Electric Speed Boat

Hello everybody this is my concept idea of fully electric speed boat design, i hope you like it. You can find info about boat on video.
Please share your comments and critics.

Regards Harun Kemali


http://www.youtube.com/watch?v=1G4DxFDWAtU

 

Nice bit of artwork, but isn't it a bit of a distant dream rather than a boat that could actually be produced and sold?

For example, you say that it has 140hp (peak). If the boat ran at, say, 50% peak power on average, then that's 70hp, or 52.22kW.

Let's say you wanted an endurance of two hours (so a practical range of perhaps 50 to 60nm at around 50% power).

The best motor efficiency you're likely to get will be around 90%, and you'll incur around another 5% losses in the controller, wiring and battery internal losses (assuming state of the art lithium batteries).

The battery pack then needs to be able to deliver about 123kWh of usable power.

To get a reasonably good cycle life, the battery pack needs to be kept within the state of charge range of between 30% minimum and 95% maximum, so the usable capacity will be around 65% of the rated capacity.

The battery pack therefore needs to be around 189 kWh.

The best readily available lithium cells have a specific energy of around 280 Wh/kg. A 189 kWH battery pack would therefore have a mass of around 675kg.

How is your light weight, high speed, boat going to cope with over 2/3rds of a tonne of battery pack?

Even if you reduced the endurance requirement down to just one hour, you're still going to need a battery pack that weighs around 338kg.

On the other hand, if you chose to use a 140hp internal combustion engine then you could have a fuel weight for two hours endurance of around 50kg.

I don't know what electric motors you're looking at, but on average high power electric motors may be around 1/2 to 2/3 the weight of an equivalent internal combustion engine, but even so the comparison doesn't look good:

140hp internal combustion engine, plus fuel for two hours at 70hp average ~ 225 to 275kg

140hp electric motors and controllers, plus battery with two hours endurance at 70hp average ~ 800 to 850kg

 

looks good. I would have single drive for the best efficiency and it would save weight. prop torque may be a problem though with such a narrow beam.

 

Jeremy that little boat should perform well with 30 or 40 hp. 140 is way over the top.

 

When anyone talks about a boat with electric propulsion I do not expect to see a more or less beautiful forms, but knowing how the designer has solved the problems that raises electric propulsion.
The topic is very interesting, so I would suggest that you explain us more the subject of propulsion, batteries, autonomy, ... Thanks

 

What is the design weight and dimensions of the boat? I am unable to watch videos from the PC I am currently working on...

From the styling point of view, I appreciate the cockpit design and the color scheme. But I am not at all sure that a single-seater is the way to go.
The appearance of the hull sides look a bit too flat and sterile, require more work imo.

But, as Jeremy and Tansl have pointed out, the real challenge is not the aesthetics in this case. The real challenge is the technical one, related to the power/weight ratio of the existing electric-propulsion technology. What are your design data?

Cheers

 

video states:

length: 4.8m
beam: 1.05m
displacement: 320kg

All carbon fiber
50+ knots top speed
140hp peak power

 

It's the 320kg displacement that's the gotcha here!

Take one crew member at 86kg, plus a 140hp electric motor at around 80 to 100kg (inc controls etc) and there's more than half the displacement budget gone, with around 150kg or less for the hull and battery pack weight.

I don't wish to be rude, but aren't naval architects supposed to start off with some specifications that make a modicum of sense before indulging in fancy designs that cannot possibly be built? (the OP is a naval architecture student)

 

It can work with a 75-80 HP outboard, but not with an electric drive - for the reasons so well explained by JH.

Unless it is designed to have less than 20 min. autonomy, of course.

 

Maybe some students start the design spiral by selecting the colour scheme.
The practical design aspects come into play during the next iterations.

 

Well, this is "only" RC-but given time and development speed won't be a problem. This may be old hat to some of you ,but I had no idea RC electric boats were this fast. Found this on a sailing thread discussing planing hulls(!) :
http://www.youtube.com/watch?feature=player_embedded&v=Do9k3iCFQWA

 

You can get speed now, but just like RC boats it's at the expense of endurance. Those very fast model boats run for a few minutes, maybe 10 to 15 minutes at best. Well over 20 years ago An Stradag held the electric boat speed record at a touch over 50mph.



Since then An Stradag has been improved and has run at close to 70mph. The big downside is that it only has enough battery capacity for a couple of runs over the measured mile, so it's endurance can be counted in minutes rather than hours.

 

I join the others in complimenting the graphics. Jeremy has described the prohibitive details with authority.

My take is that the bottom loading, if it ever gets on a plane, will be impractically high given the narrow beam, short length, and all that weight. As drawn the boat, at rest will draw 25 to 30 cm of water. Now if we could get the all up operating weight down to 125Kg or so, the boat would be great fun as well as pretty.

I wish the OP well. Perhaps he will come back with some modifications that make the project more nearly practical.

 

Firstly thank you all for your comments. I need to state that I started this design as a leisure work and cad learning study, an extensive work and engineering needs to be done for production model.

As general technical considerations:
I was a member champion team of Istanbul Technical University Solar Boat Team for 2 years. Our Boat has similar dimensions: Loa: 5.2 meters Beam: 1 m Draft approx. 12cm. Boat has semi-planning full for both endurance and sprint race. In sprint mode, with two 12 kW (peak) dc perm motors and single surface propeller she goes at the speed of 24 knots at 36 volts. Its hull weight around 30 kg and total weight including driver is around 250 kg. It has 3 lead acid starter batteries (45 kg) due to race limitations. She can go at this speed about a minute.

So I choose similar dimensions but different hull type. My weight estimate for concept is like this: 40 kg hull, 100 kg motors, 75 kg skipper, 80 kg battery pack and 25 kg other stuff (cables, seat etc.) I considered these engines as benchmark but I didn’t do a detailed research about other options: http://hpevs.com/catalog-ac-50.htm. Maybe ac-35 series or similar motor can also be used. 50 series engine has 71 HP peak power at 96 volts. As a battery I considered these batteries: http://liteplusbattery.com/lithium-ion-battery-technology/
http://www.a123systems.com/lithium-starter-battery.htm

I put two surface drives for good looking but as you stated probably one should be enough. As top speed i used hullspeed software for approximate estimation. Around 30 HP it estimates top speed as 28 knots which is considerably good result when ITU Solar boat taken into account. With 140 HP programs estimates the top speed a little bit more than 50 knots.

For endurance actually boat can go more than one hour if speed lowered to around 7-8 knots (which does not require half power) and props chanced with slow speed ones but it is not the case here I only considered going full speed. For endurance extensive tests must be done with different battery and propellers at different speeds to find optimum range.(As consideration ITU solar boat goes two hours with 6 knots but different outboard system and she has only two 40 Ah lead acid batteries but got 400 watt solar panels on her)

You can find detailed technical report about ITU Solar Boat Team here: http://www.solarsplash.com/spl_tech_report.php

 

good luck

Such projects are really interesting and it is a credit to all the people involved !! if its weight saving thats needed then not much thought has taken place with the hull and deck look tradionally beautiful in a project such as this so much of what you see is doing little to nothing at all top sides are big fore deck is big !! its all unnessasary paneling and use of materials ,remember shape can produce strength without added weight ! flats are weakest , add curves and creases produce longtudinal strength . Steps in the planning surfaces to intoduce air and help reduce skin friction with the waters surface !
A really nice video and i take my hat off to all involved, good luck and keep posting progress !! so often theres a flash of genius and something exciting and new and its never seen again and no one knows what the final out come was ! good or bad there is always room to improve on perfection !!