Can there be electric offshore race boats?

[gearhead]

I kind of thought the same thing, but I had already started it.

We could call it a historical boat if it was made, it would be the first battery powered offshore race boat!:hurray:

Anyway if we had 2000 lbs of batteries how long would that run an electric motor with the equvilant power of a 300 hp gas engine?

I tried to find some formulas but they were kind of hard to decifer and had some variables that I don't understand yet.

By the way the shot of the wing is awesome!!!!!!!!!!!

 

[Ratickle]

I can always move any thread....

Let me know.


Did you log into NAMBA and read Lohring's article there? It has all the charts and info we need....


We'd have to get his permission to steal it....:sifone:

 

[lohring]

I can always move any thread....

Let me know.


Did you log into NAMBA and read Lohring's article there? It has all the charts and info we need....


We'd have to get his permission to steal it....:sifone:

Steal away.

Using 300 shaft hp requires 375 hp or around 280 kilowatts of input power. With a 500 volt power supply you would need 560 amps to the motor. Two thousand pounds of lithium polymer batteries would be around 6330 cells. (By the way, 2000 pounds of gasoline is a little over 300 gallons.) That would allow a 135S 46P (135 cells in series with 46 of those series packs in parallel) battery of 5000 mah cells. That battery could deliver 184 amps for an hour with a 20% safety margin. Modern lithium polymer cells could easily deliver over 4000 amps, but our problem is duration. (If our goal was power like our record boat that would be 2700 hp!) Our full throttle current is 560 amps so we could safely run for only around 20 minutes at full power. That's a race length of less than 30 miles at 80 mph, probably a lot less under real conditions. The same boat with 2000 pounds of gasoline burning 150 pounds (25 gallons) per hour could run for around 13 hours at full throttle.

The solution is tough with boats and airplanes where the drag increases as the square of speed. Cars are easier because they mostly deal with rolling resistance and really don't need much power for sustained operation. Electric power plants can easily supply lots more power for short times and can recover some of the energy lost in braking. Boats need constant, high levels of power. Running a longer distance in a boat either takes more energy or a faster boat for the same power and duration. How fast can you go with 300 hp? Could you sustain this in a sea?

This all reminds me of the early days of electric power model airplanes. With nickel cadmium batteries you could run an acrobatic model around two minutes and a glider for over 10 minutes. Now, with lithium polymer batteries, you can fly an acrobatic model over 10 minutes at full power. That's plenty, but fuel powered models can run lots longer. You just don't need the extra duration in acrobatic model flying.

Lohring Miller

 

[Ratickle]

Doing some searching, I came up with $158,000 for the 6330 cells?

 

[old377guy]

I do have one question. What does any of this have to do with "Historic and Classic Offshore"?

history in the making?

 

[Ratickle]

I'm going with the answer of:

"If it happens, it's an instant classic....."

 

[gearhead]

How about something like this? Flying hovercraft could be straight out of a James Bond movie | The Sun |Features :huh:

No water resistance and still classified as a boat.

 

[Ratickle]

I think, if you review the run where they set the record, by about double the old one, you can see the water resistance was way down. But, if you are really serious about this, I think you'd have to do it in a conjunction with something like the kilo records we just had in Biloxi.

An event like that, wherever the next one may be, with a kilo, a group of the P1 guys, and an offshore race; would give you the opportunity to possibly set a record, and do a demonstration of the P1 short course and a demonstration on the Offshore long course.

So, you'd have a kilo record, about 4 miles maximum total run. A short course, maybe four laps of around a mile each? And then the offshore course, maybe 2 laps of around 4 to 6 miles each. If you had the batteries charged in between each event, maybe it would be feasible. If it were in conjunction with possible Phenomenon being there, the two combined would be a huge draw.

We need to know if there is possible a second electric record for Vee Hulls. If not, get ahold of the APBA and get one set up.

 

[lohring]

Let's design a boat. Help me pick a fast, small hull, probably an inboard cat, and tell me how much power it takes to drive it at a particular speed. Please try to eliminate hype. I can calculate a rough power plant design to go say 15 miles at that speed.

Lohring Miller

 

[Ratickle]

I'm not sure what happened to it, but I can do some checking. May be the answer as a base hull.

Earhart had a 24 Skater hull set up as a single with a vee drive and 3 speed transmission. I wonder if that would provide a base package with the requirements for lift, drag, and true offshore performance in a small, light, package?

 

[gearhead]

What would the lightest hull material that you would want to use? Is a wood hull lighter than fiberglass? What would you think as a minimum lenght for the boat and what hull design would you look for? Maybe even an old 20 ft aluminum starcraft and cut the deck down?

As far as the drive type it seems like it would be easy to make a direct drive with something similar to an arneson drive. Maybe have some height adjustment and use a rudder for directional control.

Might be able to use some kind of wing at a statigic location to provide lift and less drag from the water, not so much to fly the boat but just reduce drag and help stabilize it.

 

[Ratickle]

Carbon would have to be the lightest. A carbon kevlar weave has been the lightest/strongest combination I've seen so far in testing.

 

[gearhead]

Lorhing
What type of boat would you prefer, an outboard set up or an inboard?

How long of a boat would be best?

It sounds like you are thinking about a cat boat, I would be willing to help you find one if you would like some help.

 

[gearhead]

How about this? +++++ 25 CAT SPEED BOAT +++++ 25' cat offshore with trailer 3800.00

 

[lohring]

I need some real data from a real offshore boat. Specifically, weight power, and speed.

Let's go with two 150 KW (200 hp) motor/speed control systems. At 450 volts each would draw 337 amps. The input current with 97% speed control and 95% motor efficiency would be 366 amps each or 732 amps total. If we had a boat that could go 100 mph (your 24 foot Skater?) we would need to run for 10 minutes with a safety factor to go 15 miles. The battery would need to supply 122 ampere hours. That means 25 - 5000 mah cells in parallel. We would need 122 cells in series for 450 volts so the battery would need 3050 cells total. That's 976 pounds of lithium polymer batteries, 55 pounds of speed controls, and 225 pounds of motors for a power plant weight of 1256 pounds.

What existing hull could carry this weight plus two crew and their gear at 100 mph or more with 400 total shaft horsepower?

Lohring Miller

 

[gearhead]

1256 ibs? wow, that is lighter than a 400hp 454 if you include the exhaust and transmission and you don't have to add gas!

 

[lohring]

Yes, but it only runs for 10 minutes. You could do that on 5 gallons of gasoline.

Lohring Miller

 

[rschap1]

I'm not sure what happened to it, but I can do some checking. May be the answer as a base hull.

Earhart had a 24 Skater hull set up as a single with a vee drive and 3 speed transmission. I wonder if that would provide a base package with the requirements for lift, drag, and true offshore performance in a small, light, package?

You aren't thinking of his 25 Eliminator are ya??

 

[T2x]

I need some real data from a real offshore boat. Specifically, weight power, and speed.

Let's go with two 150 KW (200 hp) motor/speed control systems. At 450 volts each would draw 337 amps. The input current with 97% speed control and 95% motor efficiency would be 366 amps each or 732 amps total. If we had a boat that could go 100 mph (your 24 foot Skater?) we would need to run for 10 minutes with a safety factor to go 15 miles. The battery would need to supply 122 ampere hours. That means 25 - 5000 mah cells in parallel. We would need 122 cells in series for 450 volts so the battery would need 3050 cells total. That's 976 pounds of lithium polymer batteries, 55 pounds of speed controls, and 225 pounds of motors for a power plant weight of 1256 pounds.

What existing hull could carry this weight plus two crew and their gear at 100 mph or more with 400 total shaft horsepower?

Lohring Miller

A 24 Skater will carry a 300x OB (330 shaft HP) (550lbs) plus a battery and rigging 200 lbs plus 40 gallons of gas (280 lbs)=980 lbs and run 90+ mph....add 70 hp and 300 lbs and you are in the ballpark. There are lighter versions of the hull available from potato chip "pop" houses, which should last at least 15 minutes......

 

[T2x]

UPon further consideration......

A 24 skater with 2 200 hp OB's (450lbs each) plus two batteries and rigging (400 lbs) plus 10 gallons of fuel (70 lbs) will reach 100 mph carrying a weight equivalent to what you describe.....

I suggest direct Inboard drives through the transom at 2" inboard of the tunnel and 2" above the bottom with a 5 degree negative shaft angle and high rake cleaver propellers, 14" diameter/2 or 3 blades if geared 1.85:1 smaller diameter if direct driven. Mount a single rudder in the tunnel center and use the motors for docking and slow speed maneuvering.