Riding Blind with your DSMB reel

[PfcAJ]

Gee rly? I can? Oh, how I wish I had read this before I tried to sleep last night. All that tossing and turning over nothing.

Yet, you keep trying to convince me how great and safe it is without giving me any real benefits... other than to my ego for being one of the "in" guys who can.

Sadly no, it won't. People will still be making simple mistakes and getting bent trying to understand and use this system. You'll tell us that it's not really RD's fault and the sane people will shake their heads and clutch their PDCs a bit tighter.

And you'll still be over there without understanding.

It would be one thing to understand it and decide it's not for you. That's reasonable. But actively trying to not understand something is very odd, and even more odd is making value judgements about something you are trying not to understand.

To me this conversation is very similar to talking to someone who "knows" about cave diving because they saw a something on the news about an accident.

 

[The Chairman]

To me you're like someone telling me they know all about Russian Roulette because they haven't been shot in the head yet. I understand people get hurt more often and that's enough for me. I simply want better odds than those you're willing to accept. Call me ignorant. Call me skeered. I call me cautious, conservative and have never been bent. It's a conscious decision and that it won't work with a rebreather makes it even less appealing to me.

 

[kensuf]

Pete, I think you're confusing the two ratio deco's. The one AJ's referring to is really quite a bit like using printed tables generated by a computer program. The one BoulderJohn refers to is quite different, and very much like made up mysticism.

 

[The Chairman]

Pete, I think you're confusing the two ratio deco's. The one AJ's referring to is really quite a bit like using printed tables generated by a computer program. The one BoulderJohn refers to is quite different, and very much like made up mysticism.

It's quite possible. Still, it doesn't sound suitable for rebreather diving.

 

[rongoodman]

It's quite possible. Still, it doesn't sound suitable for rebreather diving.

It was never designed to be used with rebreathers, so that's no surprise.

 

[C Dub]

And you'll still be over there without understanding.

It would be one thing to understand it and decide it's not for you. That's reasonable. But actively trying to not understand something is very odd, and even more odd is making value judgements about something you are trying not to understand.

To me this conversation is very similar to talking to someone who "knows" about cave diving because they saw a something on the news about an accident.

That's my problem with your position Pete - you are coming from a place of ignorance. I've been scratching my head reading your posts, because they are very different from the Pete I know who is always interested in the details and exploring/discussing the details....

This is further complicated by that there are 2 very different RD's. I don't know much about the other one, but the GUE one AJ is referring to is both simple and rational.

 

[PfcAJ]

It's quite possible. Still, it doesn't sound suitable for rebreather diving.

It can be, depending on your setpoint.

 

[The Chairman]

you are coming from a place of ignorance.

Here's the real problem... DIR has been known for justifying itself in the past by pure denial. Their claim for a long, long time was that no one got hurt while following DIR guidelines. Mistakes, oversights, whatever and bang: those who got hurt were no longer considered DIR. They maintained their stance that no DIR diver had been hurt. WOw. I know of at least 9 peeps (six from John and 3 from me) that have gotten hurt following Ratio Deco. The defense for that is just more denial. "Oh, there's two...", "They didn't really UNDERSTAND Ratio Deco (nudge, nudge, wink, wink)" and so forth. I don't think I know that many divers bent the 'normal' way and there are far, far more of them out there. Consequently, I'm not going to be shamed into accepting something that sounds hinky and has resulted in a higher incidence of accidents. You call it ignorance, and I call it a reasonable doubt.

 

[Macan]

Impressive, did the current change during the dive of they enter the water knowing it was that strong ?, how big is the SMB?

In the Tec dive I did recently here in Curacao we had to Deco in the Current, we didn't deploy the SMB ( it was not planned ), we drift Deco until reaching the plateau where there was no current, of course the current was nothing like in the pictures, I don't know how it can be measured, but it was like fining hard and staying in the same position, that is why we missed our target when we plunged from the boat.

I teach at Anilao, Philippines and the dive site in the photo is named Beatrice. She is perhaps the most beautiful reef in Anilao but her character is very contemptuous. Her currents are strong, wicked and erratic. West of her submerged reef is the West Philippine Sea and a straight line to Vietnam, 1200km away in open waters. So, getting swept out will definitely ruin your day . I only take highly skilled students to visit her. Even then, my abort to success ratio is 4:1, 4 aborts to 1 splash.

Related to the OP's question:

* Tying knots on the line to measure depth will only work in calm waters. Ocean diving is generally anything but calm. Goes without saying that you should know how to read and interpret tide and wind conditions for your site before getting wet.

* Test the surface currents and plan your descent well. I do a rough fin test upon reaching the site. Hold the strap and dip the fin in the water and see how strong and fast the fin kicks back. If it straightens out at 90 degrees in a flash, think twice before splashing . Another test is to eyeball the anchor line. Viz is usually awesome at the Beatrice site and you can see the dropped anchor from the boat. If the anchor line (rope) bows below, expect a heart pounding dive. The depth where the rope anchor line bows will tell you if the dive is a go or no go.

* Currents are generally strongest at the surface and diminishes in strength as you go deeper. In the case of the Beatrice site, currents are mild (mild is relative of course) below 15 meters. It turns moderate/strong at 10 meters. That's the vertex where I deploy a DSMB. It becomes wild to raging mad at 6 meters, increasing in severity and intensity as you get closer to the surface. Your buoyancy, trim, propulsion skills and situational awareness are put to its ultimate test. .

* The DSMB I used in the pic is a Halcyon 1m/3.3 ft closed-end on a 30m/100 ft line. Anything bigger will drag you out. I carry a 6ft backup DSMB but will only use it on the surface in a drift emergency. Your DSMB deployment skill has to be very good. Line entanglement with your gear is bad news in a ripping current.

* Spool size matters. I use a spool that's 3 inches in diameter and 2 in. width. The large width allows me to firmly hold one side of the spool with one hand while winding-in the line with the other hand. You'll struggle to avoid wrapping your fingers with the line in a spool with a smaller width.

* Dsmb line length should be at least 30 meters. Longer is warranted depending on your dive depth. In ocean diving, your line length is generally the diagonal of a square in good conditions (mild to moderate currents). So, if you deploy a DSMB from 10 meters, you need 14 meters of line as it swings diagonally at 45 degrees from the vertex. In fast surface currents, you're looking at the diagonal of a rectangle. This means that your DSMB line can be at an angle of 30 degrees or less. At a 10 meter vertex, the DSMB may not reach the surface if your line is too short. In the photo, my DSMB was deployed at 10 meters, the 30 meter/100 ft line played out completely and remained horizontal. It was only when I was at the 3 meter stop that the DSMB broke the surface, this was with 30 meters of line played out.

* The Boat personnel should be briefed that you may surface down current from the DSMB.

* Hanging on the DSMB negatively buoyant is not a good strategy. Stay neutrally buoyant in good horizontal trim throughout the drift and ascent. Break trim as and when you need to but this is more an exception rather than the rule.

Hope this helps. Safe diving.

 

[C Dub]

Here's the real problem... DIR has been known for justifying itself in the past by pure denial. Their claim for a long, long time was that no one got hurt while following DIR guidelines. Mistakes, oversights, whatever and bang: those who got hurt were no longer considered DIR. They maintained their stance that no DIR diver had been hurt. WOw. I know of at least 9 peeps (six from John and 3 from me) that have gotten hurt following Ratio Deco. The defense for that is just more denial. "Oh, there's two...", "They didn't really UNDERSTAND Ratio Deco (nudge, nudge, wink, wink)" and so forth. I don't think I know that many divers bent the 'normal' way and there are far, far more of them out there. Consequently, I'm not going to be shamed into accepting something that sounds hinky and has resulted in a higher incidence of accidents. You call it ignorance, and I call it a reasonable doubt.

I wasn't shaming you. You clearly stated in this thread you don't know RD, and don't want to learn about it.

ig·no·rance
ˈiɡnərəns/
noun
noun: ignorance

1. lack of knowledge or information.

I still love you man!