That is not enough. There needs to be some kind of padding. I couldn't imagine resting a boat on bare wood.
At our marina, there is a variety of materials. The older ones have carpeting and some of the newer racks have been fitted with sheets of silicone rubber. It gets a good grip and won't harm the boat.
Something else that has surfaced recently on the of the racks is that they actually closely wrap the bunks with rope. Then the rope is tied off at the ends and shot with some kind of spray caulking in between the windings. Never a scratch.