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RE: [PSUBS-MAILIST] Once again



George,

I am very aware of the diving practices in Florida and many other areas around the world especially drift diving and real wreck diving.  Years ago there was a Hobie Cat going down a line of drift buoys off of Boynton Beach, FL, yanking them to the surface.  I was one of the instructors leading a group on the bottom that was snatched…not a funny situation!

 

You have to look at it from a different perspective then from an ROV or a diver.  A line ingested into the prop of a submersible could mean you are stranded on the bottom.  Current commercial and research submersibles can often drop an entangled propulsive unit if entangled but in most PSUBS this isn’t practical.  Movement about a wreck or a significant coral reef in a submersible towing a buoy is an accident waiting to happen.  Your all around situational awareness is greatly reduced as compared to a diver (who does often get entangled, either himself or in a real wreck, not a put down wreck that is stripped clean).  ROVs also get fouled but you can shear the umbilical at the ROV (the ROV doesn’t always make it back to the surface though) or some times pull ROV to the surface with the fouled object.  PSUBS do not have mush reserve buoyancy with dropping their drop weight and this may still not be enough to clear a foul.  Without towing anything, entanglement can be a big issue for submersibles.  Two prime examples are the Johnson Sea-Link submersible disaster years ago where Ed Link’s son was lost after the sub became entangled in I believe it was the Kendrick off of Key West.  This incident gave a big push to having an ROV or another submersible on site when diving around structures.  The other incident was the recent Russian incident in the North Pacific where savior was only accomplished at the last moment by equipment flown in from ½-way around the world.

 

A submersible that bottoms-out and reels out and recovers a GPS buoy to the surface introduces added complications to the sub…cable reel and control, data transfer through a submerged slip ring on the reel, additional hull penetration(s) for the data and reel power and control, space inside the sub to accommodate the added equipment, and another appendage to get fouled on.  It isn’t as simple as you suggest.

Respectfully,

Jay K. Jeffries

Andros Is., Bahamas

 


From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of George H. Slaterpryce III
Sent: Saturday, April 08, 2006 10:55 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Once again

 

You have to also take into consideration that I build Robotic underwater vehicles. so I have a slightly different safety outlook. But towing things underwater is pretty common here in florida, you can't dive without a dive flag (also known as a Jetski target). Every diver or DM drags one behind them. It's just what is.

 

Also the idea is the buoy wouldn't be "Towed" so much as the submersible would stop and take a reading at depth and then continue on it's course. I just don't want to have to surface the vehicle to get a fix.

 

as to the KISS, this is VERY keep it simple. It's one simple mechanical function of releasing a buoy, taking a reading letting the onboard computer do a calculation and then retrieving the buoy and letting the vehicle adjust it's course from there.

 

George H. Slaterpryce III
www.captovis.com