Deploying a DSMB in Cozumel...

[ggunn]

I tried to be clear in my wording. I’ve gone back and reread it. I can’t really improve on it. I even followed up to clarify that what matters is which side of the spool the line is added to and alternating that back and forth as you wind will keep all the twisting from accumulating in one direction but obviously my choice of words didn’t offer a clear enough picture. Language can be funny that way.

I understood perfectly, but I'm afraid you are mistaken. As long as the string is being wound the same direction around the spool, the twist accumulates in the same direction. It makes no difference how you handle the spool; from the spool's perspective nothing has changed. I know it's counterintuitive, but that's the way it is.

Let's say you are winding the string with it coming over the top of the spool toward you. Then you turn the spool over. Now the string is coming toward you under the bottom, but you have also flipped the axis of the spool so it points the other way. You have reversed it twice, so you are back where you started.

 

[RayfromTX]

You have rolled up cords. That should make this obvious. If you hold the roll, coil or spool stationary and add the line from one side then you introduce a twist with each revolution. Switch sides and the twists are opposite and compensate for the earlier twists. Just try it. Telling me I’m wrong about this is silly.

 

[Dave616]

More a general question about DSMB usage, though it did come up while I was diving in Cozumel.

What do you do after you surface with a deployed smb? Do you deflate and reel up your string quick before the boat arrives? Hold onto it and pass the mess to the boat? Reel and clip reel back onto your bcd, even if the smb is still unfurled?

The DM's are used to people having and using them. I roll mine up slowly from the safety stop as I ascend. By the time we get to the surface all the line is rolled, I clip the spool to the DSMB, deflate some of the air on the way to the boat, pass it off to a DM on the boat before boarding. Then I re-pack it on the surface interval. It's a really easy process- I launch my 9-footer on every dive except night dives.

 

[Dave616]

I have multiple Delrin and Stainless spools, I honestly can't say I prefer one to the other. I know I prefer orange line a spool diameter similar in size to the diameter of the rolled DSMB for easy packing.

 

[DandyDon]

My home bud once bought a reel and a huge DAN sausage. He took it to Cozumel on our next trip, stuck it in his BC pocket, and lost it on the first dive. Too bad he couldn't close the pocket.

 

[ggunn]

You have rolled up cords. That should make this obvious. If you hold the roll, coil or spool stationary and add the line from one side then you introduce a twist with each revolution. Switch sides and the twists are opposite and compensate for the earlier twists. Just try it. Telling me I’m wrong about this is silly.

Yes, I have wrapped cables many thousands of times (I have been a musician/sound man/stage hand for... let's just say since before many of the regulars in here were born), and I will be doing it again at a gig this afternoon. The difference is that when you throw that twist in every time when you wrap a mic or instrument cable, the whole cable twists all the way to the other end. If you don't believe me, try it some time with the other end still plugged in; switching hands or sides of wrapping has no effect. That's why the "roadie wrap" was invented, where you wrap once overhand and once underhand to twist and then untwist the cable, but there's two things about that. One is that in order to do it you have to reach through the loop in the cable and pull it the other way, which essentially puts an overhand knot every other wrap. You could do this with an SMB string but it would be very tedious. The other thing is that once you have wrapped a cable this way you can no longer spool it out.

When you wrap string around a spool with an SMB on the other end, the other end does not turn, so the twist accumulates. Wrapping the string from the other side or flipping the spool doesn't change anything. If nothing else, get a calculus book and look up torsion (I am also an engineer with many semesters of advanced math). That will explain it as well.

But I have a policy of not investing emotionally in disagreements over what are matters of fact, so I am done here. Believe what you want, but try wrapping a mic cable sometime with the other end attached. Seriously, try it. It will be quickly obvious; there's nothing you can do about the accumulating twist that you'd want to do when you wrap many feet of string around a spool.

 

[islanddream]

A key point in blowing up and launching a DSMB is to remember to let air out of your BCD before you start adding air to the sausage. I deploy at about 40 feet and once at the surface I keep the DSMB blown up until I'm at the boat. Sometimes in sporty seas you think the boat is coming to pick you up, but another diver is being picked up before you (due to wave height you can't see the diver) so having an inflated DSMB is important. I hand the sausage up to the DM or deck hand when I'm at the ladder.

 

[ggunn]

A key point in blowing up and launching a DSMB is to remember to let air out of your BCD before you start adding air to the sausage. I deploy at about 40 feet and once at the surface I keep the DSMB blown up until I'm at the boat. Sometimes in sporty seas you think the boat is coming to pick you up, but another diver is being picked up before you (due to wave height you can't see the diver) so having an inflated DSMB is important. I hand the sausage up to the DM or deck hand when I'm at the ladder.

If you are using an inflator, absolutely you need to do that since if you don't deflate your BCD by the same amount you'll be adding to your net buoyancy as long as you are holding onto the SMB. If you are inflating the SMB "manually", just don't inhale until you have released the buoy.

 

[Yellowdog]

Yes, I have wrapped cables many thousands of times (I have been a musician/sound man/stage hand for... let's just say since before many of the regulars in here were born), and I will be doing it again at a gig this afternoon. The difference is that when you throw that twist in every time when you wrap a mic or instrument cable, the whole cable twists all the way to the other end. If you don't believe me, try it some time with the other end still plugged in; switching hands or sides of wrapping has no effect. That's why the "roadie wrap" was invented, where you wrap once overhand and once underhand to twist and then untwist the cable, but there's two things about that. One is that in order to do it you have to reach through the loop in the cable and pull it the other way, which essentially puts an overhand knot every other wrap. You could do this with an SMB string but it would be very tedious. The other thing is that once you have wrapped a cable this way you can no longer spool it out.

When you wrap string around a spool with an SMB on the other end, the other end does not turn, so the twist accumulates. Wrapping the string from the other side or flipping the spool doesn't change anything. If nothing else, get a calculus book and look up torsion (I am also an engineer with many semesters of advanced math). That will explain it as well.

But I have a policy of not investing emotionally in disagreements over what are matters of fact, so I am done here. Believe what you want, but try wrapping a mic cable sometime with the other end attached. Seriously, try it. It will be quickly obvious; there's nothing you can do about the accumulating twist that you'd want to do when you wrap many feet of string around a spool.

Probably missing something but dosen't a good quality ss swivel at the end of the spool line make this a relatively fool proof task?

 

[RayfromTX]

Yes, I have wrapped cables many thousands of times (I have been a musician/sound man/stage hand for... let's just say since before many of the regulars in here were born), and I will be doing it again at a gig this afternoon. The difference is that when you throw that twist in every time when you wrap a mic or instrument cable, the whole cable twists all the way to the other end. If you don't believe me, try it some time with the other end still plugged in; switching hands or sides of wrapping has no effect. That's why the "roadie wrap" was invented, where you wrap once overhand and once underhand to twist and then untwist the cable, but there's two things about that. One is that in order to do it you have to reach through the loop in the cable and pull it the other way, which essentially puts an overhand knot every other wrap. You could do this with an SMB string but it would be very tedious. The other thing is that once you have wrapped a cable this way you can no longer spool it out.

When you wrap string around a spool with an SMB on the other end, the other end does not turn, so the twist accumulates. Wrapping the string from the other side or flipping the spool doesn't change anything. If nothing else, get a calculus book and look up torsion (I am also an engineer with many semesters of advanced math). That will explain it as well.

But I have a policy of not investing emotionally in disagreements over what are matters of fact, so I am done here. Believe what you want, but try wrapping a mic cable sometime with the other end attached. Seriously, try it. It will be quickly obvious; there's nothing you can do about the accumulating twist that you'd want to do when you wrap many feet of string around a spool.

You understand the issue the same as I do but you think I'm saying something that I'm not. I obviously can't communicate effectively with you. I hope others understand what I'm saying. The good news is that it isn't the problem that one might imagine as the line tolerates the twists for the most part and when it gets bad it isn't hard to fix.