Buying a boat with a saildrive - got a few questions

[Uncle G]

Our daughter went down that part of the Thames in her narrowboat last year on one of the biggest spring tides of the year. She had both the river flow and the maximum ebb tide under her by the time she got to Brentford. Consequently she had a hell of a job turning her 70-foot boat to get up into the lock. Her engine overheated as she fought the tide.

it was her first experience of the tidal Thames. She's going to go upstream next time so the tide will be easing off at the end!