Switch Single AL80 to Twin Al80, impact on weight

[dee-]

Hi,


I'm diving in fresh "cold" water up here in canada with a single catalina al80 with bcd, in drysuit, with undergarment. I need approx 30lb of lead...

I will try a twin AL80 (both catalina), with s/s BP (5 lbs) and i will dive in same config (fresh cold water with drysuit and undergarment).... I dont really know where to start with weight. A V-wight of 10 or 12 lbs is already installed on the twin.

Will a need more weight than single or less? Just want to know a target where i should start....

Thanks

 

[eelnoraa]

Definitely less weight than single. Typical single tank valve (Thermo): 1lb7oz each. So 2 single valves are 2lb14oz. Thermo manifold and valves: 4lb13oz. So the valves along is 2lb heavier. Highland band is about 2lb each, so total 4lb for the bands. You are 6lb heavier already.

And since you are diving cold water with dry suit and with 30lb of lead, will you consider using double LP85 or double HP100. You can take off almost 10lb there.

 

[dee-]

Definitely less weight than single. Typical single tank valve (Thermo): 1lb7oz each. So 2 single valves are 2lb14oz. Thermo manifold and valves: 4lb13oz. So the valves along is 2lb heavier. Highland band is about 2lb each, so total 4lb for the bands. You are 6lb heavier already.

And since you are diving cold water with dry suit and with 30lb of lead, will you consider using double LP85 or double HP100. You can take off almost 10lb there.

Thanks for your answer
It will be my first experience with double....if i like, i will consider everything !

 

[rongoodman]

Just so you know, they'll probably try to put you head down, which you will naturally compensate for getting head up, and end up thinking you need more lead at the top. Most likely, moving some to the bottom will help more.

 

[kcprofessor]

The quick answer is, "It depends...." Let's assume that the only thing you are going to modify about your rig is that you'll go from a single AL80 to double AL80's. You may have to increase the lift on your wing, but that's another discussion. Let's also assume that with your 30 pounds of lead, you are neutral at your safety stop. A single AL80 is 2.7 pounds positively buoyant in fresh water including the valve, so two AL80's are going to be 5.4 pounds positive. You have added some additional weight in the form of the manifold and tank bands, but you really aren't interested in the weight in air; you are interested in the buoyancy in water. If the bands and manifold weigh 6 pounds on the surface, their weight in fresh water is a little over 5 pounds. So you have 5.2 pounds negative for added hardware and 2.7 pounds positive buoyancy for the additional (floaty) tank. By my calculation, you might be able to lose about 2 pounds of lead, unless you bigger wing has more inherent buoyancy. Your wing has to be able to support all the lead you are carrying, plus the full tanks plus your flooded dry suit or you risk becoming a dirt dart if something goes wrong.

The key thing to remember about weighting is that it isn't about how much the stuff weighs on the surface but how much it weighs in the water. I tell my students that 10 pounds of lead and ten pounds of wood weigh the same on the surface, but wood isn't used for scuba weights for a reason!

 

[Kevrumbo]

Hi,


I'm diving in fresh "cold" water up here in canada with a single catalina al80 with bcd, in drysuit, with undergarment. I need approx 30lb of lead...

I will try a twin AL80 (both catalina), with s/s BP (5 lbs) and i will dive in same config (fresh cold water with drysuit and undergarment).... I dont really know where to start with weight. A V-wight of 10 or 12 lbs is already installed on the twin.

Will a need more weight than single or less? Just want to know a target where i should start....

Thanks

I similarly use 26lbs with a single AL80 with a drysuit in temperate SoCal ocean waters: 6lbs SS BP with 20lbs weight belt and heavy rubber jet fins to counter floaty drysuit legs & feet. Buoyancy Wing is an old Halcyon Pioneer 32.

My double AL80's are Catalina's and I use 17 to 19lbs total: 6lbs SS BP; 2 x 2lbs bullet weights in the "V" space between the tanks; a 5lbs tail weight and 2 to 4lbs in a small front weight pouch near my BP belt buckle, with drysuit & jet fins. Wing is a Halcyon Explorer 40.

In tropical warm water with a 0.5 mil skinsuit & 3 mil hooded vest, no added lead weight with single AL80 and 2lbs AL BP, with lighter jet sport plastic fins. But with double Luxfer AL80's & 2lbs AL BP, I need 6lbs in a weight pouch between my shoulder blades to level out horizontal trim, and prevent upper torso from pivoting up (with resultant knees rotating down into the silt) when taking a breath.

 

[MikeWebb]

In my sidemount setup, 4thE Arctics and fusion suit I use 15 lbs with either a one or two Ali 80's. Tropics wearing a sharkskin I need a single 3 lbs, again diving either a single or double sidemount setup.