Side current at Hatton?

[p6rob]

Had a bit of a hairy experience yesterday at one of the upper locks at Hatton. Can't remember which lock it was, possibly 40 or 41, it was one of the three just below the C&RT Offices.

As I was coming up, a cross strapped pair were coming down, so, I pulled over to the towpath and stepped off while there was still a small amount of forward momentum. However, as I was attempting to wrap the centre line around the bollard, my boat was pulling further away from the towpath. Luckily a family of cyclists came by and helped pull the boat over, just before I'd have had to let go of the bitter end. It was quite worrying as my 8yr old son was on board and, as the boat would have drifted in to the side pond, retrieving son and boat could have been interesting.

 

While manoeuvring I hadn't been aware of any side current, or cross wind or anything, however once the power was off, something seemed to take an instant hold of the boat and yank it perpendicular from the towpath.

The tied pair of boats seemed to suffer getting out and across too, whether that was because of my antics, or not, I'm not sure. The rest of the flight had been no problem at all, tiring, but right up until, then excitement free.

 

Is there normally a strong current there or was it something to do with the uphill lock emptying? Last time I did the Hatton flight was around January, going downgate, I remember the whole flight being a bit hairy but that was an extremely wet and windy day.

 

In the end it took about 5 1/2 hours from bottom to top, not sure if that's a good time but I did feel like blood sugars were going dangerously low from about lock 37. I told my son I thought I was about to have a hypo and he went and without being asked, he made me a sandwich. First time he's done that for me. He's a good kid , and to think I almost got him washed away.

 

Rob

 

[pearley]

Could it have been turbulence from the lock that the pair were exiting having just been emptied?

[David Mack]

It was quite worrying as my 8yr old son was on board and, as the boat would have drifted in to the side pond, retrieving son and boat could have been interesting.

When I found myself in a similar situation, only my son was 10 weeks old at the time, I made the foolish decision to jump from the lockside onto the departing boat. A taxi ride to A&E followed, and I spent the rest of the 3 week trip boating with a pot on my leg!

[FadeToScarlet]

Isn't that where the back pumping comes in? By the pond with the dragonfly, opposite the offices?

[p6rob]

Could it have been turbulence from the lock that the pair were exiting having just been emptied?

I do wonder if that was the cause, it would make sense, but it didn't feel like fighting a current as I pulled over. Plus the boat was pulled broadside at 90 degrees to the lock/towpath. Would outflow from the lock push the boat backwards rather than sideways?

 

Isn't that where the back pumping comes in? By the pond with the dragonfly, opposite the offices?

I think it was one or two locks further down from the dragonfly pond.

 

It's tempting to go and have an experiment. If only there were more hours in the day.

[nicknorman]

Almost certainly eddy current from the lock emptying. Knowle locks are really bad for that (deeper, and bigger paddles) but Hatton does it too to a lesser extent. If you think of the energy stored in a large volume of water at say 8', being released over a minute or two, it is quite a lot. This energy is eventually dissipated as friction due to the water's viscosity, but that is a relatively slow process and can take a few minutes to fully die down, made worse by the relatively big locks and short pounds.

 

Think of it like vortex wake turbulence from a plane landing or taking off in front of you - you are not allowed into the same bit of air for a couple of minutes or more (depending on the relative sizes of the planes) to allow the vortex to disperse, which takes a lot longer than you might at first think.

Would outflow from the lock push the boat backwards rather than sideways?

 

But the energy has to go somewhere after the initial outrush, so it forms vortices (ie goes round in circles). Water likes to form vortices, think bath plug-hole!

[Neil2]

One of the pounds at the top of the Hatton flight can get very low indeed and I recall losing rudder control once. It was weird, I came out of the lock in parallel with another boat, he turned into the lock and I just careered straight on, ending up grounded. Our boat was certainly lower in draught than the other and I concluded there just wasn't enough water to keep control of the boat. Maybe a combination of low water and a strong current could have created your difficulty.

 

I'm afraid 3 - 3 1/2 hours is a good time for Hatton but you do seem to have the makings of a good crew!

[IanM]

 

I'm afraid 3 - 3 1/2 hours is a good time for Hatton but you do seem to have the makings of a good crew!

 

Five of us (1 steering, 4 on the locks) once did Hatton uphill in 1 hour 35 minutes

[Graham and Jo]

We lost control on one of the locks near the top - I think the top lock itself. We had two boats side by side leaving the lower lock but not tied together, for no reason they split apart and we both had to stop quickly before crashing into the opposite sides of the entrance to the top lock.

 

Cheers Graham

Edited November 17, 2014 by Graham and Jo

[Tim Lewis]

Did Hatton a few weeks ago, don't remenber a side curremt though.

 

For anyone interested the following is a link to a time lapse video of the transit of the flight:

 

http://www.youtube.com/watch?v=YX5mi-ckrcA

 

Tim

[NickF]

The worst place I have seen this happen is the bottom but one pound of Johnson's Hillock. The pound is nearly round and the lock above empties into it at a slight angle so all the water in the pound starts going round in circles. To cross it was a bit like going round a roundabout as you have to go round the edge with the flow, you have no choice!

 

I could have waited I suppose but once you have realised what is going to happen it's not a problem.

 

https://www.google.co.uk/maps/place/Wigan/@53.6820353,-2.620939,159m/data=!3m1!1e3!4m2!3m1!1s0x487b04345517a4d3:0x5702a66b03f2d953