Steel vs AL—-weight

[Catito]

I realize this has been discussed before...but I remain confused. What is the general estimate related to weight when one shifts from AL80 to HP Steel 100 with all the other variables being the same. For example, 3mm full wetsuit; 12lbs; warm salt water. When switching from AL80 to HP100 reduce weights to ...?

Thanks

 

[James79]

I realize this has been discussed before...but I remain confused. What is the general estimate related to weight when one shifts from AL80 to HP Steel 100 with all the other variables being the same. For example, 3mm full wetsuit; 12lbs; warm salt water. When switching from AL80 to HP100 reduce weights to ...?

Thanks

I'm a big fan of this:
Optimal Buoyancy Computer
It works pretty well for me, and if you just want the tank characteristics, you can check the data on that tab. It even has data broken down by brand of tank, for many sizes.

Respectfully,
James

 

[swimlikethefish]

To be precise you would need more information. But the standard says 4lbs.

If you want an actual figure. Do the following:
1. Figure out who makes the aluminum tank.
2. Figure out who makes the steel tank.
3. Look up manufacturers specs for bouyancy of both tanks.
4. You have the number you are looking for.


Example #1
1. Catalina S80
2. Faber FX100
3. Catalina is +4 empty - 1.8 full, Faber is -.59 empty - 8.41 full.
4. The difference between these two tanks would be 4.59 lbs.

Example #2
1. Luxfer 80
2. Faber HP-100
3. Luxfer empty +4.4 and -1.4 full, Faber empty -7.26 and -14.76 full.
4. The difference between these two tanks is 11.66 lbs.


So to precisely answer you need to know what specific tanks. However, if just using this to guesstimate then use example #1. The tanks used in example #2 are non standard tanks. I just used them to explain how different an Al80 and steel 100 can be.

 

[rongoodman]

I'd take 3 pounds off to start with and then check again while on your safety stop. You should be able to hold it comfortably with a nearly empty wing or BC.

 

[loosenit2]

I've been making the switch to HP100s myself, still trying to dial in weight but was able to drop 4-6 lbs depending on other gear (pony, cannister light etc).

 

[icechip]

+1 on dropping about 4-6lbs, like loosenit2 said. That's what I did when I went to HP100s.

 

[PoolsOpen]

I realize this has been discussed before...but I remain confused. What is the general estimate related to weight when one shifts from AL80 to HP Steel 100 with all the other variables being the same. For example, 3mm full wetsuit; 12lbs; warm salt water. When switching from AL80 to HP100 reduce weights to ...?

Thanks

I use similar configuration. I just use 6 lbs less when using HP steel 100s

 

[lexvil]

When I go from an HP 100 to an aluminum 80 I drop about 32lbs, also drop the drysuit, hood, drygloves etc. but joking aside you’ll probably take off 4 to 5 lbs.

 

[NAM001]

I realize this has been discussed before...but I remain confused. What is the general estimate related to weight when one shifts from AL80 to HP Steel 100 with all the other variables being the same. For example, 3mm full wetsuit; 12lbs; warm salt water. When switching from AL80 to HP100 reduce weights to ...?

Thanks

All things being equal then it is nothing more than the tank differences. dont confuse weight with need of lead. weight is weight and that weight is on land. lead is a counter to buoyancy. and since we are limited to only tank contributions it is black and white. look up the tank specs and it will tell you what the weight is and buoyancy is. That now leads to the validity of those numbers. So many have found them a little off if not just plain wrong. One uses a 2.5# valve for its numbers because that is what is used in Europe. We don't use those heavy hp VALVES AND OURS WEIGH MORE IN THE RANGE OF 1.5. When ever anyone asks about their tank I tell them get a luggage scale a 10# weight and a pool./ Near empty the tank and put the weitght on it. hang it in a pool submerged totally and weight it That value is buoyancy. Then subtract the 10# weight from it. that is your MT buoyancy with that valve. IE a AL80 buoyancy of +3/-4 by doing this will not sink with out the weight to keep it down. now you weigh it and it says 9#. with out the weight it is +1 empty. No need to measure full because that is not a factor of the tank it is a factor of the gas and now you calculate that by something like 8.5# per 100 cuft.. Again that number is moot because you have a BCD to counter that changing number. The MT buoyancy does not change and is the value that drives your lead weighting,,, WITH ALL OTHER THINGS EQUAL..... Then for the MT weight put the tank with the valve on a bathroom scale and measure it for land weight. One more thing use an appropriate weight so that you get a mid scale reading on your scale. If it is a 20# scale then use weight that will sink the tank and read mid range of say 7-14 where the accuracy is better than on the high and low ends. I don't trust a 50# scale to give me a good 1.5# reading. BTW I am currently doing this very thing on some dacor and voit 72 cuft 2250 psi tanks made by PST. cant find specs so I will measure them my self.

Knowing the buoyancy difference between tanks will tell you exactly the amount of lead weight to adjust for with all other things being equal including salt vs fresh water. Fresh vs salt has its own correction methods.

 

[Catito]

When I go from an HP 100 to an aluminum 80 I drop about 32lbs, also drop the drysuit, hood, drygloves etc. but joking aside you’ll probably take off 4 to 5 lbs.

Hahaha. I am hoping I won’t drop my breakfast and lunch.

thanks