It seems odd until you understand that the designations are logically based on boat design drawings. If you look at a cross-section drawing of the boat, there are several vertical lines that divide the hull into sub-sections. Each one of these vertical lines is called a "station." The numbering starts at zero (the transom), and ends at "F.P." (which stands for "Forward Perpendicular") at the foremost tip of the boat. In the case of the Zip, there are 8 stations including "F.P.", dividing the hull into 7 sub-sections of about 24-1/2" each. Frame # "5-1/2" is the frame placed between stations 5 and 6. It is located near the base of the stem.
Frame number 5-1/2 is a very important part. As the instructions indicate, the horizontal line formed by the floor member of frame # 5-1/2 is the plane from which the rest of the boat is set up. The instructions specifically state to take extra care to ensure that this part is accurately measured and constructed.
I just finished drawing this part, and I thought it would make a good blog post to illustrate how the Glen-L plans are copied to the wood.
First of all, you fold the carbon paper in half, so that the lines you trace through it are transferred to both the wood AND the back of the actual plans. Then you place the plans on the wood, and flatten them down securely. Push pins help for this.
Secondly, trace the plans for the part you want to build. As I mentioned in an earlier post, the centerline is THE crucial reference point for the boat. ALWAYS carefully draw the centerline. Make sure you extend your traced centerline beyond the needed dimensions of the part, for this reason:
Third, draw "sight holes" that are centered on the extended part of the traced centerline. I like to trace a small coin for this purpose. Use an exacto knife to cut your sight holes through the paper. You'll need these holes to align the plans after you flip them over.
|Here I've traced out the floor timber, and have cut sight holes on the centerline.|
|Half-width of the floor timber drawn onto 3/4" Douglas Fir marine plywood.|
|Plans flipped & aligned. Ready to draw the second half of the floor timber.|
|The full floor timber drawn onto the wood, waiting to be cut out.|