Wreck Diving on Sidemount or Backmount Doubles

[cklaus]

I’m going to fundamentally disagree with @grantctobin and say that I think he’s overstated the negatives of using SM

However, it is a fact that a lot of SM divers are ill prepared and, their rig is ill conceived for oat diving, meaning that they do become a burden

I’m more than happy to dive SM in OW off boats, from all sizes - Ribs upwards

My group is very intolerant of divers that faff gearing up, because for a large proportion of the year, the surface air temp is +105F. While underwater it’s going to be the low 70’s. People (me included) get hot and grumpy real fast!

So for me I adopted Ring bungees and my tanks are clipped on and off on the boat. Inside wrecks, SM and BM both have their strengths and weaknesses, and if we’re going down that route then we should claim RB are not suitable for wrecks, which is clearly nonsense

ONe needs to look at the big picture. By that I mean the overall logistics, from loading your car with kit, then day before, to unloading it when you get back home. There are so many permutations that it’s impossible to say BM/SM is better. Realistically you go with a the system which has the least amount of downsides

The absolute most important point especially with SM is to adapt and configure your kit so that it meets the demands of your chosen diving environment, and whether your SM, BM doubles of BM single with pony, Make sure you can handle your kit without needing assistance (that’s not to say if offered you shouldn’t accept help, just you need to be self sufficient for those times when you have to be)

Having tried both, it was an easy decision for me to use SM over BM doubles, others may think differently and that’s fine

But to say categorically that SM off a boat in OW wrecks is bad, is plain wrong

Thanks for the perspective. Good info. to consider.

 

[cklaus]

I dive SM off of boats in a drysuit, 5mm gloves, hood, etc with an additional 40 stage. I don't have any issues but then, I see a fair number of people who do. Usually, those who received poor training or learned on their own. I am totally self-sufficient in gearing up but will also gladly accept help, if offered with fins, handing me my stage or right cylinder, etc., but don't need it.
I see others who are a hot mess, to say the least. They can't get their cylinders clipped or bungees hooked in without help. They take up a lot of room and time. I don't hurry to get geared up but try to be as efficient and well thought out as possible. I'm often ready to go sooner than some in BM doubles.
That said, there are times when it makes more sense to just dive BM. I have gone on day trips where there was 18 people on the boat. Crowded but still manageable. But the depths were only to 100-120 ft. I didn't need sidemount for that. Mix of rec and tech divers with plans for little to no deco. So an LP119 filled to 3200 PSI and a 40 of 50% was all I needed for each dive. I still had 140+ cu ft of gas which was plenty for that dive with a few minutes of deco. Actually 25 min bottom time with 15 min of deco and enough gas for the second dive with a similar profile.
After diving SM pretty much exclusively for months, it felt like having nothing on and was quite enjoyable.
There are also some boats that don't like to see SM divers and a few who actually discourage people from using it.
Other boats offer challenges with ladders, Fin on Christmas tree types are easy and the most friendly if the walkway at the top is wider. Narrower ones may require you to turn sideways but they still work. Other ladders that require fins off may be narrow enough that to safely navigate them you need to doff and hand up one cylinder. Some boats are cool with that, others not so much.
Best to ask ahead and be honest about your level of experience and whether or not you'll need help.

On a side note. Whether or not SDI permits limited penetration is irrelevant. They do as an option with line use as an option BUT any decent wreck class is going to require the use of a line for any penetration as part of the class. I'm an SDI wreck instructor and TDI Adv Wreck Instructor. My SDI wreck class is 6 dives vs the minimum of 3. Limited penetration only occurs on the last 2 with lines. The first 4 dives are all outside with heavy emphasis on why recreational wreck divers have no business penetrating a wreck without overhead training. Dive 4 is all about line use. Dives 5 and 6 are in the light zone penetration with a line using multiple tie-offs. These are after covering in class the number of ways you can die in an overhead as short as two body lengths if you don't know what you are doing.

Just because an agency says you can do it, doesn't mean you should. I've seen people I would refuse to do the full recreational wreck class with unless they had a serious change in attitude. Outside only for them.

Thank you for the good information. I also value the caution from you and @grantctobin regarding penetration. My plan has been to receive further training next spring; I think I'll stay outside the wrecks until I've gone through the training.

 

[RyanT]

I'm not sure if this has been mentioned upthread, but one advantage of BM is that if you lose a reg or have a valve leak, you can shut that valve down and still access the remaining gas in both tanks.

 

[NothingClever]

...which is generally jumping into insane (to some) current’s.. no down lines, no time for mincing at the surface attaching bungees

Based on a reputable source, I hear the currents on your side of the peninsula are wicked fast and that diving with your group involves a bit of vetting. I hope to pass the test someday.

 

[leadduck]

I’m going to fundamentally disagree with @grantctobin and say that I think he’s overstated the negatives of using SM

However, it is a fact that a lot of SM divers are ill prepared and, their rig is ill conceived for oat diving, meaning that they do become a burden

I’m more than happy to dive SM in OW off boats, from all sizes - Ribs upwards

My group is very intolerant of divers that faff gearing up, because for a large proportion of the year, the surface air temp is +105F. While underwater it’s going to be the low 70’s. People (me included) get hot and grumpy real fast!

So for me I adopted Ring bungees and my tanks are clipped on and off on the boat. Inside wrecks, SM and BM both have their strengths and weaknesses, and if we’re going down that route then we should claim RB are not suitable for wrecks, which is clearly nonsense

ONe needs to look at the big picture. By that I mean the overall logistics, from loading your car with kit, then day before, to unloading it when you get back home. There are so many permutations that it’s impossible to say BM/SM is better. Realistically you go with a the system which has the least amount of downsides

The absolute most important point especially with SM is to adapt and configure your kit so that it meets the demands of your chosen diving environment, and whether your SM, BM doubles of BM single with pony, Make sure you can handle your kit without needing assistance (that’s not to say if offered you shouldn’t accept help, just you need to be self sufficient for those times when you have to be)

Having tried both, it was an easy decision for me to use SM over BM doubles, others may think differently and that’s fine

But to say categorically that SM off a boat in OW wrecks is bad, is plain wrong

Agree. @grantctobin seems to believe cold water SM is very different from warm water SM which I don't see.
The main difference is in recreational diving, where a BM diver needs less space than a SM diver, so the operator will find it easier to cram a group of exclusively BM tourists onto his cattle boat. But on a tec diving trip where everybody has deco stage tanks, BO tanks, a scooter/DPV, and/or a camera rig, everybody needs space and assistance getting in and out, and there's little difference remaining between SM and BM. The SM diver has the small advantage that he can decide whether to pass up all his tanks, or only the deco stages, DPV and camera like the BM diver. SM diving takes more practice and experience than BM.

 

[Jack Hammer]

@leadduck, local conditions, boats, etc are a factor to consider, not just water temp. The OP is based in Chicago and @grantctobin recommendations are spot on for here. We dont have cattle boats. We do have waves that are very close so even in tiny little one footers the boat rocks very jerkily. I've seen quite a few experienced sidemounters have difficulty gearing up here as they are bounced all over a rocking boat. We also have seen several people all excited about the joy and simplicity of the sidemount system throw in the towel and switch their setup to back mount as it works better for a lot of people here. Even a lot of our hard core SMers prefer to dive BM off the boats.

 

[Seaweed Doc]

Unfort divemaster doesn’t mean anything in terms of overhead environment or technical training. I’d argue that on average it’s a net negative. Poo on SDI for allowing limited penetration at the recreational level with a single tank. Unequivocally f that.

Let’s assume that you’re in a drysuit and drygloves with a large amount of undergarments to loft (as you really must be in this area to do any extended range diving). Let’s also assume the local levels of sidemount training and backmount training available to you are on par with one another (they’re not).

In doubles, gearing up is as clean as sitting on the bench, necklacing your reg, connecting your suitgas, and routing your long hose. Stand up, fit through the gate, and jump off the boat. Deco bottles either tied to a down line or clipped onto you either by yourself or by crew depending on your strength level. Either way, the deco bottles are not really part of the ballast equation and at most, are ~5lb negative (50%/70’ AL80 bottle) so clipping them onto yourself at 10’ or 20’ is of no concern if they’re on a downline. There’s never a point when you’re in the water when all of your ballast is not on you. The general choice in the area are HP100s/LP85s (less so bc the Midwest doesn’t really cave fill), HP119s/LP95s. This helps alleviate the need of a massive amount of weight stored somewhere. While I think AL80 doubles are great wetsuit tanks, they’re not my top choice in a drysuit.

In sidemount, there’s three ish ways to get your bottles to you. Having them passed to you from someone on the boat, a downline, or by clipping them onto your harness while on the boat. Option 1 is pretty reckless and even worse with steel cylinders, so we’ll skip that. Option 2 involves one cylinder being clipped on while on the boat and one on a down line. Doable in aluminum cylinders, more difficult or reckless with steel cylinders. Now you need to add whatever portion of your ballast the down line cylinder accounted for onto your harness and are overweighted. Clipping bottles off with drygloves underwater is a pain depending on the harness/glove/attachment point/boltsnap combination and if you accidentally drop one, it’s gone. Connecting a wing inflator across your chest in dry gloves with 1-2 pairs of liners is difficult at best and a fools errand at worst.

Which brings us to option 3, or attaching your SM cylinders while on the boat. You’ll likely need to add leashes to the top of your cylinders to avoid stretching the bungee. So now, to get geared in, you need to put your harness on (with light can, whatever necessary weight, suit gas, suit heater...and finding a place for all of that). Clip in one bottle top and bottom, connect the bungee, run the necklaced reg around your neck, connect your wing. Then, now 50% wider than you were prior, you need to do the same on the other side. Cool taken care of. Sweet, you’ve done your modified S drill, gas is on, and you’re ready to stand up. Except now you’re taking up twice the bench width of your compatriots. If you’re out of Hammond and diving the Hume, it’s nbd if the boat isn’t full. Full boat or one of the corner seats, you’re either in the way of other divers or the last off the boat because of the amount of help and space you need. The Alma out of MKE has more space on the bench but it’s difficult to sit down effectively to put your fins on with sidemount cylinders clipped on in general. Now, you just have to jump off. Ouch, the forward gates on the Seaquest aren’t wide enough to do a giant stride safely so you need to fall in half sideways. The rear isn’t that much wider. Same story with the gate on the Molly V or the Alma, though iirc the Alma is slightly wider and might work if you’re naturally narrow and with 7” cylinders. Can’t easily clip on SM deco bottles hunched over (because you’re main bottles are already on and you can’t sit straight) and being hinged over with your primary bottles on covers where those deco bottles should be getting clipped.

Sweet, now you’re in the water and diving. All is well. Wait, is the wreck upright? Hallways work better in backmount if they are. But now you’re in sidemount and swimming canted. Admittedly nbd if the wreck is on its side. Dive comes to an end. Ah poo now you need to get out. Did you unclip your leashes in water and now need to reclip them? (hint leave them clipped). Are your deco bottles as cleanly doffed underwater as they are in backmount? No, not if they’re laying where they should be. It’s even more difficult when you have a 70-100mm dry glove ring in your way. Storm rolled in and now you’ve got 3’+waves and you’re less balanced and trying to fit in a smaller pocket/gate relative to your girth than your backmount friends. Smack goes the SM cylinder against the gate or the ladder or the rack. Wait I thought sidemount was supposed to make maneuvering on the surface easier? Once the process of getting you in a seat is finished, most people seem to need help unclipping themselves from their gear.

TLR
Cold water sidemount is a burden on the crew, your body, and the boat. There’s a small number of people that manage it, but for most it’s a pis poor idea. Learn SM when you actually need it and tip real well on those boats if you don’t need it but think it’s cool.

Thanks for this. I've only had a SM buddy twice (3 total dives) and watched a guy exiting solo SM a couple times. All were in cold water, and all required (or at least strongly benefited from) my help either pre-descent, during the dive, or post-ascent. Watching all the futzing around and issues has not convinced me SM is ever a good idea. It struck me as being categorically different assistance than, say, letting your buddy use your shoulder to get fins on. (Though I can definitely see the advantages on an intellectual level. And I have friends who dive SM, including a SM instructor, who I suspect are fully competent and self-sufficient.)

I suspect my limited observations are affected by both the cold water and the specific individuals' competence.

My perspective may also be affected by my initial training in a horsecollar BCD and small backpack: We were taught to remove the backpack and push it through ahead of us. The unit was smaller than a modern BC or backplate/wing and easy enough to push through. But this was back in the dark ages when an openwater course included decompression training and nobody thought twice about swimming up an abandoned sewage outfall to hunt with a single tank.

 

[shoredivr]

I’m going to fundamentally disagree with @grantctobin and say that I think he’s overstated the negatives of using SM

However, it is a fact that a lot of SM divers are ill prepared and, their rig is ill conceived for oat diving, meaning that they do become a burden

I’m more than happy to dive SM in OW off boats, from all sizes - Ribs upwards

My group is very intolerant of divers that faff gearing up, because for a large proportion of the year, the surface air temp is +105F. While underwater it’s going to be the low 70’s. People (me included) get hot and grumpy real fast!

So for me I adopted Ring bungees and my tanks are clipped on and off on the boat. Inside wrecks, SM and BM both have their strengths and weaknesses, and if we’re going down that route then we should claim RB are not suitable for wrecks, which is clearly nonsense

ONe needs to look at the big picture. By that I mean the overall logistics, from loading your car with kit, then day before, to unloading it when you get back home. There are so many permutations that it’s impossible to say BM/SM is better. Realistically you go with a the system which has the least amount of downsides

The absolute most important point especially with SM is to adapt and configure your kit so that it meets the demands of your chosen diving environment, and whether your SM, BM doubles of BM single with pony, Make sure you can handle your kit without needing assistance (that’s not to say if offered you shouldn’t accept help, just you need to be self sufficient for those times when you have to be)

Having tried both, it was an easy decision for me to use SM over BM doubles, others may think differently and that’s fine

But to say categorically that SM off a boat in OW wrecks is bad, is plain wrong

Thanks for the measured reply.

 

[Diving Dubai]

Thanks for the measured reply.

I try...

I do get frustrated when people decide with broad brushstrokes that the answer to the question is always black and white. It can never be, there are too many variables.

I'll freely admit I dive in a pretty unique environment but it does highlight my point. We generally dive in high current, not drifts, they're walls and pinnacles. Often the drop method is the fast boat gets it's bow close in to the rock, and a buddy pair roll off, as soon as they're off the boat reverses out to prevent it hitting the rocks. The next pair move up do final checks and repeat. Meanwhile the pair in the water have a really short window to make a fast final final check, okay and down - staying at the surface means you're holding up the boat. or you'll get blown off, needing the boat to come get you, delaying those on board who are getting hotter and more grumpy.

So for all of the above I chose ring bungees, I accept they're not as good as other methods, but they are the optimum for my circumstances.

I've tried BM doubles, I don't like them because of the weight on dry land - personal choice. Equally on our boats, the fast boat picks us up and takes us back to the mother ship. When it's choppy you don't want to be lifting a set of doubles from a fast boat that is rising and falling 3-4' in the swell. So in our case BM doubles are sub optimal - but for us in our circumstance.. Somewhere else might be very different.


I do urge people here (in my neck of the woods) to try both and then look at the type of diving they'll be doing. And once they go down a route of a configuration, get proficient with it especially with gearing up and down, and don't be THAT person.

At the end of the day gear is gear it's a means to an end, I say pick the option which is the easiest to use in any given circumstances, but don't assume that rig is the optimum everywhere

 

[NothingClever]

I try...

I do get frustrated when people decide with broad brushstrokes that the answer to the question is always black and white. It can never be, there are too many variables.

I'll freely admit I dive in a pretty unique environment but it does highlight my point. We generally dive in high current, not drifts, they're walls and pinnacles. Often the drop method is the fast boat gets it's bow close in to the rock, and a buddy pair roll off, as soon as they're off the boat reverses out to prevent it hitting the rocks. The next pair move up do final checks and repeat. Meanwhile the pair in the water have a really short window to make a fast final final check, okay and down - staying at the surface means you're holding up the boat. or you'll get blown off, needing the boat to come get you, delaying those on board who are getting hotter and more grumpy.

So for all of the above I chose ring bungees, I accept they're not as good as other methods, but they are the optimum for my circumstances.

I've tried BM doubles, I don't like them because of the weight on dry land - personal choice. Equally on our boats, the fast boat picks us up and takes us back to the mother ship. When it's choppy you don't want to be lifting a set of doubles from a fast boat that is rising and falling 3-4' in the swell. So in our case BM doubles are sub optimal - but for us in our circumstance.. Somewhere else might be very different.


I do urge people here (in my neck of the woods) to try both and then look at the type of diving they'll be doing. And once they go down a route of a configuration, get proficient with it especially with gearing up and down, and don't be THAT person.

At the end of the day gear is gear it's a means to an end, I say pick the option which is the easiest to use in any given circumstances, but don't assume that rig is the optimum everywhere

Cogent.