Bounce diving and stuck anchors

[m and m]

Hi there,
I work on a charter dive boat. We dive over rock reef which means that the anchor often gets stuck. So after guiding a dive down to 27 meters or so to with in 5 mins of no NDL i find my self on deck with an anchor that won't move. So skipper says.. "can you get the anchor free for me?" so with bearly 15 min surface time a gear up and roll over for a solo decent to 27 meters to find a anchor and drag it off a snag.

Now, its not that i am uncomfortable with the solo dive to get the anchor but i do feel fatiuged after the 10 - 15 min dive for the anchor and have had other divers say ' those bounce dives ain' t good for you!'

Has any one else had any similar experiences or advice on bounce diving?

Mat

 

[Rick Inman]

Riding your NDL, then bounce diving, exerting at depth on the bounce, feeling fatigued... I think you're answering your own question.

Tell the Skipper you'll keep an eye on the helm while he goes down (or someone who hasn't been diving).

 

[ScubaTim]

Can someone please explain the term "bounce diving" I have read/heard about it but not sure I 100% understand what it is. Sorry to interupt your thread.

 

[wedivebc]

Can someone please explain the term "bounce diving" I have read/heard about it but not sure I 100% understand what it is. Sorry to interupt your thread.

A bounce dive is a short duration deep dive usually with little or no safety/decompression stops. Bounce dives alone have statistically proven to be unhealthy and like Rick mentioned above riding the NDL and then bouncing is not a great idea, but it is done all the time as this is a common situation :06:

 

[terrasmak]

I think i would check the achor before the ascent if possible

 

[m and m]

I think i would check the achor before the ascent if possible

yeah, but how would you tell the skipper to drive up on the anchor to so that you have some slack to free it?

i guess you could send a SMB up with a slate attached and hope the skippper aint snoozing!

 

[gregor1234]

Tell the skipper to use a trip line on the anchor.

A trip line is a thin line secured to the lowest point on the anchor. If the anchor gets stuck, you drive up to the anchor leaving slack in the main anchor rode, then haul on the trip line. Because the trip line is attached to the bottom of the anchor, hauling on the trip line "backs" the anchor out.

 

[cobaltblue]

Trip line is the best idea! Keeps you from having to go back in. Saved me more than once.

 

[Charlie99]

Another possible solution is to bring along a sausage and reel, then take lots of time doing your ascent and stops.

If you take your time coming back up, it's not a bounce dive -- just another dive, but with a short SI.

One theory about why bounce dives cause problems is that bubbles that are forming in your veins get compressed as you descend, making the bubbles small enough that they aren't filtered out and stopped in the lungs. The bubbles then enter the arterial side, including places like the brain and spinal cord. If you then immediately ascend, the bubbles grow in size, interfering with circulation and causing damage.

If you do go back down while bubbling on the venous side (DAN Europe studies show that venous bubbling after repetitive dives is more common than not), then you need to stay down long enough that the bubbles passed over to the arterial side get reduced in size by offgassing.

Personally, I would take at least 10 minutes to surface, with 15 being better.

Obviously, not doing the dive and instead using trip lines or another diver is even better.

 

[keyshunter]

First, since the vessel and its passengers is his responsibility, and his alone, YOU don't tell the skipper, HE tells you. However, if you believe that his order will jeapordize your safety, you have every right to refuse.
Second, you really don't want to make a habit of doing bounces to 27 meters after leading a full dive to that depth.
Third, depending upon the size of the boat (and the anchor), unless the current is really screaming it is not too much trouble to move the anchor, but you had better know what you are doing. I have led many, many dives from boats up to 45 feet. I always check the security of the anchor on the way down, and its position on the way back, often moving it for an easier "pull".
And fourth, there are several ways to rig an anchor for a release. The trip line was mentioned, and another is with a breakaway line. Once the breakaway is parted, the fouled anchor is pulled from the head of the anchor and not the stock.