Wednesday, January 19, 2011
THE NAIVE SAILOR , TURNBUCKLES AND BOTTLE SCREWS -- CAPT AJIT VADAKAYIL
I plan to start a NAIVE SAILOR SERIES.
( if you read my blog on SNOW SHOVELLING AND BACK ACHE -- i have included a piece on rat guards--why it will fall off for the next 500 years )
the idea is NOT to be sarcastic or to patronise-- but to save lives.
People who have sailed with Capt Vadakayil will vouch, that he is a HUGE champion of the poor mushroomed sailor at sea.
(Digression: A mushroom is always in the dark and fed with lot of crap.)
We at sea are ruled by powers ashore who secured their shore chairs , by tilted playing fields and NOT merit, and their ability to compromise and be hypocrites.
So when we have a company seminar ashore , and the sailing party comes in contact with ashore party, there is so much of EGO hassles , lack of respect and immaturity.
This has to be seen to be believed.
This can never ever happen in some other professional strain , like say a world seminar of brain surgeons. An administrator ex-surgeon , who has not lifted the scalpel for 30 years , will never ever try to brow-beat or bulldoze a surgeon who does a brain operation job daily, with 100% success. This happens only with sailors.
THIS POST IS ABOUT TURN BUCKLES AND BOTTLE SCREWS--
Once i attended a company seminar in a 7 star hotel , and the Dutch Technical director was telling a group of 200 Masters, Chief officers and Chief Engineers , about how a container ship lost their containers as the lashings were lose.
And then his cure and prevention rolled into one moronic solution was to keep checking and tightening the container lashing turnbuckles every 12 hours. He went on and on--literally frothing from the mouth--
When he had got all in agreement , I got up , a cordless mike was thrust into my hand-- as when Capt Vadakayil speaks you get nothing but the NAKED TRUTH-- it must be loud and clear.
i said - " If a container turnbuckle is tightened it remains there, without loosening itself for the next 1000 years" .
there was shocked silence -- i could see the MD had broken into a wry smile as he knew , that Vadakayil would take it to the logical bitter end.
It was time to lie back and enjoy, what is inevitable.
here is a gist of what i told him--the blow by blow account may be embarrassing to read--
what is a nut and a bolt? how does the nut remain in position after tightening?
It is about elasticity of the steel bolt. This is why washer rings are used , in the absence of CHECK NUTS.
This is why the Japanese Kosaka Deepwell Pumps came a cropper. Their impeller was secured by stainless steel bolts and nuts. This usually worked lose with disastrous effects.
The Framo deepwell pump, understood this. They used nylon single use bolts and nylon washers. The impeller will NOT work lose.
So this means if if tighten a bottle screw, what you do is to bring two ends closer. Like when you tie your pyjamas with a single overhand knot.
Now you need to hold it in position. On your pyjama it will be another overhand knot to make a reef knot ( a granny knot by land lubbers ).. On a bottle screw this boils down to TIGHTENING THE CHECK NUT -- or inserting a spike so that it will not unwind.
Another option would be to introduce friction on the worms by degreasing and putting a tough layer of paint. This is why an old rusted nut and bolt remains tight despite all vibration.
So, when you tighten a nut on a blot, the bolt elongates and keeps the nut in place. On a water tight door with dogs , the supple packing pushed the door outwards like a spring and holds the dogs in place. If the packing is hard on main decks you must change the packing, as it is this suppleness which keeps the door in place.
A CHECK NUT IS SELF TIGHTENING IN VIBRATION. IT IS NOTHING BUT A SIMILAR NUT PUT OPPOSITE (OR ULTA AS WE INDIANS TERM IT.)
So next time you go on board , check your anchor lashing bottle screw, If it does not have a check nut replace it.
On chemical tankers we do NOT trust any nut and bolt system , unless it has a check nut. When i go for delivery of chemical tankers i insist that steam coil clamp nuts and bolts must have a check nut. Or very soon they will work loose and damage the sump impeller.
On brand new Japanese ships , they provide small stainless steel silver bottle screws , to secure the cabin chairs in rolling. These worms/ threads do NOT have any friction value and with every roll they loosen. After the first bad weather, all these fancy useless bottle screws with be lying here and there in pieces.
On my chemical tanker--i do NOT allow greasing of butter worth port butterfly nuts . When my ship carries Sulphuric acid or MEG FG, and if the tank cleaning port does not have check nuts , i get a light coat of epoxy paint applied on the threads AFTER tightening it. Only STUPID chemical chief officers use Silicon gun.
LESSON: So, what makes the nut remain there after tightening? the FRICTION afforded by the elastic pull of the elongated steel bolt , and the compressed soft metal washer. If not, use another nut reverse to make a check nut, which is self tightening in vibrations .
check nut with lever can be tightened manually or with a small hammer.
CAPT AJIT VADAKAYIL ( 28 years in command )