Electric launch

16ft Duffy anchored in Middle Harbour

Last Friday was nice sunny day and I’d arranged to go boating with Steven from Eco-Boats down at Northbridge. Steven’s business is to sell and rent electric boats of various sorts and I went for a tour around Middle Harbour on his 16ft Duffy launch. Looking as though it should be on an English river with its full awning its actually really well suited to the Australian sunny days.

It makes for a really pleasant way to explore Middle Harbour. The boat is kept at Northbridge Marina and we cruised around to Bantry Bay which I remember from 80’s when I sailed on Sydney Harbour in a yacht owned by me and a mate, Chris White. (You can catch up with Chris and Dianne on their blog). Bantry Bay was one of my favourite places in the harbour – its amazing because from the bay, all you can see around you is wild Australian bush.  And this is in the middle of one of the world’s busiest cities. So it was a treat to go back to Bantry Bay and find that its still as private as ever – mind you it was midweek when no one else was there – Steve tells me it can be crowded on summer weekends.

Nice luxury for an afternoon on the harbour

This boat is imported from the US and Duffy makes the whole package.  It runs on six 6 volt batteries and you can easily get a good half day’s cruising from a charge.  The prop is attached to the rudder, so its really responsive to steering and can turn in its own length.  This makes it quite easy to drive for people who aren’t experienced with boats.

If you’d like a day out on Middle Harbour and like to try out the silence of an electric boat, check out Steve’s website for all the details you need.

He also imports various electric drives for retro fitting to diesel powered cruisers and sailing boats, so its a good site for those interested in converting to fume free boating.

Speed test – not.

A glassy smooth Careel Bay beckoned me to do some speed trials.  Cos so far there’s always been a bit of wind and it wasn’t clear just how much the wind was contributing to, or slowing her speed.

So I dropped the mooring and started taking notes as she wove out through the moorings.

1630 watts = 4.5 knots

4600 watts = 6.2 knots – full throttle

Strange…  in earlier tests I was confident that she was topping out at about 6.5 knots so this is odd to see maximum speed a little less than I expected.  Perhaps those readings were wind assisted.  Anyway, back to it. I’m using the stop watch on my iPod Touch to time how long it takes to come to a full stop.  And then I can do the same test late with the standard prop. Back to neutral and then to full power in reverse.


and the watts drop off to around 700.  What was that? Can’t see any obstruction to the prop. Try forward – also in forward the maximum load is about 700 watts.

Broken ends of pin sat at a nice angle to grab the shaft

I suspect the shear pin may have broken. Now I’m worried the prop might fall off, so I throttle back to about 100 watts and she’s going along at 1.5 knots.  I haven’t gone far from the mooring, the day is still calm, so I’ll limp back ok at this speed.

Sure enough the ends of the pin have sheared off as designed and have laid against the shaft in such a way that they still grab a prop a little.  700 watts worth actually.

Speculating about the maximum speed being reduced, and remembering having hit some big jellyfish last weekend, its likely that the prop has been slipping just that little ever since the jelly fish encounter. One of them really got hit with the prop and the motor almost stalled, and it was probably then that the pin sheared.

Pin ends have rubbed a slight groove in the shaft

So its rather clever of me to have decided to do this test today in perfect calm, and discover the problem.  Otherwise I may not have noticed until the chips were down and I really needed it. I now think the clunk I heard was the pin ends swapping around as the load reversed on the prop.

Its nice that the nut didn’t come undone with the free spinning of the prop on the shaft. And drop the prop into the sea.

New Throttle

Replacement throttle lever and mounting plate

Back in Sydney Harbour about two months ago I had a problem with a wobbly throttle control.  I anchored right away in nearby Farm Cove and that afternoon Claude instructed me on making a temporary fix using Loctite to stop the bolt from loosening again.

Since then Claude has been to The Torqeedo factory and returned with a new throttle control of a new design that precludes this problem from raising its head again.

Torx bolts hold the plate onto underside of controller

The mounting plate is held by torx head bolts which I can undo with the Leatherman tool.  Crikey! A leatherman is a handy thing to have on a boat.

Removing the mounting plate reveals an intriguing connection between the throttle lever and the control box electronics.  Well, actually no physical connection at all – its uses a magnetic field for this analogue to digital interface.  This is a nice idea for a marine environment – its leaves no entry point for water.

Underside of control - no axis for lever to attach to - its done by magnets.

This job only took a few minutes (and even longer to take photos of and write about!) and I gain a spare throttle lever. Now thats fixed I have no excuse but go on with repairing the cockpit seat.

The chart is of Broken Bay, of which Careel Bay is a minor part, on the edge of Pittwater.  I enjoyed plotting our course down to Sydney, and then Port Hacking – the chart plotter was out of action due to losing the GPS antenna. Which is a pity cos it cost $475 for a new one. Even though I sometimes plot our position on a paper chart, it comes from the GPS coordinates.  So it was fun to do it from compass bearings and other coastal navigation techniques.