Ribs From Green Wood
|Home | Boatbuilding | Baidarkas | Bibliography | Glossary|
Making Ribs from Green Wood
While it is convenient to make ribs entirely out of milled lumber, there is a certain pleasure to be found in using the twigs, branches and trunks of living trees and bushes.
You can use green wood to make both round ribs such as the ones used in Unangan (Aleut) kayaks and flat ribs such as the ones used in Greenland kayaks.
Metaphysics of rib gathering
There is something compelling about gathering your own building materials. I think it has something to do with our hunting and gathering heritage. We remember every place where we have ever caught a fish or killed an animal or found gathered material for ribs because what links them all is survival. We have a special process for remembering where we encountered something useful, something that has kept us alive.
What plants to avoidWhen you venture out to explore rib species be sure you know what poison oak looks like and where it grows, especially when you collect in winter when bushes have shed their leaves. Quite often, poison oak branches will be intertwined with the branches of harmless species. Oleander bushes are also poisonous. Eating any part of the plant can be fatal. It seems to be primarily an ornamental in warm climates and therefore not likely to be found in the wild where you can collect it for rib material, nevertheless you should know what it looks like so you can avoid it.
Scouting rib materialsThe best way to find suitable rib material is to venture forth with pruning clippers in your back pocket. When you see a suitable bush or tree that is sprouting branches that are straight and lacking in side branches for the length of a rib, pull out your clippers and clip off a branch of about half inch diameter. Clear it of leaves and any small side branches and test it for bending. The branch will either bend or not. If the branch is suitable, you should be able to bend a two or three foot length into a semicircle without breakage or splitting sounds.
As you do this with different species of wood, you will find that some are stiffer than others, that some are too brittle and will break and others will be very stiff and difficult to bend and some will be altogether too pliable.
Keep in mind that you will be peeling the bark off these twigs. This will make them easier to bend. But this will also weaken them somewhat. Also keep in mind that after you peel your ribs, trim them and insert them into their mortises in the gunwales, they will stiffen as they dry and take on the shape you have bent them into. In other words, once the ribs have dried, they will be stiffer and less likely to flex than when they are still green.
The ethics of rib collectionWhen setting out to collect rib material, keep in mind local laws and customs. However, even if operating entirely in a legal fashion, try not to clearcut entire bushes or carve obvious holes into the landscape.
YieldsYields for round ribs made from shoots and branches are typically pretty high especially as you gain experience in gathering them. Some flaws in branches that cause them to break are not readily apparent until you peel them. But once you have peeled some branches and broken them, you will learn to recognize and avoid these flaws while the branches still have their bark on. As in all things, success improves with practice.
Collecting rib materialOnce you have found a good source of rib material, collect about as many ribs as you can process in a week. If you collect more, they will dry out and become useless to you. Until you become familiar with your rib stock, you can probably figure on losing from a quarter to a third of the ribs to breakage.
Growing your own rib materialsIf you have suitable land and sufficient patience, you can plan for rib stock a year or two down the road. Willow shoots cut into one foot lengths can be stuck into the ground and will grow roots and in a year or two provide enough willow shoots to rib up a boat.
Coppicing and pollarding are both methods of encouraging the growth of long straight shoots from certain trees. In coppicing, you cut the trees at ground level, encouraging the growth of a number of shoots the following year. Pollarding, likewise encourages the same effect but the cutting of the tree is done higher off the ground.
Neither coppicing or pollarding will do you any good right now, but if you have the land and plan on building more boats over the years and don't mind waiting a few years, it might be a good way to go.
In some places, ailroads cut down brush and trees that grow next to railroad tracks using some kind of very agressive lawn mower. They in effect coppice any tree that grows near the track with the effect that a year or two later, there will be a lot of shoots suitable for kayak ribs.
Peeling ribsOnce you're ready to start ribbing your boat, pick a twig of suitable length and peel it. How best to peel it depends on how firmly attached the bark is to the wood. Twigs collected in the spring seem to have quite a bit of sap in them and the bark peels quite easily. At other times of the year and especially in winter, the bark seems to be more firmly attached.
If the bark is loose, a dull knife works pretty well. A sharp knife will tend to cut into the wood and therefore give you problems. A dull knife will slide nicely between the bark and the wood. Some people have also had success with potato peelers.
If the bark is firmly attached, a spoke shave or knife work to remove the bark.
Shaping ribsIf one end of your peeled twig is substantially thicker than the other and you can't get it to bend uniformly, you can remove a little wood from the fat end with a spoke shave.
Bending ribsAfter you have peeled the rib, you should be able to bend it fairly easily without breakage especially if you start in the middle of the boat where the bends are the most gradual. If too many of your ribs break, you haven't found the right species. The whole point of collecting green ribs and going to the extra trouble of peeling the bark off twigs is that you can bend the ribs without steaming or other form of heat treatment.
All content copyright © 2005 Wolfgang Brinck. Personal non-commercial use permitted.