Electric sailboat motor: new conversion project (update: project shelved)
 

On impulse, I started a new project this week:

• Out with a 30 year old, smelly, smoky, noisy, sometimes unreliable, inboard gas engine!

• In with a quiet, odorless, underpowered, limited range, homebrew electric system! :p

The back story:

http://ecomodder.com/forum/attachmen...1&d=1272939797

I've got a sailboat with an inboard, 2-stroke, 15 hp gas engine. For the last 10 years I've had a love/hate relationship with this engine.

My biggest beef with it is actually the stink. Even with proper ventilation and intact plumbing, the slight smell of fuel and exhaust is ever present inside the cabin after it's been running for more than a few minutes. I spend a lot of time on board in the summer, so that sucks to put up with. (Various strategies have been developed to minimize it, but it still sucks.)

Reliability is my secondary beef. It has been an on and off again engine, though most years have been trouble-free.

But not last year - it started leaking (dribbling) cooling water due to some seals going bad. So in preparation for this spring's launch, I pulled the engine a couple of weeks ago, fully intending to tear it apart, replace the necessary gaskets and o-rings and reinstall it.

Changed my mind. Going electric instead.

Here's the wee beastie: it's an OMC "Sail Drive" setup. (I've got a great service manual for it...)

http://ecomodder.com/forum/attachmen...1&d=1272937939

Step 1 is already done: the engine has been pulled.

I completed step 2 this evening: shaped a plastic plug and epoxied it into the lower unit at location (12) - the cooling water intake. No longer need to pump cooling water into the boat. Cooling leak problem solved!

The boat goes in the water, motor-less, this Wednesday or Thursday. The rest of the conversion will take place afloat, at the dock.

I've played around with electric boats before. This is a little more involved than my last "project" :D ... http://ecomodder.com/forum/showthrea...sion-9015.html

I'll keep you posted.

It's the next best thing to an Azipod.
http://upload.wikimedia.org/wikipedi...Launch_010.jpg

SW - very cool. A ship sized Minn-kota trolling motor!

The Sail Drive doesn't swivel though - flow over the rudder is how I steer under power or sail.

And it goes without saying that this conversion project will be typical Darin style: ie. making best use of available resources...

I still have a pile of left over parts from project ForkenSwift:

• 2 motors to choose from,
• a sizeable collection of golfcart batteries,
• contactors,
• 2 spare controllers (I may just do a contactor controller),
• and a selection of battery chargers.

As usual, the hardest part will be coming up with a coupler to connect the motor to the input shaft of the transmission (lower unit).

Sounds like a fun project to me. Looking forward to hearing and seeing more about it. :)

I should have gotten a photo / video of the ICE in the engine compartment before I started ... but when I took it out I didn't know at the time I was going this route.

But here it is out of the boat, the 67 lb stinkpot:

(shown in the same orientation as the diagram in post #1)


http://ecomodder.com/forum/attachmen...1&d=1272980033

Coincidentally, the entire engine is almost the exact same weight as one 6 volt golf cart battery.

Which always drives home to me how much power there is in petroleum fuel...

.

And here's option 1 of the two e-motors on hand:

http://ecomodder.com/forum/attachmen...1&d=1272980644

This is the permanent magnet power steering pump motor from the forklift.

5.5 inches diameter, 11 in. long, 32 lbs.

It's only rated .88 hp, continuous duty at 48v.

Consider: the ICE is rated 15 hp, peak. But for perspective, the vast majority of the time I run the engine, I'm basically putting around at 1/4 throttle, just to get in and out of harbours/docks/anchorages. Probably using about 3 hp.


Of course, we all know electric motors can be run at outputs well above their ratings, provided you don't melt them. Since the motor won't be used in the boat for extended periods, I'm thinking a small one may be OK.

Option 2 is the twin / "backup" motor to the one in the ForkenSwift, though it's actually overkill in terms of power and weight (8 in. diameter, 15 (?) in. long, 110 lbs).

http://forkenswift.com/photos/motor-sm.jpg

It's a bit of a Goldilocks situation: the ideal motor, the one that's juuuuuuuust right, is probably somewhere in between these two.

Maybe I'll drop by the forklift place and see if the guys have something else on hand that's surplus/headed to the scrap yard.

for what it's worth
on my cal' 27 the only motor i had last summer was a 47# thrust whisper guide (and a long paddle)
i could cruise aprox 3 knots without the wiring getting hot to the touch. into the wind went ok, up to 10+ knots, then i had to get the paddle out. i think our boats are probably about the same drag. mine is a 27' poptop disp. 5500#

unless you actually need to get to hull speed, against wind and current, i think any motor with 1+ hp should be enough, especially if you can play with prop pitch/size at all.
have you thought about regen/recharge under sail?
i'm looking foreward to seeing progress

That's good info, bryn. Funny too! (backup paddle) You sail on one of the finger lakes?

Yeah, the boats sound similar. This one is ~5000 lbs.

Just for kicks I have tried my Minnkota 17 lbs thrust electric trolling motor on it a few times. At high power, on calm water and in zero wind it will go along at the equivalent of a slow walking pace. Maybe a knot or a knot and a half.

To be practical, I'll need something capable of about 4-5 knots max. I'm on the St. Lawrence, and currents around here are 1-2 knots. And of course the prevailing wind is the same direction as the current...

The actual motor I played with (attached to a more appropriate hull :P):


http://ecomodder.com/forum/attachmen...1&d=1196565056

The idea of regen has occurred to me, particularly if I use the per mag motor. But to be honest, I spend more time aboard at anchor or tied to docks than I spend sailing, so it's not a priority.

Do you plan on solar charging the batteries while on the water? I know nothing of sailing or boating, but when your batteries dead, it's dead.

Don

I do have a 35w solar panel on the boat, yes. But even without that, I'm not worried about dead batteries and not being able to get home.

An auxiliary electric motor in a sailboat isn't going to come with the same set of concerns as an electric car.

I never used the gas motor just to "drive around", and I won't be using the electric motor to do that either. It's mainly for getting in and out of the harbour ... to go sailing for the afternoon when there's a decent breeze. So electric "range anxiety" really isn't a big issue.

Also, there's 110v, 20A electrical service ("shore power") at the dock to use for charging (among other things). So the batteries can always be 100% topped up at the start of each outing.

But what if the wind dies!!?

As it happens, my favourite areas for sailing are up-river from where I usually dock, so if the wind completely dies, drifting back towards the harbour on the current before switching on the motor to come in is an option. (Drifting in the current is actually a pretty popular thing for boaters to do around here on calm days).

And there are paddles. And there's an anchor. And a kayak on board. Lots of options.

Sort of like worrying about what happens if an electric bicycle runs out of juice. Well, you could pedal. And what if the chain breaks!!? Well, you could get off and walk it. Several options.

The boat goes in the water tomorrow (crane day!). Woohoo!

But this presented a minor problem with the gas engine removed from the lower unit (transmission).

Namely: sinking quickly to the bottom of the harbour. :)

The problem is that with the ICE removed, there is an open passage up through the gear case (below the hull) into the engine compartment to feed cooling water to the ICE. And since the top of the lower unit (inside the boat) is below the waterline, you can see where this would ultimately lead. Swimming with the fishies.

(Incidentally, this is an inherently bad design. If you ever have to change the water pump impeller - not an uncommon thing to do on marine engines - you first have to remove the engine from the lower unit to get to it. Which suddenly permits water to flood into the boat. Which means of course this boat has to be lifted out of the water to replace the water pump impeller. Clearly not designed by Germans.)

So my first task was sealing up that water passage.

I removed a plastic screen from the water intake, shaped a plastic plug to fit the opening and then hammered it in. Then I epoxied over the plug (several layers):

http://ecomodder.com/forum/attachmen...1&d=1273086081

After the epoxy cured, I slathered a liberal coating of silicone over top...

http://ecomodder.com/forum/attachmen...1&d=1273086081

To be extra safe, I will also be sealing up the top of the cooling water passage, inside the engine compartment. That's my task for this evening.

And here's a view of the top of the lower unit, showing the input shaft that I'll be mating to the electric motor...

http://ecomodder.com/forum/attachmen...1&d=1273086081

Edit: I'll also be removing the impeller (which is mounted directly on the input shaft), since we don't want that spinning merrily away in a dry water pump housing.

FYI, the cooling water passage is visible at about the 8 o'clock position from the input shaft.

FYI, I'm a noob when it comes to propeller theory. I haven't read up on it yet.

But the prop on this Sail Drive is a 3 blade, 11 inch diameter, 9 inch pitch.

The gearcase has a 14:28 ratio. (Why didn't they say "1:2"?)

The maximum operating speed of the ICE is "3300-3700" RPM according to the manual.

ICE idle speed (in gear) is 600-700 RPM, and that's enough to move the boat along at about 2 knots (2.3 mph / 3.6 km/h).

It's proud of how many teeth it has. :D

Awesome, I love it. Its very cool to see a different project like this. Even though its fairly simple, its still just fun.

Ran into a potential snag this evening.

I removed the impeller, and while doing so discovered the cooling water passage isn't going to be as easy to seal/contain from above as I thought. It really needs the bottom of the ICE to be sitting on it (or some facsimile!).

On top of that, looking over the manual, there's also a small chance that the seal I made in the water inlet of the gearcase (under the hull) doesn't make the gearcase 100% watertight! Water may also be able to find its way in through the cap on the end that holds the prop shaft/guts in place.

We'll know for sure tomorrow morning when the boat goes in.

Worst case scenario is I will have a slow leak, and will have to lift the stern of the boat up with the stationary crane to sort it out (to get the relevant bits above the water line. I had to do that once to change the impeller.)

Some good news though: with the impeller housing removed, the input shaft pops right out. That means I can make the coupler on the workbench, instead of having to monkey around in the engine compartment to figure it out.

I'm 100% certain you have thought of this, but have you considered something a little more "outboard" like? i.e. shave that wart off the bottom of the hull and smooth patch it, and come up with a small electric drive that you can tilt or lift up and out of the water when under sail? Could be bow mount or stern or whatever. Oversized trolling motor basically.

maybe a rack of trolling motors, linked together? :)

If Bryn is right, you can probably horsetrade for one or a couple reasonably large purpose built trolling motors. But getting the props out of the water alltogether under sail might actually make for an improved sailing experience.

MetroMPG

Ref your cooling/sealing challenges - I have a natural law which states that "secondary effects are always Primary"

Your mind is soaring with the optimum motor, and a left-over system from history is giving you grief.

If its any help with the power required, boats like this are (used to be) powered by British Seagull longshaft outboards. Altho plated as 4 HP, I understand they measured as about 1/2HP - but they had huge reduction and swing a large coarse prop. What they lost in power and honesty they gained in propulsion efficiency.
They would give a boat your size 3 to 4 kts and be adequate for most locations (except the Maelstrom or Minches)

For your relatively short running time you could probably also add more volts to your small motor to get the required performance - and watercool it if necessary for survival:D

andrew

Under the water pump housing, the metal plate with the semicircular cutout could be remade without the cutout and installed with a full gasket under it. Liberal use of sealant and removal of the impeller and you should be good to go.

Quick update: first boat in today (I don't like being the "test" boat). The good news: no crane mishaps! (Until later.) Oh, and no leaks ... it was still floating last I checked. :D

Some good ideas/info in the past few posts. Will reply later on.

http://ecomodder.com/forum/attachmen...1&d=1273178861

http://ecomodder.com/forum/attachmen...1&d=1273178861

Turned out in a last-minute inspection before this AM's launch (with quick set epoxy at the ready) that it is sealed.

I have thought of it, but the thing I like most about the inboard is ... not having to fiddle with an outboard. No question the boat is slightly slower under sail with the Sail Drive always being dragged through the water. But it's also very nice to be able to simply turn a key, move a lever and go. It also makes the boat more user friendly for non-boaty people who might need to drive it (when I fall off).

I'd only take that route if the ICE were trashed. It's still serviceable, so I want this mod to be optionally reversible. (My current 3 year plan calls for selling this boat.)

That calls up an AWESOME mental picture! I'm reluctant to fiddle with a single outboard given an inboard option, but I have to say the nerd in me finds something appealing in the idea of fiddling with a rack of trolling e-motors. Buuuuuut, no.

I don't really worry much about this boat's sailing characteristics. It's basically a water Winnebago. Recreational vehicle only - I don't race it. (Race on other people's boats.)

you've got it sealed it sounds like :) I was sorta thinking ahead to what if it doesn't seal. so what kind of rpm will your motors put out? did the forklift guys have anything? You gonna gear it down some more and how?

You're familiar with this motor! (Or is that a common pump housing approach?)

I thought I was going to take exactly this route. But it turns out the water pump can't easily be sealed to the water intake passage. It's immersed within a flooded "compartment" - the passage actually opens inside this area, beside the impeller housing. The pump is only actually sealed on the output side (to a valve that leads to the ICE's water jacket).

True, true, good points. I do know that this boat's 15 horse twin is uncommonly big - most of the other boats of this size around here get by just fine with 7 horse singles (gas or diesel), or 9 hp outboards.

And there are still a few people who use boats like this with no motor at all. It just takes away a safety measure and forces you to be more thoughtful about using the boat.

Water cooling it at this point is out. Too ironic!

But overvolting is always an option.[/QUOTE]

The small PM motor is rated 2300 RPM @ 48v. The larger one will spin at ~2k RPM on 12v, but that's with no load (my own bench test), so I'm not sure it's a valid comparison to the other motor's "official" rating. (I actually don't know how an e motor is rated.)

Haven't talked to the forklift people yet.

I'll be away at GGP tomorrow and Sat., and busy Sunday. So next week, Plan A is to jury rig a coupler for testing and connect the small motor to the input shaft to see what happens at various voltages.

Also this evening: I used the 17 lbs thrust Minnkota trolling motor to move the boat from the harbour where it was launched to a different nearby harbour where I have a slip.

Total distance: just under 1 km.

Top speed (with a light breeze at my back) ... slower than a normal walking pace. Guessing 3-4 km/h.

http://images.shipstore.com/ss/images/min/minendura.jpg


http://forkenswift.com/album/solar-l...kota-watts.gif

Made this current draw chart when I was playing around with the solar assisted electric boat last summer.

MetroMPG

Water-cooling comment (for the small PM motor) was intended as a little sad irony.

You have already answered the "complexity of sealing" the water passages; in complete ignorance I had assumed that there would be clear cooling passages going thru the hull which you could pour full of resin, of bathtub sealant, or similar - but that would be too easy, and it wouldn't challenge you
:D
andrew

Andrew - too bad it wasn't as easy as pouring sealant down the cooling passage. Unfortunately, the forward/reverse shift mechanism also runs inside the passage, from inside the hull down to the gear case. Not so simple, this one!

---

Update: the boat is still floating! (Sending this message from on board, actually.)

I haven't yet opened the top to see if any water entered the cooling passage from below.

Also haven't done any more e-motor fiddling, not counting moving the boat a couple of times with the trolling motor (once to go back to the harbour where I launched in order to put up the mast).

The Green Grand Prix last weekend, and the EV Expo this Saturday tinkering time is at a premium.

Next week should see some action on this project.

Darin
I still think you should hook your lower unit to a bicycle and pedal around the river!

Phil

ps;I have a 153 dacron Genoa for $100 if you still need a headsail.

Phil! I'll set up chain drive if you'll pedal! :)

Sure - I'd like to have a look at that sail. Remind me next time I see you.

The drive shaft is effectively vertical - so power it with either a windmill (how green would that be:)? ) or a squirrel harnessed to a radial arm.

Viola, a REAL squirrel cage motor!

More seriously, glad you are still afloat.
A question - in you original pic of the motor there is a large "trunking" rising above the motor with an angled end. Is this the air intake?
Sucking air from low down in a boat hull is pretty hazardous, because of the possible presence of gas in the bilges. A good recipe for a runaway if the engine inhales fuel in the intake.

Following this thought along - a DC motor is an excellent ignition source with its commutation sparks - might be a wise idea to incorporate a bilge vent fan which would also cool the motor, esp. if you plan on 144V.
andrew

andrew - I think you're referring to the exhaust manifold. Items 1 / 22 in the diagram:

http://ecomodder.com/forum/attachmen...1&d=1272937939

Agreed about the danger of sparks from motor brushes. Fortunately, I don't use gas for cooking inside the boat. I use electric when at the dock hooked to shore power, or the propane barbeque outside on the stern rail.

(I do need to move my propane tank outside the cockpit storage locker though - it could potentially leak and sink into the bilge.)

And I do have a good bilge vent blower available for motor cooling should I need it.

After a hiatus for other projects since launch, I'm back at this little conversion exercise.

Started working on a "test" coupler (wood). That's my style.

I brought the motor down to the boat this evening, expect I'll make up a quick bracket/platform (wood also) and try it out before the end of the day tomorrow.

6v test first, jumper cable "contactors". Progressing in 6v increments to 24v or wooden coupler failure, whichever comes first. :D

Hi Darin
Tractor Supply Co. has a selection of steel and rubber couplings that might get your motor connected to the drive shaft.
Good luck with the installation!Let me know if you need a hand.

Phil

Hi Phil - I should check that out. I need a specific size of 14 spline coupler... wondered if I could salvage/adapt the crank end from a dead outboard from Gilbert's marine...

---

Anyway: success!

Then: failure!

The good news is: I slapped together a wooden motor mount, coupled & aligned everything as best as possible, connected the jumper cables and it whirred happily away with a minimum of vibration.

On 12v in gear there wasn't enough thrust to move the boat against a 8-10 knot breeze (guessing). No surprise there - really wasn't expecting it to. (I just slacked the dock lines and played around without leaving the slip. The wind was on the nose, pushing me back in.)

So I stepped it up to 24v and the thrust seemed more promising... briefly ... until the coupler split! Then it spun uselessly. I may attempt a repair/reinforcement and try 24v again tomorrow.

It looks like at 12v it will only be useful in calm flat conditions, much like the electric trolling motor. I'll need 36 or 48v to get any serious push from it.

Will post a bunch of pics tomorrow showing what I've done so far.

what motor specs did you wind up with?

Motor specs!

I am watching with anticipation I too have a 30 year old sailboat where the motor is on its last legs. Keep up the good work, if it goes as well as we hope I will consider following suit.

Thanks.

Well, I'll "keep up the work". There's bound to be some debate about whether it's "good work" or not.

But I'm having fun!

----

OK, some photos... Prepare to be amused!!

http://forkenswift.com/album/20-wood...er-parts-1.jpg

Above: the component parts of the test coupler v.1.0:
- wood to go over the input shaft
- the slotted disc is the hub from inside the power steering pump (the slots used to hold the pump vanes)
- the removable pump shaft to the motor (note pesky keyway style interface to the motor)


http://forkenswift.com/album/20-wood...er-parts-2.jpg

Yes, the pump hub is nailed to the wood. :) So far that part has been the LEAST trouble!

http://forkenswift.com/album/20-coupler-wood-shaft.jpg

Above: change of plans... instead of trying to clamp it on, four screws are set into the slots between the input shaft splines. More positive connection.

http://forkenswift.com/album/20-coup...od-mounted.jpg

Above: shaft & coupler installed in transmission & base plate for the (wood.. of course) motor mount.

http://forkenswift.com/album/20-motor-mounted.jpg

Ready to go!

http://forkenswift.com/album/20-coup...od-cracked.jpg

Gone! :D

The mechanical connection to the input shaft was so good that the failure point became the wood. It worked fine on 12 volts. But when I started up at 24 volts (from rest), the wood split in 3 places.

---

Since taking these pics, "work" has continued. I modified and tested coupler v.1.1 last night. It worked great ... until it failed. (Lasted many seconds longer than the first version though.)

Version 1.2 will be tried tomorrow.

I'm almost ready to invest in a metallic coupler - I hear they're all the rage these days.

lol awesome and ghetto at the same time. Gotta love Darin's projects. :)