They both dry out. St Ives is a busy beach. Nightmare in my opinion.
Hayle is a steep slip - 2WD a struggle. Parking part of the launch fee. Can't remember the day rate £15 ish guess. Quite civilized but no real facilities. Fuel 100yds away @ garage. Challenging sand bar at lower tides with bigger seas, but generally fine in anything that goes faster then the swell when needed.
Sheltered ski area controlled by local club & subject to club rules.
Pontoon at Hayle but not sure if there are any visitor berths.
PM me if you want phone number for more detail.