Backplate Slot Orientation

[ShoalDiverSA]

Hi there,

I am planning on getting a backplate cut based upon the Roger Lacasse design. I managed to find a CAD version of the design on the 'Net. I am now wondering why the topmost slots (for the shoulder straps) are horizontal?

Does this not result in the shoulder straps rubbing your neck? I did a small test run with 2" webbing and the angle that it has to turn through to make the 45 bend and then the final slot results in the straps actually converging towards one another.

For example, check this picture: http://dir-diver.com/pics/backplate/reach_backplate_large.jpg

The straps seem to be turned down into the diver's neck. The strap remains horizontal and does not seem to "give" much. Surely this is a pressure point?

Again, at the UKRS site, the straps seem to be parallel or converging:

http://www.ukrecscuba.org.uk/ukdiver/harness/kl_harness/kltreadrig02.jpg

It seems that, to alleviate this "issue"(?), some people cross the straps over:

http://www.ukrecscuba.org.uk/ukdiver/harness/aa_harness/dscf0006.jpg

Is this a non-issue? Should I rather have gotten more sleep last night? Should I do something now in the design stage to get rid of this peculiarity? Would it cause other problems to do so?

Thanks for the help.

Cheers,

Andrew

 

[Tractor Tom]

...Andrew.

I think the strap slots going horizontal is an effort to keep the straps from slipping off the shoulders of the wearer when in use. My AUL Aluminum backplate rig came to me (used from eBay) with the straps crossed and I found it very hard to get out of the rig. When I replaced the webbing with new, I didn't cross the straps, and found it a bit easier to get in and out of. I have never noticed the straps rubbing my neck as I'm always wearing either a 3 mill shorty (in tropic water) or a drysuit (in our colder Michigan fresh water). I have some light neoprene strap pads on my rig, but really don't need them.

I think you are dealing with a "non issue" here. The only time it would be an issue is if you are wearing the rig with no other protection (a bare chest) and in my case, the cheap pads would keep my neck from being chaffed.

Hope this is some help. Good question!

 

[divad]

Hi there,

I am planning on getting a backplate cut based upon the Roger Lacasse design. I managed to find a CAD version of the design on the 'Net. I am now wondering why the topmost slots (for the shoulder straps) are horizontal?

Does this not result in the shoulder straps rubbing your neck? I did a small test run with 2" webbing and the angle that it has to turn through to make the 45 bend and then the final slot results in the straps actually converging towards one another.

For example, check this picture: http://dir-diver.com/pics/backplate/reach_backplate_large.jpg

The straps seem to be turned down into the diver's neck. The strap remains horizontal and does not seem to "give" much. Surely this is a pressure point?

Again, at the UKRS site, the straps seem to be parallel or converging:

http://www.ukrecscuba.org.uk/ukdiver/harness/kl_harness/kltreadrig02.jpg

It seems that, to alleviate this "issue"(?), some people cross the straps over:

http://www.ukrecscuba.org.uk/ukdiver/harness/aa_harness/dscf0006.jpg

Is this a non-issue? Should I rather have gotten more sleep last night? Should I do something now in the design stage to get rid of this peculiarity? Would it cause other problems to do so?

Thanks for the help.

Cheers,

Andrew

I just got a cheap AL plate and have been staring at it for a couple of days for the exact same reasons asking myself the same am-I-just-being-a-meddlesome-tinker question. I need to cut single-tank slots anyway but I haven't taken the gringer to it yet.This guy RichLockyer on this board posted one solution with picture for the upper slots on thedecostop. Because of the angle of the plate compounded by the angle of the channel, the straps of most plates do "want" to cross. If you pull them straight out, there is a loop or gap between the outer edge of the strap and the BP leaving only the inside edge to bear any stress. Of course, this justs seems wrong. Its probaby fine,albeit annoying. I've decided for now to cross the straps because the dynamic of opposing stress seems intuitively, and feels subjectively, to be more stable. With the straps pulled straight out, the higher up (closer to the arm) the lower part of the strap is, the more stable the BP seems. The crossed straps allows me to lower the BP a little, which I prefer in terms of the waist strap postion, withpout loss of stability. It doesn't cut into my neck so the only downside is some interference with overhead donning and doffing but I think I don't mind the trade-off. Becase of My S-shaped back, when I raise the backplate, the top sticks out a couple of inches.With it lowered and snug, I only have to flatten my back (pull back my shoulders) to get several fingers of slack on the front of the straps. Are you still reading this? Re the lower slots, the inside slot (for the strap) is perfect but it does seem that the outer belt slot could be more vertical. I was thinking of different ways to re-slot the straps but its tricky (and kind of fun) to visualize but I'm losing interest. Since you're making your own, one simple suggestion would be to keep the strap slots out of the channel angle
preferably by narrowing the channel so tops of straps stay close together. That would get your straps a lot closer to perpendicular. Good luck with the woman. (a spanish guy said this to me once on his way out of a bar. Seems
applicable.) Yellow smiley thing.

 

[ShoalDiverSA]

...Are you still reading this? ...

Of course!

Good luck with the woman. (a spanish guy said this to me once on his way out of a bar. Seems applicable.) Yellow smiley thing.

LOL! :SmileT-sh

Thank you both for the help. I am definitely going to try to apply the idea about keeping the slots out of the channel. It might be tricky given the geometry. I have modified the drawing to include a 10deg angle on the shoulder straps. Based upon the tests I did with the pattern, it should be more like 30, so 10 is not too extreme. At R200 ($30) a shot for the plate, it is not too expensive to make a mess of the first one.

I think you are dealing with a "non issue" here. The only time it would be an issue is if you are wearing the rig with no other protection (a bare chest) and in my case, the cheap pads would keep my neck from being chaffed.

Hope this is some help. Good question!

Thanks, I haven't asked a good question for years... or at least my boss thinks so.

The chaf(e?)ing issue might be a problem because I find that even my Poseidon BC chafes a bit through my wetsuit neck. And of course I have to keep my 100th dive in mind!!!

I am going to go with the 10 degree compromise mentioned above and see how it feels.

I am awaiting the arrival of my aircell from Jet Harness - ordered today.

I am so stoked!!!

Did I mention that Jeff from Jet Harness is a great guy? "Customer care" is his middle phrase!

Anyway, enough of that. Thanks for all the pointers.

Cheers,

Andrew

 

[divad]

Of course!



LOL! :SmileT-sh

Thank you both for the help. I am definitely going to try to apply the idea about keeping the slots out of the channel. It might be tricky given the geometry. I have modified the drawing to include a 10deg angle on the shoulder straps. Based upon the tests I did with the pattern, it should be more like 30, so 10 is not too extreme. At R200 ($30) a shot for the plate, it is not too expensive to make a mess of the first one.



Thanks, I haven't asked a good question for years... or at least my boss thinks so.

The chaf(e?)ing issue might be a problem because I find that even my Poseidon BC chafes a bit through my wetsuit neck. And of course I have to keep my 100th dive in mind!!!

I am going to go with the 10 degree compromise mentioned above and see how it feels.

I am awaiting the arrival of my aircell from Jet Harness - ordered today.

I am so stoked!!!

Did I mention that Jeff from Jet Harness is a great guy? "Customer care" is his middle phrase!

Anyway, enough of that. Thanks for all the pointers.

Cheers,

Andrew

Send plans!

 

[redacted]

Try did a search on "backplate chafing". It looks to me like you are trying to fix a non-problem. I have no chafing problem with mine even with just a t-shirt. Actually, after the straps soften a bit with age, slipping off your shoulder if they are too loose is more likely to be a minor problem.

 

[ShoalDiverSA]

Interesting... Just browsing around and found that the Koplin plates have angled shoulder straps. Mmmm...

http://www.selchie.com/backplates.htm

Cheers,

Andrew

 

[divad]

Interesting... Just browsing around and found that the Koplin plates have angled shoulder straps. Mmmm...

http://www.selchie.com/backplates.htm

Cheers,

Andrew

The slots are also not in the channel. But I have given up. GLWTW.

 

[ShoalDiverSA]

The slots are also not in the channel. But I have given up. GLWTW.

LOL

 

[ShoalDiverSA]

The slots are also not in the channel. But I have given up. GLWTW.

GLWTW?