Hi,
This is a cautionary tale for anyone thinkiing about cheap electric propulsion.
I decided that I was fed up with a noisy, sometimes unreliable outboard on our 23 foot sailboat. Though to be honest, the unreliability problem was probably me, because it always worked perfectly when it didn't matter.
I had a look at the electric outboard/battery packages from Torqueedo and ePropulsion but speending $6000-$8000 to replace a $2000 petrol outboard was bit bit hard to justify to my wife.
So I looked at cheaper options like high-thrust trolling motors. I ended up buing one (24V, $700), and I had a couple of spare car batteries for testing. It worked pretty well, certainly good enough to get in and out of the boat harbour at a reasonable speed.
Then I started to get serious, bought a couple of good deep cycle batteries ($600), a 24 volt solar controller ($90), 2 solar panels ($220). Put it all together and it worked, almost. The first time we tried out the new rig, we got 3/4 of the way down the channel and the motor slowed to a crawl and stopped. Not good. Lots of people offered to help which was pretty embaassing, but the outboard came good and we limped back to the pontoon. It was only a 1 KW outboard and that was the first time we'd pushed it hard so maybe the motor had just overheated.
What to do? Buy a 2KW outboard of course, ($1800) that'll do it. But when we took it for a run it had the same problem, but this time we had a clue as to what was wrong. The voltage from the 2 batteries had dropped below 18V, but when we shut off the otboard the voltage came back up. WTF? Turns out deep cycle batteries don't handle a high current draw. There is something called the maximum continuous current which for 100AH deep cycle batteries is about 30 amps. Since we were drawing 50+ amps, that created a problem.
Bugger, I'd bought the wrong sort of batteries. I needed decent high current batteries and ended up buying 2 12V ithium iron phosphate batteroes ($700 each), and a battery balancer ($100).
Everything worked perfectly, and we found the sweet spot (speed vs range) was about 4.5 knots and 8 amps, which gave us a cruising range in smooth weather of about 70km. There was only one problem. You don't need a 2KW outboard for that sort of power, and we found the 1KW outboard did the job just fine. Then I found out about Delkors marine deep cycle batteries. They're kind of a hybrid that is nearly as long-lasting as a deep cycle battery, but also has enough amperage for cranking an engine, or running an electir coutboard flat out. They cost $240-280 each, cheaper than the deep cycle batteries I bought. Sigh..
So what did I learn besides I'm a slow learner? Ignoring the solar stuff, which I needed because the hardstand doesn't have any power nearby, I could have got a workable setup for about $1400 (I bought a better propeller). Yay!
For the more astute readers who added up what I've spent, you would have figured out that I would have saved money going for something like an ePropulsion and just shellng out $6000 for something sexy that worked. But you can't discount the value of an education.
Happy sailing.
Select to expand quotesamsturdy said..
Good story wooly. You've educated me too. Good luck mate.
Story or sales pitch from a first time poster?
Or is it just me that thinks like that 
Select to expand quotesamsturdy said..
Good story wooly. You've educated me too. Good luck mate.
Story or sales pitch from a first time poster?
Or is it just me that thinks like that
I don't blame you for thinking that. But no, I haven't got any commercial connections, unless you count people who sell me stuff.
Then again, I do have a spare couple of almost unused 110AH deep cycle batteries if you're interested. And a very nice hardly used Tohatsu Sail 6 with extended shaft and elephant ear propeller 
I've also had fun, luckily more successfully, at putting together a hybrid 12/24 Volt electrical system, a remote control autopilot and a cool co-steering system (tiller and electric outboard coupled) which makes me look like I know what I'm doing when I come into the pontoon
And I can bore you to death talking about batteries. 
Welcome Wooley3,
Very interesting. Thanks for sharing your experiences.
If someone wanted to play along and take advantage of your hard found knowledge it would look like this?
high thrust 24v trolling motor 1KW $700
Delkors marine deep cycle batteries 2x @ $280
better prop $ ?what was this and how much?
gives you 70km in smooth weather at 4.5 knots ( 8 amp draw ) in a 22 ft sailboat
add to that solar stuff if you are not recharging back at the dock.
24 volt solar controller ($90), 2 solar panels ($220)
seems pretty reasonable to me. How heavy is the boat?
Our boat is sort of a trailerable yacht, an Aquarius 23. Has a shoal draft keel with 400 kg ballast plus a steel plate centreboard. All up weight about 1.8 tonne. Any 22 foot sailboat would have to be easier to drive through the water. But our old girl has a high top cabin, so she's comfortable inside, and is dead stable because of all the ballast.
I'm a bit wary of mentioning brands I've actually used because that IS starting to sound commercial. Let's just say the actual brushless motor is made by an Electric Motor Power manufacturer in Melbourne. Nice people who listened to me when I told them what needed improving. The trolling motor came with a highly objectionable weedless propeller, so I ended up trying about 6 different brands of propellers until I found one (Haswing model 150702801, $50) that was nearly perfect. It needed to be bored out slightly to fit the shaft on the trolling motor and I had to shave the sacrificial anode ring on the motor, to stop the propeller rubbing. Also needed a longer pin for the shaft, but I now have 50 so just ask. But the end result was 30% less amperage at the same boat speed, so well worth doing.
I'd love to buy a big enough 3D printer to print my own 11 1/2 inch propeller, but that'll have to wait. There are some nutcases in NZ (on Youtube) that have a 3D printed a polycarbonate propeller that worked fine on a 25 HP petrol outboard, so making one for an electric outboard seems feasible.
The tiller linkage made the whole package a dream to use in terms of manoeuvrability.
Ok. I mentioned the Delkor batteries because I had one as a house battery, and it wasn't til after I bought the lithium batteries that I found out what I had. That was a real DOH! moment, sigh. Mind you the lithium batteries are a lot lighter and the price has come down enough that I'd be tempted to buy them anyway. Lithium batteries do have one other major benefit, and that is that their useable amp hour output is 10-15% higher than an equivalent lead acid battery.
The solar setup ended up being more, and less complicated than I intended. The original plan was to have 2 separate power systems, 12V for the lights, electronic equipment etc, and 24 V for the outboard. But when the new solar panels arrived, I found I didn't have room for all 3 solar panels.
I ended up with 2 big panels in parallel feeding the 12V system, and I used a smart 12V to 24V charger from the UK (turns on at 13.1V, off at 12.8) that uses the excess power to charge the lithium batteries.
The 160W of panel charge the house battery first, and when it's full they charge the 24V batteries.
That actually kept things reasonably simple, and separate.
I found a high amperage waterproof plug and socket, made a custom mounting plate for it at the back of the cockpit, and put the batteries under the cockpit (lot's of room) with decent sized cables. The 24V batteries take 2-3 days to charge from nearly flat so I's say it's a success.
I'll upload some pictures if you're interested, but a lot of it was ideas I got from other people, it just needed putting together
You could probably get away with the crappy (sorry) weedless prop but if you don't mind doing a bit of extra work, the better prop is absolutely worth the effort.
That's probably more answer than you wanted, but the quick answer is that the costing iis reasonably accurate, though I spent a lot more getting there.
Nice post wooly and welcome, I've been looking into elec propulsion for small boats & it's good to hear that a decent motor is made in Oz, and you've found a prop that can be adapted, economical batteries are the holy grail !
I think it would be reasonable to mention the brand of 2kw electric outboard if people like me ask.
SR
Just noticed this thread, and thanks for sharing your story and nicely informative posts. Good journey; good read.
Just mildly confused about the current draw - in your first post, you encountered problems because the motor was asking for 50+ Amps and your deep cycle bank couldn't deliver.
But then you found a sweet spot that draws only 8 Amps (at 4.5kt), still using the 2kW motor.
Just to clarify, are we comparing apples and oranges here in terms of speed, when we mention 8Amp vs 50Amp for the same 2KW motor?
Hi,
I had the amperage problems when we were going out of the boat harbour at full throttle, (over 40 amps) and initially blamed it on the 1KW motor "overheating". So I went and bought a bigger 2KW motor, and found the same problem, but at least I found out it was the batteries and not the motor. The difference was the 2KW had a LED voltage display you could see in bright sunlight, not an LCD display impossible to see. We now have an OLED display in the cabin that shows us volts amps and watts.
Our sailboat weighs 1.8 tonne and has a waterline length of about 6.2 metres. We found when we were using our 6 HP petrol outboard that anything over 1/4 throttle was a waste of time. You got a lot more noise, vibration and smell but very little extra speed. That's the trouble with a displacement hull, once it starts approaching hull speed, it takes a LOT more power to push it faster. In our case 4.5 knots was the comfortable limit for petrol power. When she's under sail, we can get well over7 knots, but she's heeling over and I guess that changes the hull shape in the water, plus the wind gives us a lot more power.
We measured speed vs amps on a dogleg course so the effects of wind and tide would be cancelled out. My wife is a science teacher so you have to do that sort of thing properly :-) What we found was that you could get 3.4 knots at 4 amps, 4.5 knots at 8 amps, 4.7 knots at 16 amps and 4.9 knots at 32 amps. That's how we decided 8 amps was the sweet spot, reasonable speed, maximum range.
Forgot to mention that the 2KW motor can draw 93 amps flat out.
The good old Pukert effect. The more current you try to draw from the battery the less you get.
Good on you for working through it and finding the right sort of battery. I'm thinking the motor draws a lot of current initially as it gets the hull up to speed then tails off to the current needed to maintain speed. Makes sense the battery needs to have hybrid characteristics, like a deep cycle starting battery if one exists.
This is very useful information. I have a 22ft boat I keep on a mooring and have been looking for ways to do away with the 2 stroke OB. I only need it to get on and off the mooring 95% of the time, but its too heavy to lug forwards and backwards all the time and too smelly to store in the boat. Then there's the problem of how to store the fuel without turning my boat in to an explosion risk.
I've looked at electric power before but have been put off by the cost. I thought the trolling motors would be too weak to move my boat at 1300kgs displacement. You've inspired me to have another look.
I have an outboard well in my cockpit which is inconvenient for a 2 stroke because the engine ends up taking up most of the foot well for the skipper. However, a small electric OB would probably fit under the floor. I'd even considered getting the lower leg unit off an old outboard and fitting a brushless motor on top, so will look in to the manufacturer you mentioned in Melbourne.
Photos of your set up would be very helpful.
Hi,
EMP's trolling motors are undoubtedly trolling motors, not outboards, but they're better than average with a nice motor designed by EMP. The models I looked at were the Pelican EMP120 (24V) and EMP 160 (48V) (www.trolling motors.com.au). EMP/Pelican have a kit without the mounting bracket (less expensive too), which might work for you. You'll love the control you get with the electric motor.
I wanted a 24V 2KW trolling motor and the Haswing Ventura looked a lot better and was 24V, but I didn't realise it ships with a weedless propeller. If you don't mind something that looks like a trolling motor, the Haswing Protruar 5.0 is less expensive and takes the sexy propeller I adapted for the EMP 120.
2 lead acid batteries is manageable, 4 gets too bit difficult unless you go lithium (you can get 24V and 48V single batteries). But most solar systems are 12/24 whereas 48 volt systems are more expensive (as are the AC battery chargers).
For your setup it's probably not worth considering Lithium batteries except for the weight saving. I got the hybrid battery from my local Delkor supplier, it's a Predator MFDC27.
Some pictures.
This is the EMP 120 down
and up
The 2KW Haswing Ventura with a weedless prop (sigh)
The back of the cockpit, motor to tiller linkage and waterproof electrical connection. The Anderson plug will go when I stop playing with motors.
The standard weedless prop you get with the Pelican and Haswing.
This is the modifed Haswing prop on the EMP 120.
Pelican have quite a nice looking remote throttle, but I suspect it' wouldn't work all that well in a sailboat cockpit when you jibed and the mainsheet caught the throttle. It's basically a 10K potentiometer, so my next project is mounting one on the end of the sailboat tiller, with a magnetic kill switch to disable the motor when it's lifted out of the water.. That'd be perfect
Select to expand quoteMicrobe said..
This is very useful information. I have a 22ft boat I keep on a mooring and have been looking for ways to do away with the 2 stroke OB. I only need it to get on and off the mooring 95% of the time, but its too heavy to lug forwards and backwards all the time and too smelly to store in the boat. Then there's the problem of how to store the fuel without turning my boat in to an explosion risk.
I've looked at electric power before but have been put off by the cost. I thought the trolling motors would be too weak to move my boat at 1300kgs displacement. You've inspired me to have another look.
I have an outboard well in my cockpit which is inconvenient for a 2 stroke because the engine ends up taking up most of the foot well for the skipper. However, a small electric OB would probably fit under the floor. I'd even considered getting the lower leg unit off an old outboard and fitting a brushless motor on top, so will look in to the manufacturer you mentioned in Melbourne.
Photos of your set up would be very helpful.
Microbe,
I went through the same thought process with my Austral 20 Trailer Sailer a few year's back, but baulked at the cost (relative to the value of the boat). A tidy solution, might be a Torqeedo pod, or a more modern equivalent, but you would have to check current costs and availability. I got the drawings in 2016 to see if it would fit between the skeg and rudder of the Austral 20 (it would be a tight squeeze) - see below. The advantages were that it would take up little space in the hull and/or cockpit, it would position the prop forward of the rudder (better manoeuvrability), the prop stays submerged, and you don't have a heavy lump of outboard engine hanging off the transom. The drawing is for a 2kW motor, but the OP suggests you might need less, say 1kW, if such a thing exists.
Very informative thread, thanks to all.
Do the electric propulsion oems provide a propeller suitable for small yachts say up to the old 1/2 ton size 9m LOA and 2.5tonnes displacement. That is a high blade area low pitch like the Tohatsu sail outboards do - which are typically 4 bladed low pitch mouse ear style to give good thrust at lower boat speeds which yachts need, but normal revs. Obviously gearbox ratios come into account also.
I realise epropulsion have their navy series but can't see such a prop there
www.epropulsion.com/navy
I found this link with a myriad of solutions including props in nozzles which would increase thrust - didn't see any with 4 blade low pitch props.
plugboats.com/guide-to-electric-saildrive-pod-boat-motors/
I am not a spark so guess it would be a matter of matching the rpm-torque curve of the edrive to the prop and yacht speed needed, also not draining too may amps.
Thank you for sharing all this great information with us Wooly. The only two things holding me back now are will the outboard drive your boat into a 30 knot headwind? That drive shaft looks very light on. And how waterproof are they? Will it handle waves crashing over it. If they get submersed are they kaput?
Great info Wooly
I have been looking at getting a EMP 80LB motor for my inflatable/ Also looking at a 12v 54Ah Lithium Ion Battery (which would cost as much as the motor...) for weight and ease of use. I understand that at half throttle I would get 2 hours run time. What size batteries do you have and what sort of run time do you get?
Thanks Neil
I'd like to start with an apology.
I've been sick with the flu, or reasonable equivalent, so when I got well enough to be bored, I finally posted my electric trolling motor story. It hasn't been particularly well put together, but I'll try and do better.
If I could justify the cost, I'd absolutely buy something like Torqueedo or ePropulsion (probably the latter) because they look sexy, and are really well designed, with some fantastic features. If you've got the money to spare, don't stuff around with trolling motors.
But my goal was to get something that did what I needed and that didn't cost any more than a good petrol outboard.
That meant I had to look at trolling motors. The only trouble with trolling motor is... well it's that they're trolling motors. Generally they have crappy weedless propellers, really basic design, indifferent waterproofing and are not really optimized in any way. But if you make the effort to do some sealing of the top. get a decent propeller and get batteries that work, you have functionality that pushes a boat as well as an equivalent rated Torqueedo or ePropulsion. And it'll survive being doused by a wave.
The shaft on the EMP 120 is thick wall 316 stainless steel and it is really stiff. I'm more worried about the strength of the adjustable height outboard mount bolted to the stern of my sailboat. The Haswing Ventura has an aluminium sheath over the shaft so it's even stiffer. I really don't think that's a problem.
I've thought about what I'd do with my 1KW or 2KW trolling motor in a 30+ knot headwind with 1-2 metre waves.
You have to remember it's a sailboat and the electric propulsion is auxiliary, not your main source of propulsion. Now if the rig goes over the side and you have to motor home, then things get a bit more interesting. It's probably time for a story.
I had a major rig failure (jib furler came loose, my fault, just bought the boat and didn't check everything well enough). We dropped the main, and held the boat to windward with our 6 HP outboard while I went up forward to try and secure the flapping jib (with furler attached). I got a beautiful set of bruises, and we found out that if someone was on the foredeck, the outboard propeller would lift out of the water when a wave came along, causing the outboard to overheat and stop. The crew weren't happy, BUT I'd gotten the jib back under control. So no outboard, jib only and we sailed back into the boat harbour. Not a great way to introduce my daughter to the joys of sailing.
Once the waves got up, the 6 HP outboard could barely hold the boat to windward (even before it stopped). We're lucky on Moreton Bay, because with the exception of when the westerlies are blowing, getting home is usually always downwind so we really only need the trolling motor for steerage.
If I was going offshore, a 5KW electric motor with 400 Ah of battery would make me a lot more comfortable. But for day sailing, with a reasonable eye on the weather, the 1 KW trolling motor with 100Ah at 24V, does what we need. Read the earlier posts for amps, speed and range.
Thanks for the great explanation Wooly and putting it all in perspective. So good!
Indeed the one that caught my attention was the 24v 1100w thruster with the intention of building it into the Skeg of a 17ft boat weighing in around 150- 200 kg. So now just need a reasonable pitched prop & a home made kortz nozzle. While I was there @ emp I had the curious notion for another project of using one of the say 1k motors with a worm drive gear arrangement to drive a shaft with a capstan on one end and perhaps a gypsy on the other, I'm sure it's been done before !
Certainly an interesting thread. Would love to go electric and this has given me some hope.
Wooly3, no need to apologize. I'm enjoying the honest accounts of your experiences. I'm finding it interesting to see the costs and limitations of the trolling motor approach. Although it seems underpowered for anything other than berthing a 20 to 25ft boat, the advantages are that it is feasibly cheap, you don't need major surgery to your boat (the biggest initial structural modification would be a mounting bracket), and you can physically take it off easily. All this is valuable information for someone who might want to experiment.
There are heaps of good youtube videos on marine propulsion systems. I accidentally found this one. Has a lot of links.
Great thread!
I am looking for an electric outboard for a Hartley TS16 (home built) and am trying to keep the costs down.
I am really curious about the options mentioned here.
It seems like a 160lb thrust trolling motor would give me similar thrust (and therefore speed and safety) to a 6Hp outboard or equivalent electric outboard.
1. What would be the drawbacks aside from looks (I actually prefer the look of the trolling motor as it is less conspicuous).
2, What is the disadvantage of the weedless prop? I am planning on using it in the ocean, would this be an issue?
3. Exactly what needs to be done to help waterproof the motor?
4. What would people recommend out of the EMP/Pelican and the Haswing?
5. what would be the best battery option out of the Delkors mentioned and the Optional 24V 75/110 or 150Ah lithium battery sold by Haswing?
This may be of interest to this thread as he installs an electric motor in a plywood boat build
janvonderbank.wordpress.com/eine-seite/
