Flat rib, Round rib

This spring we began to combine using steam bent oak frames midships, and grown, in-the-round shoots for ribs out in the ends. The result is a lighter, more flexible boat with no measurable loss of strength, and new aesthetic dimensions.

Oak ribs are strong, and their uniform shape and size make it easy to build a strong, well-shaped midsection. One drawback to oak is its' density and weight., even with light scantlings the cumulative weight adds up. We probably saved 4-5 pounds on the frame alone, compared to an all oak- ribbed sister frame built earlier. That adds up to a lot of wood shavings.

We got a 25 pound, 14 foot 4 inch skinned frame - ready-to-coat .
Tough enough to take the knocks and hard chances of day to day paddling.

Scantlings for oak ribs vary. Modern practice usually uses a "canoe" style rib, one that is wider than it is thick. A stout canoe-style rib may be 7/8ths of an inch wide, and 1/4 inch thick. A lighter rib may be 3/4 inch wide and 3/16 of an inch thick, which produces a noticeably lighter rib. A square sectioned rib, about 3/8 of an inch could be used too.(Don't forget to round the edges.)

In our scheme we use the oak ribs midships, one or two behind the paddler, the rest extending as far forward as your legs go when outstretched. Use the grown ribs ahead and behind the oak.

The main advantage of this is that you get a very fair-shaped mid section because the oak is sawn with no irregularities. It also puts the strength of oak where the paddlers weight is concentrated. Its' uniformity gives you a headstart in making the rest of the hull sweet and shapely.

Historical kayaks often used willow shoots for in-the-round ribs, and these are often recommended for modern builders too. Willow bends well, and is widely available. I have used it, but have nagging worries about its' strength and especially its' ability to resist rot in non-arctic climates.

We have had great luck with apple shoots, We've used cherry and pear too.Other fruitwoods are worth checking. Apple shoots are easy to come by where I live. A good source is an old orchard, or even a single abandoned tree that hasn't been pruned for years. If the old tree is surrounded by newer growth, this is even better, since the competition makes for long straight shoots. Abandoned trees that are surrounded by a forest are ideal.

Scantlings for ribs in the round are based on the "pinky"rule. Try to use shoots that have a diameter similar to your pinky finger. In numbers that's somewhere around 3/8 inch when peeled.

All the shoots I've worked with have the great advantage of being able to be bent into place with no steaming. Their somewhat alarming malleability disappears as they dry. Apple in particular gets quite tough and hard.

The Aleutian Kayak by Wolfgang Brinck has a good section on working with natural ribs.

Working with naturally grown ribs

There are a few considerations using grown ribs, as listed below:

You can experiment with your own local trees or shrubs too. Look for a small pith center, good bending characteristics, and woods that grow in straight runs with an even taper, with minimal or no "knuckles" joints and smaller branches coming off them.Using woods of a known rot resistance is probably a good idea too.