Blacktip Scooter- Limited To Weighting, Buoyancy and Trim

[Mo2vation]

In Salt Water, with the DeWalt 12Ah batts installed, and a medium double-ender on the nose, you can remove all plates and have it neutral in Saltwater.

Trim or Neutral. Pick one. You cannot have both with a Blacktip.

I selected Neutral - adding a loop to one of the stanchions so I can clip it off like a stage (much like Fido....) That makes it behave a little better when kicking.

- K

 

[geoff w]

With 12 AH Dewalt power tool batteries, I removed the heavy nose plate, put a big bolt snap and 1" stainless o-ring on the nose to clip it off, and it's close to neutrally buoyant in salt water. I tied on a small Trident or XS Scuba compass, which is pretty insignificant weight. I found if you let the bolt snap for the tow cord run free it's much easier to control than the way it comes from Dive-X. My preference for buoyancy was neutral and ever so slightly positive. Not sure if you can get it neutral in fresh water with the 12 AH batteries

 

[stuartv]

I put the 12Ah batteries in mine. I added a medium bolt snap to the nose with some paracord. I took out both the metal plates inside the nose, only leaving the screws in place. No other adds or deletes. Having a NERD, I don't see a need to put a compass or bottom timer on my scooter.

In fresh water today, mine seemed to be pretty much perfectly neutral.

 

[RayfromTX]

I've run the test now and find similar to what I've read.

Saltwater
12AH Dewalt batteries
Both plates removed and 3 large bolt snaps/double enders attached
At the surface it was ever so slightly positive
At 20 meters it was perfectly neutral albeit nose up.

 

[Aquanomad]

I leave for Cozumel on Thursday. It will be tested soon. I did pimp my ride though with a vinyl wrap on the tube.
View attachment 573005

Ray. That looks like a nice clean wrap! Bit of advice though. I wrapped my Genesis in a blue carbon fiber pattern vinyl to protect the body and beacuse it looked cool. I peeled it off after 1 dive! 20 minutes in I had a curious baracuda. Didnt think much of it but kept an eye out. A few minutes later there was 2. Than 4. Than 6 or 7. Seemed like every time I turned my back to throttle they got a little more brave. To the point where it got concerning. Realized I turned myself into a big attractant or lure. Never had it happen before or after that and Iv been using DPVs nearly every dive for ~15 years. Not sure where you dive but just a heads up.

 

[RayfromTX]

Oh crap, Thats a bummer. We have lots of cudas here in Cozumel. I will stay aware.

 

[Aquanomad]

Three of us.

And to get back OT, my BlackTip is supposed to arrive this week. My DeWalt 12aH batteries are supposed to arrive today.

I'm getting it into some salt water this weekend (weather permitting).

So, I would also like to know if I need to do anything to have it weighted correctly.

From the above posts, I gather that, with the 12aH batteries and all provided plated installed, it should be pretty close to neutral in salt water. Yes?

At this point, I don't think I'm too concerned about single digit #s of ounces of positive or negative.

I do think that once I get a couple of dives on it, I may work on making some PVC floats to put on the tail, to see if I can get it to be neutral and in flat trim. So, perfect weighting on the first dives does not seem critical.

Hey Stuart. I had some PVC floats on a Genesis that was attached to twin AL 72s. They ended up being tough to dial in a specific lift and the dry weight offset the buoyancy a bit. You might want to try some float arms for heavy camera rigs or this slick foam from Blue Robotics. They have lots of shapes and sizes and you can machine, glue, and paint it. Plus its rated to 800' uncoated. Subsea Buoyancy Foam: R-3318

 

[stuartv]

Hey Stuart. I had some PVC floats on a Genesis that was attached to twin AL 72s. They ended up being tough to dial in a specific lift and the dry weight offset the buoyancy a bit. You might want to try some float arms for heavy camera rigs or this slick foam from Blue Robotics. They have lots of shapes and sizes and you can machine, glue, and paint it. Plus its rated to 800' uncoated. Subsea Buoyancy Foam: R-3318

Thank you for that! That stuff looks like it would be perfect to make a buoyancy collar to fit around the back of the body of the BlackTip.

Unfortunately, $136 for one piece of it?!

I have float arms and Stix floats for my camera rig. I may experiment with those. But, after seeing this material and thinking of the idea of using it to make a buoyancy collar, I doubt that any kind of float (from PVC or a camera rig) is going to satisfy me.

And after yesterday's experience, I am VERY much interested in figuring out something. Having the nose always wanting to point straight up was very frustrating. It really seemed like it made it harder to drive - especially when trying to turn.

This scooter is really nice (for the money, anyway). But, if it had a longer tube, held 2 more 12Ah battery packs, and trimmed out flat, it would be SO much more enjoyable. At least, for someone of my complete inexperience with scooters. Maybe somebody who is really experienced with scooters wouldn't be bothered as much by the strong nose-up attitude, but it really bugged me.

 

[tmassey]

Here’s something similar (but messier): 2-part flotation foam.

TotalBoat Pourable 2 Part Polyurethane Expanding Flotation Foam

About 30 pounds per cubic foot lift and 400psi compressive strength (roughly 800 feet depth). 3/4 ft3 foam (2 quart before mixing) is <$60.

Interesting project: flotation collars. It would be interesting to know just how much lift is needed to trim it. Then you have to add that weight *back* to get it back to neutral buoyancy. 5 pounds of lift and 5 pounds of properly-distributed weight? $60 could make 6 collars. Quite a science project.

My thinking: if it were simply that easy, why didn’t the designers do that? If my math is correct, 5 pounds of lift could be gotten by a 12” diameter ring roughly 2 thick by 4” wide. (Check my *real* rough Math). Or maybe it would be better put around the shroud: certainly more moment arm leverage and more diameter making a smaller ring (or blocks between the fins). But how does that affect performance? Does it reduce resistance to torque rotation? Questions, questions...

 

[Aquanomad]

Thank you for that! That stuff looks like it would be perfect to make a buoyancy collar to fit around the back of the body of the BlackTip.

Unfortunately, $136 for one piece of it?!

I have float arms and Stix floats for my camera rig. I may experiment with those. But, after seeing this material and thinking of the idea of using it to make a buoyancy collar, I doubt that any kind of float (from PVC or a camera rig) is going to satisfy me.

And after yesterday's experience, I am VERY much interested in figuring out something. Having the nose always wanting to point straight up was very frustrating. It really seemed like it made it harder to drive - especially when trying to turn.

This scooter is really nice (for the money, anyway). But, if it had a longer tube, held 2 more 12Ah battery packs, and trimmed out flat, it would be SO much more enjoyable. At least, for someone of my complete inexperience with scooters. Maybe somebody who is really experienced with scooters wouldn't be bothered as much by the strong nose-up attitude, but it really bugged me.

How much does it need? .8# of lift is only $14. 12.34# for $136 but way more than you need.