Tweaking a Hollis H160

[Pavao]

Hmm, I also have an H160, I believe there's at least 2 versions of it, one with the LED on nose (older/1st version) and another (later version) where the LED light is no longer present, is that correct, can anyone confirm?

Mine is the one with the LED, it has a metal handle (half ring) on the nose, it also came with cam band handle strap to be attached to the body for carrying, the metal ring is kinda thin and not so comfortable to use, I'm guessing that's why the additional handle was provided for installation. When I first got it, for the first few times I used it with the cam band handle provided, installed, what I remember is that it's buoyancy was solid neutral and trim was perfect.
I didn't like how the cam buckle set on the scooter though, so I quickly rigged my own version of it, all I did was cut the buckle off and use 4 clamps to secure the handle back in, I could not find large enough clamps, so I attached 2 together to get enough diameter, worked really well and is a lot "cleaner" and slick than the cam buckle.
That however, affected the trim, it is now slightly nose light, the buoyancy difference is pretty neglectable though.
I was on deco one day, and I looped the tow cord around the anchor line we were drifting on, it wouldn't move, I gave it several pushes upward to send it to the surface (I was on the 20' stop), it sits in a 50 - 60 degre angle nose up.
This is all in salt water.

Now, I know I need to remove some weight to use it in fresh water, and those weights sit fairly up towards the nose, seems like a PITA job to get it trimmed and neutral for fresh water, and I'm taking this to the caves pretty soon.

John, have you used yours since September? And, is yours like mine, with the LED on nose?

 

[tstormdiver]

I had one of the older ones (SN#75) with the LED light (sold it to Randy g). Mine was definitely very negative, until in motion, but perfectly trimmed in fresh water. I was amazed how it would be fine, once in motion, still perfectly trimmed. It was actually a dream to handle, until I would shut it down, then I would let it hang on my crotch strap (OW quarry) when my hands were busy with other tasks. I now have a DiveX Cuda 650 (more power & longer burn time). I spent a whole 8 hrs weighting & trimming it with the front & rear weight pouches supplied. I now have it just eeeeeever so slightly negative (nearly neutral) & perfectly trimmed. I tried to communicate with Hollis about the negative buoyancy of the H-160 & was told, as stated earlier, that it would require a complete redesign of the DPV.

 

[boulderjohn]

I was on deco one day, and I looped the tow cord around the anchor line we were drifting on, it wouldn't move, I gave it several pushes upward to send it to the surface (I was on the 20' stop), it sits in a 50 - 60 degre angle nose up.
This is all in salt water.

Now, I know I need to remove some weight to use it in fresh water, and those weights sit fairly up towards the nose, seems like a PITA job to get it trimmed and neutral for fresh water, and I'm taking this to the caves pretty soon.

John, have you used yours since September? And, is yours like mine, with the LED on nose?

Mine does have the LED in the nose, and I still have it. With no weights in it while in fresh water, it is slightly negative, and it is tail heavy.

In salt water, I can add weights and do pretty well. If it is slightly negative in salt water, it isn't usually a big deal. A slightly negative scooter in a cave with a silt floor is not a good thing.

I am using a SS Viper now because of that. The Hollis is a fine scooter for those who do not want to use it in a cave.

 

[PfcAJ]

negative scooter in the ocean sucks if you drop it

 

[rjack321]

. I tried to communicate with Hollis about the negative buoyancy of the H-160 & was told, as stated earlier, that it would require a complete redesign of the DPV.

Sounds like a dreadful design and complete lack of understanding of how people dive scooters in the real world. Buoyancy and trim are just as important in a scooter as they are in the diver.

 

[lucca brassi]

I don't have scooter and i don't drive it , but looking on those hollis scooter on theirs website i think it can be buoyncy problem ''simple'' solved by switching a hollis handle .

From pictures looks it is made from pipe opened at one end or even full somehow . I think that can be simple for unscrewing and then it would be a good idea to weigh it.

With using a spring balance fixing it at point of handle you can determine a negative force at extreme end ( note all forces begin in weighting point and have different handles of torque M=F x r )

Then calculate needed volume of hollow solid body and make new handle . Because of extreme end point it should not be too big volume end because is on the top it should also hold handle always right up.

Hoply you understand me ;-))

 

[boulderjohn]

negative scooter in the ocean sucks if you drop it

Yes, but slightly negative allows for lots of time to solve that problem as it drifts ever so slowly downward. In a cave, it only has to drop a few inches to cause a significant problem. More importantly, if you realize your scooter is negative in salt water, you can adjust the weighting to make it perfect. If it is slightly negative in fresh water, you are screwed.

---------- Post added February 14th, 2014 at 05:48 AM ----------

I tried to communicate with Hollis about the negative buoyancy of the H-160 & was told, as stated earlier, that it would require a complete redesign of the DPV.

Mine had a bad speed board, which has since been replaced. In my conversations regarding this with the technicians who replaced the board, I told them about this problem. I said that if they were to just make the body a tad longer, the weight problem would be solved. If they then put the battery out to the end of that added length, it might solve the trim problem as well. They could actually make those new parts and sell them to current owners at a good price to replace the current bodies.

As I said above, people using the scooter outside of a cave won't worry about it nearly as much, so it would be only a very small subset of buyers who would need or want this. I suspect that is the real reason they have not done this.

 

[rjack321]

Yes, but slightly negative allows for lots of time to solve that problem as it drifts ever so slowly downward. In a cave, it only has to drop a few inches to cause a significant problem. More importantly, if you realize your scooter is negative in salt water, you can adjust the weighting to make it perfect. If it is slightly negative in fresh water, you are screwed.

If you've ever had a scooter fall overboard off a boat or come disconnected from a tag line you'd know the "it's just a tad negative" in salt water argument just doesn't work. When they fall off boats they are instantly 6+ft down and you'd need to be a hell of a free diver to gear up and catch it fast enough.

 

[Pavao]

View attachment 177622

What about attaching 4 capped off small PVC pipes to the 4 "arms" that hold the shroud? That's an easy job. I don't have any experience with balancing/trimming DPV's, so, I have no idea what is required, in terms of size (pvc pipes) to do the job, at what size would it start to affect the performance of the dpv?

Would like to hear opinion from those who experience with it, ty!