Tuesday, April 27, 2021

Slowing down to speed up

It was fun watching that ship stuck in the Suez canal wasn't it?  I expect that other canal boaters were like me and Kath shouting "Stand on the back or on the floating side and rock the boat." We could teach 'em a thing or two.  I don't suppose they had a shaft or pole long enough to give her a push.  

Anyhow I watched an interesting video about how she got stuck and it was interesting to see how the physics of it applies equally to our little boats and that great monster. In a narrow or shallow canal , the water has a job getting out of the way of the boat.  We've all been there, or anybody who has been down the Slough Arm or bits of the South Oxford has at any rate.  In order to get out of the way of the boat, the water has to speed up and when the bottom or side of the boat is near to the bottom or edge of the canal, that speeding up of the water reduces the pressure (something to do with a Mr Bernoulli if I recall correctly , but as it's been over fifty years since I was an engineering student, I may well not) and the boat get sucked down or into the bank accordingly, thus making matters worse.  So if you feel it starting to happen the best thing to do is to slow down and the suction lessens.  In the end you'll make better progress.

Boating is often counter intuitive ain't it?  Push the tiller right to go left and all that.  How often have we seen novice boaters (bless 'em - we were all novices once) come too fast round a corner, see another boat coming and slam on the (practically non- existing) brakes, thus losing all steering.  It took me a while to have the confidence to slam on the power to get more steering to avoid a fast approaching obstacle, but it works.

In other news, I came across this somewhat dilapidated gate last Friday:

In need of a bit of TLC, but it won't get it.  I don't suppose it's been closed for many a long year.  This is what all our lock gates might be like if the canals weren't rescued by volunteers up to their necks in mud in the middle of the last century. (In my mind I hear people saying it looks no worse than some of the locks on the Oxford).  Actually this one isn't on a canal, it's at the exit of a fen drain into the Great Ouse. See below, you can see a tupperware boat on the Ouse in the distance).

The drain cuts through the RSPB reserve at Fen Drayton near Cambridge.  The reserve is worth a look if you're out that way.  Lots of water fowl to look at and some good walks. Oyster catchers, egrets (of which Edith Piaf nearly had none) and wotnot all easy to see.  A pair of bino's helps of course.

I must get back out to Herbie soon and find out why the engine wouldn't start last week.  I don't suppose I could have turned off the diesel cock when we left her last autumn could I?  I think I might be grasping at straws there.

Toodle pip.


KevinTOO said...

Hi Neil, Here's something to test your skills on... Fun - Can you steer a container ship through the Suez Canal? link > https://cnn.it/2PLuLwo
Good luck :)

Herbie Neil said...

Kevin - I had a go and managed it at the second attempt, but I was going slow and "slaloming" all over the place. Very reminiscent of steering one of CRT's hydraulic steering work boats which I never really got the hang of.


Vallypee said...

Ah yes, we did the same thing too, Neil. About the Suez thing. Having experienced being ‘sucked’ into the shallow waters of a bank more than once, it was interesting to read about the physics of how the Ever thingy got stuck. In this case, size didn’t help but in principle, it’s the same for all boats. All relative innit? I hope Herbie is fine!