The designs are generally made by using different species of wood (although you could also use stain I suppose - but it would be tricky to get a clean line between areas with stain). Most builders apply the strips of one type of wood  a bit longer than the final area to be covered with that type of wood, then cut out the pattern and then apply the next species of wood (these strips need to be trimmed to the correct length to fit).  There are several builder's sites with photos of the process.  For example:

http://outdoors.webshots.com/album/567812618KvEvld

(look on page 6 of that site)

http://users.moscow.com/bprice/silver/

(look at deck pages on this site)

They are definintely beautiful boats!

Thanks, that is really amazing.  I do have a follow-up question.  I assume the strips bend slightly different at organic angles such as those in the redfish kayak family, rather than at a perpendicular angle to the forms.  Any idea if this technique is applicable to any kayak design, such as the petrel; or will this deform the intended overall shape of the boat?

I am no authority on this since I've only ever built a stitch and glue boat (although I've been researching a strip built boat for several years and that's my next endeavor).  Hopefully other people who have done strip built boats will chime in here. 

I don't see any reason why you couldn't use the organic/swooping strip patterns like the Redfish boats on a Petrel.  You basically have control over where the strips go by where you attach them to the forms as you're building (either using staples or staple-less methods) so you can make almost any pattern you'd like. The only limitation (although I'm sure someone has come up with a way to get around this) is if you want a pattern of small strips on the deck in an area between forms - would be tricky to get them to stay where you want them without something to attach to.  

Look back at the Okoumefest pictures from past years, on this web site.  You will see some CLC boats with amazing strip patterns.

Paul

Here are some pictures of a Mergsner that I built for my son last winter.