Towing connections - a query.

ddraigmor
17th February 2008, 12:11
This might sound daft but bear with me.

On the deep sea tugs I was on we towed with 550m (5 1/4 " circ) and 850m (4 3/4" circ) wire plus 11 1/2 " circ double nylon hawsers (towing spring). The connection sequence (from tow to tug) was usually chain bridle to wire pennant to towing spring to main tow wire.

On AHTS, when we towed rigs, the system was about 1000m of 56mm circ towing wire which was connected (tow to tug) via a bridle (chain or wire) to a pennant to the main towing wire - no spring was used.

Am I right in thinking the additional length of the main tow wire acted as a spring due to its weight and the catenary?

Also, what did other tugs use - OTS, United? Were nylon springs used or was that a Dutch thing?

Just a query!

Jonty

gdynia
17th February 2008, 12:21
Jonty

We are using nylon springs out here at the moment Barge Towing but are the stretcher type 3 in 1.

RayJordandpo
17th February 2008, 13:01
Jonty,
'Lloydsman' had two towing winches. If my memory serves me correctly, one was 64 mm (8") the other being 81mm (9") The circumference in inches equals the diameter in milimetres,that's right isn't it? We maintained that when using chain, no nylon spring was required as the chain acted as a spring in itself, although Noble Denton often differed in that opinion. All other times we used nylon springs. When Nobles where the consultants for the clients they insisted on us using a "fuse" wire which was an additional wire with a 10% less breaking strain than the main towing wire. It didn't always work. I have seen the main winch wire part and the so called "fuse' wire still intact.
Ray Jordan

JimC
17th February 2008, 14:13
Yes! the long tow wire and subsequent catenery act as a spring (shock absorber) during ocean tows. If some of you remember: the advice on using your ship's 'Insurance Wire' for towing, recommended incorporating an anchor in the middle of the towing system for that purpose. The use of a nylon towing spring was prevelant in short tow-line operation and was incorporated into rig towing by some companies in the 1970's. I remember Noble Denton's recommendations and while agreeing with them did not, as an Insurance Surveyor, insist on the nylon bit regardless. I believed then and still do, that the circumstances dictate the type of gear selected but just so long as a proper risk assesment is carried out before hand.

Jim C.

roddy
17th February 2008, 14:18
The deployment and subsequent recovery of springs/stretchers, in any length longer than the afterdeck was/is serious hazzle, when carried out at sea, requiring crew skills and numbers, both of which are now seriously depleted. The double spring, favoured by the Dutch was, I believe a serious attempt to get maximum elasticity in minimum length, for ease of handling.
Personal belief is that the spring only really comes into play, when shortened up, in shallow water or harbour approaches. sea to sea tows as with most rig moves, are usually carried out on long gear with sufficient catenary in the wire to cope with any "snatching".
It is really a matter of personal preference, previous experience, and the nature of the tow, although as Ray rightly recalls we were often dictated to by the insurance surveyor who worked from a fairly rigid script.

Roddy

jim barnes
17th February 2008, 14:29
While with OTS if my memory serves me right we never used a chain? for long tow jobs it was always a nylone rope. in the Pacific they where always full of fishing hooks due to the Japanese fishing boats using long lines of hooks, nasty things

RayJordandpo
17th February 2008, 15:04
Roddy
I believe you have summed it up spot on. Long springs were (are?) a pain in the a...

RayJordandpo
17th February 2008, 17:08
My first trip to sea in a tug was the old 'Serviceman' 1964. The trip before I joined she went to Ferrol, Spain to tow a ship back to the UK. It was the first time UTC had used nylon or synthetic towing springs (previously they used manilla) whilst towing the vessel out of the harbour the spring parted and took a young deckie's head clean off his shoulders, he'd only been married a few months. Apparently when it parted it sounded like a rifle crack. No one was really aware at that time that nylon gives no real warning when about to break unlike the "creaking" of manilla, sizal etc. We were all (and still are) very alert where synthetic ropes under strain are concerned.
Ray Jordan

ddraigmor
17th February 2008, 18:16
The springs differed on both the tugs I was on - on the 'Afon Goch' it was natural fibre - on the 'Afon Wen', synthetic. Roddy - we didn't have big crews! There were four AB's and a Mate!

I never saw any problems in using the spring myself - apart from its weight after a long dee sea tow. Then it was hard to handle. However, I seem to recall that both the tugs deployed the springs at all times - so possibly was a throwback from their gear, Dutch training and Surveyor's insistance.

Only saw a wire go once Ray. That was anchor cranking in the North Sea with a Bruce. It got up to the tail gate - no shark's jaws in them days, just the old stuff - and the bosun shouted out for everyone to hit the deck, which we did behind the rails. There was a single and very audible creak and then a sound like a gunshot. The free end of the wire whipped inboard and demolished a small skip we had stowed right for'ad.

Afterwards, he just said he had taken a look at it and it didn't seem right to him. Good job too - there were three of us waiting to stopper it off.....

Ta for the help and the background all,. Once again, the site has proven its worth!

Jonty

Andrew Craig-Bennett
1st March 2010, 12:51
This might sound daft but bear with me.

On the deep sea tugs I was on we towed with 550m (5 1/4 " circ) and 850m (4 3/4" circ) wire plus 11 1/2 " circ double nylon hawsers (towing spring). The connection sequence (from tow to tug) was usually chain bridle to wire pennant to towing spring to main tow wire.

On AHTS, when we towed rigs, the system was about 1000m of 56mm circ towing wire which was connected (tow to tug) via a bridle (chain or wire) to a pennant to the main towing wire - no spring was used.

Am I right in thinking the additional length of the main tow wire acted as a spring due to its weight and the catenary?

Also, what did other tugs use - OTS, United? Were nylon springs used or was that a Dutch thing?

Just a query!

Jonty

The towing connection that you describe with the towing chain (ideally through the tow's Panama) to wire pennant to double nylon spring to tug's main winch wire was certainly standard for the large salvage tugs owned by:

Smit
Bugsier
Muller
Luzon Stevedoring
Nippon Salvage
and some others in the Seventies.

Can't speak for others as I did not have to do with them.

The towing chain was high tensile not regular anchor chain and was tested. If the tow did not have a Smit bracket, as they usually didn't (let alone an AKD stopper!) it terminated in a number of tails which were belayed round anything that looked convincing, such as bollards, a mast house or two or even the acomodation block. It is amazing how badly welded to the deck bollards can be!

todd
1st March 2010, 14:57
Towing gear varies greatly from boat to boat eg:the older boats invariably tow on rope with a short wire or chain bridle due to the fact the recovery was made manually by a capstan on the aft deck or by messenger from the fore anchor winch.(coiling down a wire is not an option even in the calmest of weather.)
On the modern tugs with an open aft deck & towing winches etc the opposite can be used eg: short chain bridle,a nylon spring and then a wire to your winch. On one boat I was on we used an 10" nylon tripled up as a spring so as it would clear the stern when the inboard end was almost to the winch
and allow the deck crew access to the bridle chains. On others we used the ships anchor chains as the bridle/spring which prove the easiest of all the connections.(photos attached)

Jim

cueball44
5th March 2010, 17:44
when on the yorkshireman in 73 i was useing a new drilled hook attached to the combination rope for anchor snatching,i hooked up standing on the tray when we started to haul the anchor cable in the hook snapped and flew just passed my head the captain jumped off the bridge and asked if i was ok,shakeing i stuttered yes! WE NEVER USED A DRILLED HOOK AGAIN!! w.hawker.