SAR Winching and Static Electricity
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SAR Winching and Static Electricity
Sorry, maybe this is a very basic question. But is it really the case that those on the ground or in yacht should not touch a highline or winchman before they have earthed due to the risk of static discharge?
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Yes, that is correct.
RAF and RN SAR crews attach a static discharger, or 'zapper snapper' to the hook. (Can't speak for the CG chaps I'm afraid.) It is designed to dangle beneath the empty hook or the winchman thereby providing a route to earth for the static. When using hi-lines, those on the ground or deck should let the hi-line earth before grabbing it if possible.
Some deck crews on RN warships still try to earth a winchman using a long probe (in the same way that cargo hooks are earthed during USLs) but this is not necessary if a zapper snapper is in use, and it certainly not welcomed by the winchman!
On most days, however, the static build-up would be unlikely to injure any one who does touch an unearthed winchman or hook, it is just a bit uncomfortable. That said, we do think carefully before winching on days that lend themslves to the build up of static, for instance in the presence of CBs.
RAF and RN SAR crews attach a static discharger, or 'zapper snapper' to the hook. (Can't speak for the CG chaps I'm afraid.) It is designed to dangle beneath the empty hook or the winchman thereby providing a route to earth for the static. When using hi-lines, those on the ground or deck should let the hi-line earth before grabbing it if possible.
Some deck crews on RN warships still try to earth a winchman using a long probe (in the same way that cargo hooks are earthed during USLs) but this is not necessary if a zapper snapper is in use, and it certainly not welcomed by the winchman!
On most days, however, the static build-up would be unlikely to injure any one who does touch an unearthed winchman or hook, it is just a bit uncomfortable. That said, we do think carefully before winching on days that lend themslves to the build up of static, for instance in the presence of CBs.
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I saw a lad knocked over by the static discharge from a Sea King carrying an APFC at G40 once. The APFC was spinning quite a bit and the lad went forward to steady the load without earthing it in the mistaken belief that since an APFC is rubber on the outside it wouldn't conduct static. Sea Kings did seem to build up quite a lot of static though, the vision of flashes of electricity dancing about the rotor disc was quite common at night up there.
Also the potential static discharge from a Chinook can be anything up to 250,000 volts apparently, at least that what they told me on my LPC course.
Also the potential static discharge from a Chinook can be anything up to 250,000 volts apparently, at least that what they told me on my LPC course.
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Thank you very much for the reply. Should I ever have to call on your services I will remember this post, and I promise not to poke the winchman with a long probe!
Thank you very much for the reply. Should I ever have to call on your services I will remember this post, and I promise not to poke the winchman with a long probe!
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Notwithstanding the correct replies, If I was sitting in a dingy, bobbing around in a force 5 and the strop was in front of my face I'd be tempted to go for it......you never know how long it will be before it comes along again
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Originally Posted by rafloo
Notwithstanding the correct replies, If I was sitting in a dingy, bobbing around in a force 5 and the strop was in front of my face I'd be tempted to go for it......you never know how long it will be before it comes along again
Well now you know better! In any case, if it were just the strop, let it hit the water, discharge, and then use it. But I think the SOP is to have the winchman on the cable, not just the strop.
From experience as a MAOT, it f***ing well hurts if you get a static belt off a strop.
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The static discharge from the Sea King is much worse from USLs than it is from the winching wire. Any RadOp worth his salt will have grounded the static discharger before the hook arrives on the ground and for wet winching the discharger will always touch the water before you could reach the strops. The winchman would be on the wire at this stage anyway. The only real exception is when deck winching. Because the hook could snag on rigging or rails, you would be taking a bit of a risk allowing the wire to ground and this is really the only time you would get a shock. When a high-line is deployed, the RadOp would aim to place the weights at the end on the deck and discharge from the highline is minimal. On most occasions the zap is no more than you would get on a party game toy that you could buy from Maplin's - not nice but certainly not worth worrying about.
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True but I recall a story some years ago...Mid 70's...where a downed wessy 3 crew ditched (as they usually did)...and the sea state was 5 gusting 6. The crew jumped into their liferafts and along came the SAR helo to rescue them...(another Wessy 3 - alarm !!! )
The crewman was first and he grabbed the strop and up he went. The Pilot was next and although the strop was in front of him it hadn't earthed and he missed it.... SAR crew were struggling (remeber the wessy 3 FCS - Alarm again) and eventually they decided to overshoot and go round for another try. Round the circuit and they lost the survivor....Never saw him again. And that is why, if I were in my single seat and the strop was in front of my face I'd grab it and take the belt.
The crewman was first and he grabbed the strop and up he went. The Pilot was next and although the strop was in front of him it hadn't earthed and he missed it.... SAR crew were struggling (remeber the wessy 3 FCS - Alarm again) and eventually they decided to overshoot and go round for another try. Round the circuit and they lost the survivor....Never saw him again. And that is why, if I were in my single seat and the strop was in front of my face I'd grab it and take the belt.
Gentleman Aviator
A less serious anecdote ..... many years ago on the mighty Wessex, I was doing some Stage 1 (famil) training at STANTA with some U/T Ruperts from RMAS. The Officer Cadet "Hooker" during the USL phase was, I have to admit, the smartest I've ever seen ..... as was the highly bulled brass earthing probe he carried in his right hand ...
Clearly inadequately briefed (or deviously briefed by his SNCOs!) Off Cdt Rupert was unfortunately holding the earthing spike (which should have been in the ground) in his left hand .......
....and Lo, the USL was duly earthed .......
Clearly inadequately briefed (or deviously briefed by his SNCOs!) Off Cdt Rupert was unfortunately holding the earthing spike (which should have been in the ground) in his left hand .......
....and Lo, the USL was duly earthed .......
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Originally Posted by teeteringhead
A less serious anecdote ..... many years ago on the mighty Wessex, I was doing some Stage 1 (famil) training at STANTA with some U/T Ruperts from RMAS. The Officer Cadet "Hooker" during the USL phase was, I have to admit, the smartest I've ever seen ..... as was the highly bulled brass earthing probe he carried in his right hand ...
Clearly inadequately briefed (or deviously briefed by his SNCOs!) Off Cdt Rupert was unfortunately holding the earthing spike (which should have been in the ground) in his left hand .......
....and Lo, the USL was duly earthed .......
Clearly inadequately briefed (or deviously briefed by his SNCOs!) Off Cdt Rupert was unfortunately holding the earthing spike (which should have been in the ground) in his left hand .......
....and Lo, the USL was duly earthed .......
The other trick I heard of people doing was to tell the inexperienced army RM's to put the earthing chain in their pocket to stop it catching on the PSP, much zapping to delicate areas has resulted from that one.
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I remember when I was a "wet behind the ears" SAC on the visiting aircraft section at Lossie We were tasked to assist in hooking up the USL on a sea king whilst trying to attach the load I was grazed on the shoulder by the Heli hook and it knocked Me clean over the said shoulder was numb for days, a lesson never forgotten.
In the 60s, Farnborough became interested in this area and sent a team down to investigate it. They embarked on a Marine Craft pinnace with a set of measuring kit and we went out from Thorney to provide the 'guinea-pigs'. We did about a dozen 'decks' and each time I was earthed by the chap on the boat. We later heard that the readings were variable but several were 'off-scale' at >175,000 volts!!! but the ampereage was quite low
A couple of years later, wet winch training in Holyhead harbour, I was breathing quite heavily, mouth open and as I touched down on the boat deck, the earthing discharged through my tooth fillings
The singed, burning taste remained for some time
A couple of years later, wet winch training in Holyhead harbour, I was breathing quite heavily, mouth open and as I touched down on the boat deck, the earthing discharged through my tooth fillings
The singed, burning taste remained for some time
