Are DPV noisy ?

[Father]

The majority of my dives have been with DPVs.
The Sea-Do Explorer X makes noise, but not really annoying.

The Dive-X Piranha P1... I have a Gen 1 and Gen 2. The Gen 1 I find to be harsh sounding. The Gen 2 I love... it's a very deep pitch in the lower gears... almost like the exhaust on a muscle car. I'm told by my dive buddies who use Explorer-X scooter that they can hear my P1 over their scooters. I can't hear theirs over mine. I usually have to stop mine to hear others around me. When I'm diving with someone who is using my Gen 1 P1 I can hear that one over my P1.

One of my dive buddies has the Gen 3 with a belt drive. On the surface it is borderline silent. I was truly amazed when I was helping him re-program the gearing on it.
In the water, it's not nearly as quiet but by far the quietest scooter of any I've been around.

They all make sound for sure. When you dive DPVs for a while and then do a kick dive you realize how quiet it can be and how divers around you probably equate the noise to be in Central Park and hearing the car traffic from outside.

 

[Wookie]

On a scale of 1 to Jackhammer, they aren't so bad....

 

[sunnyboy]

I have a P1, belt drive. It doesn't sound very noisy on land, but seems a lot louder underwater. When you attach a go-pro to the scooter mount, the sound conduction makes it sound terribly loud on the video.

What is weird is my buddy has a gavin. That thing is barely audible underwater - just a faint whirring sound, especially compared to my P1. My buddy can hear my P1 over her scooter always. I cannot hear anything when mine is running except the larger ferry going nearby.

I know the P1 is supposed to be pretty quiet, but it sure doesn't seem like it underwater. I did send a video to Dive-X and they said it sounded fine (again, taking the sound conduction into account), so mine is not somehow "extra" noisy.

 

[tbone1004]

@sunnyboy the beauty of direct drive vs. gear reduction. The Piranha uses a very high RPM motor compared to the Gavin/24v Silent Submersions. The SS Magnus which spins at a higher RPM, and the Minnus which has a gear reduction make a considerably different noise when compared to the older motors

 

[sunnyboy]

I know. My first scooter was a Gavin. Second was a Dive-X Echo (remember those?). Both relatively quiet for the reason you post (direct drive, lower speed motor) plus the variable pitch prop.

 

[cool_hardware52]

@sunnyboy the beauty of direct drive vs. gear reduction. The Piranha uses a very high RPM motor compared to the Gavin/24v Silent Submersions. The SS Magnus which spins at a higher RPM, and the Minnus which has a gear reduction make a considerably different noise when compared to the older motors

Old news to many here, but a short course on DPV drive train choices.

The mass of the motor has a huge impact on scooter design. Heavy Motors have to be counter balanced by moving the battery forward if you want the scooter to be in horizontal trim. As you move the battery forward the hull gets longer and displaces more volume and the entire machine needs more mass to be neutral. In short heavy motors lead to big heavy scooters.

If you have two electric motors of the same mass and one runs at ~700 Rpm and the other runs at 7000 rpm the 7K motor can produce many times (10X or more) as much horsepower at the one at 700 rpm, in short spinning a motor *UP* is the path to more output per unit mass.

Here's the problem, propellers are most efficient at lower RPM's. Prop design is very complex, but drag goes up fast as you spin up the prop.

Pre Tekna DPV's used high speed motors and some form of gear reduction. The genius of the Tekna (precursor of the Oceanic Mako) was a purpose designed and built high torque, low rpm motor. Tekna had some lead acid battery explosions and Oceanic literally bought the smoking remains of that company. ( I had the good fortune to meet and work with the guy that did the original motor design. He used to own Astro Flight in Santa Monica) Brilliant motor guy.

Gavins and the earlier SS DPV's are essentially the Back end off a Mako, motor, prop, Kort Nozzle mated to a cylindrical hull of great capacity and depth rating than the Mako's.

In an effort to reduce weight (see the first paragraph) there has been a return to small high rpm motors with some sort of speed reduction. The newer Dive X scooter use this approach. The Holy Grail is a low noise speed reducer. Looks like Ben and and his clever band of engineers are making real progress. Bravo.

Tobin

 

[sunnyboy]

Old news to many here, but a short course on DPV drive train choices...

Tobin

Tobin,

Thanks. I love hearing about the history of things in the SCUBA industry. I came into scooters in 2004 when Gavin's and SS's were the big deal (for us). By 2005 the X-Scooter came out and we all bought (and loved) them.

My buddy has a Gavin short hull and I've had some fun helping replace trigger wires, reed switches and batteries. Good times!

I had a Gavin with the short and the long hulls. I have zero love for carting the long hull anywhere.

I really love how my P1 can gain extended range by just buying another battery and plugging it on to the existing scooter. I also have come to love the electronic shift trigger.

 

[lucca brassi]

Completely agree with Tobin , like scuba history

''In short heavy motors lead to big heavy scooters.''

True we have there two max extremes ( heavy BLDC motors because of their construction (rare earth magnets) and other side light Lithium battery pack , so logical it is to prolong lever (long hull ) to balance them in neutral but still need weight in cone head ( looking these pictures )

Piranha P3…Insanity | Dive Xtras

maybe is some possibility also to made gears from tough plastics like oilon ; type of nylon

Nylacast Oilon Plastics by default absorbs sounds, in contrast to metal

 

[Andrew Donn]

maybe is some possibility also to made gears from tough plastics like oilon ; type of nylon

Nylacast Oilon Plastics by default absorbs sounds, in contrast to metal

The old Farallon scooters had a nylon gear train and were loud as all get out. The motor itself by the nature of its high RPM makes a considerable amount of noise. The gears were straight cut which also didn't help in the noise department.

 

[cool_hardware52]

The old Farallon scooters had a nylon gear train and were loud as all get out. The motor itself by the nature of its high RPM makes a considerable amount of noise. The gears were straight cut which also didn't help in the noise department.

The reduction gears (and maybe the motor) are the source of the noise. Better isolation of these elements from the hull ("tuned" vibration attenuating mounts etc) are likely a more effective means of reducing the noise transmitted. This of course gets tricky when the prop shaft penetrates the same hull.

Tobin