It really doesn’t matter where you are, on the canal system, there is a golden rule about speed. ‘If you are breaking wash you ARE going to fast’. It really isn’t a case of ‘I think I am going at the right speed’. Breaking wash damages the bank. You must slow down. I have underlined must for emphasis, not should or could but MUST. No if’s ands or buts. MUST.
Of course if you don't want to slow down you could always take the other option and catch a bus. The canal, anywhere, doesn’t need speeders.
The speed at which wash breaks varies with the width of the canal, so there is a need to be constantly aware especially on the Oxford and other narrow canals.
If you don't know how fast you are going the solution is simple look behind you. Unless you see your wash you wont know if it’s breaking.
I see on the Thames there are notices at all/most the locks saying,
WATCH YOUR WASH