Deploying a DSMB in Cozumel...

[noj3333]

Just looking for some Cozumel/ drift diving specific advice regarding when ascending divers (NOT with their DM’s) deploy their DSMB’s. I’ve been to Cozumel before, but I only did a few dives, and was VERY inexperienced… our DM deployed his DSMB from depth and my wife and I surfaced using his DSMB.

Is it typical to shoot your DSMB from depth, if so, I’d expect that to be anywhere from 50-80ft? If not, do divers shoot them on their assent (50ft-15ft), or from safety stop (15’) depth?

The reason I’m asking is because I know the current can vary with depth, I want to know what to expect, and I want to have the right spool/ reel setup and ready to go…

Side note… when needed I typically deploy from shallow depths (maybe 25’ max, but often from my safety stop)… with that I use a ‘small’ DGX spool loaded with maybe 40’ of line. I’m expecting with a DSMB in the current, and a line not perpendicular to the surface, my small spool is NOT going to work well (unless it’s typical to deploy your DSMB from 15’).

Thanks for the advice.

 

[johndiver999]

The current velocity has zero effect. What you need to be concerned about is the difference in the current velocity between the diver and the surface. If there is a meaningful difference, then you will need more scope on the line.

 

[DandyDon]

I deploy from 20 feet usually. Less line to rewind.

 

[deepsea21]

Most deploy them from around 33' as most coz dives are staged dives that offer a deep initial descent followed by a gradual ascent up to shallower parts of the reef. DO NOT try to deploy it at your 15' safety stop. I tried that when I first got mine and by the time I got the friggin thing deployed I was at the surface. At 33' you can shoot it 1/2 full of air and by the time it reaches the surface it will be fully inflated. I have a 4' DSMB with an over pressure valve built into it tied to a finger spool that holds perhaps holds 100' of line. I've never deployed more of than about 40 feet of line from the spool other than when I bought it and ROLLED it all off to make sure the end of the line was knotted to the spool. Then I ROLLED (as in turning the spool, not winding around the spool) it all up again. When extending and winding your line on a spool, be it on land or under water, don't wrap the line around your spool with your hand as that twists it, you want to unroll and roll it up by turning the spool just like a winch on a truck reels the line in. Don't wrap, Roll the spool. Those who quickly wrap end up with kinks over time and that turns into attaching large swivels between the line and the DSMB to try to deal with it but that is trying to fix a problem that (in my opinion) should never exist if you roll instead of wind.

Yes, the current will carry it a bit so if you are at 33' and deploy maybe you need 40' to hand on if it is being pulled but no big deal. You'll ROLL not WIND your way up to it in time.

 

[AdivingBel]

I have a small DSMB ( I think it's only 3 ft. or so and fairly low volume) specifically for Coz because I shoot it regularly and it's easier to deploy and roll up. It's also used in benign conditions (otherwise the boats don't go out....that's just Coz) and only so the boat is there to pick me up when I'm done with my SS. I still shoot it from 30 or 40 ft. prior to my safety stop (with a 100' spool), again because it's easier at depth (starting to see a pattern?? ). All that said, it's really only an issue if you dive with a shop that lets you dive your tank and you're diving on the boat with other experienced divers ( i.e. the op lets you do more or less your own thing). It's not mandatory to shoot a bag on every dive in Coz. There is nothing wrong with surfacing on the DMs marker. Just use it when you need to. Be a "no drama" diver and you'll go far in Coz. It's really far more important where you go to lunch and dinner. Get in with the "in crowd" with the good rezzies and have fun.

 

[noj3333]

Thank you all for the advice...

I've gathered...
-It's standard practice to deploy from 20'-40'... prior to my safety stop.
-A spool with 60' of line should be sufficient...

As a side note, the operator I've booked with allows divers to 'dive their tank', only requiring that at least 2 divers surface together. With that, the operator said if divers are proficient with their DSMB they can deploy their own and surface. I'll carry my 3.3' DSMB for most dive sites, I'll also keep my 6' one in my back pack, swapping it out on the boat as needed, for use on some of the norther sites (Dive op recommendation when I asked specifically what size DSMB would be ideal).

I'll also try to be low drama... that's a goal of mine in general. I do like to practice deploying my DSMB a few times on every trip I take... In Cozumel I'd imagine all my deploys will be legitimate, so no need to shoot a DSMB 'just for practice'...

Lastly...

When extending and winding your line on a spool, be it on land or under water, don't wrap the line around your spool with your hand as that twists it, you want to unroll and roll it up by turning the spool just like a winch on a truck reels the line in. Don't wrap, Roll the spool. Those who quickly wrap end up with kinks over time and that turns into attaching large swivels between the line and the DSMB to try to deal with it but that is trying to fix a problem that (in my opinion) should never exist if you roll instead of wind.

Yes, the current will carry it a bit so if you are at 33' and deploy maybe you need 40' to hand on if it is being pulled but no big deal. You'll ROLL not WIND your way up to it in time.

I've never been told this before, but it makes perfect sense... I'll adjust my technique going forward... I was a winder, not a roller...

 

[ReefHound]

I've usually deployed mine at the safety stop. I guess I'm just good enough not to end up on the surface. The DMs deploy from deeper to give ascending divers a point of reference for their stop as the DM usually stays a bit deeper until most or all ascending.

 

[CajunDiva]

You can wind all you want, just use common sense. Give your wrist a little twist while you're winding...like any good calf roper would do

 

[ReefHound]

Or get a finger spool with a handle and just reel it up. They are cheap.

 

[noj3333]

I've usually deployed mine at the safety stop. I guess I'm just good enough not to end up on the surface. The DMs deploy from deeper to give ascending divers a point of reference for their stop as the DM usually stays a bit deeper until most or all ascending.

I've never been pulled to the surface... when I was taught how to fill mine it was stressed to me...
Regular breath in (maintaining depth/ buoyancy)... fill DSMB as much as comfortably possible, release, and resume normal breathing. The air in you lungs (and the lift it provides) just gets swapped into your DSMB... once it's released it has no bearing on your buoyancy.