The Electric Boat Thread

[John in CR]

Lock,

Thanks for sharing but I'm sure Jeremy as well as myself want to build electric boats that are useful. Make the hull in the clip longer and it's likely to go faster on the same 200W. I'm looking at building a 1000-1500lb cat that can handle another 1000-1500lb of passengers, and is sturdy enough to be comfortable 30-40miles out in the ocean, and will achieve 6-7 knots (the high end of trolling speeds for sailfish, marlin, tuna, and mahi, which a prevalent here "in season") using only 1200-1500W.

John

[BMI]

Hi to all you guys who are interested in large electric boats.
I thought I would post some info on an e-boat project here in case anyone is interested.
I am in the middle of a project where we are converting a 50 foot racing catamaran to all electric drive. This will be the most technologically advanced electric boat in the world when it is finished due to the advanced battery diagnostics and monitoring capabilities. It will be powered by three 5kW Power Pod retractable electric motors. We are just waiting for the motors to arrive from the US any day now. The 48V 240Ah battery bank is already at the boat yard waiting to be installed.
The boats' batteries will be recharged by solar panels, back-up diesel generator and re-generation (when the boat is under sail power in strong winds).
The boat has been entirely stripped out now in preparation for fitting of batteries, motors and all associated electrics.
As you can see from the below photos of the boat in its current state the boat looks pretty bare.

I will be happy to provide updates as to progress if there is interest here. There will be a full featured article appearing on this electric boat in at least two major boating/alternative energy magazines which will show to those involved in the boating industries what is currently achievable with regard to electric boat technology.

[Lock]

Lock,
Thanks for sharing but I'm sure Jeremy as well as myself want to build electric boats that are useful.

Hi John. Understand!

From the original post:

The canoe I'm planning to build is the Selway Fisher Raven on this site: http://www.selway-fisher.com/Opcan16.htm. It's a ply, stitch-and-glue, open canoe. It seems to need around 40 watts or so to travel at 3.5 to 4 kts. It's maximum hull speed is about 5 kts, but it would need around 200 watts to reach it. My plan is to build a cruising boat that I can use to travel inland waterways and lakes at normal paddling speed, hopefully with some solar cells to augment range and allow charging when not moving.
The finished canoe should look like a scaled-down version of a typical Victorian electric river canoe like this one:

Make the hull in the clip longer and it's likely to go faster on the same 200W. I'm looking at building a 1000-1500lb cat that can handle another 1000-1500lb of passengers, and is sturdy enough to be comfortable 30-40miles out in the ocean, and will achieve 6-7 knots (the high end of trolling speeds for sailfish, marlin, tuna, and mahi, which a prevalent here "in season") using only 1200-1500W.
John

Understand. My interest in eboats is mostly about 40-passenger water taxis:
http://groups.yahoo.com/group/QCYCTender/

Here is a thread you might get a kick out of:
http://www.boatdesign.net/forums/hybrid/solomon-technologies-electric-wheel-electric-motor-propulsion-systems-676.html

...I got my first electric scooter "by accident" as a way to educate myself a bit about batteries and controllers and charges and electric traction generally. Had no idea what I was getting into (meaning not so much the tech but the politics.)

tks
lOCck

[John in CR]

Hi to all you guys who are interested in large electric boats.
I thought I would post some info on an e-boat project here in case anyone is interested.
I am in the middle of a project where we are converting a 50 foot racing catamaran to all electric drive. This will be the most technologically advanced electric boat in the world when it is finished due to the advanced battery diagnostics and monitoring capabilities. It will be powered by three 5kW Power Pod retractable electric motors. We are just waiting for the motors to arrive from the US any day now. The 48V 240Ah battery bank is already at the boat yard waiting to be installed.
The boats' batteries will be recharged by solar panels, back-up diesel generator and re-generation (when the boat is under sail power in strong winds).
The boat has been entirely stripped out now in preparation for fitting of batteries, motors and all associated electrics.

I will be happy to provide updates as to progress if there is interest here. There will be a full featured article appearing on this electric boat in at least two major boating/alternative energy magazines which will show to those involved in the boating industries what is currently achievable with regard to electric boat technology.

BMI, yes definitely keep us posted on progress. Out of curiosity, did you slip a digit on the battery capacity, because that's only 11kwh of capacity, or 45 minutes of runtime with the three 5kw motors at rated capacity? For the 10m cat for which I'll soon kick off construction, my back of the napkin capacity plan is 15kwh. That is without any solar panels in the budget. What is the maximum output expected from your PV panels under optimum sun?

John

[Lock]

Beauty boat BMI! Who was her designer please (Shuttleworth?) Will you still be racing her? I understand the daggerboards as max. efficiency for racers, but if I were cruising her I would move to centerboards... (old Tornado sailor here)
tks
Lock

[BMI]

Hi to all you guys who are interested in large electric boats.
I thought I would post some info on an e-boat project here in case anyone is interested.
I am in the middle of a project where we are converting a 50 foot racing catamaran to all electric drive. This will be the most technologically advanced electric boat in the world when it is finished due to the advanced battery diagnostics and monitoring capabilities. It will be powered by three 5kW Power Pod retractable electric motors. We are just waiting for the motors to arrive from the US any day now. The 48V 240Ah battery bank is already at the boat yard waiting to be installed.
The boats' batteries will be recharged by solar panels, back-up diesel generator and re-generation (when the boat is under sail power in strong winds).
The boat has been entirely stripped out now in preparation for fitting of batteries, motors and all associated electrics.

I will be happy to provide updates as to progress if there is interest here. There will be a full featured article appearing on this electric boat in at least two major boating/alternative energy magazines which will show to those involved in the boating industries what is currently achievable with regard to electric boat technology.

BMI, yes definitely keep us posted on progress. Out of curiosity, did you slip a digit on the battery capacity, because that's only 11kwh of capacity, or 45 minutes of runtime with the three 5kw motors at rated capacity? For the 10m cat for which I'll soon kick off construction, my back of the napkin capacity plan is 15kwh. That is without any solar panels in the budget. What is the maximum output expected from your PV panels under optimum sun?

John

Only the two outboard motors will be used for normal cruising. The central motor is designed as a manoevring motor so will not be used for most of the time. We expect to get a good hour of motor run time from two motors at leisurely cruising speeds.
We haven't worked out how many solar panels we can fit yet but I will let you know when we get to the stage of deciding.

[BMI]

Beauty boat BMI! Who was her designer please (Shuttleworth?) Will you still be racing her? I understand the daggerboards as max. efficiency for racers, but if I were cruising her I would move to centerboards... (old Tornado sailor here)
tks
Lock

I am not sure who the boat was designed by originally but will chase up the details for you and will let you know. I am only the battery supplier and electrical engineer on the project. I am designing the electrical systems for the boat for the electric conversion (both power and data). As far as the original boat design goes I will ask the boat's owner next time I speak with him.

Yes, she will still be racing. This is why we are waiting eagerly for the motors to arrive. The plan is to mount them on some kind of hinged panel so they can be lifted completely out of the water by a hoist/pulley system so as to not cause any drag while the boat is racing.

[John in CR]

Beauty boat BMI! Who was her designer please (Shuttleworth?) Will you still be racing her? I understand the daggerboards as max. efficiency for racers, but if I were cruising her I would move to centerboards... (old Tornado sailor here)
tks
Lock

Lock,
Before installing any daggers or keels, look into Anti Vortex panels first. Less surface area so less drag, require no more draft than the hull itself, more effective because they reduce the water vortices that create drag and wake. Look at Bernd Kohler's work he has generously shared in the links on the right half of the page at http://www.ikarus342000.com/Looseends.htm

BMI,
Since it's a refit not a build, I assume that for the PV panels you aren't going with the ones that can be built right into the deck and walked upon. That's the route I'd love to go, if it wasn't so darn expensive. ie a craft covered almost entirely in PV above the waterline would be great. Add in about 1000lbs of lithium batteries, reefable wingsails for more efficient sailing with improved maneuverability (including reverse under sail), plus a nice size wind turbine for battery charging without sun or the need to be under way, and then you've got a near ideal boat.

I assume you plan to use BMI lithium cells. What is special about the BMS mentioned in your first post?

John

[BMI]

Beauty boat BMI! Who was her designer please (Shuttleworth?) Will you still be racing her? I understand the daggerboards as max. efficiency for racers, but if I were cruising her I would move to centerboards... (old Tornado sailor here)
tks
Lock

Lock,
Before installing any daggers or keels, look into Anti Vortex panels first. Less surface area so less drag, require no more draft than the hull itself, more effective because they reduce the water vortices that create drag and wake. Look at Bernd Kohler's work he has generously shared in the links on the right half of the page at http://www.ikarus342000.com/Looseends.htm

BMI,
Since it's a refit not a build, I assume that for the PV panels you aren't going with the ones that can be built right into the deck and walked upon. That's the route I'd love to go, if it wasn't so darn expensive. ie a craft covered almost entirely in PV above the waterline would be great. Add in about 1000lbs of lithium batteries, reefable wingsails for more efficient sailing with improved maneuverability (including reverse under sail), plus a nice size wind turbine for battery charging without sun or the need to be under way, and then you've got a near ideal boat.

I assume you plan to use BMI lithium cells. What is special about the BMS mentioned in your first post?

John

The type or number of solar panels which will be used hasn't been decided as yet.

There is a ferry here in Sydney Harbour which is absolutely covered in solar panels. It is called the "SolarSailor" and you can see it on the manufacturers website here- http://www.solarsailor.com/
When you see the boat close up it sure stands out from all the other boats with all the solar panels which cover her.

Yes, our boat will be powered by BMI batteries. Originally the boat was going to be fitted with more than half a ton of Trojan lead acid batteries. Then the owner of the boat looked into the capability of the BMI packs and decided on them instead. The total battery weight of BMI packs comes in a little under 200kg so is less than half the weight of the original Trojan battery bank for the same effective battery capacity.
The BMI batteries don't have a BMS but a VMS instead. There is a basic explaination of the VMS here-
http://lithbattoz.com.au/index.php?page ... iagnostics
The VMS allows for a laptop computer to be plugged in to a dedicated battery diagnostics panel mounted socket fitted in the boats instrument panel. The internal voltages of every cell in each of the battery packs can be displayed on the PC and errors for over charge, over discharge and over temperature are logged as is the total number of full accumulated battery cycles. The batteries have the ability of performing an automatic self check up to twice a day. If any cell in any battery is found to be out of specification or requires attention in some other way an SMS text message can be sent to the boat's owner or an email sent alerting him/her of the need to check the battery in question. Therefore the owner of the boat could be on the other side of the world many miles away from the boat and will know at all times of the condition of all the batteries in his/her boat.

[Lock]

Gawd I love that Solar Sailor. Hadn't checked their site for a long while now. Nice to see developments and growth (apparently) in the offing for them. Didn't see any pics of the "real" Solar Sailor at first, just computer renderings of future stuff, so my fav Solar Sailor pic:

SolarSailor.jpg (52.42 KiB) Viewed 1829 times

John, tks for the link to Kohler's Anti Vortex work. Very interesting and will read later. Love the idea of built in swim platforms (smile)

...and I still say BMI's project is a Shuttleworth
Lock

[BMI]

Gawd I love that Solar Sailor. Hadn't checked their site for a long while now. Nice to see developments and growth (apparently) in the offing for them. Didn't see any pics of the "real" Solar Sailor at first, just computer renderings of future stuff, so my fav Solar Sailor pic:

SolarSailor.jpg

Lock

Wow...what a great pic and such a familiar sight to me as it heads out from Circular Quay and a bit past the Opera House.
I will have to take a pic personally and post it for you when I see the boat on my next trip in to the city.

[Lock]

I'm looking at building a 1000-1500lb cat ....another 1000-1500lb of passengers ...sturdy enough ...comfortable 30-40miles out in the ocean, and will achieve 6-7 knots ...using only 1200-1500W.John

...been thinking about this. I know you mentioned wing sail (was sorry Walker was never able to make a go of his)... but 2HP approx for the electrics seems a little optimistic. Just thinking of tidal races and ocean currents where ya need a few knots across the bottom just to keep up with the water headed in the opposite direction! Especially in light airs. Or if you want to tow somebuddy or something... fight a fish? Hopefully your topsides will be super smooth too ta keep down the windage... Dick Newicks boats always had very "slippery" topsides:
http://www.jumpcut.com/view/?id=570EB9864F4711DB9FA92EF149F8C96D
BMI's "Room With A View" also looks pretty slippery...
tks
loK

[John in CR]

I'm looking at building a 1000-1500lb cat ....another 1000-1500lb of passengers ...sturdy enough ...comfortable 30-40miles out in the ocean, and will achieve 6-7 knots ...using only 1200-1500W.John

...been thinking about this. I know you mentioned wing sail (was sorry Walker was never able to make a go of his)... but 2HP approx for the electrics seems a little optimistic. Just thinking of tidal races and ocean currents where ya need a few knots across the bottom just to keep up with the water headed in the opposite direction! Especially in light airs. Or if you want to tow somebuddy or something... fight a fish? Hopefully your topsides will be super smooth too ta keep down the windage... Dick Newicks boats always had very "slippery" topsides:
http://www.jumpcut.com/view/?id=570EB9864F4711DB9FA92EF149F8C96D
BMI's "Room With A View" also looks pretty slippery...
tks
loK

Lock,

I want to take a shot at a charter fishing boat based mostly on a sailcat form, but primarily electric powered, in an effort to virtually eliminate fuel costs, which typically run $500-$1000/day here. I'm thinking $20-$50/day to fuel the generators for the higher power runs out and back, but run on batteries while trolling, which is at 5-7knots of water speed. I got the 1500W for 7 knots from the boat designer, but plan for some extra length as a hedge. It's that trolling at low speed for 6-8hrs on batteries that we want to be highly efficient. It's open ocean and I don't think direction matters, so with a biplane rig of small wingsails as assist, wind should only help our cause.

In addition to minimal fuel costs, boat motion will be far less than a monohull, and the lack of vibration and noise of a big diesel, will make for a far more pleasant outing for the passengers. Hell, this boat won't even have the sail flapping and rigging noise of a regular sailboat.

Regarding sailwings, there a plenty of functional ones, and they practically own the wind powered craft records on both land and water. Also, I'm look to size them for assist, not primary power, so that's last on the list and I'd probably just go with a pair of large surfsail rigs for the wind assist, and work on my ideas for soft wingsails after the concept is proven.

I'm confident that I can build a lightweight seaworthy boat. I'm no marine engineer, so I'm going on faith regarding the power requirements, but it doesn't take much to go relatively slow (well below hull speed with these aspect ratios) if you aren't dragging the big wake of a typical boat at 6kts, and under wind power these hulls have proven to do over 20 knots.

My main concerns are more about the concept working for deep sea sportsfishing. eg Does the noise and big wake pulled by a traditional rig attract the fish, but I think my last captain's beliefs were just old wives tales. If sound is an attractant, we can just drop a transducer underwater, and to me the wake only obscures the baits in tow. The patio sized deck will a tremendous advantage, but the devil will be in the details (setting up so the mate can easily get down to the water to haul in a 500lb tuna or marlin, etc.). One thing is for sure, it will be hugely different from current charter fishing, and I can't think of anything much more fun to test, so we'll see. Worst case, it doesn't work, and with small changes I convert it and sell it as a sailboat with a hybrid electric/diesel drive.

John

[Lock]

The boats' batteries will be recharged by solar panels, back-up diesel generator and re-generation (when the boat is under sail power in strong winds).

...or perhaps moored in a river or ocean current or tidal flows... Nice exerpt here from a vid about midaeval Paris with boats moored in the Seine river using water wheels turned by the current to mill grain(starting at 2:55):

tks
lok

[Lock]

*Bump*
Nice site here (in German... ya can use Google Translate for English if ya like) showing more work with kort nozzels on a small eboat:
http://www.sinusleistungssteller.de/Brummer.html





...which leads to:
http://www.e-jet.org/

Their largest design (they are not in production yet):
E-JET-170L-8000:
Input voltage 24 to 48V
Input power up to 8KW
Thrust / bollard pull up 120kgf
Diameter 230mm
Rotor diameter 170mm
Length 170mm
9kg - Weight 9kg



Wundervoll!
tks
Lock

[Jeremy Harris]

All has not gone dead on the electric boat project front. Some things have been much harder, and taken far, far more time to sort out than I had hoped, though. The really big challenge for a very low powered boat such as this project is maximising efficiency everywhere in the system. I spent a lot of time wringing every last lost watt from the electrical systems, then discovered that some of the mechanical parts soaked up far more power to drive than I had hoped. After a lot of fine tuning, I now have a motor that is around 90% efficient at cruise power and a gearbox and drive system that only soaks up about another 5 to 6 watts.

The last challenge, before I get to integrate all this stuff into the boat, has been to get an efficient propeller. Boat propellers are generally pretty dire, I've found. Boat designers don't worry about prop efficiency too much, they pick a diameter that suits the boat and then just make sure the engine is much bigger than really needed, so they have some headroom to play with when it comes to losses. For electric power, particularly where I'm hoping to be pretty much solely reliant of solar charging, I've needed to develop a propeller that will do much, much better than the standard small diameter, wide blade chord, high rpm boat prop. I tried model aircraft propellers, and these do work very well, much, much better than a boat prop if they are made big enough and can turn slow enough to be efficient. The really big problem with them is that they collect weed extremely quickly, so are practically useless.

Luckily, the human powered boat people have been facing the same problem, as they only have a very modest amount of power to play with as well. A chap in Australia, Rick Willoughby, has come up with a neat way of making a folding prop. If the blades catch a bit of weed, then they fold back under the extra load and it slips off. Apparently this system works well. I've spent the last couple of days making a set of stainless steel blades. The starting point is a strip of stainless steel sheet, that is twisted to the correct pitch angles (checked with templates at four radial stations. This is then cut to a rough profile shape and has stiffening pieces silver soldered to the root section:



The grotty bottom one is a near raw blank, the top is a partially finished blade.

The blades are then hand ground to shape, using templates to get the right aerofoil section at each point. This doesn't take as long as some may think, perhaps an hour or so per blade. Much of the time is spent checking to make sure both blades are identical and follow the templates accurately.

This is a shot of the finished blades in a partially finished hub:



They will fold backwards (down in this picture) if a bit of weed gets caught on one. The other thing that helps this weed clearance method is that the prop only spins at around 400 rpm at cruise speed, as it's 13" in diameter, massive for a very light two person river boat.

The drive system for this uses a right angle gearbox. I'm currently working on the moulded fairing that fits around this to reduce drag. The motor is my re-wound, low Kv, Towerpro, fitted with Hall sensors and driven by a modified low voltage xeichang 116 six FET controller. The boat hull is one of these pedal boats, minus the pedals: http://www.swallowboats.co.uk/content/view/94/30/



Jeremy

[Malcolm]

Very nice work on the propeller Jeremy. It's a surprise to me that conventional boat propellers aren't very efficient. I'd always assumed that the wider blade profile was chosen because of the difference in viscosity between water and air. Over the years there must have been a considerable amount of research into blade efficiency, so I guess there must be other factors that affect the choice of blade section. You mentioned fouling – could cavitation become an issue? I imagine the slimmer blade design spins faster as well?

[Jeremy Harris]

There a few generalisations when it comes to props. The blade chord is pretty much proportional to the amount of power you want the prop to absorb, so more power = wider blades (or more blades). Prop blades are really just twisted aeroplane wings, and just like aeroplane wings, long thin ones are much more efficient than short fat ones (think of gliders as being probably the most efficient wings going). The downside with long thin blades is that you can't spin them very quickly, as the maximum tip speed is limited by the shear strength of water. If the tip moves too quickly, then the pressure difference between the high and low pressure side of the blade will cause the water to vapourise, producing cavitation.

Big diameter propellers are a designers nightmare, too, because space need to be found for them. They need to be protected from hitting the bottom during accidental grounding and need to be well clear of the hull to avoid tip interference. They also need either lower rpm motors, or reduction gearboxes, due to the need to turn them slowly. A small outboard motor may only have a 6" prop and will turn it at maybe 2000 rpm or so, but it's total efficiency, from engine power to power in the water, may only be around 20% or so. Using a big, slow turning, prop, with long thin blades allows high efficiency, but at the cost of some installation headaches. I've made the whole motor lift up under the stern, like an outboard but fitted into a slot in the bottom of the boat. This gets around the ground clearance problem and also allows the boat to be trailered fairly easily (I hope).

The design software I'm using, Javaprop, can also design props for aeroplanes, all you have to do is change the values for viscosity and density. Given the same sort of requirements it designs props for either air or water that look pretty similar. I've had a lot of help from folk over on the Boat Design forum, especially the human powered boat people, who are working at similar power and speed levels.

Jeremy

[Lock]

Hi Jeremy... re protecting props... did you consider/discard a steerable nozzle a la Kort? To offer some protection to the prop plus obviate the need for a separate rudder?
Lock

[Jeremy Harris]

Hi Lock,

I did look long and hard at Kort-type nozzles (specifically the Rice nozzle, as it's a bit more efficient than the Kort). After discussing it with people on the Boat Design forum, who had some knowledge of these things, I discounted it, not because it was inefficient, but because they are reputed to collect weed very easily (they apparently act a bit like weed vacuum cleaners).

My prop is steerable, as I've made the gearbox at the bottom of the leg able to rotate. I does still mean that I've lost a shallow water capability, but I'm reasonably happy with that compromise, as most of the time the boat will be used on inland waterways with at least 2 or 3 feet of water.

For another application, where the prop diameter is limited to 8" maximum, I am looking at using a Rice nozzle. This is for a sailing boat, that normally has a small outboard, but the designer wants to try efficient electric power. The idea is that an on board wind generator will be able to keep the battery topped up, allowing enough power for the motor to be used to get the boat to and from it's mooring.

Jeremy

[Jeremy Harris]

I've now finished the prop and hub. Here's a picture with the blades open:



and another with them folded back in weed clearance mode:



I just need to get the leg finished now, so that I can give it a test.

Jeremy

[dnmun]

you do nice work. very nice.

[12p3phPMDC]

Yea, that's awesome!! Good work!

Are you able to silver solder stainless with a low temp torch like mapp gas or propane?

[Jeremy Harris]

Many thanks for the kind words.

I silver soldered those bits of 316 stainless together using Castolin Eutectic XFC1020 fluxed silver solder rods and an ordinary butane/propane mix torch, one intended for DIY plumbing etc. It takes a while to heat the parts up, but seems OK for small stuff like this. The only downside to using this stuff is the price, the silver solder rods are pretty expensive.

Jeremy

[FeralDog]

Jeremy... Great job!
May I inquire; do you spend much time "on the water"?
In short, if your planning to travel shallow water you will very likely shear your prop. Nope, you will shear OR bend that prop.
Have you built in any shear pins ? Do you have easily/cheaply replaced blades?