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Old 18 September 2017, 14:56   #71
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Originally Posted by Last Tango View Post
Now I’m intrigued.

26kn for 90mins giving a range of 40mls Hmmmm?

80Hp (60Kw) for 90mins would be 90 Kwh Three times the capacity of the battery.

So it can do 26kn…. it can run for 90mins…. but it can’t do both.
Even if it could, it’s not going to get you from Kyleakin to Canna and it certainly isn’t going to get you back.
No displacement figures but I’m guessing when it’s sitting on a trailer it's not going to be towed with any, currently available, electric car.
So this “future isn’t now” and it looks like what’s coming in 2019 ain’t going to cut the mustard either.
"Normal use", aka, cruise speed.

But keep in mind, this boat is designed as a tender, not a primary boat.

The original fuel tank was only about 12 gal w/ turbo 140 hp 4-st, so the endurance was quite similar when operating it at WOT. Less than an hour, although the speed was definitely more impressive.

29 mph is a perfectly acceptable top speed though for a 4m tender.
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Old 18 September 2017, 15:07   #72
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"Normal use", aka, cruise speed.

But keep in mind, this boat is designed as a tender, not a primary boat.

The original fuel tank was only about 12 gal w/ turbo 140 hp 4-st, so the endurance was quite similar when operating it at WOT. Less than an hour, although the speed was definitely more impressive.

29 mph is a perfectly acceptable top speed though for a 4m tender.

How do you recharge a tender while aboard the main craft...
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Old 18 September 2017, 15:12   #73
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the motor is most efficient at 54% throttle according to their own spec so i assume they propped the boat to get it in that range at best speed for the hull in use.

if that is the case then the outboard is being used at 43hp which nicely equates to about an hour at roughly 14/15 knots and the batt is flat. to get 90 min run time normal use must be off plane and pottering about, fine for a tender.

maybe to recharge it the outboard has regenerative charging and you tow the tender with the big boat to charge it
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Old 18 September 2017, 17:54   #74
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It may not be a long range boat but many boats aren't used for long range
IE tenders, sailing club safety boats, harbour launches etc
As for charging a tender most boats big enough to carry a decent size tender will have on-board generators or be on shore power at night
Plenty of people knocking the project but not everyone's boating needs are the same.
It wouldn't suit me but I can see practical uses for an electric boat and will be interested to see how it performs once in the water
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Old 18 September 2017, 18:09   #75
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How do you recharge a tender while aboard the main craft...
Tender garage in the stern.

Jet is ideal because there's no lower unit that sticks out, and the boat is short.
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Old 19 September 2017, 02:04   #76
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Morning last tango,

Thanks for your post and calculations

Its exactly what a good debate needs! I hope to post all real statistics when i test the rib. To give all a precise understanding of where the technolgy is presently.
I also pleased, as i do not need a boat that I will run for 5hrs at 20kn's.
My goal is to do some wake boarding with family, fishing and some coastal exploration trips etc, all at low cost, low noise and polution free.

As your approximations have highlighted, its presently all about battery technolgy and cost of batterys. Very exciting when you see where the automotive industry is moving and the marine industry has historically followed suit.

Have a great day
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Old 19 September 2017, 03:55   #77
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Quote:
Originally Posted by HDAV View Post
How do you recharge a tender while aboard the main craft...


Anyone who has a budget big enough for a 4m jet tender, and especially an electric one has a boat big enough to charge it! Of course that means it is burning diesel to do that (unless he waits till its back on shore power in the marina) but it still looks eco, and avoids the inconvenience of having smelly, flammable petrol on board.

I think Ken makes an interesting point about club safety boats. They need to go fast for short periods, spend hours bobbing around, need good torque for towing dinghies, often are pulled out and stored ashore, and have headaches with fuel storage and transport. Add to that reservoir use where fuel makes water authorities anxious, and the perception of noise in beauty spots and they could well be one of the relatively early adopters...
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Old 19 September 2017, 06:31   #78
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Anyone who has a budget big enough for a 4m jet tender, and especially an electric one has a boat big enough to charge it! Of course that means it is burning diesel to do that (unless he waits till its back on shore power in the marina) but it still looks eco, and avoids the inconvenience of having smelly, flammable petrol on board.
It's interesting they've gone for a jet drive rather than a prop they obviously think the reduction in range due to the jets inefficiencies is outweighed by the benefit of using a jet.
With regards to charging, many large boats generators will be running at night with little load therefore some of the spare capacity can be used up by charging the tender so the diesel being burned could in certain circumstances be very little.
And no guarantee that the shore power used for charging isn't from fossil fuel anyway
I can see a future market for electric boats
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Old 19 September 2017, 12:51   #79
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.......I hope to post all real statistics when i test the rib. To give all a precise understanding of where the technolgy is presently.
I also pleased, as i do not need a boat that I will run for 5hrs at 20kn's.
My goal is to do some wake boarding with family, fishing and some coastal exploration trips etc, all at low cost, low noise and polution free.

As your approximations have highlighted, its presently all about battery technolgy and cost of batterys. Very exciting when you see where the automotive industry is moving and the marine industry has historically followed suit.......

I can see where you're coming from and I'd imagine you'll get a lot of fun out of it.
As I said my calculations are "back of a fag packet" standard and as you say the proof of the pudding is in the eating.

I think there is excellent potential for the technology in, for example, canal and inland water boats where the power to weight ratio isn't waiting to bite you in the ass. Charging opportunities will also be easier to provided.

However looking at most 5mtr+ RIBs, they are typically bunker-ed to give 100miles+ and powered to the tune of 100-150hp per ton. Battery technology as it stands can't come anywhere near this and their weight would have to be a tenth of what it is just now to compete.

Add to this their "green" credentials and cost reduction drive is not all it might be....

https://www.greentechmedia.com/artic...onmental-risks


The car industry has a better chance with this but there is going to be a monumental cost for putting the charging infrastructure into place, and HM revenue is going to have to recoup the 32 Billion fuel duty from somewhere.
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Old 19 September 2017, 13:40   #80
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Electric rib project

Quote:
Originally Posted by Last Tango View Post
I can see where you're coming from and I'd imagine you'll get a lot of fun out of it.
As I said my calculations are "back of a fag packet" standard and as you say the proof of the pudding is in the eating.

I think there is excellent potential for the technology in, for example, canal and inland water boats where the power to weight ratio isn't waiting to bite you in the ass. Charging opportunities will also be easier to provided.

However looking at most 5mtr+ RIBs, they are typically bunker-ed to give 100miles+ and powered to the tune of 100-150hp per ton. Battery technology as it stands can't come anywhere near this and their weight would have to be a tenth of what it is just now to compete.

Add to this their "green" credentials and cost reduction drive is not all it might be....

https://www.greentechmedia.com/artic...onmental-risks


The car industry has a better chance with this but there is going to be a monumental cost for putting the charging infrastructure into place, and HM revenue is going to have to recoup the 32 Billion fuel duty from somewhere.


I agree. As a (super)yacht tender, there is probably a market & practical application. But in the wider boating world the tech needs to mature exponentially before it can come close to fossil fuel. I just can't reconcile the logistics of a battery. How would it work on a mooring? Camping? Long round trip e.g around Mull? You could apply the same questions to the car market. As a city runabout electric is perfect, however, towing a 2tonne boat 1200 miles is a different kettle of oysters.
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