BLADEFISH Sea Jets - A Completely Different Approach

[cool_hardware52]

It's possible that it might go 3.5 M/h, but it would only be for a couple of minutes,

No it isn't. With a 210 watt motor you won't reach 3.5 mph ever, regardless of the battery used. Hook it up to an extension cord wired direct to Hoover dam and you still have a 210 watt motor.

To go 3.5 mph will require about a 1500 watt motor. A 1500 watt motor alone weighs more than 10 lbs.

and not the "70-20 minutes" specified on the website. A Lithium Ion Battery has an average energy density of 200W/Kg, which means that if the scooter was 3/4 battery, it's still only 684 W/H, which isn't nearly enough to meet the advertised specs.

Regarding the battery. The claimed weigh of the entire device is 10.2 lbs. If 1/3 of this weight is actually battery you would have about 1500 grams of battery.

At 200 watt hours per kg you expect to have about 300 watt hours of stored energy. 300watthours/210 watts = 1.42 hours (at ~1 mph or less)

I'm amazed at how many people trust advertising more than math.

It's a sad reflection on the education system in today's United States.


Tobin

 

[Web Monkey]

No it isn't. With a 210 watt motor you won't reach 3.5 mph ever, regardless of the battery used. Hook it up to an extension cord wired direct to Hoover dam and you still have a 210 watt motor.

I didn't see the 210W motor spec.

Regarding the battery. The claimed weigh of the entire device is 10.2 lbs. If 1/3 of this weight is actually battery you would have about 1500 grams of battery.

I was being generous and gave it 3/4 battery weight, in case they were using a new lightweight motor.

Terry

 

[deeper thoughts]

So based on the only first hand report from Rapid diver so far, it gets a thumbs up

 

[cool_hardware52]

I didn't see the 210W motor spec.
I was being generous and gave it 3/4 battery weight, in case they were using a new lightweight motor.

Terry

Once you "back out" the weight of everything that's not battery, case, electronics, motor, prop, shroud, handles, 1/3 for battery is probably generous.

Battery cost is also a factor. Li-Ion typically sell for about $2 per watthour. If the battery in the Bladefish is 300 watthours you have a ~$600 battery in a $800 scooter. I seriously doubt it exceeds 300 watthours and it very may well be smaller.

Motors require copper and magnets. There really aren't any magic light weight motors that produce 2-3x the output per unit weight.

The current champs in terms of watts per unit mass are brushless, but they still require copper windings and heavy magnets.

Tobin

 

[Matt S.]

As you said, there still may be a place for the product. I wish vendors would not just repeat the manufacturer's BS specs though. (And not just for this product, that is a general comment on retail.)

Tobin, you should make scooters.

 

[VinoBambinos]

I was asked to video a pool test of the Bladefish 5000 by my LDS, my wife along with a teenage female diver and one of the instructors tested it in the pool. At first glance I was impressed by how easily they maneuvered the scooter.

My interest was based on the fact that I am not a strong swimmer and usually struggle to keep up with the others in our group, so I grabbed one to give it a try. I laid on the bottom of the pool and hit the triggers and it couldn't budge me, then I decided to assist it by kicking, with some effort I was finally able to get moving, but not at any real speed and when I tried to make a turn I came to a complete stop and not quite neutrally buoyant I began to sink.

After watching the other divers I realized they all were kicking as they would normally, and physically each of them were small by comparison, the largest being the instructor who is 5’-6” and 155lbs. I on the other hand am 6’-0” and 188lbs.

The other three riders all thought it was fun, but none said they would use it on a regular basis. My final conclusion was that I need to spend more time in the pool building up my leg strength.

I’ll try to post some footage on YouTube later this week…If I do I’ll post a link.

 

[ProfessorAronnax]

I was asked to video a pool test of the Bladefish 5000 by my LDS, my wife along with a teenage female diver and one of the instructors tested it in the pool. At first glance I was impressed by how easily they maneuvered the scooter.

My interest was based on the fact that I am not a strong swimmer and usually struggle to keep up with the others in our group, so I grabbed one to give it a try. I laid on the bottom of the pool and hit the triggers and it couldn't budge me, then I decided to assist it by kicking, with some effort I was finally able to get moving, but not at any real speed and when I tried to make a turn I came to a complete stop and not quite neutrally buoyant I began to sink.

After watching the other divers I realized they all were kicking as they would normally, and physically each of them were small by comparison, the largest being the instructor who is 5’-6” and 155lbs. I on the other hand am 6’-0” and 188lbs.

The other three riders all thought it was fun, but none said they would use it on a regular basis. My final conclusion was that I need to spend more time in the pool building up my leg strength.

I’ll try to post some footage on YouTube later this week…If I do I’ll post a link.

I'm 200+ and it towed me with no problem. Did you realize it has 3 speeds and were you holding it properly? There is no way the 5000 wouldn't move a 155# diver-something's wrong with this picture.

 

[VinoBambinos]

I'm 200+ and it towed me with no problem. Did you realize it has 3 speeds and were you holding it properly? There is no way the 5000 wouldn't move a 155# diver-something's wrong with this picture.

Re-read my post...I'm 188lbs not 155, and as I stated it would only move me when I made the effort to move myself. Once moving I felt I had to continue to kick to keep it moving and to make a turn I had to bend completely at the waist and then kick out of the turn.

 

[ProfessorAronnax]

Re-read my post...I'm 188lbs not 155, and as I stated it would only move me when I made the effort to move myself. Once moving I felt I had to continue to kick to keep it moving and to make a turn I had to bend completely at the waist and then kick out of the turn.

What color was the scooter you were using? All black or black and orange

 

[VinoBambinos]

What color was the scooter you were using? All black or black and orange

It was the 5000 not the 3000, and actually it was black with red on the handles.

About 5-7 minutes of runtime before I used it, but it had been fully charged by the manufacturers rep who was on site for the demo.

And yes I know the scooter has three speeds, I tried them all...and I held it per the reps instructions (arms extended and slightly below my body).

Understand that I'm only stating my experience. As I posted earlier, it towed the other three riders quite well.

I could see it used for snorkeling or extremely shallow dives, but as someone who carries a camera and likes to stop to check things out closely I'd never use one.

YMMV