In the little Hamlyn "Sailing Handbook" under the heading "Other channel markings" is the following:: "Minor channels in creeks, rivers and so on are usually marked with sticks or branches of trees, called withies, stuck into shallow water on either side."
There are still a few such sticks to be found on the Estuary mostly in the channels leading across Greenbank into the Clyst and "withies" is or was the local fishermen's name for them.
"Withy" is the country name in Devon and elsewhere for the willow tree and therefrom for the wands of the willow. Withycombe Raleigh, a neighbouring parish to Lympstone, was presumably once a valley of the willows. 'Withy' is an Anglo Saxon word with Old Norse cognates, closely related to the modern German word for a willow, 'die Weide'. Is Widecombe In the Moor perhaps another Willowdale?
Once, for many hundreds of years, perhaps back to prehistoric times, before the coming of buoys and the International Buoyage System, the channels of the estuary would have been marked only by such withies. They stand to their places on the banks remarkably well. Wind and tide seem to find it difficult to shift them. They are, however, hard to find by day and impossible by night.
The few surviving examples of such sticks on the Exe seem not to be from the willow but they are 'withies' none the less. "A good man steers between the withies." should be a proverb. "He sailed between the withies." - a fitting epitaph for one who always managed to steer clear of trouble.