Building a under water diving platform

[boulderjohn]

It drove me nuts. With the 16 pounds of weights the instructor gave me lying on the bottom was easy, but when I inhaled all of me went up and when I exhaled all of me went down. The idea of pivoting on the fin tips made no sense to me even as a student. I eventually muddled through it somehow, but some of my classmates required ankle weights.

It was pretty much the only issue I had with the class, but it was big. We spent more time on it than any other skill and it was the only one I couldn't do "properly". I have to say that it left me with a distrust of PADI that has never quite gone away.

Do you know how it became part of the course in the first place? Were early divers all foot heavy and thus the fin pivot was inevitable if you were only using breath control to get off the bottom? I guess it's possible with a doublehose reg which positions the steel tank fairly low, weight belt and rubber fins.

Why are you assuming PADI invented that exercise? PADI began operation when NAUI was near bankruptcy and canceled a major instructor training program scheduled for Chicago because they wanted to concentrate their efforts in California. The Chicago NAUI group became PADI and used the same instruction they had been using as a branch of NAUI. I am pretty sure all the major agencies used pretty much the same instructional techniques.

The group I assembled to write the article on neutral buoyancy OW instruction included dive historian Sam Miller, and he was tasked with finding out how instructing on the knees (etc.) started. He learned it was there from the start because there was nothing other than the lungs available for buoyancy control--they didn't even have wetsuits at first. Some of the exercises in scuba are holdovers from an era before the invention of the BCD.

BTW, 16 pounds is way too heavy for pool training. It is the product of on-the-knees training. The students must be overweighted so they can stay comfortably anchored to the floor. What enables them to be comfortable on the knees makes buoyancy exercises very hard because of all the extra air in the BCD.

 

[lowwall]

Why are you assuming PADI invented that exercise?

I'm not assuming that, my guess was that it predates PADI. It would have been more clear if I had said "Do you know how it became part of OW courses in the first place?"

My distrust of PADI because I was introduced to it in a PADI OW course. It was so obviously stupid that they should have either stepped in to fix it much earlier or nipped the whole thing in the bud and prevented it in the first place. As the largest agency they have the means and IMO, the responsibility, to pay attention to this kind of thing.

The group I assembled to write the article on neutral buoyancy OW instruction included dive historian Sam Miller, and he was tasked with finding out how instructing on the knees (etc.) started. He learned it was there from the start because there was nothing other than the lungs available for buoyancy control--they didn't even have wetsuits at first. Some of the exercises in scuba are holdovers from an era before the invention of the BCD.

I know that. Similar to how snorkels became a requirement as there was no surface buoyancy device and LA County did all the early training on beaches that required a long swim out to the dive site. But my question was specifically about the fin pivot which is only natural if you are trimmed foot heavy. Do the early dive rigs (doublehose reg, steel 72, weight belt, no wetsuit, rubber fins) result in a foot heavy trim?

BTW, 16 pounds is way too heavy for pool training. It is the product of on-the-knees training. The students must be overweighted so they can stay comfortably anchored to the floor. What enables them to be comfortable on the knees makes buoyancy exercises very hard because of all the extra air in the BCD.

No kidding. That was another obvious issue although I didn't realize it as a student. The instructor I had for the OW referral reduced it to 12 pounds (in sea water as well) and I was quite a bit happier.

 

[NothingClever]

@Fishdip

The utility shelving split up into sections to form a table will require coupling and anchoring. While it will get you going, I’m not sure it will last long depending on the volume of divers using it.

The most useful one I’ve seen was:

1) a fairly large platform for simultaneous use by two instructors with three to four trainees each or three or four technical instructors with one to two trainees.

2) it was made of PVC pipe with enough space underneath the deck for swimming through. More on that in a second. Above the deck was a “handrail” all the way around with one of the four side open (no “handrail”). The handrail gave instructors a “target” for new divers to work on buoyancy control and spatial judgment and for advanced divers to work on buoyancy control while back-finning. It also allowed the instructor to tie off a 50m spool and have new divers learn their kick count back and forth multiple times. I remember tying off to learn how to reel in a spool, too. The number of vertical posts underneath the deck made for a nice training tool for junior divers to make it through a stretch without touching anything. Adding left and right turns through the “maze” developed helicopter turns for advanced training.

3) The steel mesh decking attached to the PVC pipe with heavy duty zip ties was covered with sunshade mesh screen material secured neatly with zip ties to the steel mesh to make unintended landings harmless. This was great for new divers in their first open water sessions in the ocean and for technical divers working with twinset for the first time and then deco bottle management.

This was not an inexpensive apparatus but it really set a noticeably higher standard than the other dive resort that had unleveled steel grate with holes, sharp edges and protruding ends.

A smaller version of the one I described above could be fabricated with several instructors pooling the money.

 

[NothingClever]

@boulderjohn and @lowwall - can you guys take your sophisticated version of “PADI sucks!” and “Does not!” exchange somewhere else? Rather off topic in the DIY sub-forum, no?

 

[Fishdip]

@Fishdip

The utility shelving split up into sections to form a table will require coupling and anchoring. While it will get you going, I’m not sure it will last long depending on the volume of divers using it.

The most useful one I’ve seen was:

1) a fairly large platform for simultaneous use by two instructors with three to four trainees each or three or four technical instructors with one to two trainees.

2) it was made of PVC pipe with enough space underneath the deck for swimming through. More on that in a second. Above the deck was a “handrail” all the way around with one of the four side open (no “handrail”). The handrail gave instructors a “target” for new divers to work on buoyancy control and spatial judgment and for advanced divers to work on buoyancy control while back-finning. It also allowed the instructor to tie off a 50m spool and have new divers learn their kick count back and forth multiple times. I remember tying off to learn how to reel in a spool, too. The number of vertical posts underneath the deck made for a nice training tool for junior divers to make it through a stretch without touching anything. Adding left and right turns through the “maze” developed helicopter turns for advanced training.

3) The steel mesh decking attached to the PVC pipe with heavy duty zip ties was covered with sunshade mesh screen material secured neatly with zip ties to the steel mesh to make unintended landings harmless. This was great for new divers in their first open water sessions in the ocean and for technical divers working with twinset for the first time and then deco bottle management.

This was not an inexpensive apparatus but it really set a noticeably higher standard than the other dive resort that had unleveled steel grate with holes, sharp edges and protruding ends.

A smaller version of the one I described above could be fabricated with several instructors pooling the money.

Could you post a picture of the mesh you talk about?

 

[NothingClever]

Try this. Copied from the Home Depot application on my phone.

https://www.homedepot.com/p/12-ft-x-8-ft-Black-80-Sunblock-Shade-Cloth-with-Grommets-for-Garden-Patio-W1SDP8012008B/316846052

 

[Fishdip]

Try this. Copied from the Home Depot application on my phone.

https://www.homedepot.com/p/12-ft-x-8-ft-Black-80-Sunblock-Shade-Cloth-with-Grommets-for-Garden-Patio-W1SDP8012008B/316846052

Guessing the heavy duty mesh wire is what PPL call “chicken wire”?

 

[NothingClever]

No, true chicken wire is too light and won’t last. I’ll look up something appropriate from Home Depot or Lowe’s when I get on a proper screen.

 

[Fishdip]

No, true chicken wire is too light and won’t last. I’ll look up something appropriate from Home Depot or Lowe’s when I get on a proper screen.

Thats what I was thinking. And thanks!

 

[FF / EMT]

I wonder if it’s legal to just dump a “platform” in a body of water you don’t own?