Dive Rite Transpac BC

[JSC]

Don,

I won't give you an opinion on which is better the TP or the BP wings but I can talk about the drag. Oh by the way I have nothing against DIR either. The difference in drag of the two harnesses is negligible at the speeds we are talking about up to about 6kts (has to do with laminar flow). Now wings are another story... here is a post I made on another board:

I'm not answering the question: which is better bungee or no bungee? I just want to discuss the resistance of the two, as it seems to be in question. Please note that predicting vessel resistance in an open fluid is probabilistic and laminar and turbulent flow make it impossible to exactly calculate resistance, but you can get close by making some assumptions.

To estimate the resistance of a diver you would treat a diver like a submarine. The most important item in reducing resistance in a submarine is reducing the profile (teardrop profile is considered the best) then reducing wetted surface area (friction), smooth lines (friction/turbulence) and appendages that drag (turbulence/Profile).

If your wing flows free (not bungeed) then you increase your wetted surface (see below*) and increase your profile (see below*); in addition your wing is now a loose appendage (possible flopping affect adds to turbulence). If the wing is bungeed like the OMS then your profile does not decrease by much and the surface area stays about the same and you add the appendage of the bungee as well as the resistance from the "wrinkles in the wing" (not smooth lines/lots of turbulence) probably your worst case. (*)If the wing is pressed (not necessary to be tight) against the back you can basically ignore the surface area under the wing and it would not be considered an appendage. Ideally the Diverite "theory" is probably the best; the profile is reduced and the bungee is kept under the wing. This leaves a smooth surface on the top (reduction turbulence) of the wing and a small profile keeping the wing close to your back (reduces wetted surface/profile).

The only time you would really notice a difference is using a single tank on a scooter. Using dual tanks not enough of the wing is exposed to tell the difference in the appendage drag and the speed of the average diver (not using a scooter); the drag coefficient is probably next to nothing.

As always I am open to discussion or corrections -assuming I made any sense

JSC

 

[Atomox]

Rick,

I have used both as well. I still have the transpacs, I hate to get rid of anything even though the harnesses have not been used in quite some time (use the wings all the time). In my opinion the doubles setup with the transpac is not as stable or as functional as a BP/wing setup. I have crushed 1 QC on my crotch strap (set the tanks on them). I no longer have any QC’s because of this and the general lack of need for them on all of my gear.
I would agree that there is a definite NIH attitude from the DIR crowd. It is funny because they have been known to take apart another manufacture’s gear and then say that they can make it better & cheaper. I have yet to see the cheaper part though.
I also use more than the “approved” number of d-rings. They are needed for functional reasons with cold water and gloves. But for the most part the DIR hymn is danceable and has a good beat.

Brad

 

[tomcat]

Hey iguana don,

no offence intended but when you assume prima facie that DIR is the better way, it sure sounds like the first step towards overconfidence and self-righteousness.

when making comparisons, people have to first agree what the criteria are, how they are measured and finally, the conditions under which one setup is determined to be "better" than another. until this is done, i don't see how anyone can demonstrate conclusively that DIR is a better way, even though it may in fact be.

you and i know that there are 1001 situations that a diver can be faced with and it is unlikely that any one setup can satisfy them all. the reason why you have not seen contradictions as to why DIR is not the better way, is because nobody is disputing that DIR makes sense. they are just questioning whether it is THE better way.

as for whether a b/p wings setup is more streamlined than a transpac, although i do not have JSC's knowledge, i was thinking that the two setups seem similar enough. with all the other gear that cave divers carry along (pony bottles, cannister torch, etc), the small difference in wing profile is hardly the straw that will break the camel's back.

if you can fight a 4 knot current in an overhead environment carrying all that stuff, i don't see what difference it makes whether u are using a b/p or a transpac.

do correct me if i am wrong.

actually, even though this is not my thread, i'd still like to know whether the transpac has any significant advantages over a regular back inflated bc, for the typical recreational diver who will not move into tech diving.

tomcat

 

[Iguana Don]

Confident in my system and equipment. Confident in the fact that it has been proven through miles of caves without any accidents. Confident that teams of divers and dive profenssionals have thought this system out way ahead of me.
Standardization of gear configuration and utmost belief in the buddy system.

Yes I am confident, not overconfident, I am intelligent enough to know that the sea can come up and bite you in the ass and you not be ready for it, but smart enough to know how to handle it or avoid it.

We can hash this out till the next millenium, so let's just agree to disagree. You dive your ways & me & my buddy will dive mine.

ID

 

[guanacodiver]

Hello Mick, I own a Transpac II and it is just the most confortable BC I have ever worn, it is great and can be confifured to almost all dive scenarios. I use it with a set of travel wings for traveling to the tropics and it works great.

This BC can also be customized to have as many d-rings as you want, you can add pockets to it etc, in my opinion it is a great setup.


Have Fun