You can also get all rubber, which I would favour, as it would have a little more give, but either would be maintenance free and survive a coming together better than any wood
I fitted rub rails on my ferro boat using Iroko using 2 layers and scarfing the shortish lengths with the scarf joint facing to the aft
First layer was bolted through and glued using Sikaflex and the second layer just glued on using Sikaflex.
I then glued a strip on the top and bottom to seal the joint screwing toe rails and stanchion bases to the top of the rub rails again sealed with Sikaflex.
Thanks all for another educational session Happily have made contact with a guy who has an abandoned 21ftr of similar vintage in a far flung corner of his property and will be over to his soon to exchange a few beers for the port side rail and dibs on s'board if needed in future!
Happy days