these turbine alternaters are easy to make

how do you figure out the power required to drive a hull
that boat is rated to cruse at 10 and max at 14 with two 230 hp diesels
thing is there is a conversion from internal combustion hp to elect hp
I think its based on the idea that electrics get higher torque at lower rpm and internal gives higher torque at higher rpm
but whats the magic formula

I could base it on the 28 hp elect in the Chevy S10 replacing a 190 hp internal combustion
which works out to a 6.8/1 ratio
or 37.1 hp for the warp11 x 6.8 = 252 equivalent hp
in which case Im at 1/2 the hp I need given that that boat was just rebuilt and had two 230hp engines installed
although I did gear the thing down to half its rpm so that should double torque and therefore hp
so Im back to being properly powered

still it would be nice to know how to calculate for drag/power =speed

well Kay9 looks like you hit it on the nail so far
but Im still trying
hell I even increased the cost by fifty percent and got twice the battery life maybe three
but
its still 6+ tons of batteries and $36,000 not including the monster genset

 

At 6 tons (I feel your dream-boat must weigh more than that), to need/use that diesel HP, give the idea of electric drive a miss, as the numbers will never crunch... Think of my example - a very easily driven hull-form (long, shallow and skinny) and less than 5 tonnes design loaded maximum...

I am still looking at running the gensets whilst motoring - the electric only mode should give me 30minutes to get alongside and secure at the fuel berth, or, to quietly depart early morning without disturbing the neighbours.... and the batteries meet all house needs, so, no gas stove, or, gas fridge, or, gas hot water system and I am still thinking of the need for a small self contained gas BBQ...

Electric should be used only where the design is readily adaptable and one recognises that the top speed is significantly lower - well under "hull speed"... and replaces around 40HP of diesel engine or less... I am not aware of a formulae/rule of thumb to convert between the diesel & electric form, - as both can be designed to meet different performance criteria, and yet meet some of the performance objectives of the other system...

 

well your right of course Im just playing with the numbers to try and determine the actual values of things

nother little gem is that there is an out gassing issue with all those batteries discharging as fast as Im thinking
things would have to be ventilated and confined to safe areas
and would still need to be distributed properly for trim and stability

was hoping the electric drive would work out but by the time I calculate for thrust to mass Ratio and so on its starts getting uglier
its not the start up costs that are so prohibitive but the mass considerations


I think the Sophia has 12 tons of ballast if I remember and she is only 46' not 57'
point being that its not unheard of to carry round that much weight as ballast
and that hull is not intended to plane anyway

three of those gorrila batteries could be used with the wind turbines and a small generator capable of recharging one at a time to power the operating systems
just not real worth it to power the drive system
or at least not that I can see so far although the start up costs when compared to a few tanks of fuel arent all that bad

on the plus side they do have some great new batteries out there
on the down side they are pricey

these guys got it down when it comes to cars
seems like someone should be able to do the same thing with yachts

http://www.teslamotors.com/

they use a Zillion tiny AA batteries crazy as that sounds

my theory is that eventually every boat out there will be wind wave or solar powered in some way with electric being the transfer medium in most cases

the mass is offset by the lack of engines and lower fuel requirements also the smaller gen set if you consider only charging half the bats at a time or less
also your idea of the azipods saves on drive shaft and coolant system so thats a little weight savings right there

in the end I havnt added up all the mass considerations but Ill bet there close
its still a disadvantage for the electric but Ill bet its within a thousand pounds or two of being the same
after that its a matter of finding out if that boat carries ballast and how much
my bet is it does and its probably not a small amount

the original was 45000 lbs displacement
with the wood probably not exceeding 4 tons of it
more likely 3 but I havent gotten to that part of the comparison

speaking of which
whats the proper ratio of thrust to weight for this kind of vessel
can I just go with 45000/460hp/7=electric hp needed

 

I tried to work it out when I first got into thinking electric drive and could not get any real/satisfactory answers - the nearest being from the electric motor marketing side suggesting 10 or I think up to 17hp in the leisure end of the market - commercial then takes a giant leap to large diesel or gas turbine generators and large electric pods in the likes of large tugs or larger and specialised design to meet a particular performance criteria... Thoosa had the biggest single unit recreational stuff...

The biggest problem for me is in getting 8000W at 48v (say 170+Amps) nominal out of batteries without doing serious damage to the long term viability of the battery even if recharging occurs at 50% discharge - worry about battery overheat, gassing, plate buckling and chemical degradation and who knows what else? - - - We needed better batteries 5 to 15 years ago so the technology had time to mature and get refined...

All this stuff has a large component of "black magic" for me as I just find some info and gradually build a "database" - - my limited knowledge is only based on that variable/inconsistent source... my base formulae is Watts = Amps x Volts, then use algebra to work it out and rule of thumb conversion factor is .8 (80%) from and to in motors and generators as a rough suck-it-and-see idea... The other "black magic" twist is the "pulse mode electronic controllers", as it seems to be able to push juice down a wire better than pure DC current....

I have seen some stuff published in USA a year or so ago on a couple of electric boats but quite ugly with masses of pv panels on relatively broad beam (inefficient) catamaran hull configurations and do not go very fast or far...?

 

Custom microprocessor-controlled lithium-ion battery with 6,831 individual cells. Weight 992 lbs. - - From the Tesla species - and a 375 volt AC induction air-cooled electric motor with variable frequency drive. Output 248 peak horsepower (185kW) and 276 ft/lbs (375 nm) of torque. Redline 14,000 rpm. and a big gearbox to reduce the revs to ? x 100rpm at the wheels....

Now that is getting near usable storage capacity and energy output rate for a battery - pity about the price???

 

In my opinion

170 amps is too much for 12v batteries, cables, connectors
You need to raise Volts

50/60 Amps is more a target to me for long term cruise, 100A for short term

Keep in mind that : Watt lost = Total Resitance x I² As you can see, no Volts in the formula !

So more Amps, more lost Joules
More Joules = more heat = more failure = more fire risk.

Also, cost of copper, cost of electronic for commutation and conversion, low reliability, and fire risk, all this rise with Amps, not with volts
there is no good reason to play with amps...except to keep volts low to protect man from electrocution danger.

 

all points well taken
I left out the losses due to resistance to keep things simple but mentioned em earlier
theory is I just wanted a rough idea of feasibility

I was thinkin I would need 000 cable
about 200' to connect everything
0000 if I wanted to play it safe
although so far its not looking to practical
the huge batteries require huge cable and the amp load is really high on the gensets

those gorilla batteries might work well but they are only 8 volts and kinda heavy
424 lbs each
but hold 1100+ amps and give 800+ over 8 hours
I think and I bet they are shedding heat at that

what hull are you thinkin of converting
once you know the hull and its normal displacement and requirements you can start crunching numbers a lot easier

on that old Elco
disp was 45000 lbs
power was 460 hp
so is a 100lbs to 1hp a standard weight to thrust ratio or is it kinda low kinda high
whats the rule of thumb on that

 

Did I miss a link to a page detailing these magnetic bearing based turbines? I'm a computer science student, but dabble in house design, and would like to run the numbers for including something like this.

They may not be as efficient as standard windmills, but I do think they would be easier to secure in a heavy storm for home built units.

 

they are supposed to be able to handle up to 100mph+ winds
and they do not swing violently in gusty conditions

if you google
virticle wind turbines generators vawt
in video
you will get hundreds of hits many describing how to build them

and the scuttle but is that they are more efficient than standard

B

 

Boston, look at the link at the bottom of my posts - that is what I am building... @ 10720 pounds and with 2 x 10 hp outboards (petrol), the figures show 536 pounds per hp as a comparison to yours... an easily driven boat (basic sail area of 72M2 or 775 square feet with main and #2 jib)...

kistinie, I think I have that covered as the torqeedo electric outboards have a peak draw of 4000 watts each at 48 volts and each has its own bank and leads from battery to motor of about 3 metres (10ft), as there are 2 banks - one in each hull, under the aft berths and the "outboard mounts are close to the aft bulkhead of the berth/cabins... - the gensets are forward in the chamfer area of the bridgdeck, between the pair of forward full width main bulkheads (aft one holds the mast step)... The images at the website are pdf files and can be used to see in more detail by clicking on the thumbnails...

 

those cats are all the rave down in the Caribbean
and way to go on the low power usage
1 hp per 536 is really good
the shallow draft of a cat is really helping out with that although you will have more surface area

whats your max speed at that hp
and how long can you go on batteries alone
or is it a continuous run genset

wind turbine later and your self generating while you sit around
although pv are easier to hide in that design they are more expensive

B

oh and those bolt on electrical stern drives are really slick
17 hp eh
whats the specs on that
how many amps at how many volts

 

Boston most of those questions will be answerable in about 12 months... I anticipate less than 30 minutes under batteries alone and the gensets will automatically kick in when load and charge level determines a need.... a little bit complex as there will also be about 2KW of Photo-Voltaic panel potential as well.

It seems that wetted surface is not that big an issue - wave generation is first big hindrance as that determines what is generally called (wrongly) "hull-speed", but as in many things relating to word usage in English, an accepted term (much like "hoovering" instead of vacuum-cleaning)....

Once a hull tries to attain a certain speed, (lets still call it "hull speed"), its stern falls into a wave trough whilst the bow tries to climb over the one it is generating, and, - climbing uphill in water requires lots and lots of "horsepower" just to stay there - riding the hump... instead of humping the ride. - - Long skinny hulls, as per some modern cats, do not produce a bow wave so readily or so big as most monohulls, so require a lot less to make them go well...

In some comparisons I did on average expected output watts/kg pv seemed to have a slight edge in the 1500w+ region and also on the watt/mass and about par on watts/$ to have installed... That was a couple of years ago so things could have changed.... On a sail boat co-gen is a good option too but as a supplement as sailing is about 10 to 20% of the time or less...

 

ok whole new twist
I was just over on another thread and remembered some calculations I had worked out concerning flywheels
a 200lb wheel with a diameter of three feet ( if Im remembering this correctly ) spinning at 10,000 rpm other than being a bomb also contains a huge amount of potential energy
only problem I can think of is that its going to want to find its own stability due to gyroscopic forces
it could be set in gimbals to negate some of those forces
and it will need a safety cage anyway
but
hmmmmmmm
time to go crunch some numbers
I know two of em contain enough energy to bring a one ton car

 

Even in gimbals, it will induce immense forces against any change in momentum and direction - try this experiment - get the front wheel of a bicycle, holding one side of the axle and spin it up, now try walking a short distance, in a straight line at various angles to the line of spin of the wheel and also try moving forward and then turning to head in another direction.... Try holding the axle in a horizontal position with the wheel spinning for and aft, then try with the wheel spinning across your heading, and also with the axle vertical - still having difficulty?

 

sucks cause the fly wheel is so efficient in storing energy