DIR buoyancy?

[jplacson]

Ok, please bear with me guys and gals. I recently switched to a Halcyon 27 I'm gonna be using it for the first time this weekend. And I wanna get my buoyancy right. Now, the test I know is the eye-level test... empty tank, empty bladder, full lungs, float at eye-level.

A DIR friend of mine said that the DIR way is neutral (empty bladder) at 15 feet with an empty tank.

Do both tests provide the same results? Thanks so much!

 

[Albion]

The eye level thing is really a PADI (or possibly any basic dive agency) check to get bouyancy roughly right, however it is not realy accurate

It doesn't matter whether you are diving DIR, PADI or whoever you need to be able to perform a safety stop at 15 feet in your most bouyant condition, that is with an empty or near empty tank (500PSIG). a litle air in the bladder won't hurt but idealy empty bladder too

 

[Uncle Pug]

You want to be able to make a controlled ascent at the end of your dive.

From 10' to the surface it is especially important that you be able to make a very slow ascent.

It is nice to have some gas left in reserve at the end of a dive... but it might be necessary for you to use that gas in an emergency so you shouldn't be counting on it as a part of your weighting system.

Still... to practice with and empty tank is not practical... so with this in mind use a minimal amount of gas.. say a couple hundred pounds. And do the test in shallow water <10'.

Take along a portion of your weighting in the form of shot bags that can be dropped 1~2# at a time. Find the least amount of weight at which you can still remain neutral breathing normally at ~5' with no air in your wing... and no extra air in your drysuit if you are diving dry. With inhalation you should start to rise and on exhalation you should start to sink.

 

[jplacson]

Ok... I was planning to mess around with my weights after every dive... that way I don't waste my time, and I can just finish off my gas at a safety stop.

 

[Uncle Pug]

jplacson once bubbled...
that way I don't waste my time

I don't think that working out your weighting is a waste of time... though I understand what you are saying.

however... this is important enough for you to make it the reason for the dive. Don't skip the step of taking drop weights into the water to work this out.

Drop weights will not be convenient for a regular dive... so go ahead and do your dive. Then get out of the water and change your weighting so that you have some of it ditchable in small amounts.

Go back into the water (shore dive) and spend enough time at 5' that you breath your tank down to a couple hundred PSI.

Now start dropping weights and test your buoyancy.

 

[jplacson]

Oh ok... so I can do the test at 5'? That's cool... I was actually going to have my instructor help me out and hand him my weights.

I already dive with just 4# prior to getting my BP/wings. I've been talking to Seajay about the whole thing.

Basically I'm fine already...I'm just going into the trim thing...which, from what I gather from everyones replies...really takes time, and is a trial & error thing.

My concern now is seeing if I still need those 4# after trying my AL BP/wings... or if I can ditch it all togther...or if I'll need a 2# trim on my tank strap. Maybe I'll find out that an SS plate will be much better for me... who knows... my 1st dive this weekend will be to figure out my final trim Thanks... I just wanted to know how to test it all properlly... I think I'll try all 3 tests... eye-level... 5', and at 15'.

 

[Diver0001]

jplacson once bubbled...
Ok, please bear with me guys and gals. I recently switched to a Halcyon 27 I'm gonna be using it for the first time this weekend. And I wanna get my buoyancy right. Now, the test I know is the eye-level test... empty tank, empty bladder, full lungs, float at eye-level.

A DIR friend of mine said that the DIR way is neutral (empty bladder) at 15 feet with an empty tank.

Do both tests provide the same results? Thanks so much!

Hmmm. First of all, I don't think it's very practical to be doing a bouyancy check in 15 feet of water with an empty tank......And as UP said you need to make a controlled ascent *all* the way to the surface.

I'd say do it empty bladder on the surface lungs 1/2 full at eye level tank empty. You can do it with the tank full too but then you need to calcuate the weight of the air. For an AL-80 that's about 2.5 kg. In other words when you work it out with a full tank you'll need to add another 2kg or so to compensate for when the tank is empty.

I'd check at the beginning and at the end of the dive if it's your first dive with this kit.

R..

 

[cnidae]

A simple way to do it is too take a tank in the water with a 100lbs in it with your buddy empty your dry suit & bladder, breath off his reg at a normal breathing rate. You should start to sink very very very slowly when you do your weighted right.

 

[jplacson]

Thanks to everyone who replied! I got my weighting down more or less... I'm down to just 4# total... I'm trying to see if I can ditch 1# more... :lol: Although I think 4# is the least I can go cuz of my tank... (AL80 is about +3.5 right?)

My current config is just the AL BP and either the 2#STA or 2# trim weighting.

Thanks again!