BLADEFISH Sea Jets - A Completely Different Approach

[cool_hardware52]

LOL at anywhere near 3 mph you wouldn't be able to do any of those body contortions as the drag from the scoot would pull you straight back - especially without a tow chord and harness.

I own a 3mph scooter. Verified with timed passes over a surveyor checked 1/4 mile underwater course in Lake Tahoe.

43 lbs total, 1150 watthour Li-ion battery. The motor alone = the weight of a Bladefish.

These scooters produce in excess of 75 lbs of thrust. Verified using a Bollard pull test and load cell. It then follows that the drag of a skilled diver is about 75 lbs at 3 mph.

Drag increases as a the square of the speed. To go from 3 mph to the claimed 3.75 mph requires (3.75/3) * (3.75/3) * 75 lbs or ~117 lbs.

How long could any diver hold onto, even using both hands, a scooter producing 117 lbs of thrust?

To keep things in perspective:

The typical reasonably fit human can produce ~1/10 hp continuously for moderate periods.

1 hp = 746 watts. 1/10 hp is ~75 watts. The bladefish claims to have a 210 watt motor. 210 / 75 = 2.8

If a diver is used to moving across the reef with a relatively inefficient 75 watts of swimming power and they get a hold of almost 3 times that much power with turning a propeller it will *seem* like they are flying with much less effort. Moving at 100 fpm (1.14 mph) vs 50 fpm (.57 mph) is a big jump, but it's *NOT* 3.75 mph

Drag increases as a function of velocity squared. Power increases as velocity cubed.

If my ~3 mph scooters require ~1100 watts then to reach 3.75 mph would require (3.75/3)^3 x 1100 = ~2150 watts. A motor capable of delivering 2.150 Kilowatts or almost 3 hp is going to to weigh about 20 lbs.

The Li-Ion battery necessary to drive 2.15 kilowatts for an hour will weigh ~25 lbs.

How do you get a 20 lbs motor and 25 lbs battery into a 10.5 lbs scooter?

Tobin

 

[PvtStash]

If they turned it on and put it in the water and then saw how fast it went (without a diver)... perhaps 3.75 mph is possible in That scenario?

 

[cool_hardware52]

If they turned it on and put it in the water and then saw how fast it went (without a diver)... perhaps 3.75 mph is possible in That scenario?

1) It's a supposed to be a DPV or Diver Propulsion Vehicle, with no diver what is it?

2) The "cover story" is they tested it with a 60 lbs snorkler

3) It's clearly unstable, without a diver to control it and resolve the torque a "free runner" won't follow any predictable course.

Tobin

 

[ProfessorAronnax]

You guys have absolutely got to try one(evaluating a product without using one first is pretty goofy)-then you'll see first hand. Beyond the power of the unit is the portability-this is a very big deal for those of us who are tired to lugging heavy equipment on our shore dives. The BladeFish 5000 only weighs about 10 pounds and carries very easily.

In the water I find it does exactly what I want it to do-conserves my gas, extends my range, is helpful in currents and is fun.

I own an Apollo, a Sea Doo Explorer, and a VS Supercharged(and more). I would end up grabbing the VS Supercharged(the least powerful of the bunch) just because it was nice and light and I don't like making a bunch of trips from my truck to my entry point. The BladeFish really takes this to the next level. Oh, and it's probably the simplest piece of Scuba Gear you'll ever own-To charge you plug it in-When your through diving-you rinse it off-maintenance free and simple

If you want additional power and speed your going to need to go with a much bigger, pricier unit. If you want a great little DPV the BladeFish 5000 can't be beat

 

[deeper thoughts]

You guys have absolutely got to try one(evaluating a product without using one first is pretty goofy)-then you'll see first hand. Beyond the power of the unit is the portability-this is a very big deal for those of us who are tired to lugging heavy equipment on our shore dives. The BladeFish 5000 only weighs about 10 pounds and carries very easily.

In the water I find it does exactly what I want it to do-conserves my gas, extends my range, is helpful in currents and is fun.

I own an Apollo, a Sea Doo Explorer, and a VS Supercharged(and more). I would end up grabbing the VS Supercharged(the least powerful of the bunch) just because it was nice and light and I don't like making a bunch of trips from my truck to my entry point. The BladeFish really takes this to the next level. Oh, and it's probably the simplest piece of Scuba Gear you'll ever own-To charge you plug it in-When your through diving-you rinse it off-maintenance free and simple

If you want additional power and speed your going to need to go with a much bigger, pricier unit. If you want a great little DPV the BladeFish 5000 can't be beat

I will be going to the reef Thursday and Friday. Am looking forward to using these scooters again and again! My wife and I are VERY satisfied customers

 

[cool_hardware52]

You guys have absolutely got to try one(evaluating a product without using one first is pretty goofy)-then you'll see first hand.

Can you cite a single instance in this thread where **ANYONE** has offered an evaluation of the Bladefish who has not personally used one?

I haven't seen any member do so.

OTOH there are numerous posts where members, including myself, multiple times have evaluated the Marketing Claims made by the manufacturer.

These claims are outrageous and one need not purchase and or use the device to reasonably reach this conclusion.

Tobin

 

[TheMadDane]

I saw/held played with one at the Santa Clara Dive show last weekend. Bamboo Reef dive shop (Monterey) will start to rent these out in the future. It is VERY light and compact but as described, incredibly noisy! I'll deffinately rent one to try once they have em in stock.

 

[mikes351]

I saw/held played with one at the Santa Clara Dive show last weekend. Bamboo Reef dive shop (Monterey) will start to rent these out in the future. It is VERY light and compact but as described, incredibly noisy! I'll deffinately rent one to try once they have em in stock.

You said that this was noisy, what kind of noise are we talking about? From the blades or internals? Can you give me a better idea of it operation?

 

[TheMadDane]

Sounds like a roto rooter, has a high pitched sound very "Gear" related, almost like your tumbling small rocks in a rock tumbler/polisher.

 

[cool_hardware52]

Sounds like a roto rooter, has a high pitched sound very "Gear" related, almost like your tumbling small rocks in a rock tumbler/polisher.

Small high speed electric motors can produce more power per pound, but propellers loose efficiency when turned at high speed.

One solution is a gear reduction, but they are usually noisy and gear boxes cause power loss.

Most "tech" scooters use special high torque, low rpm motors that directly drive the propeller. These motors are larger heavier than the equivalent power high speed motor, but they eliminate the need for a noisy, loss prone gear box.

Tobin