Planking is just as contentious. Theres a web of requirements with a sweet spot in the middle: durability (rot resistance), workability (with cutting tools), strength, lightness, ability to bend and not fracture (Whats the opposite of brittle? Pliable?), low movement and high abrasion resistance are all desirable.
Cedar has been called the Boatbuilders Friend. Ill put aside the question of which cedars really are cedars for the moment. Western Red Cedar, Yellow Cedar and Port Orford Cedar (and all the other names by which they are known) are durable and much lighter than Larch, the traditional British planking, but theyre also softer. This boat will be beached, so whats durable and hard? Larry Pardey planked his boats with Teak. Fantastically durable but heavy and quite a challenge to work. Not to mention desperately expensive and politically incorrect on at least two levels.
So what will I be using?
Paul Gartside specifies Yellow Cedar or Spruce for the planking of his design #127, the sheerstrake and transom should be in mahogany. That should be the end of the discussion. Do what the designer says. But Yellow Cedar is imported from North America and Mahogany is a tropical hardwood. Its not Teak, but its not entirely uncontroversial.
Id like to use domestic timber if possible. Sadly most of our Larch now comes from Russia or Scandinavia. Thats little better than importing it from North America. Its also much heavier than the timber specified and will make a difference to the weight of what should be a small, easily handled boat.
What other choices are there? Adrian Morgan is finishing an Iain Oughtred design in Scots Pine at the moment. Our only native conifer has been so thoroughly harvested that Morgan can now trace the provenence of his timber to the Queens estate at Balmoral! Perhaps using domestic timber is asking too much?
In stark contrast was the response I got from Tristan Stone at Stones Marine Timber. It should be understood that Tristan runs a boatyard as well as a timber yard and so specialises in a few timbers imported from North America and sawn specifically for marine use. Four days after contacting him I have a selection of offcuts sitting in my front hall for testing.
I also have the benefit of his knowledge and experience. His yard maintains a fleet of clinker dinghies built of Sitka Spruce, the timber with the highest strength to weight ratio. He was very happy to talk through timber choices, where the trees are felled, which way they should be sawn and so on.
Im "testing" these in a few, subjective ways. So far Ive planed the edges and faces in both directions and planed a sloping rebate (gain or jerrold) on one end of each plank.
To be fair all five planks worked very easily with sharp tools. One look at the reversing grain on the Khaya Mahogany had my Stanley 5 1/2 champing at the bit. No tearout, no difficulties whatsoever. It was lovely to work.
In fact only one of the planks put me off. The Western Red Cedar felt indistinct under the rebate plane and I could only plane the face in one direction. No amount of honing and plane adjustment could encourage an even shaving despite the apparently straight grain of this rift sawn piece.
If I had to pick a winner so far it would be the Yellow Cedar. Very crisp to plane.
Each plank has wonderfully straight grain, is quartersawn, or in the case of the Western Red Cedar, rift swan, and clear (free of knots). These qualities are, perhaps, even more important than species when comparing how easy they are to work.
Once Ive cut them to a similar thickness Ill bang some nails in and see which splits the least.
Then I need to work out how to simulate half a century of use in a couple of months. I might just ask someone who maintains old boats.
contd in Planking Timber 2
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