DSMB Deployment

[Paulo]

What are people's preferences for DSMB deployment and why? Deploy on the bottom? Deploy mid water? Deploy on a stop?

Do you do different on different types of dives?

[Hellenic Diver]

Generally I find skippers want you to deploy as soon as you leave the wreck. In which case I deploy from bottom.

For drift, as soon as I hit the bottom

CO2 for me.

[Chriselliott]

Our skip wants it sent when you're doing your 5m stop at the mo. though sometimes it's from the bottom. I prefer sending it from deeper to be honest. As long as you confirm with him/her beforehand and your dsmb is identifiable then there shouldn't be an issue IMO. If they know then they should have an idea of ascent time (OC diving) and if its wildly out then then they could be ready for any potential issues

[Paulo]

Generally I find skippers want you to deploy as soon as you leave the wreck. In which case I deploy from bottom.

CO2 for me.

I generally like to deploy from the bottom. As it gives you students something to ascend on, it helps keep groups together, one person can work the reel while their buddy controls the ascent rate just above themm and it gives the surface cover plenty of time to track your drift.

However, I have been helping with a course recently and the instructor only wants the students to deploy from 5m. His reason being that if a reel jams they are less likely to get hurt. To me it is worst time to get a student to put up a DSMB as they have not had anything to help them ascend on, they are in the zone where their buoyancy is most difficult to control (I have seen the same student on 2 consecutive dives drop from 5m to 10m and shoot to the surface from 5m)

[GLOC]

Deploy from wherever the skipper wants it from (primacy) or mid-water (normally 21m for a deco dive) or shallower if the dive is less than 30m. Either suit inflate bottle or manually inflate using nipple on the side (not open-ended bag).

Reasons,

1. the skipper is king, so if he says 30m like he did last week on a 50m dive, we deploy from there.
2. 21m because I am doing at least 3mins there pretty much whatever deco I am doing on a 40m+ dive.
3. 15m or less because the stops start there for a 30m or shallower dive.

You shouldn't be doing mid-water stops unless you have relatively decent buoyancy control. If you are on a 30m dive and have ended after 20-30mins, the current could be running. Doing your dSMB deployment from 5m means you might be away from the wreck and the skipper needs to know where you are, that is the point of a dSMB after all!

I understand the 'don't want to be dragged up from deeper than 5m' argument but getting enough gas in the bag to stand up is hard work unless you are using crack bottles or CO2. I would rather the instructors made sure that the buoyancy skills were sorted as that has greater applicability than getting people to yo-yo sending a bag up from 5m.

Regards

[Pd1000]

All depends on the situation for me - sending it up from the bottom on a 30m+ dive isn't ideal as: 1) more line to wind in is a pain in the ar$e, and 2) it may be too deep for the spool I prefer to use. If possible I'll send it up mid-water between 10-20m as it'll be full by the time it hits the surface (without having to fully inflate it), but if a tide is running I would send it up from the top of the wreck/shallowest point of shelter so I'm not drifting away from the site before I deploy it. I try to do it before the shallow stops so I don't need to get it nearly full before releasing, and don't have the hassle of inflating it where pressure differences etc. make buoyancy control harder.

In saying all that - I normally signal at my buddy to do it instead. :angel:

Edit: Gloc said it better!

[The Duck]

Where ever the skipper wants it sent from.

[Paulo]

I dont understand why a skipper would say that you would send it up at say 30m in 55m of water. Surely the distance you will have travelled in the time it takes you to reach 30m and deploy is only going to complicate trying to locate divers later.

If everyone deployed from the wreck, how does that complicate things for the skipper?

[Tel]

On the bottom, either on the wreck at the end of my dive or straight away if I come off it.

If i'm on a drift i'll jump in with it as a SMB.

[GLOC]

I dont understand why a skipper would say that you would send it up at say 30m in 55m of water. Surely the distance you will have travelled in the time it takes you to reach 30m and deploy is only going to complicate trying to locate divers later.

If everyone deployed from the wreck, how does that complicate things for the skipper?

Because the normal deployment was at 21m and he didn't want people to be faffing at that depth doing switches and drifting from the wrecks. 50m deployment means you have to have a reel, and the bottom part of the ascent is done at 9m/min to reduce the ongassing. Have you ever tried to ascend at 9m/min and reel in line at the same time? Don't. It will end in a cluster.

The surface vis was 50-100m and we had 4 teams of 2 in the water. It all worked out ok as all the bags appeared very close to each other. Underwater vis was 1-2m :(

Regards

[Roy]

The surface vis was 50-100m and we had 4 teams of 2 in the water.

Regards

Teams of 2?? Did you lose somebody?

;)

[timmyg]

I've nothing to add other than echo GLOCs points.

Personally I only deploy my DSMB on the bottom if its shallower than around 25m. a; more gas consumption by me b; more line to reel in (& generally there's only a 30m spool on my blob).


TG

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[JPTaylor]

1. the skipper is king, so if he says 30m like he did last week on a 50m dive, we deploy from there.

How would they know where you'd deploted from?

I'm on a rebreather, I don't make ascents with a reference (either shot line or DSMB). In GLOC's case above I'd send it up from the wreck regardless.

My safety thrumbs skipper's wishes!

[MikeF]

it's again one of those situations where one size never fits all and the specific circumstances of the dive need to be assessed.

Unless there's a specific need to bag off at depth I only carry a small 40m reel and put it up at 20m or first stop. Diving in good surface visibility where tidal streams are not that severe this works well.

However, there are certain situations where this is not the best option. Sometimes if the tide is running to the point where you can't really hang on anymore and you're ascending from say 60m plus with a lot of stops, you'll travel a long way before you're buoy surfaces. If this happens and the surface visibility is limited you really need to bag off the wreck to give the skipper a chance to see your buoy before it dissappears. I've done wreck dives where you can surface 2-3 miles from the wreck by the time you've done your stops. You've probably gone 1/4 of a mile or more before you've hit 30m and put up your blob. unless the surface vis is 1/2 mile or more it's bag off the wreck if you want to avoid a long lonely wait on the surface.

In those circumstances when you bag off the line screams off and you need a proper reel. finger spools are for backup or warm water / shallow diving.

[JPTaylor]

Unless there's a specific need to bag off at depth I only carry a small 40m reel and put it up at 20m or first stop. Diving in good surface visibility where tidal streams are not that severe this works well.

My default is to bag off from the wreck, I take a 70m CD reel with Buddy crack bottle DSMB, have a 120m reel for deeper stuff. Much easier to deploy from the wreck rather than faffing about mid-water & I cannot see why a skipper would prefer mid water deployment? The "sooner the better" would make more sense surely!

Otherwise, it's return to shot & lazy shot. Then I'll typically deploy shallow once the lazy is drifting, rather than staying on the lazy as it can get a bit crowded otherwise.

[Timw]

My default is to bag off from the wreck, I take a 70m CD reel with Buddy crack bottle DSMB, have a 120m reel for deeper stuff. Much easier to deploy from the wreck rather than faffing about mid-water & I cannot see why a skipper would prefer mid water deployment? The "sooner the better" would make more sense surely!

Otherwise, it's return to shot & lazy shot. Then I'll typically deploy shallow once the lazy is drifting, rather than staying on the lazy as it can get a bit crowded otherwise.

Same for me and most of the people I dive with.

Maybe i'm a bit slow but I really don't get the fixation with spools and waiting until 21m to send it up. If winding a long spool from 50m and controlling your ascent rate is an invitation for a clusterf*** then use a reel that is suitable for the depth and take the hassle out of the whole process. My spool sits in a pocket as a final backup for two reels or for when I'm overseas doing non deco dives.

As a skipper, I want to know when my divers leave the wreck so I can follow them - they can easily drift for 1/2 a mile before they get to the 21m stop. As a diver, I want the skipper to know where I am as soon as I leave the wreck.

[timmyg]

I totally disagree with the argument that you have a 70m reel for primary & a spool for a backup, especially if you deploy from the bottom.

1. Your backup should be similar to your primary so you are familiar with it.
2. If you need to deploy your backup you can't do it from the bottom.

As for the argument that winding in is a Faff I can reel is a spool just as quick as my buddies can their reel.


TG

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[JPTaylor]

I totally disagree with the argument that you have a 70m reel for primary & a spool for a backup, especially if you deploy from the bottom.

You obviously haven't heard of a "Mary Poppins" ascent :D

My backup is only a 50m compact CD reel, just hang one to it when all the line deploys....... but never have a problem getting my primary up, so to speak!

[GLOC]

Traditional ascent rates are 9m/min to somewhere around the 75% of depth mark, then 6m/min to somewhere around the 50% mark. This covers most dives to 50-60m. Beyond there, the intermediate stops are going to be a little longer.

9m/min is 1m every 7 secs (roughly). Winding in at that speed, even using a reel, is going to be a challenge at the same time as controlling your buoyancy, even more so if you are on a CCR with three bags of air to manage.

TimW, if I am on your boat and you say shoot from the wreck, I'll do it, but I'll likely be extending my deco from what I had originally planned because I will not be able to manage 9m/min.

However, in the depths that the majority of folk are diving, 50m to 21m is about 5 or 6 mins. For you to drift 1/2 mile, you would need a 5kt current to go that far! Notwithstanding that, if you aren't used to sending a bag up mid-water, then it could take you more than a few minutes to sort your proverbial out and easily end up 1/2 mile away.

Regards

[JPTaylor]

9m/min is 1m every 7 secs (roughly). Winding in at that speed, even using a reel, is going to be a challenge at the same time as controlling your buoyancy, even more so if you are on a CCR with three bags of air to manage.


Based on my experience & Ross's dive profiles, most CCR divers ascend at close to 5m/min. I use this value in desktop software.

But, I still don't see the disadvantage of deploying from the wreck, a know location, as opposed to somewhere near the wreck, where "near" depends on the current strength.

On OC you'll have a limited/planned bottom time & may well leave before the currents running. ON CCR you'll stay on the wreck until the end of slack or some time after when the currents really starting to run.

[Allan Carr]

If I'm doing deeper stuff, I tend to use my big McMahon reel rather than my small pocket reel so that I can reel it in much quicker. I don't do much below 30m these days and the small reel suffices for that. I use a Buddy DSMBi and it only takes seconds to deploy and I generally deploy from the bottom. At places like the Farnes where we are close in to pretty sheer underwater cliffs, I'll swim out into clear water to allow the boat a safe pickup and deploy mid-water.

[Timw]

Traditional ascent rates are 9m/min to somewhere around the 75% of depth mark, then 6m/min to somewhere around the 50% mark. This covers most dives to 50-60m. Beyond there, the intermediate stops are going to be a little longer.

9m/min is 1m every 7 secs (roughly). Winding in at that speed, even using a reel, is going to be a challenge at the same time as controlling your buoyancy, even more so if you are on a CCR with three bags of air to manage.

TimW, if I am on your boat and you say shoot from the wreck, I'll do it, but I'll likely be extending my deco from what I had originally planned because I will not be able to manage 9m/min.

However, in the depths that the majority of folk are diving, 50m to 21m is about 5 or 6 mins. For you to drift 1/2 mile, you would need a 5kt current to go that far! Notwithstanding that, if you aren't used to sending a bag up mid-water, then it could take you more than a few minutes to sort your proverbial out and easily end up 1/2 mile away.

Regards

If you've got someone on a VR£ they'll take significantly longer to get to 21m than everyone else! That delay can spread your divers a fair bit. Ok, so 1/2 a mile may be a bit of an exaggeration but even a couple of hundred metres from the start datum (shot or GPS) before a bag appears can be be tough to spot - even knowing the direction of the current. This gets even harder when it is windy as it rarely takes you in the same direction as the current. I guess this is the view of a slightly paranoid skipper who only relaxes when I know where all my divers are (also one bag each unless specifically agreed otherwise but we won't go there again in this thread :x:).

Personally, I find it easier to ascend at a steady pace with a reel - it gives a point of reference and I know the rate to wind to meet my ascent rate it also keeps my Shearwater in view so I can monitor the PPO2 as well. Dumping gas from loop, suit or wing is no more difficult that during a free ascent.

Gloc, you're welcome to come out and dive from my boat anytime (if we ever get any decent weather and you don't mind slumming it on a rib). I may even make a special exception and let you bag off from 21m. :nod:

[SonicStomp]

Deploy from wherever the skipper wants it from (primacy) or mid-water (normally 21m for a deco dive) or shallower if the dive is less than 30m. Either suit inflate bottle or manually inflate using nipple on the side (not open-ended bag).

Reasons,

1. the skipper is king, so if he says 30m like he did last week on a 50m dive, we deploy from there.
2. 21m because I am doing at least 3mins there pretty much whatever deco I am doing on a 40m+ dive.
3. 15m or less because the stops start there for a 30m or shallower dive.

You shouldn't be doing mid-water stops unless you have relatively decent buoyancy control. If you are on a 30m dive and have ended after 20-30mins, the current could be running. Doing your dSMB deployment from 5m means you might be away from the wreck and the skipper needs to know where you are, that is the point of a dSMB after all!

I understand the 'don't want to be dragged up from deeper than 5m' argument but getting enough gas in the bag to stand up is hard work unless you are using crack bottles or CO2. I would rather the instructors made sure that the buoyancy skills were sorted as that has greater applicability than getting people to yo-yo sending a bag up from 5m.

Regards

What reel are you using for the deep deployment?


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[GLOC]

What reel are you using for the deep deployment?


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I would use my Pathfinder but I have never needed to because all the skippers I have dived with have been happy with a mid-water deployment. For the 30m deployment, I used a 45m spool. At 30m, the ascent rate is between 6m and 3m/min depending on the exposure at 50m.

Regards

[Major Clanger]

How would they know where you'd deploted from?

I'm on a rebreather, I don't make ascents with a reference (either shot line or DSMB). In GLOC's case above I'd send it up from the wreck regardless.

My safety thrumbs skipper's wishes!

My preference is always from the bottom, unless I've ascended the shot to avoid a deep deployment, for practical reasons including the wish for a reference. The skipper that tells you where to deploy from is the same one that also says what happens on the boat is his responsibility; what happens in the water is the diver's responsbility. Even the call to return to shot may need in-water modification or only return onyour bag may need modification, such as we experienced last week when the brief was to return to shot but we had to modify that in-water. I heard today about shots being pulled on a trip elsewhere before all divers were back in the boat or all accounted for in-water as the brief was ascend on your bag. Seems a pretty risky practise to me if someone had a snafu and was coming back up the shot, which apparently two were when the shot started to get pulled. CO2 bag down to 50m, below that then it's the crack bottle dsmb if not coming up the shotline.

[Janos]

I generally bag off from the bottom. Or close to the bottom at least - I tend to work my way up to the highest point of the wreck, keep going, and by the time I've got my reel and bag ready I'm a few metres above the wreck.

My reel's nice and easy to use so I don't have any problem with reeling up from 60m. Below that it tends to be shots/trapezes.

Janos

[SonicStomp]

I would use my Pathfinder but I have never needed to because all the skippers I have dived with have been happy with a mid-water deployment. For the 30m deployment, I used a 45m spool. At 30m, the ascent rate is between 6m and 3m/min depending on the exposure at 50m.

Regards

Thanks


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[Janos]

The surface vis was 50-100m and we had 4 teams of 2 in the water. It all worked out ok as all the bags appeared very close to each other. Underwater vis was 1-2m :(

I would not dive with a DSMB in those conditions - even if I was the only buddy pair in the water. I'd be using my reel to lay a line to guarantee a return to the shot.

Janos

[jturner]

What are people's preferences for DSMB deployment and why? Deploy on the bottom? Deploy mid water? Deploy on a stop?

Do you do different on different types of dives?

All about conditions for me: rapid current diving on a pinnacle with scattered group, I'd deploy from leaving the bottom. Drifting along a reef edge or through a channel, probably wait until later. Not much going on and easy conditions, from the safety stop.

[thetrickster]

Gee, I don't think I've got a hard/set rule for when to send the bag up.

Non Deco Dives - (don't give me that crap about every dive being a deco dive) :giggle:

If diving by a detached mole / break water / reef - probably at 10m, if there was any current, as we would be doing the safety stop where the skipper would know roughy where to look for us.
If diving out on a wreck, I would send up, at the point we leave the wreck, if there was no shot line.


Deco Dives

If clam, and no current, and we have a visual point of reference - the 21m stop, so the skipper knows roughly how much longer he has to wait around for us.
If the current is blowing, or is predicted to be blowing, send up from the bottom.
If we have no visual point of reference, again from the bottom.


All these I would tell the skipper I'm doing.

Personally I like having a reel to hold on to, even in super clear/calm waters..probably a psychological thing...:think:

[Capt Morgan]

I deploy from the bottom and use a retractable dog leash.
Takes a bit of practice but I can almost get the stops bang
on now. It's like a lift you just push the button and go up. :giggle:

[Ken Hawk]

Pmsl :d:d:d