Electric propulsion ideas (and introduction)

[Jeremy]

Hi,

First post, so please be gentle...........

A bit of background:- My only canoeing experience was a long trip up the Thames to Lechlade well over 40 years ago (in the Scouts) plus a day out in an open canoe paddling around in the Florida Everglades a few years ago. I learned to sail in and around Falmouth as a young chap, including racing a Working Boat, and went on to build a small yacht, which I sold about ten years ago. I've also built a couple of cars and an aeroplane, converted my recumbent bike to electric power and am part way through building an electric motorcycle. We also hired a Broads sailing yacht, with an electric inboard, a few years ago and found it to be a superb way of travelling serenely through some of the quieter waters.

I've long had an interest in Edwardian electric canoes, ever since seeing a superb article in Wooden Boat magazine many years ago. Now that I've got some reasonable experience in modern electric power systems, I'm seriously thinking about building a very light 2 person version, with a cruising endurance of around 4 to 6 hours.

I've looked at available propulsion units, like converted trolling motors, but they seem horribly inefficient by modern standards. I like the idea of having a tiny inboard motor, with no outward sign that the canoe has any form of "artificial" propulsion. In recent years, radio control model development has led to the ready availability of some very nice, lightweight, brushless motors that can deliver very high power levels (up to 6 or 7 kW at around £100 each). Obviously a canoe doesn't need anything like that power level, but this does mean that bigger motor can be purchased and derated for longevity.

In my electric power experiments, I've accumulated some “spare” parts, including a small brushless motor rated at 2800 watts, 80 amps maximum, a electronic speed control, and a couple of HTD pulleys etc. I also happen to have a tiny prop left over from another boat project, that looks as if it might well do this job quite well (although I’d prefer a small folding prop). The photo (edit: whoops, the forum won't yet allow a photo, guess it'll have to wait until I've posted a couple more times) below shows my accumulated wealth of “spare parts”, total cost around £120. I also have a 36V, 10Ah LiFePO4 battery on my bike that I could use for this project. It only weighs about 5kg, yet will deliver around 350Wh with no problem at all. Assuming a light canoe only needs around 70W or so to cruise (which seems reasonable based on the research I’ve done so far) then this system would hopefully give me about a 5 hour endurance for a total added weight to the canoe of maybe 10kg.

Now to the real reason for posting here! I’ve been looking at canoe designs for the past few days and have read lots and lots of posts on here and elsewhere. I’ve narrowed my choice down to stitch and glue construction, as I’m not sure that my woodworking skills are up to strip planking, and would prefer to buy a kit, rather than build from plans. I’d also prefer a “multi-plank” design, just from an aesthetic viewpoint, rather than one of the more slab-sided designs about.

I think that the Selway Fisher Prospector design looks to be a good bet, but would very much appreciate some other opinions from all the experts here! My intention is to keep the canoe very light, as I want to be able to transport it on roof bars (empty weight, less battery, of no more than 35 – 40kg, preferably less). Total length needs to be no more than 16ft 6" in order to fit in the build area I have available. My intended use is solely calm water cruising on rivers and lakes. I will almost certainly fit out the interior rather like the Edwardian canoes, with a couple of low seats with removable backrests.

So far I have found two kit suppliers, Jordan Boats and Seabird (woodenboats.co.uk). All advice or alternative suggestions would be most welcome.

Jeremy

[Twisted Firestarter]

Hi Jeremy

Interesting first post, welcome by the way

I’m also interested in electric boats and would suggest the Electric Boat Association is a good place to start …

http://www.electric-boat-association.org.uk/

I’ve had a couple of electric boats although both were bigger than a canoe and they ran on Lynch Motors…

http://www.solarnavigator.net/cedric_lynch.htm

If I was going to build an electric canoe I’d probably look for a cheap 2nd hand canoe to start with because you

will probably need to cut holes in the hull for the stern tube.

Just to add another suggestion for a light weight self build canoe there are these kits…

http://www.gaboats.com/boats/

I look forwards to hearing more about your plans and seeing some photos.




TFS

[bigH]

Hello Jeramy and welcome, Canoeing on the everglades,done that,it was also my first trip in a canoe, the wife and I did it one year and found it so relaxing on our last day in Florida that we did it again on our next trip over there. I have built a couple of canoes,now I have a Old Town 14ft Osprey,and have just bought a folding canoe,(same as used by the SAS). I also have a small 2 stroke outboard I been known to stick on the rear of my canoes. I have also Dabbling with batteries as well,I am half way through putting together an wooden electric car, from plans modled on a 1898 french car,a 3/4 size, the original (in pic) was very small to start with. could PM you on this later if your interested? , Take plenty of pics of your projects, sounds interesting, for we older guys anyway.for now, again, welcome. be safe.bigH

[Lloyd]

If I were going to make an electric canoe I would just propel it with a good quality cordless drill.

No sense trying to reinvent the wheel?

Variable speed, decent battery life, spare batteries can be swapped out on the fly in a second, and best of all you only need a 1/4 inch hole for your prop shaft. You could take the prop out of the chuck, plug the hole and have a normal canoe in seconds.

You could get fancy and re-engineer the motor casing on the drill and have a better speed control lever and multiple battery slots in a case but still, it is the cheapest option I can think of.

Must give it a go with an old fiberglass canoe some time.

[Jeremy]

Thanks very much for the welcome and the useful ideas. I love those geodesic designs, although having built an aeroplane that was covered with Ceconite I'd have to say that I'd be a bit worried about making a hole in it. The electric drill idea is delightfully wacky, a real example of a bit of lateral thinking. Hopefully my post count will now allow the photo I tried to post earlier to appear, as it shows the bits I already have:



That motor (top left) is just 63mm (~2 1/2") in diameter, yet can deliver 2800 watts for 30 seconds. It's nice and efficient, and has no brushes to wear out, so should be very reliable if run at relatively low power for long periods of time. The best bit is the price, that motor was about £35, pretty cheap for the power.

I'd love to just get hold of a cheap second-hand plastic canoe and experiment, but know that in my heart I really want something that looks "right". That means (for me) something that has a reasonable amount of varnished wood on show and also something that has the look of an Edwardian electric canoe to some degree.

If I had the time and skill, I'd go for a strip planked build, but this could turn out to be a horribly expensive experiment if I were to mess it up. I'm reasonably confident that I could build a neat stitch & tape canoe. Has anyone any thoughts as to whether or not a Selway Fisher Prospector might be a good starting point for this project?

What I'd like to aim for is something that looks a bit like a slightly smaller, and much lighter, version of this SF Silent Explorer canoe, with just seating for two:



Jeremy

[TGB]

If I were going to make an electric canoe I would just propel it with a good quality cordless drill...

Would give a literal meaning to the wording 'white-water' and 'drill time'.

I agree, an interesting intro. I look forward to the self-build blog.

TGB

[bigH]

Hi Jeramy, I think it might be worth you thinking about building your own wooden canoe. that way you could build into the bottom of it suitable wood areas for the shaft drive to exit. these stitch and glue realy don't take that much time to put together. just a thought. be safe.bigH.

[Jeremy]

Thanks again. I've pretty much come to the conclusion that a build is the best way to get what I want, and to be able to make the modifications needed to fit a shallow keel to take the shaft and protect the prop.

I'm fairly certain that the Selway Fisher Prospector kit is the best bet, but would love to get hold of an accurate side view drawing so that I can overlay the propulsion stuff and see whether it looks feasible.

I've found two kit suppliers for the Prospector design, Jordan Boats and Seabird. Does anyone have any experience of kits from either of these companies please?

Jeremy

[DougR]

Interesting idea.

Where are you planning to put the prop?

One of the issues neatly solved by the electric trolling outboard is that of weed clearance - just lift the engine and clear by hand. A conventional set of stern gear (stern tube/propshaft and fixed rear prop) makes this impossible.

Some of the canal boat folks move the prop forward and have a removable "Weed Hatch" to allow access.

[bigH]

Hi Jeramy, I must admit it is just about the right style for what you have in mind. I have built a prospector and still have the plans, some where. just poped out and looked in garage but no luck, on their web site www.selway-fisher.com there is a view of the prospector line drawing it might help knowing it is 17ft long. be aware that it is quite heavy at 95+lbs,I was thinking of getting it onto your roofrack, one of the reasons I sold it on and got something lighter. just a thought.be safe.bigH.

[Jeremy]

Thanks very much for the tip about the weight. I've been looking at the figures given by Sea Bird Boats (http://www.woodenboats.uk.com/canoes.html#plywood), which give a weight of 55lbs, although I see that the Selway Fisher figure is 65lbs. I suspect both err on the side of excessive optimism!

My plan is to fit the prop at the aft end of a skeg, rather like this layout on the much bigger Brambling. but without the motor "pod":



Instead of using the motor "pod" as shown above, I think I'd rather go for a straightforward, lower drag, mount like a bigger motor boat. With the prop well forward, I should be able to fit a weed hatch and also include a wholly underwater rudder. I may need to partially tunnel the aft lower hull area to get the small prop tucked in far enough, but I'm hoping I won't have to, as it'd lose a fair bit of efficiency.

I've made a start on the drive this afternoon, by boring the drive pulley to fit the motor. The next stage is to make the reduction mount and then test the motor drive unit. It might seem a bit backwards to be sorting the motor system first, but I really want to try and understand whether or not such a system can be made to fit before I order a kit.

Jeremy

[bigH]

Just to add, that would be 95lbs built with 6mm ply. be safe.bigH.

[Jeremy]

I've just spent a happy hour tracing the outline of the Prospector side view into CAD and then overlaying the side view of the Brambling on to it and scaling it down to see what the proportions look like.

Overall, it looks like it will work, so I've gone on to draw the outline of the skeg, prop and rudder, to scale, on the Prospector side view:



The seat is sketched in roughly to scale, but needs to be checked against the plan view yet to see if there's enough width in the hull at this point. I'm pretty sure there's room for a weed box above the prop, but will need to check this too with the plan view.

I think I'm pretty close to going ahead and ordering a kit - does anyone know the relative pros and cons of either of the two kit suppliers, please?

Jeremy

[jimegret]

You might find these posts of interest - http://www.woodworkforums.com/showth...=10486&page=33
Scroll down to Skywoolf's post quoting me Jimegret.

I am now well into my Selway Fisher Christine build.
When I had it stitched together loosely what was to become a sharp point stem had a 'transom' shape. Just a thought.
Jim

[Twisted Firestarter]

Not what you have in mind but what about Lloyds cordless

drill idea set up like a Thai Longtail outboard.

No holes in the hull so you could leave the motor behind if you

feel energetic and the reverse steering would be awesome

unlike a conventional stern gear set up. Just some thoughts but

it sounds like you've made your mind up

[Brainflex]

I love the concept of this, good luck and keep us informed please.

Lloyd, brilliant bit of lateral thinking.

[Lloyd]

For hanging off the back, a concrete mixer would work pretty good once you got the prop balanced. Not sure I think laterally or wacky or what but I have been known to solve a lot of problems with not much of anything to go on.


This thread has got me thinking of some "delightfully wacky" ideas now. Some real Wile E. Coyote stuff.

[Jeremy]

The odd coincidence here is that small prop I have (the one in the picture I posted earlier) came off a motor unit that looked very like that cement mixer. It was a 1.5hp two stroke engine, with a reduction gearbox connected to a 4ft long drive shaft. The motor had a transom clamp with a swivel and was designed to be fitted rather like those long stern drives used in places like the Amazon. I bought the whole unit from a salvage place in Cornwall and intended to use the motor in a small runabout (mounted conventionally as an inboard) but never got around to it. Luckily, I kept the prop in my "may come in handy one day" store...........

I've now transcribed the plan view of the 15ft 8in Prospector into CAD and it does look very much as if I can make everything fit OK. I may need to relocate a couple of thwarts, but can probably add some extra stiffness with the seat structure.

I'll probably go for 4mm ply; if need be I'm sure I can add some local stiffening if required. The long keel should massively stiffen up the bottom panels, I hope. I'll probably make the keel as a foam cored ply box, to keep the weight down.

Next steps are to order a kit and clear out the workshop to create a bit of space................

Jeremy

[ShagRock]

Hi Jeremy - very interesting idea! This raises lots of ideas.

1) multichine yes, but how many chines? The more you have, the more complicated the build. For example you could go with 4 planks per side and still get a reasonable approximation to a round bilge hull.

2) I might opt for a square stern transom, say just 3 or 4", which would give a nice hold for a rudder. This is common for canoes that use rudders. Also it's easier to set up a prop that extends out from the rear transom near the bottom. A 'skeg' can be fastened (similar to small sailboats) that will protect the prop and to which the bottom of the rudder can be attached. This also allows a low profile depth so that the canoe can still operate in shallow waters. Also, the transom stern gives a nice internal space at the rear to set up your inboard motor. Many of the motorized guide canoes are designed this way. Finally, it is not complicated to add a transom design for most of the double-stemmed canoes. Usually this can be worked out with the designer.

3) I like Lloyd's drill idea! I have heard of people using motors from weed cutters; the cordless ones. In the south seas, small agricultural 'pump' engines are very popular in small and large ocean canoes; but I'm not sure how small a size these come in.

As to S&G designs, if you don't overdo the epoxy use, you can have a 16' boat at half the weight of a same size fiberglass one.

You might get some additional creative ideas if you posted this type of question on the Wooden Boat or Boat Design Forums.

[Gibbo]

I've been thinking of adding an electric motor to my canoe for a while but I've got so many other projects on the go that need my attention before pursuing this one. That said I have been giving it some thought:

• I didn't want to drill a hole through the hull so was thinking of a L-shaped arm that would mount on the gunwhales and drop down into the water.
• I like the idea of being able to remove the motor assembly so that when portaging/ putting in and pulling the boat out the prop assy will not be damaged.
• I was going to submerge the motor into the water attached to the L-arm. A colleague of mine designed and built a mini ROV (remotely operated vehicle) that was submerged and used this method to steer the ROV. He originally was going to put the motor in a sealed can filled with WD40 (for lubrication and water blocking) but on advice just submerged the whole thing in water with no problems.
• Battery would be a small car battery secured in the boat - is the power too much, could I get away with something smaller, say a motorbike battery?
• The motor would be fixed i.e. not directional as the boat's attitude can be changed using the paddle as a rudder.

Gibbo.

[bigH]

Hi Gibbo, I don't think a motor bike battery would do the job, more amps needed. Also a deep cycle battery is required as the deep discharge and re-charge would soon ruin a normal battery, deep cicle batteries are used in golf carts and invalid carrages. I am building a small single seater electric car, (1898 copy) and will have to buy deep cycle batteries for the job,dearer than normal ones, but last much longer. be safe. bigH.

[Jeremy]

Sorry for the delayed reply, life got in the way................

I like the idea of a removable motor, the snag is trying to engineer it. A conventional inboard arrangement is simpler to build, particularly as the motor I have in mind needs a reduction drive. The motor and drive system can be quite lightweight; my motor (a Towerpro 5330, see here for info: http://tinyurl.com/cfx7qd ) only weighs 679g and the motor speed controller only weighs around 120g. Batteries can be very light indeed, now that high capacity, lightweight, lithium cells are so readily available. The battery pack on my electric recumbent bike (a 36V, 10Ah LiFePO4 unit) only weighs about 3.5kg, yet gives a range of around 25 miles at about 15mph.

Although my knowledge of the finer points of canoe design is minimal, I've done quite a bit of work with electric propulsion systems over the past year or so. I wouldn't advise the use of lead acid cells unless someone is on a really tight budget. They are exceptionally heavy for their usable capacity and have a limited cycle life (just a few hundred charge/discharge cycles).

As a direct comparison with modern cell technology, if I wanted a usable 10Ah capacity from a lead acid battery pack I would need about 12Ah of actual capacity, as lead acid cells cannot usually deliver their full rated capacity when used in a deep cycle environment (LiFePO4 cells can easily deliver full rated capacity even for repeated deep discharge). A 36V, 12Ah sealed lead acid battery pack will weigh about 11.5kg, cost about £90 and last maybe 400 cycles. A 36V, 10Ah LiFePo4 pack will weigh about 3.5kg, cost about £200 but last for at least 2000 cycles. Cost per cycle through life for lead acid comes out at around 22p, cost per cycle through life for LiFePO4 is actually much cheaper, at around 10p.

As an estimate of range/endurance for such a battery pack, assuming that a canoe uses around 70 watts average from the battery, then that small LiFePO4 battery will be able to deliver cruise power for around 5 hours. It would be quite possible to carry two or three, plus maybe a solar charging panel, to allow extended cruising. With no extra battery packs, but just a 25 watt solar panel (about 1000mm x 500mm) fitted endurance could be extended up to around 7 hours or so.

To give an idea of the size of such a small battery, here's a picture of my converted recumbent bike. The battery is the black box under the seat:



This is the battery pack I will most probably use, at least for initial experiments.

On the topic of which canoe to build, I'm in a bit of a quandary. I'd originally thought that a SF Prospector would be a good choice, but I hadn't spotted either the Wren or Raven plans. I now find myself drawn towards the looks of the Raven............. Decisions, decisions..........

Jeremy

[Gibbo]

I like the idea of a removable motor, the snag is trying to engineer it.

Here's me thinking that's the easy bit... I was thinking about some kind of g-clamp arrangement that would either clamp to the thwart(s). I can make most of the things myself or get them made/ welded at work which helps plus I usually CAD my designs up using my SolidWorks 3D software first.

Batteries can be very light indeed,

I like the idea of light and didn't relish the idea of a car battery but having done no research into power sources that was the first thing that sprung to mind. Mind you the price you quoted seems steep to me - I have Scottish blood you know.





Nice bike by the way. I've ridden one of these a few years back and quite liked it.

I built a Raven (see my blog if you like - link at the bottom) a couple of years ago. Nice boat to paddle but I'd probably not put the bilge runners one since it makes it difficult to turn.

Gibbo.

[Jeremy]

I think it'd be straightforward enough to build a "cement mixer" type drive that just clamped on to the canoe somehow, as all that would be needed would be a motor, reduction drive and long drive shaft, plus some sort of clamp as you describe. Below is a sketch of the motor and reduction drive I'm playing with. All the bits are "off the shelf", the mount is a bit of 2" x 3" x 1/8" alloy channel, the bearings are standard bulkhead mount self-aligning ones, with grub screws to hold the shaft securely and take the thrust, the pulleys are ordinary 5mm pitch 15mm width HTD ones. It'd be easy enough to put this is a sealed box with just the long drive shaft sticking out and use it as a "cement mixer" type drive. The daft thing is that the pulleys, belt and bearings cost more than the motor.........



The shaft can be hollow to save weight, I'm looking at using 12mm OD x 1.5mm wall stainless tube, rather than solid bar.

I may re-engineer this to save a bit of weight with the bearings, as they seem to be almost as heavy as the motor.

Batteries are easily sourced via eBay, just do a search on "LiFePO4" and you'll get dozens of hits. Some of the vendors are a bit dodgy, but one, pingping227 is excellent, I know lots of people who have used his battery packs and found them to be excellent. The initial cost is a bit steep, but as I showed earlier the whole life cost will be a fair bit cheaper in the long run. At around 1/3rd of the weight of sealed lead acid batteries, and factoring in that these LiFePO4 batteries come complete with a "free" charger and they don't seem to be such poor value.

For a simple system, then 24V is probably more than enough. One of those TowerPro 5330 motors will set you back around £35, a suitable electronic speed control can be had for around another £40, add in £5 for a servo tester to use as a throttle control and you're all set. If you can find a cheap source for pulleys, a belt and some bearings then you're well on the way to a fairly cheap, high performance, drive system.

I suppose the easy answer would be to buy a Minkota trolling motor for around £250, but it wouldn't be half as much fun.................

Jeremy

[mike1942]

would your electric motor drive a hydraulic pump then you would not need a shaft at all...Mike

[Jeremy]

It's all about efficiency, Mike. The hydraulic pump would sap a great deal of power even at no load, probably more than is needed to drive the prop at cruise speed.

I did some testing today with the toothed belt drive reduction amnd was a bit shocked to find that the belt drive on it's own used 24 watts. This is far too big a loss, so I've re-wired the RC model brushless motor to star configuration from delta, which has lowered it's rpm per volt, and increased it's torque per amp, so that I think it will be able to directly drive a prop OK. I'm in the middle of machining up a prop shaft and motor adaptor, so I can go down to the local pond and do some static thrust testing. The system I have built so far looks a bit like one of those dugout canoe, long shaft, propulsion units, but I want to fit this inside, like a conventional inboard.

The motor is only 63mm in diameter, yet produces so much torque at low rpm that I cannot stall it by grbbing the shaft. Best of all, it seems very efficient, so much so that I think I can power it by solar cells.

I know that Cedric Lynch did this years ago, but it wouild be nice to have a very light and very stealthy looking electric canoe, with flexible solar cells bonded to small decks at either end. This looks possible, as the power demand could be as low as 40 watts for 3.5kts, I believe. Fitting 60 watts worth of solar panels looks possible, and coupled with a 36 volt, 10 amp-hour battery I think it should be possible to cruise all day for free.

Jeremy

[Twisted Firestarter]

The motor is only 63mm in diameter, yet produces so much torque at low rpm that I cannot stall it by grbbing the shaft. Best of all, it seems very efficient, so much so that I think I can power it by solar cells.

I know that Cedric Lynch did this years ago, but it wouild be nice to have a very light and very stealthy looking electric canoe, with flexible solar cells bonded to small decks at either end. This looks possible, as the power demand could be as low as 40 watts for 3.5kts, I believe. Fitting 60 watts worth of solar panels looks possible, and coupled with a 36 volt, 10 amp-hour battery I think it should be possible to cruise all day for free.

Jeremy

Just remember as a rule of thumb flexi panels are a lot bigger than regular PV's per output and around twice the price

Good luck though, I'm keeping an eye on this thread with great interest

[mike1942]

Hi Jeremy..on Apollo Duck the marine Brokerage webb site under canoes & kayaks there is a canoe with an external motor drive raked at about 30 degrees for sale the guys contact details are 01270585172 name of Charles.....kind regards Mike

[Gibbo]

A friend of mine recently borrowed and fitted a small outboard style electric motor to his Apache and said that it was really difficult to control. I think the motor was rigid so didn't do any steering. Don't know if it was his setup or if it's a general problem with this approach?

Any ideas?
Gibbo.

[mike1942]

Hi I think Jeramy is thinking of putting a rudder on hangings on the stern this should counteract any control problems...kind regards Mike

[Jeremy]

Thanks for the tips. I am indeed planning on fitting a conventional rudder. The power unit is essentially the same as a normal inboard, with a skeg to take the prop shaft under the hull and provide some directional stability.

I now have a set of plans for the Raven and am looking at making a 1/8th scale model first, to see if the idea looks right (drawings are OK, but I'd much prefer to see it in the flesh to get an idea if it looks right).

I've just finished brazing the motor mount to the end of the 1" diameter alloy prop shaft tube. Next step is to machine up the lower bearing and fit a suitable low drag lip seal. Then it's off to a pond to see how much thrust I can get per amp, as that will give me a good idea as to whether or not the idea is feasible.

Thanks for the tip about the flexible panels, I've done some digging about and it seems that you're spot on. My best bet might be an array of smaller polycrystalline solar cells, as this looks likely to give enough power to at least act as a range extender.

It'll be nice to be able to cruise, stop for a brew, and have the batteries top up whilst your sitting around. I like the idea that it uses no resources, either, other than the energy required to build it.

Jeremy

[fatherfay]

Hi Jeremy, yours looks like a really interesting post. I have built a Selway Fisher Prospector and am quite near you, (Southampton). Would be delighted to help out your development - possibly as a test bed if you need one? Send me a PM if you'd like to meet up, even if it was just to check that a SF Prospector is too large for your needs! Cheers.

[Jeremy]

Thanks very much for the kind offer, I may just take you up on it. I've purchased plans for the Raven now, but wonder if the Prospector might not be a better bet.

As I'm primarily looking at electric power, with paddling as a "get you home" measure only, the issue of stability has crossed my mind. From what I can gather, roll stability is enhanced to some degree by paddling. I should gain some additional stability by lowering the seats to lower the vertical C of G, though.

I'm not particularly bothered by a canoe with low initial roll stiffness/stability, as long it firms up quickly. SWMBO may well be rather more perturbed though - she managed to get quite alarmed when our canoe was rocked by a suddenly awakened 'gator in the Everglades (mind you, she's a bit short sighted and didn't see it "sleeping" on the surface when she bashed it's snout with her paddle).

The intended use is quiet water only, just smooth rivers and lakes, so ultimate stability is probably less of an issue than initial tenderness. How do you think the Prospector might compare to the Raven?

One option that sounds attractive (as I'm happier working with composites than wood) is to investigate those hulls linked to in the General area made by Composite Dynamics. Provided that they are light enough, then one of their Prospector hulls might be a better starting point for this project.

The good news is that I've finished bench testing the motor and speed control system tonight and am pretty pleased with the outcome. I can run the propeller right down to around 100rpm and still have massive amounts of torque, whilst only drawing very small amounts of power. Although this motor will happily deliver up to around 2.5kW, by tuning the motor control system it looks like I've been able to still maintain efficiency at around 90% at just 30 to 40watts. This bodes well for maximising endurance from a small battery.

I've just weighed the motor, stern tube and prop and it comes in at a fraction under 2kg. Add in the battery pack and controller and I should be able to stay under about 6.5kg for the complete propulsion system.

Jeremy

[DougR]

....
One option that sounds attractive (as I'm happier working with composites than wood) is to investigate those hulls linked to in the General area made by Composite Dynamics. Provided that they are light enough, then one of their Prospector hulls might be a better starting point for this project.
....

Might be worth a test paddle in an example of your chosen hull before committing to a lengthy build.

Apache group offer thread probably worth considering - several folks have them and speak highly of them for smooth water use.

[fatherfay]

What did you suggest using for a stern tube? That's usually been my sticking point for an inboard setup. Not sure where to source them from!

[Jeremy]

I've been experimenting with ways to make a stern tube and this is what I've come up with so far (the inboard end):



It's a 1" diameter, 16g wall thickness light alloy tube, with a motor mounting flange machined up from a bit of 2 1/2" light alloy bar. The motor is a re-wired Towerpro 5330-10T model aeroplane motor that can deliver up to 2800 watts (about 3.75 hp) peak, but will be much happier when run at a more modest power level of around 70 watts or so. This motor is fairly cheap (around $49 or so).

I've modified the motor a fair bit, by adding three internal Hall position phase sensors, which allows me to use a very cheap, relatively high voltage, electric bicycle speed controller (this one: http://tinyurl.com/czvgeg which costs just over £30 inc P&P). These mods combine to allow the motor to deliver very high torque levels at low rpm, making it better suited to driving a prop directly.

The other motor modification has been to change the internal wiring configuration from delta (these motors are ordinary three phase ones) to star. This reduces the rpm per volt by a factor of about .58, and increases torque by a factor of about 1.73, which again helps when it comes to driving a prop with reduction gearing.

This afternoon I've been working on a prop shaft and lower bearing/seal arrangement. I still need to do some more work on this, but it's getting there. I'm hoping that I will be able to do some tests to see how much thrust I can get from this in the next few days. I've now got the motor and controller working well, so it's really just a matter of finishing the lower end of the stern tube.

Jeremy

[xhairs]

i have been following this with both interest and admiration...

it seems to me that with you coming to canoes from another field of expertise will have opened up many eyes to the idea of motorised power...

would the prop be outboard... or in a tube like an impellor and will you have to contain some form of lubricant inside the shaft...?

[joe.ford]

i have been following this with both interest and admiration...

it seems to me that with you coming to canoes from another field of expertise will have opened up many eyes to the idea of motorised power...

would the prop be outboard... or in a tube like an impellor and will you have to contain some form of lubricant inside the shaft...?

I'm just curious how your going to stop the water coming in? I'm guessing that the shaft will be horizontal and under the water line.

[DougR]

I'm just curious how your going to stop the water coming in? I'm guessing that the shaft will be horizontal and under the water line.

I've seen a variety of approaches.
1. - simplest - the tube is raked at an angle sufficient to put the inboard end above the LWL. Needs no attempt to seal

2. Stuffing box/ Packing gland at the inboard end - popular and effective.
3. Specialised sliding lip seal - http://www.lakesterngear.co.uk/seal.html

4 - Low voltage and fresh water - just submerge the motor - I've seen this work but its "scrapyard challenge" style engineering.

[Jeremy]

I've looked at using a normal oil seal, a lip-type neoprene seal with a 12mm ID, as a shaft seal and it looks OK. It does add some friction though, so a better system might be as Doug suggests, to just lift the inboard end up clear of the water line.

I'm still exploring other options for best efficiency, as I'd really like to use solar cells to keep the battery pack charged and be free from any reliance on an external charging source. It seems that the human powered boat people know a great deal about this, so I'm taking the time to read up on developments in that area.

There's nothing wrong with Scrapheap Challenge technology, though. Take a look here: http://www.channel4.com/science/micr...llenges_7.html and see if you can spot a familiar name amongst the Experts, or here: http://www.channel4.com/science/micr..._airboats.html for some fun pictures............

Jeremy

PS: Yes it is me at the helm of the contraption with the surf boards

[travellas]

Very interesting project- great attention to detail- looking forward to hearing how it develops.

And I'm a fan of Scrapheap challenge . . .

[Jeremy]

Thanks for the compliments, I really hope that I can make something that meets my aspirations for a nice, silent and relatively eco-friendly means of exploring quiet waterways.

Scrapheap was fun, in fact loads of fun, but is bl**dy hard work. It really is against the clock and the build day is around 15 hours of hard graft (you get a lunch break, plus they take ages faffing around with cameras and stuff, which eats into build time). Great bunch of lads though, plus we won.............

I'm re-thinking my plans about the canoe, as I really want to get on the water this summer. I'd love to build a canoe, and have bought a set of SF Raven plans, but in my heart would want to build something beautiful, like a cedar strip plank hull, clear finished. I don't have time for that right now, so, having looked at Flounder's excellent work on fitting out that Apache, I'm leaning towards something similar.

I could do with a bit of advice from those of you with far more experience than me, to be honest. I can easily adapt a glass fibre bare hull, as I'm comfortable working with composites (plus I have quite large stocks of glass, kevlar, CF and resin already), so either one of the part completed hulls from Apache, or perhaps one from Valkyrie, looks like a better bet.

My requirements are for something able to carry two people, plus a modest load (just suitable day-trip refreshments), on smooth water (non-WW rivers and canals, plus lakes) and be car-toppable for someone who is only modestly fit. The electric power system should only add a couple of kg to the hull weight (excluding the battery pack, which can be dismounted for transport). Good initial stability is fairly important, so I don't want an overly-tender hull shape. I will almost certainly fit the seats lower in the hull than would be normal for paddling, which may help with stability a fair bit. Directional stability should be reasonably good, as I don't want to have to constantly correct the course with rudder, as this will sap power (I'm looking for a very efficient power system so that it can run on largely solar power).

I'm currently leaning towards the 16ft Apache, as a bare hull with gunwales fitted. If anyone has any comments as to whether this is a wise choice then they would be most welcome.

Jeremy

[joe.ford]

I just remebered this picture for some reason. Is this what your aiming for?

[Jeremy]

Ahhh.... Cedric Lynch and his electric record making canoe!

I'm aiming for something a little less "Heath Robinson" (I've every respect for Cedric, but his creations aren't always as neat and tidily built as I'd wish for). I've now made three cardboard models, to try out the so-called tortured ply build method, and am getting closer to what I'm after. This afternoon should see the final cardboard model, followed by an eighth scale plywood model (I've been to the local model shop this morning and bought some 1/32" ply).

Here's a picture of the part finished propulsion unit:



As you can see, I've moved away from the prop shaft through the hull idea, for a couple of reasons. One was the added vulnerability of a permanently mounted skeg and shaft, the other was the difficulty in getting a good shaft angle through the hull.

Luckily I managed to find a very nice (and cheap) angle gearbox, intended to be used with a powerdrill. It was only about £20, complete with keyless chuck (which may come in handy for something!). The gearbox has three ball races, one needle bearing on the input chaft and proper helical cut bevel gears, with a 1.25:1 reduction ratio. It's also nice and slim, so won't disturb the flow in front of the prop too much (once I've built a faired leg and skeg around it).

I machined up a new output shaft from stainless steel and fitted a lip seal to a machined bearing housing that supports the extended output shaft. Similarly, I've machined up an input shaft, from 1/2" x 16g alloy tube, machined a boss to fit the motor and shaft together and machined down an 8mm AF socket as a drive at the other end that fits the 8mm AF hex spigot that was on the original gearbox.

Total cost of parts for the motor system is now running at around £95, so not much less than the price of a trolling motor. It should be a lot more efficient, though, as it's optimised for low power consumption at canoe cruising speeds. I have spent around 5 hours machining up parts though, so perhaps that needs to be added to the cost!

It has occurred to me that a unit like this could easily be used as an "Electric Paddle". If the shaft were extended, the motor sealed and a throttle control fitted to a top handle, then you could just hold it over the side and go...........

Jeremy

[Jeremy]

Here are a couple of photo's of my progress with making cardboard models of my tortured ply design. Much as the CAD stuff helps, there is no real substitute for making a model to see how things will work out.



The larger one in the centre is the current favourite. It's a bit beamy, but should be nice and stable without the added stability from paddling, plus it should have good load carrying capacity. One thing I have learned, is that it's tricky to get a nice, fair join at the centreline. The panels want to go off at an agle at the turn of the bilge, leaving a sharp edge right on the midline, like this:



The way around this seems to be to have a wider centre section, so I'm currently making a wide, laminated ply central rib that I hope will allow the corner at the midline to be faired a bit better.

On the big centre model I experimented with two central ribs, spaced apart with a strip inserted to better fair things, like this:



I don't think this is necessary, and am fairly sure I can smooth things out without needing an extra strip down the middle. It looks possible to make the hull about 15ft 4" long, and 38" wide, using just two sheets of 4mm ply, plus some framing. I'll post details once I'm reasonably sure that I can get it to work, as it might be a reasonable way to make a budget, lightweight canoe that's capable of carrying two plus some baggage.

Jeremy

[ShagRock]

Great 3D models, Jeremy! Your project continues to get progressively more interesting. This is 'just to my eye', but the middle wider model has a real nice 'canoe shape'! The beam is 38" which is not considered wide in a canoe having auxiliary motor power...that's only 2" wider than some prospector models at 36".

Just a thought, off the top, and maybe out in left field; but what if the wide central band you show was siting on the 'inside' and made of plywood. The sharp tension point of the narrow central rib gets spread out considerably, and in essence would serve the same function as the double ribs you have in the model and provide a much wider gluing surface. This would be a takeoff on methods used in double planked/veneered canoes.

Btw, I'm curious how you fold the three sided plywood, i.e., clamp one side first, attach two points and fold the third, etc.? No doubt, you're read this article. I got it theoretically, but I still don't have a grasp of what he uses (in real life) as the beginning leverage point...has to be attached or kept in place to start the bending? http://koti.kapsi.fi/hvartial/torture/torture.htm

[Jeremy]

Thanks for the compliments.

Great minds think alike! I made a wide centre rib for the (hopefully) final model last night, by laminating up some strips of 1/32" ply, over a bent spruce rib, to try and do just as you suggest.

In practice, that centre design doesn't actually do any 3D bending of the skin at all. It pretty much bends in just one (twisted) plane, which is an interesting concept to get one's head around, as the shapes just look very good indeed. I got my inspiration from that link you gave, which in turn came from Xhairs build thread.

The technique I've used on the models is to glue the skins to the centre line of the keel, plus the flat side of the centre rib, and let that go off. The next step is to pull the edge up to the inwale, starting at the centre and working towards the ends. For the model I used contact adhesive to secure the skins, so was able to glue both parts and then just pull and push the skin into place. I've no doubt that this will be a lot harder with ply on the real thing. It's quite amazing how the skins go really stiff, even with the thin card, once they are curved into shape

Once I've got a design that works, I will turn the drawings into pdf files and post them here, as they might be of use to someone else. I'm hoping that the canoe should turn out fairly light, not much more than the weight of a couple of sheets of 4mm ply plus some glass cloth and epoxy.

[ShagRock]

I noticed your project got a mention on the famous (or infamous) Wooden Boat Forum.

http://www.woodenboat.com/forum/show...hp?t=97160/htm

[Jeremy]

Thanks for that, it's interesting to see that people are watching developments here!

I have partially built the final ply model, from which I'm hoping to produce the full size canoe design. I've opted for a small transom, that will be hidden in use by a dummy pointed stern section that contains the motor unit. This will be hinged at the top edge of the transom, so that the whole pointed stern/motor section can be pulled up clear of the water for beaching etc.

Here's a picture of the partially built ply model, showing the wide centre rib to try and smooth the transition between the sheets out.



This model is eighth scale, so is just under 2ft long. The ply skins are glued to the keel and just need pulling up to the inwales, stem and stern. The skins are cut from the scale equivalent of two 8' x 4' ply sheets, simply cut at an angle down the long axis. They will need trimming to size once they are bonded in place.

Jeremy

[travellas]

I've opted for a small transom, that will be hidden in use by a dummy pointed stern section that contains the motor unit. This will be hinged at the top edge of the transom, so that the whole pointed stern/motor section can be pulled up clear of the water for beaching etc.

This is a very nice solution. Looking forward to following the build!

[DougR]

As this is a low power application...

http://www.chem.umn.edu/services/lec...Cu-Zncell.html

Lunatic fringe?

[ply n epoxy]

hi there,
Very interesting post. I`d just abandoned my electric propulsion quest. The best I came up with was this cheap trolling motor http://www.whitbyanglingsupplies.com...8b3bdb421ff2f1 and a gel battery 30a/hr. Weight was only 2.2 kg and 6 kg but at 15 amp motor rating I`m told the battery would only give 30 minutes range as anything more than 50% battery draining drasticly shortens lifespan( I`m guessing that at half power 7.5 amps would still only give 1 hour range??). Project abandoned.
Then your post and I`m inspired......Your motor and battery pack sound great with a much better range. I`m happier with wood than with electrics so would prefer to buy than make but trolling motors seem so inefficient. I guess its a volts/amps/watts thing and liFePo4 packs all seem to be 24 volts or more. Any other off the shelf ideas??. Of course this would be the easy answer...... http://www.torqeedo.com/en/sn/image-...eos/ultra.html
Good luck with your progress.

[MotoMike]

Dang it. I am very anxious to see that finished project. Time is cruel to me in yet another way.

[Jeremy]

Thanks for the words of encouragement, they are much appreciated.

The trolling motors are pretty good value for their intended purpose, which is moving relatively heavy fishing boats around slowly. The snag is that they tend to be pretty inefficient when it comes to moving a very low drag boat like a canoe at normal speeds.

Cedric Lynch used a home made motor on his solar canoe to ensue good efficiency. In effect I'm having to do the same, although I've modified a model aircraft electric motor to better suit use on a boat.

Hopefully I should have another progress report later today, once I've worked out a small snag with the tortured ply construction method.

Jeremy

[Jeremy]

OK, I think I've resolved the slight snag with the tortured ply model. I've now abandoned the idea of a fixed keel, stem and stern and instead will stitch the centreline of the panels together before pulling them over the wide centre rib and up to the inwales.

I've built an upside down strong back for the model, to hold the centre rib and ends of the inwales in the right place, and with the right sheerline. The centre join will be classic stitch and glue, which should be easier to do, and result in a lighter hull, than using timber.

The problem I encountered was really as much to do with the scale of the model as anything else, I think. I couldn't get the 1/32" ply to pull up into a neat fold at the bow and stern, due to the width of the keel (which was already as thin as I could reasonably make it).

Anyway, all is far from lost, as I think that, if anything, the new construction method should be better. Having the inwales supported by the strongback should make the job of forcing the ply down and around them a lot simpler.

For the full size canoe I will need to go and get a lot more clamps, though. I can see that my modest collection will need to be substantially increased!

Jeremy

[DougR]

....
For the full size canoe I will need to go and get a lot more clamps, though. I can see that my modest collection will need to be substantially increased!

Jeremy

Have you taken a look at the construction method for the Unicorn and Tornado hulls?

[Jeremy]

I've got a copy of the Tornado catamaran drawings, downloaded from the web, but I'll own up to not having looked at them in that much detail, as I wasn't at all sure that I could persuade that cylindrical shape into a classic canoe shape.

Knowing what I've learned now, I think it will work with the "four piece" method, as there is enough extra in the amidships to allow the greater beam. I can say that getting my head around the 3D shapes that a flat sheet can take up has been a challenge.

I've not seen the Unicorn plans, but will Google for them, thanks!

Jeremy

[ShagRock]

Jeremy..interesting how your thinking process continues to evolve to new ideas! So are you planning to epoxy the sheets along the keel line first, before bending?

I was also wondering if nylon web racket straps might be useful in this process..I've seen this somewhere but not able to find a link. Anyway, a flexible batten of some sort could be fastened to the edge of the plywood to prevent the straps from cutting into the ply. All sorts of rigs and jigs, like come-alongs, are employed in bending natural wood, metal, etc. I think some uae a similar approach for stretching canvas unto canoes.

Anyway, looking forward to your next update!

[DougR]

....
I've not seen the Unicorn plans, but will Google for them, thanks!

Jeremy

I was thinking construction method rather than plan... I've go the leaflet somewhere.....

The Unicorn is made as a stitch and glue where the two principle panels are epoxied together at pre-determined angle(s) - effectively setting the "deadrise".

The gunwale line (plan view) is formed by a hole cut in another sheet - and this takes the place of many of the clamps - ratchet straps - spanish windlasses...

[Jeremy]

Sounds like an interesting way to hold things in place, I'll have to take a look at how it works.

(edited to add: I found this link: http://www.instructables.com/files/o...2UF3SYTM0N.pdf that shows the "hole in the sheet" jig method.)

I've been working out the order of doing things a bit with the new model, although it's still very much an experiment! Last night I stitched two panels together down the centre and then glued them around the centre rib, holding them tightly in place with a Spanish windlass affair, wrapped around the whole canoe.

This worked well, but this morning I realised that another improvement would be to just butt join the panels on the centre rib line whilst they're all still flat, then bend the whole lot around the rib and glue it in place. It might be a bit stiff to bend, though, so perhaps another experiment might be called for.

Anyway, this morning I pulled the panels around the inwales and was pleased to find that it was quite easy to hold them in place. I used three thin strips of spruce as temporary outwales and these helped to pull the panels in tight against the inwales.

The glue is still going off, so I need to wait a while to see the result. One obvious problem is that the keel line now bulges down at the bow, so I need to think of a simple way to pull it back up. The bow went together very nicely indeed, though. I drew out the shape on the panels, before fitting them, and it looks like no trimming at all will be needed.

I should have another photo or two this afternoon, once I'm able to remove the clamps. I feel I'm pretty close to having a workable design for a "two sheet" canoe that doesn't have a multitude of seams to glue up. Fingers crossed..............

Jeremy