Plate positioning on back

[cool_hardware52]

I can see how trim would be affected by lowering the tank, but the basic complaint of valve gouging skull would seem to be an over riding reason to do so. Can't trim be readjusted following the modification by placing some weight high on the plate?

Having your head touch the reg is not a big deal. In doubles it's a given. Ever wonder how all those divers using doubles manage?

Rest assured they did not cut new slots, or etc. etc. You can't move doubles way down you back and still reach the valves.

Stable horizontal trim and buoyancy control are the foundation pretty much all other midwater skills are built on.

Dropping you tank 'till the lower end hits you in the hamstrings is just silly.

Lower the plate a little, turn the tank a little, and get used to it, or find a more conventional tank and valve.

Tobin

 

[4sak3n]

I will stick with everything I said and remember what I told you, they will tell you I am wrong, but I am not being hit in the head either. Before I did anything further, as I have already said, 70% of your problem appears to be related to that funky tank and all that other "stuff" that I cannot seem to foucs my eyes on. It may be that netting that is hurting my vision.

Just for my curiousity, what tank is that, what is that round thing around the neck, what regulator is that and what is that other "thing" below the regulator. Even with my glasses on I cannot figure that out.

N

The tank is 12,2L Faber steel dumpy. It is specially designed to be squat like that instead if long and thin like normal 12s. What for I have no idea (seems silly) but they are the only 12s my club has and since I am a little bit of an air hog I use them.

The regulator is an Aqualung Calypso.

The "thing" below the regulator is a viz disc. It is a local standard that is used in conjunction with viz (VIP?) stickers. Every dive shop here in SA uses one which has the same info that the viz sticker has (last visual, tank WP and serial number) except in an easy to read place. It might be unnecessary but it is standard for each dive shop to put one on when they do viz here and it doesn't get in the way at all.

Some photos that were promised. Sorry that the detail didn't come out well but I used a cellphone camera. The measuring device is a standard ruler 30 cm (1') long.

Reg:

The first stage (including yoke assembly) is about 145mm long ( ~ 5,8 inches).

Valve:

The valve, from where it joins the neck of the tank, is about 70mm long (~ 2,8 inches). The distance from the bottom of the tank neck to the top of the valve is approximately 110mm (~ 4,5 inches). The width of the valve where the knob is is about 80mm (~ 3,2 inches). From the shoulder to the top of the valve is approximately 210mm (~ 8,4 inches).

And for fun, the beaten up viz disc:

Thanks for your help everyone, it is great to get a wide variety of suggestions even if everyone doesn't agree. It gives me differing viewpoints.

But I guess there is just no way of getting around getting into the water and adjusting the harness until I am happy!

 

[Colliam7]

The tank is 12,2L Faber steel dumpy. It is specially designed to be squat like that instead if long and thin like normal 12s. What for I have no idea (seems silly) but they are the only 12s my club has and since I am a little bit of an air hog I use them.

It appears that you have a trade-off. If anything, a 'fatter' tank should move the 1st stage out a little further from your head and reduce the problem of contact, but the taller valve moves it up from the nape of the neck, where contact isn't as likely, to a position right at the occipital region of the skull, where it is more likely. Two questions: 1. Do you have the same problem with 'normal' 12L tanks? 2. Have you tried a STA (can you borrow one from a club member, for example)? My first reaction was to suggest at least trying a STA. I have several of the older Dive Rite ABS models, and they move the tank out from my back about 0.5 inches, without any noticeable effect on trim. I am certain the head contact is annoying - I have a similar problem when I have to use a DIN-to-Yoke adapter on a yoke tank valve with my DIN reg, and it is a real irritation. Definitely tweak the plate position, and crotch strap length, as Tobin suggested. But, the tank valve height may be a substantial part of the issue.

 

[Nemrod]

Do you get thrown in jail if you remove that disc because I assure you, if so, I would be in jail? I even remove those tags from my mattresses and dude, that disc would be in the landfill. I am not being mean, but that is just plain dufus, it makes no sense at all and it is just clutter, probably wind up getting torn off and littering the seafloor. Whenever I think the US is turning into a police state something like this comes along and reminds me that it is not.

Using an STA alone will not help, you must lower the upper camband so it does not fall off the shoulder when you lower the tank. The little short and fat tank with mega long neck is amplifying the problem. Have you ever noticed this head banging thing rarely comes up with divers using the more standard BC jackets and so called back inflate rigs? Have you noticed about 90% of them have a single camband. Have you noticed that many of those rigs have built in stops to keep the tank down lower? The excessive C/C distance between the cambands and their position on virtually all plates and STAs is why the only divers routinely getting hit in the head are BP/wing divers. Yeah, it happens with other rigs but not nearly so often. I have seen maybe three single camband rigs actually try to drop a tank, one it was a cheap little camband that was worn nearly in two and it snapped, another it was threaded incorrectly by a new diver and the third was my wife's when I (I) did not install it correctly because I was busy trying to rig my own gear up and thought, I don't know why I would though in retrospect, figured that a diver with some 25 plus years of diving experience (her) could rig her own tank, silly me. One central camband is all that is really needed. I tell you this, that netting will contribute to loose bands and tanks wanting to squirm off on their own adventures. N

 

[cool_hardware52]

Using an STA alone will not help

Correct.

The little short and fat tank with mega long neck is amplifying the problem.

Right Again.

The excessive C/C distance between the cambands and their position on virtually all plates and STAs is why the only divers routinely getting hit in the head are BP/wing divers.

1/2 Correct. Most Sta's force very high tank positions. Most Direct Mount Plates do not.

The Camband spacing on most STA's sold are about 11" Center to Center. That's easy to see as the camband slots on most STA's are centered on the bolt holes normally used for mounting doubles to a backplate. These holes are at 11" centers.

One of the key advantages of a Direct mount plate (Sta-less) like a DSS plate is the much lower position on the plate of the upper camband slot. Using the cambands slots in a DSS backplate results in a upper camband position relative to the plate that is about 3 inches lower than it would be using a conventional STA.

The camband slot location on a DSS plate is actually lower than the position of the camband slot on the modified STA you offer pictures of as an example of how to "fix" the "Problem". This is not a "problem" in a well designed direct mount plate.

Tobin

 

[Nemrod]

Quote frm cool:

"The camband slot location on a DSS plate is actually lower than the position of the camband slot on the modified STA you offer pictures of as an example of how to "fix" the "Problem". This is not a "problem" in a well designed direct mount plate."


Well, maybe I am not seeing what your seeing but it does look like he has a DSS rig and several DSS rigs have had the same problem which is generic to the species. You used the words, "well designed," OK, hmmmmmm.

BTW, if you actually read what I said before always asking for proof and jumping on me for my practical solutions, you will note that I also mentioned he could lower the tank further by looping the camband under. The positon I cut the slots for my rig on MY STA was for my use, I could have cut them lower or done a number of different things--including making a STA with only a single central camband, oops, I think I did that and it works real good.

*edit to properly attribute quote to prevent confusion.

N

 

[cool_hardware52]

The camband slot location on a DSS plate is actually lower than the position of the camband slot on the modified STA you offer pictures of as an example of how to "fix" the "Problem". This is not a "problem" in a well designed direct mount plate.

Well, maybe I am not seeingwhat your seeing but it does look like he has a DSS rig

Nemrod,

First you correctly attribute the problem to the odd tank and valve combination, then you try to fault the DSS gear. Which is it?

and several DSS rigs have had the same problem which is generic to the species. You used the words, "well designed," OK, hmmmmmm.

Really? "several DSS rigs"? Please elaborate. Must be a lot of odd tank /valve/ reg combos out there that I've never seen or heard of before.

I've realized long ago that you actually believe that you know more about the goods that I design and sell than I do. I assure you that as a designer and manufacturer that maintains close contact with his customers I'm in a better position to know if my users are encountering a particular problem or not. If we had a high incidence of "head to reg" complaints I'd know about it, and would have had a solution that did not involve "looping cambands" or die grinding new slots.

BTW, if you actually read what I said before always asking for proof and jumping on me for my practical solutions, you will note that I also mentioned he could lower the tank further by loopingthe camband under.

At the risk of being repetitious, lowering the OP's tank is not practical solution, regardless of how one does it. Poor trim is almost certainly the result.

Tobin

 

[Nemrod]

Quote from cool:

"At the risk of being repetitious, lowering the OP's tank is not practical solution, regardless of how one does it. Poor trim is almost certainly the result."


Well, let' see, people have had good trim for years without tanks hitting their heads. The problem is the tank (OP's) is to high which coupled with valve and the long cylinder neck I agree probably is affecting trim and therefore positioning the tank correctly will only improve trim. If the tank is so high it is hitting the head it is incorrect and to the extent that most all "tech" plate systems including apparently yours seem to mount the tank to high, trim will only be improved by proper tank position, ie, lower. It is a common problem, generic to plates of all sorts. You only have to look around and see how high the tanks are when on a plate, much higher than what is typcially see on other types of rigs. Since you want to extrapolate what I said to DSS specifically, knock yourself out, it applies there as well.

There have been numerous threads concerning tank posion and head hitting, do yourself a favor and do a search tobin. You should remember many of them since we have had this argument over and over. They usually start out general with somebody complaining their tank is hitting them in the head and then you jump in the middle of it to defend DSS when usually it has never even been brought up. When it is pointed out your product suffers the same problem you get all wound up. Sorry, but if the shoes fit, wear them I guess.

We occasionally agree from time to time, the poor fellow in S. Africa does not have a problem with his plate and BC so much as his odd tank. Having that huge bottle hiked up behind his head certainly cannot produce a good trim so lowering it using any of several of the methods I have provided and explained to him will only serve to improve his conditon regardless of what brand of equipment he is using. This is kind of like the fable with the King who had no cloths but only the little boy would admit seeing that the king had no cloths. You can pretend the tanks are not to high--often--but in fact they are and it is usually BP/wing users who tend to complain of it most often.

I offer solutions, several of them, and you just stomp your feet. You and your buddies can go ahead and send me some more hate mail, I am still right, more often than not, but heck, every now and then----cannot be perfect.
N

 

[4sak3n]

I raided our equipment room and got my hands on a 10,4L Luxfer aluminium cylinder and a 10L Faber steel.

The Luxfer's Divetek valve is ~70mm (~2,8") from top to where it is threaded into the tank and ~170mm (~6,8") from top to the shoulder of the tank.

The Faber's valve is ~60mm (~2,4") from top to where it is threaded into the tank and ~140mm (~5,6") from top to the shoulder of the tank (although this was harder to measure because it too has an irritating net).

So I guess if I have no luck adjusting the harness (which I still intend to spend a lot of time doing) then I'll just switch to a 10L steel instead of a 12L. I can deal with the head issue _if_ I want to do some deep dives and need the extra air.

 

[cool_hardware52]

"At the risk of being repetitious, lowering the OP's tank is not practical solution, regardless of how one does it. Poor trim is almost certainly the result."

This diver has already lowered his tank quite a bit below where it would be if one was to use a conventional STA. Lowering THIS diver's tank is the issue, not whether or not ANY diver might benefit from a tank position lower than what is possible with a conventional STA.

If the tank is so high it is hitting the head it is incorrect and to the extent that most all "tech" plate systems including apparently yours

Please show me one other DSS user, who is direct mounting, using our plate and wing, in order to solve a "head to reg" problem who needed to:

1) Buy a STA

2) Modify it as you recommend.

seem to mount the tank to high, trim will only be improved by proper tank position, ie, lower. It is a common problem, generic to plates of all sorts. You only have to look around and see how high the tanks are when on a plate, much higher than what is typcially see on other types of rigs.

Even a casual survey of divers using conventional BC will find that they are predominately out of horizontal trim. While it is possible in some jackets to achieve horizontal trim, it is seldom the reality. Jackets are by in large designed, and sold based on their performance at the surface, not at depth.

To argue that backplates need to emulate the hips down, heads up position that jackets tend to produce, by lowering the tank, displays a lack of understanding of one of the key benefits of a BackPlate and wing.

Since you want to extrapolate what I said to DSS specifically, knock yourself out, it applies there as well.

Well, maybe I am not seeing what your seeing but it does look like he has a DSS rig and several DSS rigs have had the same problem which is generic to the species. You used the words, "well designed," OK, hmmmmmm.

When you posted the statement above were not specifically stating that DSS rigs have a problem?

There have been numerous threads concerning tank posion and head hitting, do yourself a favor and do a search

Yes there have been many threads about heads hitting regs. The cause however was invariably the use of STA's that force to high a tank position. You have repeatedly offered your solution of a modified STA. Your modification results in essentially the same tank position as a DSS plate offers "out of the box"

Again I'll ask you to find a single example of a DSS user, with our plate and wing, that reported such a problem.

We occasionally agree from time to time, the poor fellow in S. Africa does not have a problem with his plate and BC so much as his odd tank.

Correct

Having that huge bottle hiked up behind his head certainly cannot produce a good trim.

It's not hiked up behind his head, the valve and reg are, but the mass of the long necked tank is already quite low on the back plate. Lowering it further is very likely to produce hips down, heads up trim.

Try to focus here on the problem reported, i.e. head to reg contact. The OP has not reported ANY TRIM Problems.

I offer solutions, several of them, and you just stomp your feet.

Your "solutions" will only cause other problems.

You and your buddies can go ahead and send me some more hate mail.

We have exchanged maybe two or three PM's, none for perhaps a year or longer. I have never sent you anything that might be remotely characterized as "hate" mail. To suggest that I have is simply false.

Am I surprised that you might receive hate mail? Hardly.

Tobin