SCUBA in Commercial Diving

[DCBC]

...I have a job pending that's going to require me to use a Pneumatic cut-off wheel. I've never used one underwater, is there inherent dangers with using one underwater? I'll be cutting a chain that is wedged between a boats "wheel" and the "nozzle", it was sucked in at low water while docking.

Mark, there's always a risk when cutting chain under tension. There aren't any safety considerations underwater that you wouldn't take if you were doing the same job topside. Be careful that you're safe. Good luck.

 

[hammerb_99]

DCBC, Thank you for your prompt and courteous reply. The chain is not under tension so that should not be an issue. I'm just trying to play the job out in my mind first, i.e.: low to zero vis., lots of air bubbles from the tool itself and lastly trying to do no more damage (specifically in regards to the prop.) then has been possibly caused already.
Thank you again.
I'm going to try to take a before and after photo of the job.

 

[sealark]

I did that exact chain job 10 years ago. One link stoped the engine caught between the ss prop and nozzle. First thing I did was hook a come along onto the link and crank it tight. Then cut the chain flush off at the prop. Hoping it would come out from the come along pull. No luck. Wound up cutting into bottom of link into the link and weel tip. Finally kaboom the link came out from the come along strain and cutting the wheel and link. Total time in scuba about 5 hours. Most time was rigging compressor for cutting. And come along in zero vis. Escambia river Pensacola Fl. Air temp 35 degrees middle Feb. They never call in the summer. Loved it... good luck.

 

[MScorpa]

Greetings,
I'm new to this forum and looking for some technical advice. I just read most of the messages in this thread and I'm well aware of most peoples feelings regarding "commercial" work with SCUBA. I would never sell myself as a "commercial" diver but I do however perform dive work around our local docks, mainly for the commercial fishing vessels. I have a job pending that's going to require me to use a Pneumatic cut-off wheel. I've never used one underwater, is there inherent dangers with using one underwater? I'll be cutting a chain that is wedged between a boats "wheel" and the "nozzle", it was sucked in at low water while docking.
Thanks, and stay safe.
Mark

I'm assuming the depth will be relatively shallow so it should work without problem, especially if you have a compressor with decent pressure output. The obvious danger would be cutting yourself so keep the wheel well away from your hands. Make sure the boat engine is locked/tagged. When you are finished blow all the water out of the tool and oil it heavily so it doesn't seize up.

 

[hammerb_99]

Thanks Sealark &MScorpa,
The depth is approximately 8 feet, so it is a shallow dive. I had the come-a-long idea in mind; I just wasn't sure as to whether or not I'd gain anything from it. I attempted to beat it out with an 8 pd. maul to no avail, (didn't move in the least.) I had the same feeling as to cutting the chain flush with the prop. then either beat the remaining piece out with a maul and spike or make a "relief" cut into the remaining piece (which sounds a lot like what Sealark eluded to, I'm not about re-inventing the wheel.) As for cleaning any and all of my tools such as my knives, lights, hand tools etc. I try my best but find that the salt water ends up winning in the end. However some of that could be my own fault, I usually use a “harbor freight” type tool for this work. I really appreciate the input. I'm scheduled to do the job next Wednesday, so hopefully I can post my outcome then.
Thanks, Mark

 

[sealark]

Put the come along on as tight as you can. That way as you grind it will have tension on it. If it moves a small amount tighten it and smack it with hammer. Then if no move grind some more. I ground on the wheel side. Of the link as it was more open than on the nozzle side. I still use the die grinder today I used on many underwater jobs. Like said oil it after every use heavily and soak the bearing end good.

 

[muddiver]

Soaking your tools in anti-freeze on the job when they're not in the water helps a lot as well. Most anti-freeze has rust inhibitors and will displace the water as well.

 

[Bombay High]

I like using the anti freeze before blowing with compressed air, as the compressed air drives the salt water deeper into bearings and other components, where it otherwise might not have penetrated.

 

[hammerb_99]

Thanks for all the info.
I've soaked my cutoff wheel in oil and seems to be doing fine. I will try the anti freeze next time around.
The job took about 2 1/2 hrs of underwater time, about 4 hrs. total. Vis. wasn't very good so I wasn't able to get any good pics. I would have grossly underestimated the time for the job if it wasn't for the heads up. The hardest part was getting and staying on a cut. I would stop periodically to check my progress and getting the wheel spinning and back in line on the cut was a little harder then I thought. Much easier work topside!
Stay safe,
Mark