On my regular walk along the Ouse, I recently noticed a largeish sea-going boat suddenly slam on the power as soon as it had rounded the bend after the houseboats by Fulford Ings - despite the faded "six knots" sign.

It created a huge wash, which pounded against the banks, where birds and other creatures may be nesting above or below the waterline.

The smell of exhaust also lingered for more than 100 yards.

Obviously, it would be impossible to place sleeping policemen on that stretch of the river, but should there not perhaps be speed cameras?

Roderic Vassie, Belle Vue Cottages, York.