Like sjk mentioned, the recent issue of Popular Woodworking has an article on the spring joint. They mention that the gap should be big enough to just slide a piece of copy paper through it, or at most a business card. I am going to be using this method to build an alaia, which is basically a solid wooden surfboard. I think that the spring joint will work well for this scenario. If not, well then it won't be much of an issue, as I have broken plenty of boards in the past.