCruiser carries 400kg of water ballast 90% of the time. If you were on a mooring, you could just replace a great chunk of that with battery. You would need to be able to get them out for towing if you wanted to use an unbraked tailer.
The problems I see are how to charge the batteries without taking them out of the boat. I think the best way might be to book into a local marina for the odd night and just plug them in. If I am taking anyone out overnight in Poole Harbour, we often spend one night in Poole Quay marina, just so we can enjoy the fleshpots of Poole for a night. Can you recharge a couple of big batteries over one night? I have no experience of this.

[Edwin Davies 2]

Tony, Have you worked out why the outboard proved to be so unreliable?
My thoughts on the Battery/electric drive is that high performance batteries can be just as difficult to maintain in 100% condition as mechanical motors. This is all the more pertinant if you only use them in emergency. Am I to assume you are a battery engineer? If so please ignore this post.

[Tony]

Hi, Edwin.
Outboard problem seems to be petrol starvation - blocked jet, maybe. This despite regular servicing and filtering all petrol before use. The machine typically will run perfectly for days - even weeks - at a time, then slow  down and stop while in use for no apparent reason. Often it will sulk for a couple of days and refuse to start despite anything I do and then, next morning, no doubt feeling well rested and in need of a little change of scenery, it will start first pull and pretend that nothing has happened - until the next time it packs up. Infuriating and potentially dangerous, hence my interest in Torqueedos, Flovers, Kenwood Chefs and egg whisks.
   No, I am not any kind of engineer  (although I did have a No.15 Meccano Set and a Mammod stationary steam engine as a kid in the 1950s - does that count?), but the newer Lithium batteries seem pretty bomb-proof compared to small internal combustion engines and even lead/acid glass mat batteries are ok if you dont have to lug em about. The major disadvantages seem to be that light weight = heavy expense and, of course, how do you recharge the damn things when miles from the mains?  Solar power needs too much area and wind power needs a dirty great noisy thing on a stick. Both are expensive bits of kit and both are something else to get in the way on a small boat  and eventually go wrong.
   The 'Keep It Simple,Stupid' guys are yelling OARS! OARS! by now, and quite right, too - but you cant row a cabin boat against wind and tide. At least, I cant.
The electric motors available at the moment seem to be well up to the task of powering a small (or not so small) boat but I dont think batteries are the answer. Perhaps fuel cell technology needs to be developed a tad more - or someone needs to perfect a pocket sized fusion reactor - before  anyone who is not based at a Marina can power  up an electric boat for more than an hour or so. I think I will trade in my outboard for an old Seagull. They NEVER go wrong, or so  am told!

[Julian Swindell]

Tony, don't go Seagull. Whilst other engines set out to drive you mad, Seagulls actually try to kill you. Their proponents will always tell you how easy they are to work on. That should tell you something...
I have used Seagulls in the past and count myself lucky to still be alive with both arms more or less intact.
If you don't hear anythng more from me it is because the "Friends of the Seagull" have found and terminated me.

[Edwin Davies 2]

Tony, another thought that came up in conversation, batteries are valuable and attractive items and may be stolen.

I have used the small Seagull and the Silver Century model. No problems, but like any rotating machinery they need to be treated with respect. They are also noisy and smelly and leave a trail of oil on the water. I do remember the handbook reminding us that voices carry over water better than the engine noise. So refrain from commenting on people in other boats or on the bank.

If it was a blocked jet in your motor it should be easy to clear. I am not convinced that is what it is. It is unlikely it would clear itself while sitting idle. I would not like to row any boat 5 miles, unless I had planned to do it. After lots of training. Good luck.

[Julian Swindell]

Has anyone been to the London Boat show to see the new BayCruiser 23? I was there on Sunday (it was very quiet and no one was going out on the external pontoons). The big BayCruiser has an electric sail drive leg. Solid Bronze with a folding prop. I shall be interested to hear how it works in practice. It is non retractable. The decks are beautifully laid Douglas fir. I shudder to think of me stomping around on my boat with Poole Harbour mud all over my feet and a weedy anchor on the foredeck. I don't think timber decks would suit me. But they look beautiful.

[Rich Maynard]

Yes, I was there on Sunday and I saw her too.

Beautiful!

[Edwin Davies 2]

I was there yesterday, Tuesday, she did look good, I asked about the beautiful deck and Matt said they were trying out test patches of coating to see what protection would be best. The show was very quiet. The last time I went was around 1972 at Earls Court, it was heaving then.

[Tony]

Hi,Guys.
        Re- BC23.  Did you get any photos of that electric drive? Is the leg protected from grounding in any way?

Julian. Did it look as if it could be mounted to tilt in an existing outboard well - as you suggested earlier?
 
(PBO quote the price of the BC23 as 30-odd thousand quid. I supposed that a big chunk of that was the drive and batteries. Perhaps the deck helped a bit, too.)

[Julian Swindell]

I didn't get any photos of the electric drive. It was solid bronze, with a folding bronze prop. The motor wasn't in place. I should think it cost as much as my whole boat. Matt said it finished level with the bottom of the keel, so was fairly well protected. It doesn't tilt, but it possibly could be made tiltable. I would be concerned about drying out on it as the whole back of the boat could be held up on it. I don't know if the PBO price included the electric drive or the Douglas fir deck. Or the laminate sails and dyneema rigging, which weren't on show. This boat is going to be quite something when it is finished.

[Jeremy]

Hello all, my first post here, although I've been looking in from time to time over the past few months.  I've been playing with electric propulsion for a fair while now and am in the final stages of developing a low power propulsion system, suitable for an electric version of Winsome.

I took one of my prototype brushless units over to Swallow Boats last Autumn and Nick and I drove around the estuary for ten minutes or so with it driving the Storm 15 at hull speed, in calm water, on around 350 watts.  Winsome needs much less than 100 watts for river cruising, so my plan is to have solar charging that will keep the battery topped up whenever (if ever....) the sun shines.

Tony started this thread with a "wish list", which is exactly how I set out to design a complete system about 10 months ago.  My wish list was:

At least 6 hours endurance on battery power

Cruise at 4kts on rivers and other inland waterways

Ability to solar charge at as high a charge rate as practical without spoiling the look of the boat

Total system efficiency (from charge to thrust) greater than 70%

Propulsion system weight as low as possible

Battery cycle life at least 1000 cycles

Zero battery maintenance

Low battery hazard rating (no toxic materials or risk of fire)

So far, I have a sealed battery system that provides just over 1kWh of usable power (enough for around ten hours of cruising at the expected power level) in a sealed box that weighs 11.6kg.  It uses Lithium Ferrous Phosphate batteries, that are very safe, unlike other some other lithium chemistries.  Cycle life should exceed 2000 cycles and calendar life should be around eight to ten years.

Cruise speed power is determined by the hull resistance; as Winsome was designed to do around 4 kts with only pedal power (probably around  100 watts) it was a near-ideal hull to use.

Getting good system efficiency is a great deal of work though.  Ordinary boat props are fairly poor, they waste around 30% or more of the power you put in to them.  The answer to this problem was to make a prop, but it turns out that the thin, high aspect ratio, blades are superb weed catchers.  The way around this problem was to make the prop blades fold, so that if a bit of weed gets caught the throttle can be eased, the blade folds back and the weed (hopefully) slips off.  The prop design I have now (12" diameter, 10" pitch, 700 rpm at full power) should be around 84% efficient, just about as good as it's possible to get with a practical prop.

Next, I looked at motor efficiency.  Electric motors are generally pretty good, but the best are, without a doubt, the brushless permanent magnet ones developed for high powered model aircraft.  These are tiny, yet deliver upwards of 6kW (8hp) in a package around 3" in diameter and weighing about 1.5kg and cost around $100 or so (take a look at this one, for example: http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=5142&Product_Name=Turnigy_80-100-B_130Kv_Brushless_Outrunner_%28eq:_70-55%29).  I opted for a much smaller motor of the same type, one rated at 2800 watts, then altered it by fitting internal position sensors and changing the wiring from delta to star (these are three phase machines) so that I could run it on a better type of speed controller.  The big advantage of under-running one of these motors is that it's efficiency improves, as the copper losses are very low when it's run at low current.  My motor now has losses that range from just over 1 watt at idle speed to around 12 watts at full power (200 watts), so is always running at better than 94% efficiency.

To drive the big prop slowly (for good efficiency) I needed to reduce the motor speed.  Changing the wiring from delta to star dropped it's peak rpm to 56% of the original, so that the motor now runs at about 1500 rpm at full speed.  This was still too fast, so, after playing with toothed belt drives, chains etc I ended up buying an expensive 2:1 reduction right angle gearbox.  To my horror, I found that the gearbox absorbed around 14 watts on it's own, so I had to modify it.  I removed the top oil seal (oil seals soak up around 4 or 5 watts each) and then removed all the internal grease.  The gearbox is now filled with oil and is sealed to the drive leg, like an outboard, so has no need of the upper seal.  This reduced the gearbox loss down to 6 watts.

The speed controller is a cheap ($22) one intended for an electric bicycle.  It's been modified to make it work on 13V and to reduce it's internal losses.  The output FETs were changed to very low on-resistance types, so the controller loss is now between 0.8 watt and 2 watts, depending on power setting.

All the electrical parts are sealed into watertight alloy or polycarbonate housings, with neoprene seals.  All cables are fitted inside watertight flexible nylon trunking, so I'm hopeful that it should be reliable in service.

I still have a great deal left to do, including getting the hull and fitting all this stuff, plus sort out the solar charging system.  I've purchased some raw silicon photovoltaic cells (108 of them), plus a very neat, high efficiency, maximum power point tracker.  I'm either going to make a canopy, with the solar cells on top, or I may see how many I can get on the deck area.

During this lengthy development process I have learned a great deal, so if anyone else wants to have a go at designing a similar low power propulsion system I may at least be able to advise on things I've tried that have failed!

Jeremy

[Tony]

Hi, Jeremy.

Being the sort of handyman that can cut himself with a rubber mallet I am most impressed with your post.
 
An electric drive Winsome with solar panels sounds like the ultimate duck hunter to me - a veritable Pond/Canal Raider. Visions of sunlit, green water, water lilies, herons in the reed beds, etc. Nothing to disturb the peace except the click of the odd shutter ... and the occasional popping of a cork. Roll on summer!

A few comments:-
1.   1 kWh  Lithium Ferrous Phosphate batteries. What is that in Amp.hours? (I should be able to work it out - something to do with V/IR I bet.) Where did you source them? Were they horrendously expensive? How do you plan to charge them if the solar power isnt up to it?
2. In my experience folding props tend to stay folded when covered with weed. Is the sloping shouldered weedless pattern prop too inefficient?
3. How did you make/acquire the alloy and polycarb. housings?
4. Your comments on modifying the electric motor and speed controller leave me LIGHT YEARS behind. Field effect transistors? When I learned physics the EL 84 triode valve was considered cutting edge! ( Come to think of it I still have that home-made SW receiver somewhere... in a box with the QSL cards I think.)
5. I am certain that there is a big market for a 6kW salt water proof propulsion system out there, once someone gets to grips with rapid re-charge and easy exchange of batteries... or develops a practical fuel cell that doesn’t cost the earth.
6.  A 1kW system, with the efficient drive train you have worked hard for, would be useful for manoeuvring quite large boats  in crowded marinas,  even if it has limited tide-punching potential.  Just how much juice can be squeezed from 1m2 of solar panel these days? Any hope for a self contained system yet?
7.  If you – a private individual -  can bring this system to a level of practicality that suits your needs, how much cheaper could it be mass  produced  by  a firm like Sillette?  Get the bugs out of the power supply  situation and reduce costs to as far under £1,000 as possible and many people would  prefer an electric system to the infernal combustion engine.  So much less to go wrong!
8. My own attempts to get the Four Sisters electrically powered for this summer have ground to a halt. At this rate my first experience of electric propulsion is going to be a mobility scooter!

Keep up the gopod  work.
Tony