Disadvantages with sidemount [Archive] - Cave Diver's Forum

View Full Version : Disadvantages with sidemount

stairman

10-16-2007, 06:46 AM

10-16-2007, 06:58 AM

I can't think of a single disadvantage to sidemount. If you can't handle switching regs, you don't need to be underwater at all.

Kelly Jessop

10-16-2007, 07:05 AM

I guess the question would disadvantage as compared to backmount
More task loaded since you'll have to keep track of 2 gas supplies.
Unless you rig long hoses,then air sharing can be more difficult.

MengTze

10-16-2007, 07:48 AM

I am thinking about setting up a sidemount rig in the near future.I have never tried it and would like to hear any disadvantages some of you may have encountered,other than having to switch regs after breathing thirds.I saw a nomad for sale on the gear exchange and the post read,sidemount is just not for me.I sent him a pm asking him why but he never wrote back.I have a petite daughter who wants to do basic cave next summer,and thought clipping on single tanks in the water would be so much easier than having to listen to her gripe about the weight of a twin set out of the water.

I guess I dropped the ball on not responding. I do not see disadvantages per se, it is just not for me. Some things in life just do not sit well. Like eating a baked potato, is also not for me. Something being 'just not for me' does not mean disadvantages, it is a preference thing.

JDostal

10-16-2007, 07:51 AM

Not much, disadvantage wise. You have to keep track of a your gas supply a little closer, but other than that it is awesome.

You will always be tweaking your reg a little bit, to get that hose just perfect or something like that. Well, not always, but they do seem to always be a work in progress.

skip

10-16-2007, 09:10 AM

sidemount takes a few dives to adjust everything. I would not recommend it for a petite daughter, unless she enjoys messing with gear, tweeking arrangements of hoses, mounting angles, etc. I set up sidemount, and after a dozen dives still am not happy with it. still "tweeking" things to get trim right, comfort, etc. But then I'm doing it pretty much on my own without a sidemount guru by my side. (well, I was, but am now on medical leave from diving).

My stepdaughter too complains about a single al80 (weight, carrying it around), but I could not imagine her putting up with sidemounting for even one dive. Just too much going on to get ready to dive. One of the things I don't like is carrying the tanks to the water.... too many trips back and forth wear me out more than the one walk with doubles on my back (or two walks with stages/deco).

-skip

chimie007

10-16-2007, 09:35 AM

Anyone has any reading material on SM ? I looked at the Nomad manual but that's all I could find.

JDostal

10-16-2007, 09:41 AM

Rennaker's website has (had?) some decent stuff on it. He used to have a whole section on converting a Transpac and converting a jacket BC to a sidemount setup, but I can't seem to find it now. It was really well done, there were parts lists and everything.

Advanced Diver Mag has the manual for the Armadillo harness on their website, that's a decent read too.

IANTD has a Sidemount/Nomount course and the manual is pretty good reading. An instructor friend of mine ran me through the course and it was nice having that mentoring for the first dives.

This is an interesting article on hoses with sidemount
http://www.cavediver.net/archives/articles/SidemountbyJay.htm

akcaver

10-16-2007, 10:17 AM

I cannot find a disadvantage to sidemount, except that when you go back to backmount (ex: to take a course) you feel extremely off balance in the water. I feel sidemount is a safer rig (in gas supply sense), and it is much easier to go dive the out of the way places accessible only by canoe. Also, I had a reg failure diving sidemount once and it took me all of 5 seconds to turn off the valve, in backmount it may have taken me 30 seconds.

Gary

10-16-2007, 10:40 AM

thought clipping on single tanks in the water would be so much easier than having to listen to her gripe about the weight of a twin set out of the water.
quite likely. :)

I generally think backmount is easier to learn on once in the water. LP85 are great backmount tanks as well as great sidemount tanks. If you keep them as independents you could swap them between sidemount and backmount fairly easily. The rules for swapping regs are the same in independent tanks whether on your sides or on your back.

HP100's make good backmount tanks for ladies but are a little too negative for comfortable sidemounting IMO. LP85 hold the same amount of air with "cave fills".

I am thinking about setting up a sidemount rig in the near future.I have never tried it and would like to hear any disadvantages some of you may have encountered,other than having to switch regs after breathing thirds.
I remembered discussing this a few weeks ago on TDS so I just grabbed it from there (sorry to repost and plagerise):

Pros of sidemount:
1. Sidemount is more comfortable than backmount.
2. Sidemount allows you to enter the water / cave / hole in dirt off rickedy ladder with minimal effort. You can bring your tanks down separately.
3. Sidemount is easier on your back.
4. Sidemount is more cave friendly than backmount rigs. Unless you're digging a rabbit hole. But generally, you won't destroy the top of the cave as in backmount. (Don't flame me about buoyancy, trim etc...) Everyone at 1 time or another has hit the top of a restriction.
5. Trim is insanely efficient ad EZ.
6. You are much more streamlined when scootering, not to mention less impact on cave. Refer to #4
7. Easier to do bubble checks, and freeflow isolations. I CAN SEE EXACTLY where the leak is, and can change to the appropriate regulator instantly. I don't have to mess with an isolator. (nothing against isolators, I backmount also)
8. I can still breathe from a free flowing reg by throttling the tank valve. It takes the skill of a child turning a garden hose on and off. If that's too much task loading, well... I can't help you.
9. IT WEIGHS LESS!!! Bands, manifold, isolator, all adds weight. Makes my fat ass easier to trim :-)
10. Much less investment for a setup, as you can use 2 tanks you have around already.
11. MUCH Lighter to take with you when traveling, and gives you the opportunity to dive double cylinders in areas of the world that don't always have doubles for you to use. You can use any 2 tanks. Refer to #10
12. Much easier to get into and out of a canoe / john boat etc...
13. Ever tried to rappel with a set of doubles?

The ADVANTAGES of Backmount are:

1. Isolation of 1 free flowing reg will still give you all your gas supply. ( Although I covered this already Refer to #8 )
2. Extra weight for cold weather drysuit divers.
3. Easier to manage on cattle boats
4. Keeps Chiropractors busy
5. Lightens your wallet.

--------------------------------------------------------------------------------

I'll agree with most of your reasons limitedly.

When it comes to comfort I'm far happier in my (independent) backmount rig and I find sidemount tanks are not always as cave friendly as many people think they are.

I have to admit I have ten times the number of dives in backmount as sidemount (1000 vs 100) so familiarity is probably part of the reason and I'm into my 3rd sidemount rig now and each one is better then the last. I'm more likely to look at the dive I'll be doing and decide which rigs to use - but more then likely go with independent backmount as opposed to sidemount.

1. Sidemount is more comfortable than backmount.
Well sidemount 40' sure are small and comfortable (feels like diving wearing nothing ) but when it comes to larger tanks, more air, stages, etc I find back mount more comfortable.

2. Sidemount allows you to enter the water / cave / hole in dirt off rickety ladder with minimal effort. You can bring your tanks down separately.
If you are talking about boat diving sidemount it not well suited to getting on and off a boat in rough water. Handing tanks onto the boat separately saves the embarrassing site of a sidemounter trying to climb up a ladder with tanks still on. Best suited to cave environments or VERY calm seas.

4. Sidemount is more cave friendly than backmount rigs... Everyone at 1 time or another has hit the top of a restriction.
I hear this a lot. I have probably been more conscoius then most in avoid contact. I find sidemount tanks wobbably and wide - nicer to the ceilings but harder on the walls - so much so tha I hate diving them in most caves. I'm much more comfortable with being 20" high and 24" wide (with stay where you expect them tanks) then 12" high and 44" wide with wobbably change buoyancy during the dive not always together or even strait tanks.

Not only do you add 20"+ of wide to reduce 10" of height but the 10" of height you loose is still consumed by your head and feet that must be up there anyway if you are looking where you are going or doing a modified flutter kill for propulsion. The only time loosing height benefits you is if one is laying flat with your legs extended strait out behind you. Even then sidemounts will change buoyancy during the dive and the backs may float consuming all or more of the height gain as the bottoms attempt to drag along the ceiling on the exit.

No, sidemount tanks are NOT more cave friendly. The advantage is divers without a metal barrier are more conscious of not banging their head against the roof - but are they paying proper attention to their tanks out to the sides beating on the walls? In my opinion they aren't.

Some otherwise untouched passageways in Ginnie bear the evidence of sidemount passage but are completely free of backmounter passage - it all has to do with the shape of the passage (and care of the diver).

5. Trim is insanely efficient ad EZ.
If you mean that the sidemount tanks will trim you so that you fall into the standard position - well yes - as long as you have the tanks weighted right. If the tanks are floatly or you roll you have whole different situation.

My backmount is far easier to trim then sidemount. I can roll, pitch or yaw any direction or degree and hold it with zero effort in backmount. Rolling in sidemount is what you do to see if your rig is well designed: if the tanks don't fall off the rig then it's a good sidemount rig. They aren't particularly stable at any angle other then the one and are very touchy about tank buoyancy characteristics.

Backmounts really hold the winning position for ease of trim. Almost anyone can put on almost any pair of doubles and expect them to trim reasonably with little concern for adjustment. With similar effort, concern and adjustment as the sidemounter needs to apply anyone should have champion trim in backmount.

7. Easier to do bubble checks, and freeflow isolations. I CAN SEE EXACTLY where the leak is, and can change to the appropriate regulator instantly.
YEP. THE most clear advantage of sidemount.

10. Much less investment for a setup, as you can use 2 tanks you have around already.
This is great when traveling. I carry weights on a cam band to trip any AL80 and I can be in the water in sidemount with a fraction of the effort to find doubles (but more then twice the effort of using them as singles).

13. Ever tried to rappel with a set of doubles?
Ever tried to rappel when wearing sidemount? (with the tanks) ;-)

Seriously in Australia they had great success lowering independent doubles down a whole on a rope. No concern with the damage to the manifold. Why they didn't use sidemount for that I'm not sure - but they preferred indies for these holes (probably less trips with the crane setup).

BACKMOUNTS:
1. Isolation of 1 free flowing reg will still give you all your gas supply. ( Although I covered this already Refer to #8 )
Yep but
Manifold: freeflowing one reg will empty both tanks - pretty dern quick.
Independents don't have that problem and get the whole air anyway.

3. Easier to manage on cattle boats
Easier to manage a larger numbers of tanks.
Fewer trips to set up.
More solid and predictable.
Easier to learn on
Easier to find commercially produced gear
Fewer "unique fixes" to problems no one has encountered before

A couple of "big ones":
Doesn't depend on the forbearence of gravity, a rubber band and a rotating mount off of an unspecified hip size to determine where and how the tanks sit on an individual. (extreme case: women with big hips have sidemount tanks that ride like snow plows.)

One can roll over onto one's back without the entire rig changing it's reaction to how it is attached!

Sorry to steal your great post Mike.

Puttzer

10-16-2007, 04:04 PM

If you're short you may find the tanks hit the sides of your thighs and that can get uncomfortable/annoying real quick.

Also short arms will have a longer stretch in handling the tanks: getting on, off.

I'm one of the short people that prefer back mounted tanks?

Craig G.

10-16-2007, 04:07 PM

I think everybodys said it, side mount is the way a cavers cavediver prefers to dives. It takes a lot of work to get your system the way you want it and learn how to trim your self. But after that, you will open up a new world of cave diving to yourself. There are so many sidemount sites in comparison to back mount sites that only have side mount entrances and bore hole after that. I feel side-mount configuration is a cavers aproach to cave diving and back mount is more of a divers aproach to cave diving. Not all cavedivers are cavers! some lean more toward the diving end while some lean more toward the caving end. In my personal opinion if you lean towards the cave end sidemount is probably for you :-D

aainslie

10-16-2007, 04:31 PM

Gary makes a good point about sidemount not necessarily being as cave friendly as you'd expect. The commonest is probably the SPG - most sidemounters have these sticking forward like antennae. If you're not careful (and I've made this mistake) they can ride too low and cause drag. if the bottom is soft, you run the risk of leaving a long ugly trail in the clay. This also destroys vis for anyone unlucky enough to be behind you. In general you have to be very aware of how your hoses run, both HP and LP.

My experience has been fantastic. I went sidemount almost immediately after finishing my training, and loved it - I haven't done a BM cave dive since. I now do a fair percentage of my sea dives sidemount also. It's fun watching the DM's face when I gear up.

The "gas management" issue I find to be a non-issue. Amongst other things, your trim tells you whether to swap over once you're used to it. Which brings up another advantage of sidemounting - with stages, you can "load balance" by breathing stages and the SM cylinder on the heavy side until everything balances out. This often is not only good for trim, but a sign that your gas management is going well too.

I think some people give up too soon. It takes 10 or so dives to "dial in" before you're comfortable. A bit like drysuits - initially they seem worse, but then you wonder how you did without them. Some of my friends started and then gave up which was really sad for me as it's left me diving solo sometimes even when we're in cave country at the same time.

DeepSea

10-16-2007, 05:06 PM

I have primarily sidemounted for the past year using an Armadillo and either 104s, HP 100s or AL80s. I have learned that there are caves where side mount is best and where backmount is best (to me...I know Joel will fight me on this).

I just got back form Mexico and was diving backmount. I realized that because a lot of early exploration in Mexico was done in backmount there are a lot of restrictive areas that lend themselves to being in backmount (tall and narrow). If you were in sidemount you would either superman or turn 90°.

The systems and cenotes we explored in previous trips to Mexico (all sidemount) were new so the restrictive areas are short and wide :twisted:

Randy Thornton

10-17-2007, 12:35 AM

I am fairly new to side mount. I have found Wayne Kinard at Amigos Dive Shop in Fort White, to be a very good resource for "all things side mount". He has been doing it for quite a while, and has been known to give the "side mount manufactures" a lot of much needed feedback on their designs.

MichaelAngelo

10-17-2007, 04:21 AM

WOW folks what a great thread. Its been a pure pleasure reading each and every one of these posts. I think I learned alittle something more about the sport I love with each post. Bravo folks bravo.
Heres my new side mount story. I am currently out on tour and stuck in San Fran. ( yeah I ***** and moan about not being able to cave dive but truth is it don't suck out here). I did my first sidemount dive in Monterey bay this past monday. The Dive shop guide was alittle concerned about this strange cave rig but he had heard my name before so off we went. Well it worked just fine. Entering with my tanks already attached was great. The wieght being on my hips lowered my center of gravity so the surf was far more easier then with back mount. Less drag thru the kelp. The only odd thing was that the elephant seals which are used to single tank back mounters got really curious about me. They keep circling me poking at my tanks on the side. I truely think they were wondering why they weren't on my back. Dumb animals I think not.
MA

10-17-2007, 09:00 AM

Related to disadvantages . . My experience has been

1) It takes twice as many trips to the water before and after the dive than in backmount. So you're trading off one heavy trip with two kind of heavy trips to get to the water.

2) Once in the water, you have to put everything together. This can be aggravating when you've got 20 people trying to get in at the same time, or the water basin is deep and you are flinging tanks on with little place to stablize yourself till you get it on.

3) Another issue in deep water basins is where to put your tanks till you're in the water. It's a little aggravating in PI for example.

4) I only have a set of LP 95's I'm using for sidemount. My backmounts are E8-130's. So if I want more gas to do a longer dive, I've got to either go backmount or eventually break down a set of 130's.

5) I HATE switching regs to the hose that has the 7 ft on it. I have to pull some length out to get it to my mouth. The hose is bungied to the tank. When I switch back to the shorter hose, then I've got to tuck that excess back in. Then my hose doesn't lay perfect like I set it up on the surface. In my opinion, the 7 ft hose does not abode well on a sidemount rig. But I don't have but maybe 25 - 30 dives sidemount. So some of mine may be lack of experience or a better way to configure it. If you don't switch regs more frequently than thirds, you risk getting off balance. I usually switch at 6ths.

6) Oh . .and watch out when using swivels on the second stages. The movement can cause them to unscrew from the hose. This happened to a guy in Little River. It also happened to another on the surface. And it happened to me when I was walking with my reg in my hand at home. The damn second stage just fell off. Make sure you check the tightness before dives.

chimie007

10-17-2007, 09:19 AM

10-17-2007, 09:34 AM

If you don't switch regs more frequently than thirds, you risk getting off balance. I usually switch at 6ths.

I'm a bit confused with this part. In backmount, we all have staged tanks (multiple) on our left side and we all carry can lights that weight a few pounds at minimum. Breathing a third of a cave filled 108 is only at most 4# lighter. Enough to create off balance ? Is it an issue because in SM the wing is not laying up around the double and creating a left and right side to balance like in BM?

Well, I switch for 2 reasons. One is tighter gas management between bottles in case one fails. And then also the one you are referring to. I can feel one tank getting slightly lighter than the other if I wait till I get to thirds. With sidemount, the weight of your tanks are not in the center of your back like they are in backmount. So even a few pounds difference will cause you to list to one side. Think about holding one weight in one hand, but not the other. The farther to the side you extend your arms, the more noticable that 3 lb weight is.

Another example, when I set up my rig, I was listing to one side. I could not figure out why. My buddy suggested rigging up each tank and putting them on a bathroom scale. When I did, I discovered that one tank was 3 lbs lighter than the other. When I added a 3 lb weight to the lighter tank, I trimmed out.

Gary

10-17-2007, 11:46 AM

I usually only switch 3 times in a dive
tank 1 at 2/3
tank 2 at 1/2
tank 1 at 1/3 or to ballance the final pressures

I also arrange it so my long hose is on tank 2 so that I'd be donating the long hose from the mouth (as the standard donation scheme) from halfway in, thru max penetration, and almost halfway out again.

I've never had a left/right ballance problem but I imagine they are posiable. As mentioned we survive any number of stage bottles carried on one side we can probably ignore some pretty extreme imballance in tank pressures. :)

Another drawback to reg switching though is those places that the water is so nasty you don't want to pull one reg out of you mouth to put the other in. I've had at least one dive entering and exiting on the same tank because of the water. :vom:

chimie007

10-17-2007, 12:17 PM

Looks like one can find every flavor of SM around.

I just got myself a used SM rig. Should be here next week. I have got a lot of thinking to do concerning gear config, hose config and gas management. I will be diving with my current BM buddies so I need a 7' hose somewhere. Jay's link got some good info about mixed BM and SM teams.

Mike Edmonston

10-17-2007, 04:24 PM

Sorry to steal your great post Mike.

No problem Gary, Hope it helps the OP. BTW, you could have taken out the part about my fat ass :D

Moonfuzzy

10-18-2007, 12:53 AM

You can easily fix the 'multiple trips to the water' headache by bringing a cart and using it. (It also helps to save your back!)

My negatives:

#1 - I use more air in sidemount. It feels like I have more drag, but it easily could be a lack of experience. Also I think - Being female I have hips, and the tanks flare out more than I see on a man.

#2 - I find attaching stages hard in sidemount, I guess because the tank attachment points are farther back than when I am in doubles.

I'm not sure one way or the other what may be best for your daughter to learn cave in. I'd say that it is a lot easier to 'get up and go' with a backmount set up, if the tanks are not a huge burden to carry. I use HP 100's and I can even put them in the fill bin myself : ) I'm not sure if 85's are lighter or not, but they are another nice choice. I prefer independent doubles to manifolded doubles for reasons already stated by others above.

As far as sidemount goes, there is a lot more fussing around once you are in the water. You can tend to draw a crowd. Attaching the tanks is similar to staging, and that is a skill that gets easier with time - I wonder if a new diver would want to put up with it while learning everything else too... up to them I suppose. I'd bet that if you started her on 40's or something like that she may like sidemounting ; )

stairman

10-18-2007, 05:27 AM

OFG-1

10-18-2007, 08:11 AM

The main disadvantage that I have is trying to get tank bungees to match my pink fins. I mean, no one has pink bungee anywhere, and between the inconvience of having basic black for my regulator hoses, the black chrome on my old dive rite first stages, the clashing reds and yellows of the Armadillo emblem, and the pastel blue of the inside of my drysuit underwear, the bungees are just too much. Ive had to go to the clear catheters just to stay sane. I mean, it IS after labor day.

Mike Edmonston

10-18-2007, 08:33 AM

Wow,thanks for all the good info.Yes shell have to do the class on backgas for sure,since sidemount is considered a specialty.Two 40s would sure be light but penetration on 6ths would be nil.Maybe instructors allow 3rds for tiny tanks since the main reason for 1/6th penetration is to keep out of deco.

I'll tell you what's really really nice, strapping on a set of steel 51's (or 53's can't remember exactly). They are about the same size as AL40's but they are negative, and small small small...

I use them in OW diving, specially on cattle boats. Lots of air, great for photography, and I just clip in and go. Once I'm back on the boat, I just pull my tanks off, and keep my harness on. This way I'm not fighting with the other crowd that's getting their poodle jacket BC's on. When they drop the ladder, I grab my tanks, clip them in and go. Takes me about 30 seconds. You will tend to draw a crowd though lol.

10-18-2007, 08:45 AM

Gary

10-18-2007, 09:08 AM

At least back when I started I remember 72cuft being the minumum tank size (2x 72 cu ft I think for apprentice/full) for cave class. I guess there still are 72's around but I wouldn't want to be standing anywhere near the fill station. ;-)

For that reason and just usable gas volumes I'd think LP85s probably the smallest reasonable tank. I guess there are HP80's which are just tiny and cute but I've never heard of them actually being used by anyone. They are short enough maybe they'd make good sidemount tanks. :lol:

HP100s are the same size as LP85s but are a little more negative in the water. For sidemount I think most people prefer the 85s for bouyancy characteristics (thou AL80 with a 1 lb weight near the bottom is nice also).

In backmount tank bouyancy characteristics plus or minus a pound or two are insignificant but in sidemount it's a big deal. I don't think many people starting in cave training should want that kind of headache. For backmount the HP100s are far better tanks then the LP85s just because they can be legally filled to 100cuft and the bouyancy and surface weight are so nearly the same.

Gary

10-18-2007, 09:12 AM

Er... ya. What Slüdge said. ;-)

Daedalus

10-18-2007, 09:42 AM

The main disadvantage that I have is trying to get tank bungees to match my pink fins. I mean, no one has pink bungee anywhere,

Here ya go pal, you will just have to import it.
"15 metres 6mm full colour pink - £20.25"
http://www.jimmygreen.co.uk/chandlery_products/shock_cord.htm

Mike Edmonston

10-18-2007, 09:55 AM

The main disadvantage that I have is trying to get tank bungees to match my pink fins. I mean, no one has pink bungee anywhere,

I also have a complete roll of pink harness webbing for ya if you're so inclined to match. Hell, I'll even throw in yellow webbing for the crotch strap.

chimie007

10-18-2007, 10:08 AM

Yes shell have to do the class on backgas for sure,since sidemount is considered a specialty.

Not exactly. I met a couple from Tampa at the DO last year. They did (were still doing some) all their cave training in SM from the get go. They were an older couple (late 40s-early 50s) and I figure they decided BM was too heavy for them.

Before I met them, I thought that SM was a specialty. It looks like it doesn't have to be. For someone that has only dove single tanks before, I don't think it would be much harder to go for SM instead of BM from the get go. There is a learning curve with doubles anyhow. Plus, trim and valve drills are always an issue with new BM divers. Two things that appears to be easier in SM (from what people are saying here).

It's a different stories for tech diver switching to cave (like I did) since I was already comfortable in BM. It would have made no sense to me to do my cave training in SM.

chimie007

10-18-2007, 11:19 AM

Rennaker's website has (had?) some decent stuff on it. He used to have a whole section on converting a Transpac and converting a jacket BC to a sidemount setup, but I can't seem to find it now. It was really well done, there were parts lists and everything.

Well I found it but no images. Makes it hard to understand

http://web.archive.org/web/20041220071943/caveexcursions.com/rennaker_s_sidemount.html

Line Squirrel

10-18-2007, 12:14 PM

From what I have seen, some instructors will teach you through full cave in SM gear.

That said you probably won't be issued a SM card because you didn't take a SM class. That's not to say you can't learn all the SM tricks later and with a good mentor be a good SM diver but make no mistake, just because you went cavern through full in SM gear does not a SM diver make.

Can you go SM diving W/O a SM card...of course you can. Just like you can use a DPV in LR or JB W/O a DPV card. But I took a class to learn the tricks from the best, Brian Kakuk. He was in town, had the time, I had the time so we did a class.

For instance, anybody that did these skills during their cavern through full cave please chime in. Here are only three examples of skills I was required to do in my SM class.

In the water, find a nice flat rock and:
1) Stand on your head, flood & clear your mask.
2) Stand on your head, flood your mask, remove and replace one tank, clear mask.
3) Stand on your head, flood mask, remove both tanks simultaneously, replace both tanks, clear mask.

You say, those are rediculous skills, why would anybody need to know how to do that? Well, when you use sm for "some" of the reasons it was intented for you often take one or both tanks off, you could have a tank off, going head first down a rather tight chimney and dislodge your mask.

There are many more skills that I learned that simply aren't covered in traditional cavern through full cave classes, with or without sm gear.

Mike Edmonston

10-18-2007, 02:09 PM

RescueTechDiver

10-18-2007, 08:44 PM

I did my cave course in SM with Brian Kakuk

As for a disadvantage to sm you have to buy two press gauges! :twisted:

Brian Kakuk

10-18-2007, 11:07 PM

Learning to cave dive in side mounts is no more difficult than learning in back mounts. MANY British divers started in side mount, although in the beginning, good trim was not really an issue in the cold muddy caves of Europe.

My first few years of cave dives were in side mount and now all of my students from Intro (if they are going through to full cave) are now trained while in side mount configuration. I no longer teach back mount after intro, and I do not teach back mounted doubles for any course. Back mounted rebreathers are the only exception.

There are two reasons I no longer teach back mount for cave diving. The first is that I do not feel that manifold doubles are truly redundant. They are not redundant until AFTER a valve is closed, IF it can be closed when it needs to be, and as fast as it needs to be, IF the diver knows which valve to actually close to solve the problem (without being able to see the casualty).

Independant cylinders are truly redundant. If a diver sticks by the 3rds rule or better, then they will never be without enough gas to get back to the entrance/deco even if they lose one entire side of the rig.

The second is that I feel that side mounts do have less impact on the cave IF the divers are diving in large cave (where most beginning cave divers usually dive). If a side mount diver goes into side mount passage, then he will obviously have more inpact on the cave as that is the nature of side mount caves.

From a safety standpoint, the valves and 1st stages are protected under the divers arms and the divers body would actually hit the cave before the valve/regulator would. Even though statistically the deaths or near misses from manifold impacts are low (read Sheck Exley's Caverns Measureless to Man, about the dive to the back of Tunnel De Atlantida in the Canary Islands), it still gives me a warm fuzzy feeling knowing my valves are protected and right where I can see them if something WERE to go wrong. It also makes me feel good knowing I can throttle the valve and make use of ALL the gas in the tank even if there were a burst HP hose, or a massive regulator free flow. Not a very efficient option with back mounts.

There are some differences in training:
1. Mixed teams (side mount/back mount) gas sharing and planning. Side mounters are taught how to deal with manifold emergencies for thier prospective dive partners as well as valve emergencies with other side mounters.
3. Gear configuration to accomodate gas sharing (yes it can be done in side mounts just as easy as back mounts).
4. Gas monitoring of two separate gas sources - for safety and trim
5. Valve throttling drills for simulated burst HP hose/Regulator free flow

I find that my students find thier trim FASTER in side mounts than in backmounts...especially if in a drysuit, but also wet. These students are not certified as Side Mount Divers after the full cave course. Side Mount Diver is a different course all together, where divers are taught much more independent thinking on gas planning, gear configuration, cylinder manipulation and confined space techniques.

If you have a good instructor who knows the rigs, they can keep the student from having to go through all of the constant tweeking that has been mentioned in this thread. I know many good side mounters who have not tweeked in years.

Students can leave the full cave course with great trim, great technique and a safe configuration after completeing their training while in a side mount configuration. It has been done many times.

As for any negatives for side mount, all of the issues that I have read in this thread can be dealt with in a real side mount course. It's all about good training and proper configuration from the beginning, same as any diving activity. If beginning scuba divers just decided to learn to do it on thier own without proper training, well then I guess there would be a lot of tweeking involved along the way, if they survived long enough.

That's my (very opinionated) story and I'm stickin to it.

Brian Kakuk

10-19-2007, 02:31 PM

Hi Mike,
Hope you get a chance to visit. Nope, no connection to Dan's and Ralph's yet, but I've added about 2,000 feet to Ralphs and about 6,000 to Dans since you were here. Amazing. According to Fred's survey, the ends of the Dans/Ralph's lines are about 300 feet apart...hopefully closer since I put in 400 feet on the end of the line Ralph's line two weeks ago. It's hard to post trip or exploration reports from here without making it seem like advertising on this forum.

Sorry but I won't be able to attend DEMA this year. Will miss seeing all the N. Florida crowd, but will be busy here with reseach diving over.

Safe diving,
Brian

10-19-2007, 04:20 PM

I'm new to SM diving, too. But here's my experience.

Related to disadvantages . . My experience has been

1) It takes twice as many trips to the water before and after the dive than in backmount. So you're trading off one heavy trip with two kind of heavy trips to get to the water.

Use a truck cart. Put all your bottles - SM, stage, deco on the cart and roll to the water.

2) Once in the water, you have to put everything together. This can be aggravating when you've got 20 people trying to get in at the same time, or the water basin is deep and you are flinging tanks on with little place to stablize yourself till you get it on.

I'm not there yet, but I've seen the gearing up process go quite smoothly in the water without a bottom to stand on.

3) Another issue in deep water basins is where to put your tanks till you're in the water. It's a little aggravating in PI for example.

I used the deco bottle cave line hanging there to hang my tanks on. It made it much easier.

4) I only have a set of LP 95's I'm using for sidemount. My backmounts are E8-130's. So if I want more gas to do a longer dive, I've got to either go backmount or eventually break down a set of 130's.

I just broke down all my doubles. I also found that I need less gas in SM than I do in BM, much less gas.

5) I HATE switching regs to the hose that has the 7 ft on it. I have to pull some length out to get it to my mouth. The hose is bungied to the tank. When I switch back to the shorter hose, then I've got to tuck that excess back in. Then my hose doesn't lay perfect like I set it up on the surface. In my opinion, the 7 ft hose does not abode well on a sidemount rig. But I don't have but maybe 25 - 30 dives sidemount. So some of mine may be lack of experience or a better way to configure it. If you don't switch regs more frequently than thirds, you risk getting off balance. I usually switch at 6ths.

I haven't really noticed this and I use a 7' hose, too. It sits pretty much the same as it did in BM. I also switch at 6ths, not so much for balance as for better (IMO) gas management.

6) Oh . .and watch out when using swivels on the second stages. The movement can cause them to unscrew from the hose. This happened to a guy in Little River. It also happened to another on the surface. And it happened to me when I was walking with my reg in my hand at home. The damn second stage just fell off. Make sure you check the tightness before dives.

No swivels here.

BTW, not picking on you, just noticed some similar issues I've encountered. I'm still learning about SM and this thread has been great.

skip

10-20-2007, 06:06 PM

Line Squirrel

10-20-2007, 06:50 PM

RN wrote:
"I also found that I need less gas in SM than I do in BM, much less gas. "

how can that be? is there something not the same other than placement of the tanks? I don't think the manifold weighs enough to make a difference. anyone else see less gas consumption with all other things equal?

-skip

Two reasons, probably because RN's trim is better and I also believe sm is inherently more streamline, I know my trim is better, and I too use less gas.

You asked about tank placement. That is a big part of the answer, your not "plowing" as much water in SM.

10-21-2007, 05:15 PM

RN wrote:

"I also found that I need less gas in SM than I do in BM, much less gas. "

how can that be? is there something not the same other than placement of the tanks? I don't think the manifold weighs enough to make a difference. anyone else see less gas consumption with all other things equal?

-skip

mmcauliffe already answered the question, but I'll confirm that as my thoughts, too. With the tanks at my sides rather than on my back, I'm creating less drag through the water. This means less effort moving through the water. Since going to SM I've been doing no stage dives I had difficulty doing with a single stage before. Part of this is my recent move to Florida and diving caves every week, but a large part is also due to my switch to SM.

aainslie

10-21-2007, 06:23 PM

I think part of the reason my SAC reduced after switching to SM is I stopped crapping myself that something up around my manifold was going to blow up and take all my gas with it! :)

10-22-2007, 08:23 AM

It is hard to compare SAC rates in different configurations, because there are a lot of reasons for it changing. Things like, current, comfort level, etc. Some people use smaller tanks in sidemount, and that reduces frontal area, and thus drag. If you feel more comfortable in sidemount, that will reduce your SAC rate, even if you actually have *more* drag.

Jay

10-26-2007, 09:56 AM

Just a few comments to add.

I have used LP 45's, al 53's, al 80's, HP 80's and 100's, LP 85's, LP 98's, LP 112's. The 45's are ridiculously awsome. The HP 100's and 85's are great. I do prefer the LP 85's as you get a little more gas if you want. :)
The 112's are the same length as the 85's, just 8" in diameter.

I have dove LP 130's SM in Eagles a number of times (and other shallower caves for long dives), they are a little harder to get on, but once in the water they are pretty comfortable and you are never going to come close to thirds unless you want to decompress for a long time. :)

My first SM dive in Cow was with HP 100's and I found I went 5 minutes further in on those then BM 98's with a cave fill.

I have a pool, so I dialed in my Transpac rig so it is incredibly comfortable and adjusted perfectly. I am much more comfortable in the water in SM then BM. BM is like walking on stilts after a few beers compared to my SM rig.
I also use a unique OMS 45# wing that had two overpressure pulls and one for the inflator. I found that I could flip it over and swap one of the OP pulls with the inflator. Voila! My inflator is under the wing and on my left shoulder! And I still have a OP pull on the top and bottom of the wing for any position I find myself in. This and a cuff dump on a 5mm neoprene dry suit is an incredible combination.

For some reason, the first time I SMed with two stages, my stages fell into place perfectly, much less noticeable then two stages BM. Just lucky in that respect.

I am comfortable with two stages and two small deco bottles on SM, If I were to do more, it would have to be BM, but I have no urge to dives bigger then that now.

Scootering the first time with a 1" crotch strap was a mistake I remedied quickly! :evil:

Set up is the key, there is no reason to be dragging your gages or have problems with a 7 foot hose. Adjust it, fix it, whatever. That's the best part about SM, choose the tanks, gear, etc that make's it most comfortable for you.

Gas management is a non-issue. Like FW said, if that is too much for you, don't go in a cave period.

I feel much safer and a lot more comfortable. Sometimes while waiting for someone to come through a restriction or run/un-run a reel/jumo or just drifting out of a high flow cave I will lace my fingers together around muy light head, rest my elbows on my tanks and just drift/ hangout. It is pretty sweet.

aainslie

10-26-2007, 11:27 AM

That's the best part about SM, choose the tanks, gear, etc that makes it most comfortable for you.

People keep saying this. Why is this different from backmount?

Do you let others tell you what tanks, gear, etc to use based on what's most comfortable for them?

Oh, yeah, that's right. Some people do. :roll:

I think it's because instead of manifolds and bands, you just need some cam bands which can be instantly changed to any size tank. The manifolds and bands are a serious investment. I have 2 sets of doubles, but 5 sets of sidemount tanks... in part because some of those sets are also stages, deco cylinders etc..