Trimaran tour boat with steerable long-tail electric motor ... or what else?

Trimaran tour boat with longtail electric motor ... or what else?

Hi there,

As the winter has set in and the boat building is not possible I am sitting in front of the computer and contemplating about a hybrid tour boat for my company that I can build myself and will have these characteristics:

- will be stable
- have a shallow draft of max 40cm when loaded with 12 people and luggage
- will be rugged and able to endure a lot of abuse and easy to repair
- have electric propulsion that is quiet, rugged and an autonomy of 4 to 6 hours at low speed - 8 km/h
- have an alternative power source as a four stroke engine as a back up or for those longer trips

Now for those skeptical people out there that say the electric is not worth it and all that - the boat is used for wildlife watching in a reserve for day tours that last up to 8 hours but average 5 hours.

I did study most of the propulsion systems on the market and have been into boats for about... all my life, but in the end I came up to the conclusion that the simplest and most durable propulsion system for shallow - weedy waters would be a longtail electric motor.

Yesterday I have started to play with Sketchup and came out with this idea you see in the attached pictures - a steerable longtail motor. The inspiration came from Tom Kane's shallow water drive but I wanted to avoid the complexity of an articulated shaft.

From the pictures you can see the way this should work - the motor is contained in the metal box and the tilting - panning system is upside down compared to a traditional longtail. I have intentionally let the propeller part be heavier and have came with the idea of springs tensioning the whole motor to push the prop downwards. In order to control the trim I have attached a cable to the tail of the motor and routed it with a roller through the pivoting point of the system to the deck. I will have to find a way to control that tilt either with a hydraulic cylinder or with a winch ... any ideas would be welcome . The drive will pop up in case of an obstacle and will be kept down by the springs when reversing.

The whole steering will be done with a hydraulic cylinder mounted on the deck just like you see in the picture. The other challenge is to see if I can steer the two motors with the same hydraulic steering pump. I think a switch valve can do that and is readily available. - Anyone did that before?

One more problem is the motor cooling and that is the tough one... as the box is sealed passive air cooling will be difficult unless I put a hole in it and connect some flexible tube to blow air with a fan or something... Water cooled motor can also be used with a keel cooler of some kind? Any ideas are welcome.


This is about the motor part but the second part is the trimaran:

- The hull arrangement is so critical with this multy-hulls and the shape of the hull is a challenge. I have put together 3 hulls that are identical and could be made in one mold made of wood plates. The work with fiberglass is not so difficult and one of the cheapest approaches in this case. I was inspired by the Grainger Delta 6 boat https://www.youtube.com/watch?v=OQI3SEC4vOU and the reason for that pontoon being moved forward is to give more buoyancy to the front as from my experience the clients always rush to the from of the boat and make the boat unbalanced. I have seen a smaller pontoon boat tipping the people forward and over the board when all of them rushed to see a bird...

Another reason for this would be making the boarding easier.

I positioned the middle hull higher so it will just be submerged when the boat is fully loaded so it will have less drag and be more efficient but have no clue if this is a good idea or not. I am also not too sure about the hulls shape and the efficiency of that?

Any ideas and suggestions are welcome and please don't be too harsh it is just a concept that might see the light of day.

The technical details:

Length of the boat - 9m
Beam - 3.2m
Hull widths - 0.6m
Desired draft - 0.4m
Electric motor power - 15 - 20kW - direct drive - no reduction. (Lynch or brushless?).
Propeller - traditional 3 blade prop depending on the final boat specs.
Outboard power - 30-50 hp whatever I can find cheap on the second hand market.
Battery bank - Lithium Ion - Nissan Leaf battery pack?
Solar panels are also an option as seen in one of the pictures - can fit 8 Kyocera 325W Polycrystalline Solar Panel KD325GX-LPB - approx 3000 EUR and 250 kg to hang on top...

Cheers,

Daniel

 

The initial post was getting long so I continue...

The other readily available options on the market are:

- Inboard systems in the range of 15-20 kW costing about 10.000 EUR - like Mastervolt and many others...
- outboard conversions like Aquawatt - 11.000 EUR for a 20kW - the problem with this type of conversions is inefficiency and noise - you always get that wining noise. There are some cheaper Chinese versions but I would not buy that in a million years...
- The true electric outboards from Torqeedo that are great but not for my application, I don't trust them for the long run and don't strike me as sturdy machines that will run for 600 hours/year. The new "commercial" Deep Blue 40hp outboards are nice but cost 40.000 EUR to run... wtf...

The DIY systems are by far the cheapest:

Motors in this range are

- Lynch motors (brushed) - 1400 EUR for a 15kW model
- Emrax brushless outrunner motors - 2500-3000 EUR for 40 kW @ 700v but can be run at lower voltage.
- Golden motors - about 800 USD for a 10 KW water cooled motor and 400 USD for the controller - that is the cheapest there is at the moment but still have to purchase from China.

In this case I have to go with a 48 volt system as this is the safest or even a 72V for better efficiency.

What would be the power needed to drive this boat at hull speed? How do you calculate multy hull speed? I just took one hull and made the calculation than multiplied with 3... that gave me 2 hp/hull for a 9km/h speed in total 6 hp that is about 4.5kw. To fight the current and the weeds that sometimes occur on the lakes the extra power will be needed but at this speed I will need a 25kW battery to give me 5 hours of autonomy. I admit this power calculations are not my thing but I am sure someone here can give me some idea. I know Gonzo is the cat specialist .

My calculations for such boat would be:

3 hulls in one mold - about 3000 EUR
Decking and hand rail, cabin, toilette - 3000 EUR
Electric motor and controllers plus bat monitoring - 4000 EUR
Motor housing, prop, shaft and steering system - 1000 EUR
Battery bank - aprox 6000-7000 EUR
Outboard motor and accessories - 2000 EUR
Solar panels about 3000 for 2.5kw - 3000 EUR
Other stuff...3000 EUR

Total - 26.000 EUR

Considering a minimum of 600 hours/year of use and a lifetime of 8 years for the batteries that will give me about 4800 hours - that is a 5.8 EUR/hour.

In 600 hours with a four stroke outboard I would consume about- 600h x 5 liters/hour = 3000 liters of gasoline x 1.3 EUR/liter = 3900 EUR/year (that is and optimistic fuel consumption).

In 8 years I would have to replace the outboard anyway and I would have consumed 31.200 EUR worth of fuel. The price difference between the full electric and the gasoline would be about 12-15.000 EUR so in the end the gasoline one would cost 31.200 EUR fuel + 11.000 the boat itself = 42.200 EUR/8 years or 4800 hours.

The cost per hour of operation would be - 8.79/hour if the fuel price stays at 1.3 EUR/liter...


Too much information and a lot of variables I know plus the unexpected that can change that price...

Sorry for the long post put now you have my reasoning for such boat...

Cheers,

Daniel

 

<<edit>> I took the whole post down. I read the OP's 8 km/h as 8 mph, and went way off on a tangent.

 

Let me try again

Yodani, can you post a map of the area and indicate your routes and the distances and speeds of each leg? Also indicate if electric only or if generator is OK. This is needed to make any kind of estimate of system size. I still think your electric cost estimate is off by about 50,000 EU. I think you should look at industrial VFDs for the size boat you want, and I don't think a longtail is to way to go. You can paddle or drift through the weeds, perhaps with the aide of a tiny sail. In the Everglades where I used to work (and did the occasional birdwatching tour for serious birders), it was flat out illegal to touch bottom or touch the seagrasses or plant life. Captains lost their privilege of operating in the park if they did that. Some birds, and access to them, were strictly regulated.

Your choice of a trimaran needs to be very carefully considered. It is not an efficient hull form for the speeds and weights you are looking at, and it would be crap to maneuver. Which isn't to say it is the wrong hull either. You can get the guests up higher on a big flat deck, and that might be a selling point if the photography and viewing is better, especially if there are other tour operators. But I think a monohull would be better considering the outrageous cost of electrical propulsion. Unless you can secure an exclusive contract to operate your tours in that area. That changes things quite a bit.

Your cost estimate of the cost of operating an outboard is off by at least a factor of 2. Most operators in the Florida keys lease outboard and hang new ones every 6-9 months. Old OB's work in rental fleets, but not in tour operations.

The cost of the electric system needs to be looked at full circle. You may need the power company to supply you a new service to deal with the battery chargers. The chargers for either lead or Li are going to cost you many thousands of Euros. A basic 7kW 30Amp car charger costs about $4000 US. You have to decide on a voltage, And 12 or 24 isn't going to work. 72V might, but there may be regulatory issues since 72VDC can kill you.

A very rough conversion is that you need 100 pounds of lead batteries to get the energy equal to 1 pound of gasoline. So your 5 ltr/hour X 5 hours = 42 pounds of fuel or 2 tons of lead batteries. That is with no reserve at all.

Lets say you use 24 size 8D marine deepcycle traction batteries arranged in four strings of six at 72 volts (about 14,000-15,000 euros with wires and battery boxes). You will want four chargers of about 400 Amps each to charge this bank. That's a 120kVA electrical service (about 2.5 times the household service in the US). The batteries, chargers, and service connection will almost cost what you have budgeted for the boat. Now add a decent gen set, say 30kW (enough to run one charger). Add a VFD and drive motor, and you begin to see where the money goes. And you begin to see the size of the components you are dealing with.

 

Why not a catamaran? Better load carrying, better control of trim when passengers move round the boat. Probably lighter and with lower resistance, Certainly only two hulls to make will be a bonus

If you go the longtail route in forward gear the prop will stay down, it's in reverse that you need to hold it down. Nothing fancy needed. It is wise to fit a circular guard round the prop as you don't want it ever to touch the hull sides!

An aircooled engine is possible, but noisy, you need to check whether the cooling waterpump can lift to the height you need. I guess you are working in fresh, not salt water - which helps

Check out this similar boat

http://www.derickreynolds.co.uk/E36 Trentham Gardens.htm

http://www.trentham.co.uk/trentham-gardens/lake-and-lakeside-activities/take-a-boat-trip

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Traditional long tail motor run shallow waters and are weed resistant (jets are closest to true weedless) because of a very small high pitch, inefficient prop (my Thai prop is 6"). They cannot be run in reverse easily in shallows, because possibility of hitting bottom/obstructions and resulting cantilever effect. If you slow down in reversing, rudder control will be ineffective. The prop can push up to a stop going forward, and will dive down in reverse but it is not a big factor because of the long lever arm involved. I ran a homemade 2 HP electric motor Thai many years ago mainly for experimental, didn't like it much. The motor and lever arm were close to balance with the prop hitting an angle stop at full power forward, and hanging down at an angle stop when off.

An automatic kick up outboard design would be the best way to go IMHO, because of the quick maintenance possible (very short down times). Perhaps a gang of several Torquedo style using self designed belt gearing for quiet operation, or converted jet drives if the weeds are bad.

The battery weight, costs and charging issues can be minimized by carrying the smallest pack needed for a couple of round trips and quickly "dump" charging them while loading passengers. Or maybe use fewer batteries and 2 dump chargers- one at each end if the trip is long, and the infrastructure is there. Dump charging from larger stationary battery banks was used in the past for electric drag racing events. Solar is still not generally cost effective, IMHO. Here's a commercial version to study and rent for ideas: http://eboatstampa.com/

Hope this helps.

PC

 

Thank you for your replies.

It is for sure that I have sub estimated the costs but let's recap with some real data:

1 brushless motor - 20kw water cooled - made by Goldenmotor - 2000 EUR
1 motor controller - 1500 EUR
24 kWH lithium battery from Nissan Leaf - 5700 EUR
1 battery management system - 1700 EUR
1 5kw battery charger - 1600 EUR
8 Kyocera pannesl for about 2.5 kw - 3000 EUR

Total of 15.500 EUR

I am new to this and I might have missed something here. Please let me know what other things would need to be included.

About charging the batteries and needing a 30 kw generator - I think a 5kW charger would do the work ok if used together with the solar panels. One thing I have omitted from the calculation is the cost of the charging .... oups.. my bad.

So if we take a catamaran and scrap the trimaran what would be the power needed to push this along with 7-8 km/h and what would be the range with a 24kWh battery like the one in the link?

I have seen most of the solar boats ever build and posted on the internet and the most interesting are just like the one Richard posted. Do you know more details about battery and performance of that catamaran ?

My boat will have to fight the current too in the spring when we have a 5km/h stream for about 6 km. The short tour is 45 km and the long tour is 65 km. Most of the time with a slow boat the short tour takes about 5 hours so it is in the range of electric boats... or so I think .

A man can dream ...

Daniel

 

Your battery charger is about 2% of the size you want, and <edit> getting the other components to work together is going to be a challenge. Battery voltage is 182X2 Volts for the Leaf. Controller input is 96 volts max (interesting controllers, I haven't seen those). A DC brushless motor could work if you can get those controllers to function reliably at that price. But I suspect you will end up deciding wet lead batteries are the way to go. Battery dumping probably doesn't make sense for just one boat, but if you had a few of them, it could.

So to get the leaf batteries to work, you reconfigure to 91 volts, and you need two of them (just like the car)to get to 24kWh, and the charge controller now needs to work in this configuration of 4P12S modules of 2P2S "LiMn2O4 with LiNiO2" cells. That would take some calling around to verify. This would appear to cut the weight of the batteries by a factor of 9 relative to 8D lead format, and I am suspicious of that. If it had worked out to a factor of 6, I'd be more inclined to believe it.

The discharge rate is 7.2 kW for the leaf for rating purposes, but I couldn't find out the charge rate, though one comment I dug up suggests it might be about 1/3 of 7.2kW. That means a 9 hour bulk charge time, followed by a few hours of constant voltage charging, so maybe 12 hours to get 24kWh into the pack?? On the otherhand, there is this guy - http://www.mynissanleaf.com/viewtopic.php?f=31&t=15825. So what is the charging regime supposed to be for this battery?

 

I watched the Trentham boat being built, it's launching and the first engine trials. Maybe 10 years ago, maybe longer? But I haven't seen it in use. I suggest you contact Trentham direct (why I gave you the link!)

It was built by Andy Fox (who also built the Plastiki) but his boatbuilding company no longer exists.

12 people plus day luggage is say 1T. The basic open deck 9m catamaran might weigh 1.5T as a charter boat, plus engine/batteries. So say 3T, pretty typical for a cruising 9m catamaran.

To do 8Km/h, or 4 knots, you wouldn't need much power, a 4hp outboard would easily do that in flat, calm water, a 9.9hp high thrust would get you to 6 knots in most wind/wave on a river

You'd do maybe 16-18 knots with 50hp outboard. My similar proportioned Skoota 28 does 16 knots with twin 20hp outboards.

http://www.sailingcatamarans.com/index.php/designs/6-powercats/264-skoota-28

I'm afraid I know little about electric power but obviously with so many electric cars these days the technology is now available. One of my customers is the "main man" in the USA for car charging systems

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

I have yet to see an electric street legal car in the US. I have seen all kinds of oddities - Diesel Wankels, Sterling cycle pickups, propane conversions, Bio-diesel conversions, A two-stroke Caddy 500, but not one electric car on the road. I had never heard of the Leaf, I assumed it was a foreign badge, but I see some are made in Smyrna and sold in the US. Which begs the question why can't I find diddly squat about the battery tech and charging systems? At any rate, the tech does appear to be getting more integrated and it should be getting easier for the DIY crowd to put something reliable together.

From a business standpoint, however, the electric boat falls flat. Even if you get the break even point of operations to be equal to the petro boat, the upside is only one third the upside of the petro boat. You need three electric boats to run the same number of trips as one petro boat can. And business folk tend to be biased towards opportunities with large upsides. So you are looking at a very "slow money" business model with electric. What happens when some birder reports some rare thing they saw in your area and you wake up to find 100 people on your dock?

An alternate scheme would be something like this uses, which should be a drop-in solution with outside fast charger options. But I'm not sure how the speed control works. It could be hydraulic as well as electric.
http://assets1.mytrainsite.com/500028/eagle_tugs_spec_sheet_-_mtt.pdf?r=1280

 

IIRC the Trentham boat was electric because fossil-fuel-powered craft are banned from the lake. So there was no alternative. That may well also be the case for the OP

I have seen electric car charging sockets being used in California and also in the UK. I believe all new Vancouver, Canada housing developments must allow for electric car charging in the driveways

An electric car is no more fuel efficient than a fossil fuel car. It is cheaper to run because power stations don't pay GBP1.37 a L, (or USD 2.50 a gal) for their fuel

Richard Woods

 

I thought electric transport is much more efficient especially when used without battery losses (bullet trains) because there is no heat engine and associated thermal limits and losses (Carnot cycle).

Seems like electric fuel can be less costly when easily switched to the cheapest generating fuel dictated by market forces. Our local electric power source runs on alternate blends of coal/natural gas/nuclear/wind/solar with the greatest percentage coming from gas at the moment. The expensive exotic fuel sources are there for hedging in case of price/source disruptions when they might well be the only, and therefore cheapest sources. So at the moment an electric car in our area is mostly a lowest fuel cost per therm nat gas car.
Crude to petrol is not particularly more efficient/cleaner/cheaper without subsidies than any other source, cradle to grave...

That's the theory anyway...

PC

PS: How about this deal at LAX and some other places: http://www.lawa.org/welcome_lax.aspx?id=8705 I believe the parking was also free awhile back.

 

. In September alone Tesla sold over 2000 of its S model in the US. Its world wide sales are many times that. It was Motor Trends car of the year 2013. I saw several when I was in Canada this summer. Tesla is bringing out its X model soon( 4 wheel drive SUV) and once it completes what is to be the biggest battery factory in the world ( Nevada or California) it plans to sell more of its upcoming economy model than all the Fords sold in the US. They need the batteries to keep up with demand.

 

You will get the same Green credits by using propane as fuel for a 20Hp Honda 4 stroke.

The engine life will extend 2x-3x or more and the exhaust is breathable.

Probably 1/5 -1/10 the cost of electric drive with zero engineering risks.No $10K battery replacements.

Dockside charge electric has a SOURCE , (usually coal) .transported by train.

Propane comes thru a pipe line.

AS I understand it Tessla takes a lo$$ on every car produced , the stay in business by selling credits to auto makers that fail the gov required efficieny edicts.

Selling indulgences for a profit will die eventually

 

@philSweet

The parts I put together where just for the pricing and to see what would be the cost of that setup. Those Leaf batteries are configurable in banks with required voltage. A new battery from Nissan will cost about 6000 EUR and it is a 24kWh pack. There are 10kW chargers a bit more expensive but you will need a good shore connection. In my case that would not be too difficult. Dump charging is not an option unless it is subsidized by the state.

Lead acid batteries at this moment are not a viable solution because on the long run they are more expensive than lithium. First they weigh a hole lot more (on a boat that size it will not be a problem), second they last about 800 charges if you are lucky, third- they can be discharged to max 40% of the capacity plus they can not be fast charged and have problems with low temperatures.

This is a good read - http://www.bruceschwab.com/uploads/li-vs-la.pdf

I think technically it is viable to get a motor - controller - charger setup to compete in price with a diesel setup. As for the batteries this is still the tricky part as you have to pay upfront just like buying the fuel in advance for the next 5 years. This way you have to be sure that business is running or else...

@ Richard

If the price is the same for the long run I think for my kind of business electric will be a good choice. Birdwatching is a tricky business and this kind of transportation can be a bonus and a marketing gimmick to attract more clients. With electric propulsion we will be able to access even more places forbidden to thermal engines.

@ Fred

This is not as much for green credits as it is for the quiet running. I would switch to LNG or CNG for all my boats if there was any infrastructure for refueling and some regulations in place. The reason for that would be - cheaper fuel, lower noise and emissions and no more theft of diesel .

One thing is for sure - for an efficient electric boat this will have to be build from ground up and it should be a multihull. This has been done before and there are dozens of boats running full electric on lakes etc. The ridiculous part is the price of those boats.

Look at the operating costs of the Torqeedo Deep Blue - http://www.torqeedo.com/us/electric...al-operators-and-green-boaters/operating-cost

A last generation four stroke in 90-100 hp range will cost about 7000 EUR... the 80 hp Deep Blue costs 2.5 times more for the motor alone and it has 3 moving parts. I know the cost of R&D and all the bla bla but in the end it's a wash-machine powered by a battery. Did I mention the plastic prop for commercial use?

Also the battery ... a 13kWh for 15.000 EUR just because it is water tight?

I think it will take 5 to 10 years till this will change. Till then I will have to do my R&D and hope for the best.. but at half the price I think this is worth it.

Daniel