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

[MetroMPG]

Originally Posted by MetroMPG

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!

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

[MetroMPG]

Originally Posted by dcb

I'm 100% certain you have thought of this, but have you considered something a little more "outboard" like?

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).

shave that wart off the bottom of the hull and smooth patch it

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.)

maybe a rack of trolling motors, linked together?

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.

getting the props out of the water alltogether under sail might actually make for an improved sailing experience.

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.)

[dcb]

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?

[MetroMPG]

Originally Posted by moorecomp

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.

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).

Originally Posted by lightflite

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.

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.

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

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

But overvolting is always an option.[/QUOTE]

[MetroMPG]

Originally Posted by dcb

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?

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.

[MetroMPG]

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.






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

[lightflite]

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

andrew

[MetroMPG]

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.

[Philscar]

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.

[MetroMPG]

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.