This film was factually incorrect in a small but crucial detail that almost certainly made an equal contribution to Larry's survival as his drysuit.
The kayak Larry was paddling, a 'Puffin' by Nimbus, was not the model used in the film. Larry's kayak had two-part hatch covers each consisting of an inner neoprene cover and an outer hard cover. The inner neoprene covers were missing in Larry's kayak and because of this, in the rough seas they were in, water was able to enter the hull. The film mentioned that Larry's kayak contained 'a ton of water'.
Larry's kayak differed in another very important respect from the one paddled by the actor. While the actor's kayak had a hull divided by bulkheads into two compartments and a cockpit, Larry's kayak had a Minimum Volume Cockpit that enclosed a smaller volume than the actor's kayak cockpit but which, importantly, also left the hull as a confluent space. This meant that onboard water entering the hull equalised fore and aft preserving an even trim enabling Larry to keep his direction paddling for land for much longer than an equivalent situation in a kayak like the actor's. Thus when he eventually did capsize he was much nearer to land than he would have been otherwise. This fact has been overlooked by George Gronseth who reviewed the incident in Sea Kayaker magazine.
Given the facts as I understand them, Larry's kayak's unusual buoyancy design made an equal contribution to his survival as did his drysuit.
See: Gronseth, G. 1993 "Saved by a Dry Suit" Sea Kayaker magazine Vol.10 No.1 pp34-37