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Post by SeaRat on Oct 28, 2005 14:55:51 GMT -8
Duckbill, We'll start another thread to deal with this problem. But if you don't know that your inhalation hose is intact, do you want to start drinking the whole ocean John
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Post by JES on Oct 28, 2005 15:16:17 GMT -8
I wonder how many of the new Mistral owners are not truly conscious about the importance of a double hose regulator location. I have only seen one person using a new Mistral at Wazee and he had it way to high. I have heard conflicting stories on the new Mistral performance and I wonder how much is from operator error (again tank positioning) and unrealistic expectations. I have lent one of my Royal Aqua Master to a couple of friends and explain about tank positioning. Half way though the dive I look at them and after using their BC, their regulator has climbed above their head. Even the best breathing Royal can’t make up for that pressure differential. The people in this board know about regulator location, but I don’t think the general diving population does. Luis, I think that you're probably correct in your hypothesis concerning regulator positioning / unrealistic expectations and potential owner dissatisfaction. I wonder if the owner’s manual even discusses this issue and even if it does how many divers would actually take the time to read it?
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Post by luis on Oct 28, 2005 16:24:55 GMT -8
I was really wondering the same thing after I wrote that post.
Even if tank position is mentioned, I think many people have to experience it to believe it. Even after I explained to my friends I don’t think they took that seriously. I have even thought about using a crotch strap (like duckbill mentioned) myself, I don’t feel like I really need it but the thought has cross my mind.
You are also probably right in that a lot people probably don’t read manuals unless they have to.
Does any one have access to the owner’s manual?
I would also like to see a break down parts list. The last time I new even a local USD dealer didn’t have the parts list or repair manual.
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Post by nemrod on Oct 28, 2005 17:05:52 GMT -8
Tech and DIR are the driving force in diving now, wannabees and the real thing. They wear their tanks exceedingly high ostensibly so they can manipulate the valve by reaching behind. Why someone would need to manipulate the valve on a singles rig is beyond me but nonetheless this is why the tanks are worn higher and higher--cave style. This is not a PadI invention or something in the instruction material in a basic course, I just know that is the chief reason people wear the tanks so high now. In fact, popular dual band Tech BP and wing combinations place the tank high and it is diffucult to lower the tank and still engage the upper band. If you place the top band a couple of inches below the neck on the typical BP you will find the tank sitting very high. I use a BP and it took some effort on my part to adjust the thing to allow me to push the tank down, still, it carrys the tank higher than I would prefer. Why not just one band, well, DIR is all about redundancy it seems so they have two. The lower band could be centered or used as is and just drop the tank down and forget the upper redundant band. People dove with a single band for years and still do. Anyway, you won't find it in Nasds or PadI or whatever instructional material, it is Tech wannabee style and I assume the majority of new Mistral owners are not vintage and probably come from the tech arena and therefore are going to have their tanks hiked up over their heads. Besides, I played around with that Mistral a bit in the pool and it does not seem as sensitive to position as original type double hose regulators, why, beats me, that is just my observation. If I were to design a truely 21st century double hose as I have said before, it would be pilot valve servo assisted and the pilot valve, very small would be located in the mouthpiece and connected to the main LP chamber via an inner sense tube that runs up the center of the hose and into the regulator body. That way the breathing effort would be assitted as usual by venturi effect but the cracking effort would be like a high performance single hose because that would be seeing ambient at the mouth. This would also put the initial burst of air at the mouthpiece, the main flow controlled by the main diaphram position following behind whose opening would be "assisted" by the pilot valve". This is essentially how the Tekna T2100 functions. I would endeavor to keep it's physical dimensions and appearence as close to the real thing as possible but, alas, until dive manufacturers start thinking out of the box and put function before form (style) we will be stuck with plastic look alike junk. James
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Post by SeaRat on Oct 28, 2005 17:23:42 GMT -8
I was just at the LDS, and put the new Mistral on my set of doubles. I had to raise the position of the tanks, because the new Mistral does sit lower on the back than normal double hoses (a plus, by the way). It breaths quite nicely out-of-water, and I have not had it in the water. I did look at the manual, and there is a photo/diagram which discusses positioning of the demand valve in that manual. So new divers should be aware of it. It appears that the venturi is very efficient in the new Mistral, and that the increased diameter of the hoses contributes to very nice breathing characteristics. It could be that this is why Nemrod could not sense as much difference in positioning as with other double hose regs. With very good breathing characteristics, loss of a couple of inches would not matter as much (you wouldn't hit the "difficulty threshold" for breathing as easily).
John
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Post by duckbill on Oct 28, 2005 17:42:43 GMT -8
The new Mistral appears to be longer from the yoke connection to the front of the demand stage than the old Aqualung. Is it? If it is, then the tank may have to be raised for the regulator to clear the top of some backpacks. Then again, that would place the demand stage closer to one's back, aiding a little in breathing characteristics in most basic diving positions. This is all assuming the owner wants to leave the demand stage where it is, attached to the 1st stage.
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Post by William Bonney on Oct 28, 2005 18:35:25 GMT -8
James How do the techies dive with the tanks over their heads? I found years ago, that if my tank with a single hose was too high, it'd smack me in the back of the head every time I looked up. Wearing the tank low with single or double hose was the norm for me.....and the guys I dove with.........how do these new techie's do it without banging their heads?I-AM-SPAM?
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Post by nemrod on Oct 28, 2005 18:45:47 GMT -8
william Bonney, your question is excellent and if you follow threads on the Scubaboard you will see that periodicaly the "head hitting" issue is discussed at length, yeah, it hits there heads and if you notice, many DIR divers (perhaps wannabees or perhaps not) wear helmets. Now I understand that it an overhead environment---helmets---but not open water. Anyways, yeah, the tank valves commonly hit their heads and it is an issue that gets discussed, and which I have observed happening. They have this idea in their heads that they need to reach the valve---I understand reaching the valve with an isolation type while in an overhead condition but what the heck is it in open water--never mind because I am dragging this way off topic so forget it all, me bad.
James
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Post by SeaRat on Oct 28, 2005 19:20:41 GMT -8
James,
You're not bad, and tank positioning is a topic that is applicable to the new Mistral because of its design (lower than the tank valve), and the use of tank-mounted BCs currently popular with most divers. I do not like my scuba tank high, but I have two reasons, not one. The first is what you have stated, but with a different twist--hitting the back of the head. I used to (in the 1960s and 1970s) be a USAF Pararescueman, and we periodically had to do water jump missions. Jumping out of an airplane like a HC-130, with its prop blast, was not a pleasant way to enter the water. We got turned every which way but loose, as they say, and this is as the parachute was deploying out of the deployment bag/static line (which stayed with the plane). If my tanks were anywhere near the head, we would have had problems. The same can be said for a water entry from a high boat. These could be lift-threatening injuries to the back of the head from only a 15 foot jump (which was the equivalent of our water entry speed when parachuting too). So, I don't like that thought, or the thought of a long hose wraped around my neck (DIR style--though I've tried it a few times). So that's the first problem with the high tank position, but it could be argued that it's infrequently a problem.
The second happens virtually on every dive, and that is the problem a high tank position in the backpack creates for surface swimming. If you don't use any floatation on the surface, then with the tank high, it pushes your head underwater further, making the snorkel less effective because of wave action going over the top of the snorkel (and hence, the call for snorkels with protection from wave action). You could swim on your back, which many DIR types prefer (probably subconsciously because of their tank position being too high). You could depend upon your BC to float you higher (and waste air doing that), or you could simply position the tank lower and enjoy a better surface swim. Sometime I'll do some diagrams on this to show the physical forces, but right now, I've got to wash the dishes;)
John
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Post by JES on Oct 28, 2005 20:17:10 GMT -8
... I used to (in the 1960s and 1970s) be a USAF Pararescueman, and we periodically had to do water jump missions. ... John, So you were a USAF "PJ". Many downed aviators owe their very existence to PJ's for rescuing them from harms way. Pararescue Creed: It is my duty as a Pararescueman to save a life and to aid the injured. I will perform my assigned duties quickly and efficiently, placing these duties before personal desires and comforts. These things I do, "That Others May Live.". I respect and admire your dedicated service to our country. Regards, Joe (CDR, USN)
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Post by SeaRat on Oct 28, 2005 22:34:48 GMT -8
Cdr. Joe,
Thank you, Sir.
I have a lot of respect for the Naval forces too, as we coordinated a lot of activities with the Navy. In your position, I'm sure you contributed to a number of actions too. I'm sure Veteran's Day has special meaning to us both.
John
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Post by luis on Nov 3, 2005 12:31:38 GMT -8
Yesterday I went to a dive shop in Boston who is a US Divers dealer. I was talking to them about the parts I need for the modified Royal Aqua Master nozzle.
I ask her if I could see the parts break down for the new Mistral. She didn’t have one so she called USD technical support. Technical support told her that they haven’t published one because being a new product they want them returned to the factory if any service was needed. This way they could keep track and identify any problems. Obviously her next question was: have there been any re-occurring problems showing up. To which he answer that a people have been complaining about breathing resistance, but that has been identified as poor tank/ regulator positioning by the users.
I just thought you all would find it interesting what USD technical support is saying about their regulator.
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