How to improve position of tanks SM

[jawaputih]

It’ll come from sliding the waist rings forward, but what I can’t see is what style of bungee attachment you’re using. If they are dive rite style Ring bungee (with a choker on the cylinder valve), it’s unlikely you’ll ever get them to behave and torque properly with aluminum cylinders.

How To Setup Sidemount Loop Bungees

An illustrated guide to the optimal setup for sidemount loop bungee systems.

scubatechphilippines.com

I do indeed use Diverite Ring Bungee, I found it much easier to clip in the tanks that way. The standard bungees that came with the Nomad are very tough, I had a hard time getting them around the tanks until I changed it to the ring bungees that where also included in the package. I will be happy to try other configurations in the future thou.

How do you like the Nomad LS so far? I’ll be doing my sidemount course late this year or early next year in one.

I don't think I have the experience to really comment on it as I dont have comparison material. I did a Padi Sidemount rec course many years ago using a Hollis SMS50 and it did not have a whole lot of weight or I was overweighted but it did not provide much lift. I did not do any SM again until I did the TDI Sidemount course about a month ago using my own gear. Not everything is easy to get here in Indonesia and I happen to know the distributor for diverite here so it was an easy choice. So far I like it more then the SMS50. It also takes time to find the right settings/configuration for you and your sidemount gear, time I did not really have with the SMS50.

 

[tbone1004]

cam bands are too low on the tanks. Measure the distance between the upper bungee and the hip attachment point. Set the bottom of the cam bands that distance from the center of the valve outlet. That will sort out the top of the tank position.

Bottom is having a sliding or second attachment point when they get empty.

Ring bungees can be made to behave but by the time you get them to behave they are harder to attach than a loop bungee. The loop bungee that comes stock with the LS is sufficient. They loosen up a bit with time, but if you want them to behave then the bungees need to be quite tight to hold them in position. You get used to it with practice but if you make it "Easy" to attach then it will look sloppy. No way around that one.

 

[jawaputih]

cam bands are too low on the tanks. Measure the distance between the upper bungee and the hip attachment point. Set the bottom of the cam bands that distance from the center of the valve outlet. That will sort out the top of the tank position.

Bottom is having a sliding or second attachment point when they get empty.

Ring bungees can be made to behave but by the time you get them to behave they are harder to attach than a loop bungee. The loop bungee that comes stock with the LS is sufficient. They loosen up a bit with time, but if you want them to behave then the bungees need to be quite tight to hold them in position. You get used to it with practice but if you make it "Easy" to attach then it will look sloppy. No way around that one.

Thank you for your response, I wonder what is wrong with my top tank position as it feels pretty much back already and if I move the cam bands up to match the distance, would that not lift the back of the tanks up even more?

 

[Jens Bölte]

Hi,

moving the cam band up/down mainly moves the tank up/down along your body. Anyway, I agree that your cam-band should move up. It is much too low. It might be that the bungee loop pulls too strong on the valve moving your tank out of „trim“. As mentioned by tbone1004 measure the distance between your arm-pit and the lower attachment point. Set this distance to the center of the upper attachment point and the eye of the boltsnap when it is facing up.

What is your problem with loop bungees? When stretching the bungee, stretch it first sideways before moving it forward over the attachment point. The loop bungee length is correct when you are able to stretch it with some force up to your nipples. Note that the hand holding the tank should turn the valve as much as possible to the bungee loop.

Best wishes Jens

 

[tbone1004]

Thank you for your response, I wonder what is wrong with my top tank position as it feels pretty much back already and if I move the cam bands up to match the distance, would that not lift the back of the tanks up even more?

The height of the bottom cam band determines what the top of the tank is going to do. The farther down it is, the more it will drive that tank up towards your face. The downside of having the cam band too low is that it forces the bungee to stretch even farther because it is trying to bridge a gap that is too big and that causes the bottom of the tank to angle back the way it is in your picture even more than it already would from a bad attachment point.
The length of the bolt snap leash, the size of the bolt snap itself, and where it is attached will determine most of where the attachment point of the tank ends up in relation to your body.
The length and strength of the bungee cord determines the angle that the tank is in relation to your body. If you use a loop bungee it can also impart some rotational torque on the bottle that can help roll the bottle outwards from your body *counter clockwise on the left and clockwise on the right when you are looking down at the bottles* and this will help keep the bottles from flopping around. It does roll them "up" towards your butt but that just dictates a lower front attachment point which is not a bad thing with floaty aluminum tanks.

Of note, this should all have been gone over in both of your sidemount courses... If it was not you clearly did not have a qualified instructor *of which there are sadly exceedingly few, but that's another subject for another day*. In any instance, measure the distance between the bungee and the waist belt where you are attaching, set the bottom of the cam band to match that distance. Show us a picture of your actual rigging because there may be issues with that as well, then go dive it and come back and post some more pictures. If that fixes it then please ask for your money back from your sidemount instructor who clearly doesn't deserve it, and donate it to Scubaboard.

 

[jawaputih]

The height of the bottom cam band determines what the top of the tank is going to do. The farther down it is, the more it will drive that tank up towards your face. The downside of having the cam band too low is that it forces the bungee to stretch even farther because it is trying to bridge a gap that is too big and that causes the bottom of the tank to angle back the way it is in your picture even more than it already would from a bad attachment point.
The length of the bolt snap leash, the size of the bolt snap itself, and where it is attached will determine most of where the attachment point of the tank ends up in relation to your body.
The length and strength of the bungee cord determines the angle that the tank is in relation to your body. If you use a loop bungee it can also impart some rotational torque on the bottle that can help roll the bottle outwards from your body *counter clockwise on the left and clockwise on the right when you are looking down at the bottles* and this will help keep the bottles from flopping around. It does roll them "up" towards your butt but that just dictates a lower front attachment point which is not a bad thing with floaty aluminum tanks.

Of note, this should all have been gone over in both of your sidemount courses... If it was not you clearly did not have a qualified instructor *of which there are sadly exceedingly few, but that's another subject for another day*. In any instance, measure the distance between the bungee and the waist belt where you are attaching, set the bottom of the cam band to match that distance. Show us a picture of your actual rigging because there may be issues with that as well, then go dive it and come back and post some more pictures. If that fixes it then please ask for your money back from your sidemount instructor who clearly doesn't deserve it, and donate it to Scubaboard.

Thank you so much for all the information.

Does this picture help to show my rigging? Unfortunately my next dives wont be until end of september. I am using dive rite travel stage straps on the tanks and I am basically using what is described by Tody Style SM setup or ISE. 1 100cm reg hose, 1 80cm reg hose.

 

[tbone1004]

@jawaputih Need to see the back side of the clips and how long the leashes are/how big the bolt snaps are.

I'm not a huge fan of the ISE setup and there are other things that I'll say about your inflator hose configuration in the future but we have to get your tanks fixed first.

Also, why is your crotch strap so loose? Tight crotch straps are critical in sidemount to keep the rig held down on your butt where it is supposed to be. The shoulder straps are really only there for a convenient place to clip things but the waist strap and the crotch strap need to be pretty snug.

 

[jawaputih]

@jawaputih Need to see the back side of the clips and how long the leashes are/how big the bolt snaps are.

I'm not a huge fan of the ISE setup and there are other things that I'll say about your inflator hose configuration in the future but we have to get your tanks fixed first.

Also, why is your crotch strap so loose? Tight crotch straps are critical in sidemount to keep the rig held down on your butt where it is supposed to be. The shoulder straps are really only there for a convenient place to clip things but the waist strap and the crotch strap need to be pretty snug.

For the crotch strap being lose, not sure why. I did not notice it until the photo. I guess its because I attached it while sitting down, I will pay better attention to that. So the boltsnap in the bottom is 10cm(4 inch), the leash is basically as short as it can be.

Then about the D-Ring, its all the way back so I guess that needs to move forward a lot.

 

[tbone1004]

Rigging is fine, just needs to be shortened on the tank. Keep those bolt snaps on as short of a leash as possible, that is critical.

Without seeing the back of the rig while you're wearing it I can't make specific D-ring recommendations, but if you're diving aluminum tanks you need 2 on each side or to use sliding d-rings. That position is probably fine when the tank is full but after about 700psi/50bar consumed you need to move them down to a d-ring generally around your hip bone.

 

[jawaputih]

Rigging is fine, just needs to be shortened on the tank. Keep those bolt snaps on as short of a leash as possible, that is critical.

Without seeing the back of the rig while you're wearing it I can't make specific D-ring recommendations, but if you're diving aluminum tanks you need 2 on each side or to use sliding d-rings. That position is probably fine when the tank is full but after about 700psi/50bar consumed you need to move them down to a d-ring generally around your hip bone.

Great thanks for the advice, I will make a photo on the next dive, hopefully end of this month and get some extra D Rings before that to try out. I guess I might as well take the buttplate off while I am diving ALU.
Curious also about your recommendation on the inflator hoses as you mentioned something about it. I was not too happy with the positioning myself, thought about clipping both on the right side of the shoulder d-ring instead of 1 right 1 left, instructor adviced against it, mentioned that could be confusing as too which is primary but its a bit in the way now also for the dump valve cord that is basically at the left shoulder. Not too many people seem to be diving with dual bladders..