last time we did the Marple flight the boat got hung up on protruding brickwork in two locks going downhill - cant remember which ones but others had same problem going both up and down. Huddersfield narrow, difficult to get to edge at the lock landings because of silt and no dredging (at the time, may have changed now) so we landed at the tail/ head instead. Grounded in the little tunnel just west of Hudd but that's been opened out so it may be deeper now. Pennine crossings well worth it, go for it.