Tuesday, 6 August 2013

Clover and Fazeley demonstrate thumblining

Thursday 18th July 2013

It was 0630 when we crept past Clover and Fazeley, the working pair of Joshers which came past while we were eating in the Crystal Palace in Berkhamsted the previous night.

It was only when looking back at the photos that I saw that at least one of the crew was up and about.

We started down the locks on our own. It's always a bit frustrating to arrive at a lock to find that, not only is it against you, but also that the far gates are open. Oh well. Turn the lock and prepare to go down. But up cycles Sarah who says that the pair are on their way and could we let them go first?

Here they come past us, looking wonderfully laden.

I saw them through many of the next locks, and witnessed them using "thumblining", a technique I'd heard of but not seen before. The motor enters the lock on the left, while the butty lines up to come alongside.

The act of displacing a lot of water from the lock helps to bring the butty to a gentle stop. As it comes past the top gate the steerer lassos a small pin by the collar. I'd not noticed these miniature "bollards" before. I expect there's a proper name for them.

As the lock begins to empty, the crew set up the thumblines. These are thin ropes attached, in the butty's case, to the looby on the mast and running to the handrail on the bottom gate. Here the line is attached in a way which holds as long as the line is behind the gate, but which releases when the boat, and hence the line, comes forward of the gate.

This shows the line attached to the looby.

When the lock is empty the gates are opened and the motor starts to leave the lock. This is where the line from the butty comes into its own (as I understand it). The movement of the motor out of the lock causes a rush of water to flow in to replace that which had previously been displaced. This tends to push the butty backwards, which would, unless restrained, damage the rudder on the cill or the top gates. The line attached to the handrail does this restraining job.

At a different lock I tried to photograph the moment of release of the line from the handrail - this is as close as I got. The butty, having released the short line to the mini-bollard (name please?) by the top gate quoin, now moves forward under tow again from the motor. This brings the line to a position where the tension on the "knot" is released, and the line simply falls away to be grabbed by the steerer as he passes.

And that's it. The gates are left to us to close.

I didn't really notice how the line from the motor to the handrail operated. I assume it worked in a similar way to the butty's in that it prevented the motor's rudder hitting anything when the bottom gates were opened.

The whole procedure was very slick. The lines were fixed at precisely the right length: too short and the boats would be held too close to the bottom gates, preventing them from opening; too long and the boats would crash against the cill.

Now could someone please explain why, on a broad canal, pairs don't navigate breasted up to each other?


Leo No2 said...

Thumbing - you might enjoy this of the pair thumb lining. Takennimunderstand my amine Askin.


Breasted up or singled out - I think it is really just to do with the distance between locks - more effort for the motor when breasted up but may be worth asking Ray Oakhill http://nbstronghold.blogspot.co.uk/ who volunteers for the Narrowboat Trust.


Leo No2 said...

Doody got the incorrect link (but you may have enjoyed it anyway). This is the thumb lining one http://www.youtube.c...h?v=w60O-21PYzs

Leo No2 said...

And finally I might get it right - thumb lining at about 7 mins.


So sorry.

Brian and Diana on NB Harnser http://nbharnser.blogspot.com said...

Here is I bit I shot of it being done last year at Bucky


Halfie said...

Kathryn, thank you. That's a superb bit of filming at Watford, and it shows much more than my still photos.

Brian, thank you too.

Steve Parkin said...

I have also got a You Tube video on thumb lining although I called it "Automatically opening canal lock gates" for the uninitiated. It is a single boat operating single handed.