so i have been doing a substantial amount of reading online about different side mount rigs available and there are a few i am looking at. however, some of them are described as being for warm water diving only, due to the relatively low lift capacity. "they" say that due to the extra weight we need to carry for cold water (because of dry suits, steel tanks etc) that the lift capacity is too low. and everything i have read about choosing a proper sized wing seems to support this thought.
i am confused by this. let me explain why. then you can point out what i am missing and why i obviously have no idea what i am talking about.
i try to weight myself (no matter what type of tank or gear i am wearing) to be neutral (or slightly negative) at 10 or 15 feet with low gas (maybe 500psi if max is 3000psi) and my BC emptied. so at this point obviously the lift capacity is a non issue as i am neutral. so when do i need to add gas to the BC ?? and how much lift do i really need ?? i would need to consider that when full (as opposed to having 500psi) each tank would have maybe 5lbs more gas in it. if diving doubles, thats about 10 lbs. so i need at least 10lbs lift in my wing to counter act that extra 10lbs of gas at the start of a dive. i also need to consider that i want to be able to float comfortably on the surface with my head out of the water. i have seen it mentioned several times online that an average head with a hood on it, adds about 10lbs negative when above the water. so if i use that as a rough guess, that means i now need 20lbs of lift in my wing (10lbs gas + 10lbs for my head) at the start of the dive to be able to float comfortably. so if i had a wing with 20 to 25lbs of lift, i should be fine right ?? i have no intention (at this point) to carry added tanks beyond the two. i don't have to worry (as back mounted double divers do) about whether my wing will float my rig if i take it off. so what am i missing.
no matter whether i am in salt, fresh, diving wet, dry, cold, warm, using steel or allum tanks, i will always be weighted close to neutral with low gas in the tanks at my safety stop depth. the only lift i seem to need is the extra gas weight plus keeping my head above water. apart from that, i can see needing some extra lift possibly for wet suit compression (if i wore a wet suit), but i dive dry. so any compression will be offset by me adding gas to the suit.
now if i was looking at a worse case scenario, and had a flooded suit at my deepest part of the dive, i would be dumping lead anyway to hopefully do a controlled ascent. i would not rely only on my wing lift to get my back to the surface. and if my wing fails, well then the lift capacity becomes irrelevant.
so lets hear it. am i crazy or what ?? what am i missing ??