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Electric propulsion and conversion questions


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20 minutes ago, Sabre said:

There are some really big positives to going electric and making the switch is very, very tempting! Quiet and simple to maintain being the most obvious pro's but as soon as a generator/genset is added then aren't those benifits lost and in fact increase the complexity?

Day sailing from a plug in marina seems viable but I just don't see it working well on a typical cruising yacht (yet). 

 

Fair comment. Don't forget the incredible level of low speed control and torque.

You either need shore power or a good amount of solar. Solar limits you to doing consecutive long trips only on sunny days or with time to charge in between. Most cruisers only sail in fair weather and it's usually sunny when there's no wind, so that can be OK.

A cheap, lightweight portable genset can sit in a locker for peace of mind and get pulled out once a year if you need it in a pinch.

Of course it's better if people plan their trips properly and make small changes to their behaviour so they never need a generator and enjoy their sailing more, but sometimes it's needed as a cure for "range anxiety", even if it is never used it makes people feel better about taking the leap to electric, then they adapt and realise they didn't need one after all.

If you need to run your engine more than a few hours it's usually due to bad planning (taking on a longer trip than you have time for, or going in the wrong direction for the weather)

A $400 generator is a better option than $10,000 of extra battery capacity which you only use once a year. You can get rid of the generator next time you upgrade the batteries when battery prices are lower.

Full electric propulsion might not be right yet for yachts kept on swing moorings but they do all need an outboard for the dinghy. a light weight electric one is absolutely perfect for the short trip out to your mooring. Throw it in the car with no worries about smells, oil stains, cancer or explosions! There's no cooling water circuit to flush out and no impeller to break either. The motor is in the bulb at the bottom so it is naturally cooled by the sea water passing over it. Everyone hates their  unreliable, high maintenance outboard. NZ is just about the only country in the developed world where two stroke outboards are not already banned.

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8 minutes ago, harrytom said:

It all sounds good as far as propulsion goes.So what happens when you turn on the freezer?Drop in power/speed 

A freezer uses about 50-60 watts, negligible compared to propulsion. You won't notice any difference.

Some people use a separate 12v house battery and a 48-12v charger (necessary if you have a 12v windlass), others just have a 48-12v converter for smaller loads. A 48v windlass makes a lot of sense but they are hard to find. That will change.

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5 minutes ago, syohana said:

A freezer uses about 50-60 watts, negligible compared to propulsion. You won't notice any difference.

Some people use a separate 12v house battery and a 48-12v charger (necessary if you have a 12v windlass), others just have a 48-12v converter for smaller loads. A 48v windlass makes a lot of sense but they are hard to find. That will change.

I talking about belt driven freezer off motor.I should of been clearer.

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7 minutes ago, harrytom said:

I talking about belt driven freezer off motor.I should of been clearer.

I don't see why a belt driven freezer would use much more power than an electric one. You could perhaps put a pulley on the propshaft but I've never seen it done. Remember there's no gearbox so there's no neutral, you can't run the motor without turning the prop. How would you run the fridge at anchor? Better to just use an electric freezer.

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42 minutes ago, syohana said:

I don't see why a belt driven freezer would use much more power than an electric one. You could perhaps put a pulley on the propshaft but I've never seen it done. Remember there's no gearbox so there's no neutral, you can't run the motor without turning the prop. How would you run the fridge at anchor? Better to just use an electric freezer.

Engine driven fridges use an eutectic storage plate. The compressors are always an order of magnitude more powerful than the biggest 12v system.  Thus they freeze holdover plates in under 20minutes when power is in abundance.

Run the engine once in the morning, freezer/fridge are done for the day and if you're not careful you've frozen your beer. 

1 hour ago, harrytom said:

I talking about belt driven freezer off motor.I should of been clearer.

With electric you'd get rid of the engine driven compressor and switch to an electric compressor (another thing you need to factor in).

If you stick with a holding plate, this requires you to get into the habit of leaving the fridge on all the time runing off the solar so that your holding plate stays charged, otherwise it will take a day or longer to draw down your holding plate at 60watts.

If you switch to an evaporator plate then you'd just run the fridge as a normal fridge but this of course requires modifying your existing fridge/freezer to get rid of the holding plate or at least fill it with expanding foam. 

Either way, all those engine driven things need to be taken into consideration. Eg watermaker. 

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The reason why the engine driven units were so energy hungry was that the units were designed to pull down the temp in the storage plate as fast as possible due to the engine usually only being run for short periods. Then the storage plate continued to pull heat from the freezer/fridge box while the system was off.

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Interesting stuff, but tempered with the reality of my sailing profile it just doesnt work, also I am aware of a number of well known cruisers that have had to change back to diesel after converting to lecky once the reality of living with it set in.

For super keen Rum racers ideal, but for the Barrier at Easter and the Bay at Christmas type yachty we have a way to go.

PS Torqeedo not really made in Germany, and they do have an exact sail drive replacement for those that want/need it.

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I have probably spec;d more yacht props than anyone else in NZ over the past ten years and always calculate to use the full torque and horsepower of the diesel / gearbox combo.

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1 hour ago, waikiore said:

I have probably spec;d more yacht props than anyone else in NZ over the past ten years and always calculate to use the full torque and horsepower of the diesel / gearbox combo.

With a fixed prop you can only use the full torque at one chosen RPM.

If you set the prop to use the full torque at maximum horsepower (say 3200 rpm) then it won't be using anything like the full available torque at any other RPM. therefore if you read off the torque curve that your engine can produce 20hp at 2200 RPM, that's not actually true because you didn't set the prop to fully load the engine at 2200 RPM, you set it to be fully loaded at 3200 RPM.

Selecting a prop for maximum peak horsepower output results in the engine revving much higher than necessary at cruising speed, basically unloaded. Since you spend most of the time at cruising speed your system will be inefficient most of the time.

CarpeDiem could probably reach the same cruising speed at much lower revs with a prop optimised for the cruising speed, but then they might be over-propped at WOT and unable to get up to the max revs of the engine. If you only run at cruising speeds, being a bit over-propped can be good. CarpeDiem thought they were using most of their horsepower at cruising speed because the revs were relatively high, but the revs are high because the prop is not optimised for that speed and it's running unloaded.

Brunton's Autoprop is a clever solution to this catch-22 because it changes the pitch all the time according to the torque. It's for keeping revs low when motor-sailing too. I'd be interested to experiment with an Autoprop with electric propulsion where there's huge torque available at the low end, it might need a redesign for the electric torque curve though.

 

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25 minutes ago, Black Panther said:

Coincidentally we had dinner last night with a couple that sailed here from Seattle,  35fter, all electric. Happy as and would never go back.

Ava and Pajo? They are real sailors who use their sails. They get by with a tiny battery capacity and minimal charging capability. Respect to them for doing it right. It's about having the right attitude, remembering you're on a sailing yacht and not a motorboat with a mast.

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On 30/03/2021 at 10:31 AM, syohana said:

We have one Torqeedo 1103C left in stock, that's equivalent power to a 3hp petrol outboard. Priced only a little higher than the Chinese ePropulsion clone but it's actually made in Germany and to a very high quality.

We also have Combi outboards from the Netherlands which are bulletproof, solid aluminium, no plastic parts. they will run for longer than the whole lifetime of a petrol outboard before the first quick service to change seals and bearings. They cost a little more to buy but the lifetime cost is far less than any other petrol or electric outboard, especially if you use them every day. Lifetime means not just your lifetime but the grandkids lifetime too!

You do need to overcome that initial big spend but then you reap the benefits of zero maintenance and no fuel or oil to buy. If you use it every day it can pay for itself in one year. You can keep the initial spend down by using lead acid batteries if the boat will take the weight.

 

Mmmm... looking at a few NZ outlets the 1103c is about $4900 , presumably a fair chunk of that is the Lithium battery, the 2hp Yamaha is $999. I get the bit about the cost saved in fuel etc but at nearly 5 x the cost its a big ask. I'm guessing prices will come down in time as they will for electric cars. With the brushless motor in the hub and a much reduced parts count overall the skin would look to be much cheaper to manufacture at scale.

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4 hours ago, Frank said:

Mmmm... looking at a few NZ outlets the 1103c is about $4900 , presumably a fair chunk of that is the Lithium battery, the 2hp Yamaha is $999. I get the bit about the cost saved in fuel etc but at nearly 5 x the cost its a big ask. I'm guessing prices will come down in time as they will for electric cars. With the brushless motor in the hub and a much reduced parts count overall the skin would look to be much cheaper to manufacture at scale.

A second battery retails for around $1600.  The 1103c batteries are ~35ah Lithium Manganese, so at $1600 it's expensive for what it is. 

So the motor is expensive no matter how you look at it.  And adding that too a non electric ready cruising boat you have the added expense of charging, presumably overnight so your dinghy is ready for use the following day.

My Yamaha 3hp 2-stroke cost $1150 in 2016.  Since then it's had exactly zero $ spent on servicing and maybe $200 on fuel, oil and carbon credits if that. 

I can't find any numbers on the break even usage when compared to petrol. It simply doesn't stack up for me. I wish it did, I would love to make electric work for me financially or even be closer than it currently is.  But $3000 is still a lot of money. 

Either the price has to come down or regulation and fuel levies need to come into effect to drive adoption. 

All that said there are some cheaper options out there than the Torqeedo. Especially so in the DIY space. I have worked out that I could get into a 85lbs thrust motor with a 40ah lithium battery pack for around $2000.  If this petrol outboard of mine ever packs it in... 

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SYO some props are controllable pitch -or like mine have two different pitch settings, not the Autoprop which sets itself -not ideal in a big and bouncy sea, check out Torqeedo pricing in the UK for an indication in a competitive market where it really lies against other small (four stroke) outboards. 

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Spokes person was on zb Yesterday talking about EVs and basically Toyota will not fully commit to EV until child labour stops in the cobalt mines.

 

 Given that more than half the world's cobalt comes from the DRC, that one fifth of it is extracted by artisanal (or informal) miners, and that around 40,000 children work in southern DRC where the cobalt is mined, there's a chance that our phones contain child labour.

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23 hours ago, Black Panther said:

Yes. Coincidentally there's is a sistership to a previous boat of ours.

They have a website at sailingcinderella.com if anyone is interested in their story. I have invited them to visit the forum here and give their perspective.

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