A contact rescue is certainly an option if the victim is unconscious and your boat isn't available fast enough, perhaps you are at lunch when the accident took place. An unconscious swimmer needs extra care to ensure they remain face up and breathing. Unconscious swimmers are certainly at risk for C-Spine injuries which require special handling. Check their helmet and back to look for evidence of severe injuries. If awake, do their extremities work right, any tingling in the extremities? Ask if they took a hard head shot. Go on any intermediate trip these days and you will find that half the boaters have helmets that don't fit right. Many helmets also have very thin padding as well. For these paddlers, a hard head shot is going to cause a concussion (due to roll back) or transfer a great deal of energy to their neck. Be extra careful with head and neck injuries.