Ok thanks for these. In the end I have closed them without I stitching everything.. phew. I put the boat on a pair of sawhorses without the cradles so that the whole weight bore down on the keel at the point where it touched the horses. The gap closed and I was able to pull the zip ties nearest to the horse tighter. Moving along and adding the weight of a small toolbox to the bow bulkhead I was able to get them all tight.