A normal k1 n a marathon k1 looks the same. the big difference is the weight. a k1 built for marathon can go as light as < 8 kg n the boat will need to be impact resistant to a certain degree for rough transitions during portages or even knocking of boats while paddling.
the rudder will need to be sensitive for good directional changes and of course will need to be durable too, in case of any trauma.
