The thinking behind a flat stem is "a nervous breakdown", for the following reasons :
1. Initially the inner stem had to be bevelled correctly and symmetrically on both sides. This is a running bevel from top to bottom and had to be picked up from the waterlines on the plans with recourse to Pythagoras.
2. Subsequently the cut out for the bow knee needed to be cut out centrally and square which is a delicate operation since the very thin lips at the keel are in danger of snapping and so correct support on a plywood template was necessary.
3. Then the inner stem was mounted square in all directions and glued up to the bow knee and hog which also has a running bevel picked up again from the drawings with recourse to Pythagoras.
4. Then the port garboard was mounted using a complex arrangement of clamps, Spanish windlasses. The torsional forces at the bow were phenomenal at this stage and, in fact, twice, after 36 hours, the epoxy didn't hold and the garboard split away at the bow. - I ultimately discovered the reason for this. My epoxy/colloidal silica mix was too thin and the epoxy was running vertically down the joint leaving too thin a layer. I subsequently made a much thicker mix where the epoxy/colloidal silica clung to a stick held vertically which was successful. I was near to tears at this stage.
5. Having noted the forces encountered on the port side and finding accessibility for clamps, Spanish windlasses etc more limited with the presence of the port garboard I was constrained to use leverage from this latter garboard to mount the starboard garboard. In order to try to safely do this I reinforced the port garboard inner stem and bow knee structure with a sheet of fibreglass soaked in epoxy.
6. Upon mounting the starboard garboard the same demonic forces manifested themselves in different ways and, in spite of repeated planning and dry runs the epoxy slip condition came into play. Ultimately this starboard garboard was mounted but with a slight asymmetry at the bow compared to the port. In fact the starboard garboard edge is also slightly higher (or lower) than the port by about 1-1.5 mm.
7. Subsequent strakes were then mounted with all their ensuing problems which I won't go into here, but just to say that as the inner stem /stem thins so any asymmetries become more pronounced to the eye.
8. Having completed the planking the outer stem must be mounted and should have a running bevel which follows the line of planking from deck to keel on both sides. The angles at three points on each plank from the flat face of the inner stem were measured and recorded and, again making recourse to Pythagoras, the running bevel on the outer stem was calculated.
9. Naturally, these bevels should be symmetric, but, since the demonic forces were again determined to have their way, the lines traced for the outer part of the running bevel were not completely symmetric and consequently I took the best average symmetric position and faired two symmetic curves on either side of the outer stem outer face centreline. The outer stem was then cut out slightly proud of the outer face of the inner stem and shaved to a bevel lying outside the symmetric curves on the outer face.
10. I then epoxied the outer stem to the inner stem. Having done so I then proceeded to reduce the outer stem flush to the inner stem with a spokeshave. I must thank Laurie Smart at this point for his excellent advice on how to approach this delicate issue. You must realize that if you mess it up at this stage you ruin the boat.
At this point if I shaved beyond the faired curves on the outer stem, I would have lost my reference points and it would have been almost impossible to put 2 new faired curves on the outer stem. However, having shaved down to these two lines it didn't look right. And so, in the lower region of the outer stem I went beyond these lines and tried to create fair curves up to the junction of the existing curves running to deck level. This took hours and on many occasions I was once again near to tears.
Having finally obtained a result which I consider is aesthetically pleasing whilst flat in some regions, I have also succeeded in retaining my sanity. - I think ...
I hope this answers your question and thank you for kind words.
I count myself lucky that there still remains some "thinking" behind the flat stem :-)
