Misc BP/Wing questions

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Scared Silly

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Over the weekend I finished assembling my first set of doubles (AL80 with Highland Band and a SeaElite Manifold). Everything went very smoothly. The only thing that is bothersome is that it seems like the bolts supplied with the bands are 1/2 inch too long. Once I have the BP and wings on the threads stick out about 1/4 inch past the wing nut just far enough that I can feel it poking into my back.

I did some searching and found that some folks solve this by adding a stop nut so that the backplate does not flex so far back. I am currently trying this but it would seem that you really the BP to sandwich the wing aganst the tanks. Any thoughts suggstions?

The other item is that I have been looking at different tanks and configurations and the required lift that I will require from a wing. Currently, I have a 55lb wing which from my calculations the most I would need is around 38lbs of lift. So based this I could get away with a 40lb bladder. But given mfg ratings are done a bit different and that if I did really need want the full lift capabilities would it be a bit better to size up a little bit to something in the 45 lb range rather than push it so close?
 
If the bolts are too long, you could always cut off the excess with hack saw or wheel. You have to remember that the bolts supplied are the same as the ones for the 8" diam bands and the extra you get is from the 7.25 vs 8 diam
 
Scared Silly:
Over the weekend I finished assembling my first set of doubles (AL80 with Highland Band and a SeaElite Manifold). Everything went very smoothly. The only thing that is bothersome is that it seems like the bolts supplied with the bands are 1/2 inch too long. Once I have a the BP and wings on the threads stick out about 1/4 past the wing nut just far enough that I can feel it poking into my back.

Where are the ends of the bolts with respect to the tanks? If you placed a straight edge across the tanks, parallel to one band, would the end of the bolt extend past the Diameter of the tanks? It should not. As long as the bolts don't project past the plane of the tanks it would be truely remarkable to be able to "feel" the ends of the bolts. Place your back flat against a door, or a wall, now check how much room there is between your spine and the door. Without rolling into a ball most people cannot get their spine to touch the door.

Scared Silly:
I did some searching and found that some folks solve this by adding a stop nut so that the backplate does not flex so far back. I am currently trying this but it would seem that you really the BP to sandwich the wing aganst the tanks. Any thoughts suggstions?

You do want the trap the wing between the tanks and the plate. That's what really keeps everything in line. If you are using a lightweight plate a stop nut might help, but should not be required with a SS plate.

Scared Silly:
The other item is that I have been looking at different tanks and configurations and the required lift that I will require from a wing. Currently, I have a 55lb wing which from my calculations the most I would need is around 38lbs of lift. So based this I could get away with a 40lb bladder. But given mfg ratings are done a bit different and that if I did really need want the full lift capabilities would it be a bit better to size up a little bit to something in the 45 lb range rather than push it so close?

How did you calculate your required lift?



Tobin
 
Scared Silly:
Over the weekend I finished assembling my first set of doubles (AL80 with Highland Band and a SeaElite Manifold). Everything went very smoothly. The only thing that is bothersome is that it seems like the bolts supplied with the bands are 1/2 inch too long. Once I have a the BP and wings on the threads stick out about 1/4 past the wing nut just far enough that I can feel it poking into my back.

I did some searching and found that some folks solve this by adding a stop nut so that the backplate does not flex so far back. I am currently trying this but it would seem that you really the BP to sandwich the wing aganst the tanks. Any thoughts suggstions?

The other item is that I have been looking at different tanks and configurations and the required lift that I will require from a wing. Currently, I have a 55lb wing which from my calculations the most I would need is around 38lbs of lift. So based this I could get away with a 40lb bladder. But given mfg ratings are done a bit different and that if I did really need want the full lift capabilities would it be a bit better to size up a little bit to something in the 45 lb range rather than push it so close?

I agree with Tamas just use a hand grinder or hacksaw and then use some emery cloth or sandpaper to smooth out the rough spots.

As far as the wing stay with what you have. One of my wings is setup for doubles with a Dive Rite 55 lb wing. It has handled two 120 HP steel tanks and two 80 AL sling tanks with no problem. It's better to have a little more lift and not need it than not have a enough. Remeber that your wing needs to be able to float your tanks full at the surface.

My two single wing setup both have 40 lbs of lift and easily float a 95, 100 or even a single low pressure 120. I dive in a 3mm suit and use no weight. I use very little air in my wing at depth so I could get by with a smaller wing on these two setups.
 
cool_hardware52:
How did you calculate your required lift?

Just the way you have posted :D.

Rig Weight
Dual HP120 full 2 x -11 = -22
bands/manifold -3
bp SS -6
regs -2
lights -3
misc (reels, dry suit inflation) -2

Total -38lbs

Exposure Suit

Dry Suit 15
Gas 18
Dry suit inflation 2

Total 35lbs

This is worst case (i.e. greatest amount of gas) Also with my dry suit in fresh water and minimal clothing 11lbs was needed to sink with minimal exhaling. So I added 4lbs to offset clothing and salt water. The dry suit (DUI 200CX) bouyancy was probably the most surprising as I had never done this test before. I would guess that my 4/3 suit would be similar. I will try it next week.

I will check the bolt lenght tonight. I would guess that as Tamas noted Highland sends out the same length whether for 7.25" or 8" bands.
 
Scared Silly:
Just the way you have posted :D.

Rig Weight
Dual HP120 full 2 x -11 = -22
bands/manifold -3
bp SS -6
regs -2
lights -3
misc (reels, dry suit inflation) -2

Total -38lbs

Exposure Suit

Dry Suit 15
Gas 18
Dry suit inflation 2

Total 35lbs

This is worst case (i.e. greatest amount of gas) Also with my dry suit in fresh water and minimal clothing 11lbs was needed to sink with minimal exhaling. So I added 4lbs to offset clothing and salt water. The dry suit (DUI 200CX) bouyancy was probably the most surprising as I had never done this test before. I would guess that my 4/3 suit would be similar. I will try it next week.

I will check the bolt lenght tonight. I would guess that as Tamas noted Highland sends out the same length whether for 7.25" or 8" bands.


You should be fine in a 40-42 lbs wing.

Tobin
 
I don't know which bolts Highland mills uses, but the bolts I have are threaded on both ends, so I just take up the "excess" on the other side of the tanks. If these are Hex bolts (with a head on one end) you could also spin a nut all the way to the head so as to take up the excess as well...

But cutting them off is probably the cleanest solution, just be sure to put a nut on the bolt before cutting so you can unscrew it and smooth out the threads after cutting.

Aloha, Tim
 
cool_hardware52:
Where are the ends of the bolts with respect to the tanks? If you placed a straight edge across the tanks, parallel to one band, would the end of the bolt extend past the Diameter of the tanks? It should not. As long as the bolts don't project past the plane of the tanks it would be truely remarkable to be able to "feel" the ends of the bolts. Place your back flat against a door, or a wall, now check how much room there is between your spine and the door. Without rolling into a ball most people cannot get their spine to touch the door.

If I place an edge over one band the bolt end is approximately 1/4 inch below the edge. So the bolt does extend past the tanks. If I place my back against a wall I can feel a ball point pen between my spine and the wall. I guess I am truly remarkable :D. My mama always said I was special. I should note that I have not have the rig under water yet. So I am only feeling the bolt ends on dry land.
 
Scared Silly:
If I place an edge over one band the bolt end is approximately 1/4 inch below the edge. So the bolt does extend past the tanks. If I place my back against a wall I can feel a ball point pen between my spine and the wall. I guess I am truly remarkable :D. My mama always said I was special. I should note that I have not have the rig under water yet. So I am only feeling the bolt ends on dry land.

I'm having a hard time following your description. If you laid the tanks down on a flat table, diver's side down, would the bolts gouge the table?

They should not. If they project beyond the plane of the tanks they are too long.


Tobin
 
No the bolts would not gouge the table, they would clear it by 1/4 inch. So they are not too long - I think I am AB Normal :D
 
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