Dive Rite Transpac II BOUYANCY PROBLEM

[TexasMike]

Originally posted by seabass
2) lay flat on your back.

A minor correction if I may...

Don't try to lay completely flat on your back. Just lean back as if you were sitting in your favorite recliner watching a movie. This is usually enough to achieve a very comfortable position on the surface.

 

[diver gadget]

UP
Would I not be corect in believing that the proper BP/wing/harness that you speak of would also be back bouyancy and tend to push someone on their front when over inflated on the surface?? I have not used one so I am no expert but just seems logical that back bouyancy BC's would end up pushing you forward. I do dive the Transpac II and love it! Don't really have a prob with it pushing me forward as I don't enflate it much on the surface and lean backward's

 

[Uncle Pug]

Originally posted by diver gadget
Would I not be corect in believing that the proper BP/wing/harness that you speak of would also be back bouyancy and tend to push someone on their front when over inflated on the surface??

It's not been my experience with a proper BP/wing/harness...
I've even tried to float intentionally face forward and go limp... it takes little movement to roll me at least onto my side... passively ~ maybe a small wave... thinkaboutit... heavy tank, ss bp, now on top, bouyant lungs underneath.... over she goes!

Anyway contrary to what Mike suggests I find that laying out flat on my back is not only relaxing but is a great way to swim out or back in... especially with the doubles... it is after all, the world's largest water bed... I think that is one of my favorite parts of the dive!

Ooops, I digress in my revelry...
Nah, it don't floatcha on your face.

BTW I don't use an AL80 on the back and I wear a weight belt when using a single.

 

[diver gadget]

I have just bought my first set of twins and when in water have no problam at all of staying face up, but I believe that with an AL 80 and when I did use the weight pouches and over enflated the BC it would try to push me face down. By lying backwards it was fine.

 

[DiveRite-SW]

Twins. Now that's a great idea. Had my eye on a couple lately, but what if one of them doesn't like to dive?

Any back-inflate bc/harness concept will put the center-of-flotation farther back than a regular 'recreational' bc, since the inflation mechanism is (by design) all at the back of the body. This is what makes them work so well underwater - they almost 'suspend' you in a horizontal position. The rec-bc, on the other hand, is designed to ensure more of the neutral or face-up flotation, just as you are used-to.

The idea is to counter-act the tendency to 'push' you face-first on the surface by trimming the weight-system location to allow a sufficient amount of neutral stability (not buoyancy) without over-exaggerating the tendancy to roll or flop. To do that, one should experiment with the location and amount of weights on the belt (or in the weight-pockets), in the trim-pockets (if so equipped), and maybe even strapped to the cylinder(s) itself. Some manufacturers even sell little trim-pockets that can be affixed to the tank-strap, that have velcro-flaps.

If you're using doubles or a big heavy steel single, however, it may not be necessary to compensate for the back-flotation, depending on how much neoprene you're trying to sink. They can be darn heavy by themselves!

Just remember that, if used as a recreational bc-rig, it's a good safety practice to allow sufficient droppable weights, in case you get in trouble and need to jettison that extra negative-buoyancy.


Now maybe if I could just get the twins to CARRY my stuff, it wouldn't matter if they wanted to dive.... (ummm, yeah it would)

 

[wheezy]

WOE THERE BIG FELLA..........

What's all this stuff I'm hearing. Especially the 34lbs part??? yikes..

I've realized that MOST people that have this problem have the BC Inflated to the point where it's going to pop.

How much air does it really take to keep you afloat? Using less air in the bladder should help.

just relax and pretend you are in a lazy boy, and keep those knees bent. You should be fine.

Good Luck

 

[jonscubas]

I really appreciate all your replies. I will be out beach diving this weekend and will try it out again. This is the outline of my gear reconfiguration:

I have the 2, 4 lbs trim weights attached to the small D rings at the back of the harness. I also moved the Dive Rite integrated weight pockets to the far rear almost to the small of my back, no longer on the sides of my obliques. I am also down to 8 lbs on both sides. My grand weight total with trim weights and integrated weights is now 24 lbs. I will be using a steel 95 this weekend instead of a steel 80. I will leave the Rec Wings bladder cinched up with the bungee cords, and will not put too much air in it when floating at the surface. In fact, I will also try it with the bladder empty, and 750-500 psi in my tank near the finish of my dive for testing.

I will also try to lean back, with my knees bent and legs curled slightly backward and relax at the surface.

In conclusion, I appreciate all your time in giving me your advice. If I still experience the same problem, I will look at mounting tank weights. If that does not work, I will be changing BC's for sure.

 

[wheezy]

just for the heck of it...

I use the same bc.

I'm 6'5" 220lbs. I DO NOT use the trim weights. I DO use the integrated system. I keep the pockets on my sides, more towards the front actually. 12 lbs in each side with an aluminum 80 10lbs on each side with a steel 95.

Seems to work great for me, but everyone is different. By the way that's also with a brand new 7mm full suit with integrated hood, 7mm booties and 7 mm gloves... and yes it's cold where I dive.

Good Luck

 

[jonscubas]

Figured out the problem. Moved the integrated weight pockets back, removed 4 pounds from them, so only 12 pounds in pockets, plus 8 lbs trim weights on harness. Cinched up bungee cords tight, I mean tight! took some air out of BC. Went beach diving for the test, with a steel 80 Cu tank.

Floated fine, able to stay upright, best of all was able to surface swim in on my back, like I wanted to.

Thanks to all of you, it was the combined advice from all of you that gave me all the ideas to try out and it worked!

Great JOB! Happy Diving ALL!

 

[Rick Murchison]

Originally posted by Uncle Pug
The solution is ebay.

Then get yourself a proper BP/wing/harness.

OK... now I'm back to being Uncle Pug.

First bad advice I've seen from you, Pug.
The face-down moment is a function of back-inflation, not the Transpac. The difference in face-down moment between the Transpac and a BP is zero to marginal, depending on BP material, with the heaviest SS being the best.
The solution is to either position the body so the center of buoyancy is under the center of gravity - accomplished by kicking back onto the back and getting the bladder under rather than behind you, or to move the CG aft and the CB forward (when viewed from an upright position on the surface) by adding negative buoyancy at the tank - change to a steel tank, strap a weight to the tank, etc.
Rick