DPV research

[lostsheep]

Feature that everyone wants, quiet. Regardless if you are the user or just someone who is also in the water.

I'm just gonna be that guy.

I have a gear driven piranha, it's loud as phawk. My buddies say that they love it cause they know when I am there (especially when I am not leading.)

I'll never be that guy with straight pipes on my hot rod cause it is straight up annoying but on a dpv...I am not too sure.

Is a quiet scooter really that important?

 

[Wibble]

Does noise equate to inefficiency?

Dive Xtras released a firmware update on the Blacktip which massively quietened it down. Something to so with a sinusoidal waveform to the motor.

 

[lostsheep]

Does noise equate to inefficiency?

Dive Xtras released a firmware update on the Blacktip which massively quietened it down. Something to so with a sinusoidal waveform to the motor.

Noise takes energy, period. Conservation of energy is a thing.

How much is lost via noise, I have no idea, nor how to quantify it.

Perhaps @Jon Nellis or @Jona Silverstein have data on this?

 

[Gone for diving]

Well I guess you could record the noise and play it on a speaker and measure the watts.... it would be close aprox
It will be very low I would guess less than 5 watts.
Your gear set will use more power than the noise.
Direct drive is the least wasteful.
But the brushless motors always seem the have the high frequency whine. I believe it's from the wire slightly vibrating as the current is pulsing though it.

 

[Rayk]

Is that Aquazepp R&D dept?

 

[OTF]

Do any of the DPVs on the market use a wet-running brushless motor without a shaft seal? That could be interesting. Not talking about the pool toys based on multiple small Blue Robotics thrusters, but a proper big motor. Although BR did just come out with new larger thruster that could be interesting here. Too bad their quality is so spotty.

 

[Markus MDDT]

Do any of the DPVs on the market use a wet-running brushless motor without a shaft seal? That could be interesting. Not talking about the pool toys based on multiple small Blue Robotics thrusters, but a proper big motor. Although BR did just come out with new larger thruster that could be interesting here. Too bad their quality is so spotty.

Is this a leading question?

Magnetic propulsion

It is not magnetic transmission, but... electric motor working in full water immersion. No shaft seals, direct water cooling and amazing performance.

seacraft.eu

 

[Akimbo]

Submersible AC motors with wet windings have been mass produced since the 1950s for submersible water well pumps. The reason that most DPV motors are inside the housing is they need the displacement and less expensive models run DC motors instead of AC inverters.

Submersible motors are also more of a problem in salt water. They are hard to flush with fresh water and dried salt buildup can add a lot of drag. They have been used on manned deep submersibles for years since the motor mount can be rotated for steering instead of using a rudder. ROVs (Remote Operated Vehicles) tend to use multiple fixed thrusters for steering since they are AC and cable powered and more space constrained.

 

[geoff w]

I've learned from my Blacktip experience one of the most important factors to having a DPV that gets used is, for recreational divers, it needs to be capable enough, reliable enough, powerful enough and affordable enough so there is a community of divers who can go out together on DPVs for fun. With a robust community, you can also make new dive buddies outside your immediate circle of dive friends, and you also get a lot of innovation as far as add ons and improvements. It doesn't have to be the absolute greatest DPV, it just needs to be good enough. Readily available commodity batteries are great, because you can leverage large company R&D and manufacturing economies of scale. Open source ESC means you can leverage the collective ideas and efforts of many instead of trying to compete with much fewer resources, and you have a large pool of expertise to draw from for future bug fixes and new features. For the majority of divers out there, it's hard to find something that checks all the boxes better than the Blacktip that is attainable

 

[Akimbo]

for recreational divers, it needs to be capable enough, reliable enough, powerful enough and affordable enough so there is a community of divers who can go out together on DPVs for fun.

Reliability is critical. Nothing will ruin a brand faster than a few angry stories on ScubaBoard and Farcebook about having to swim a dead DPV back to the beach or boat. A flooded DPV would be a disaster since it could kill an inexperienced diver or force them to jettison it. Let's not even talk about an implosion.

Another factor for the larger recreational market is dry weight. Most divers will be lugging this thing to the water's edge or down a long dock to a boat. This argues in favor of a smaller unit with easy battery changes versus one that will last for a day of diving.