trimming tapers on spars, for a lug rig on Dory?

just a FYI of what worked for me, I used a hand held circular saw as suggested in manual, and it worked fine to trim the tapers. but here are a couple of tricks I found as I did it, for others to use. these ar enot in the manual.

On the mast, I did a single cut for each surface and went around. so instead of doing two cuts on one surface and then going 90 degrees and doing two cuts there, I did one cut, turned 90 degrees, then one cut, turned 90 degrees and so on all the way around. mrking them as i went. that way I could always maintain the base of the circuar saw on the left of the mast where it had plenty of surface area to remain stable and so I always cut on the right side only. So my cuts, being supported by the larger surface on each side, were perpendicular. if you hypothetically marked each side with an A B C D the pattern was A B C then D going around counter clokwise, and not A A then B B.

on the yard and boom I did the same but laid them out on my horses side by side so that when cutting one on the right you have the other always on the left again to provide a solid platform for the base of the saw and I went back and forth betweeen the two as I went so they always presented a uniform height. if one were to mark the sides one would be  1 2 3 4 and the other A B C D. the pattern would then be 1 A 2 B 3 C 4 D and you would be changing the sticks left to right with each cut so that you are always cutting on a board that is the one on the right ( permits a solid base for the saw again) and each stick will have the same vertical height along the cutting surface. cuts will be perpendicular.

And before I started I marked the ceter of each end so that I had that as a reference point later to even things up. once you cut every side you lose that point if not already marked.

I also found that very sharp a plane gets rid of any unevenness pretty well but when sanding it helps to attach sandpaper to a long two by four, a couple of feet long, and along its entire edge and use that. it provides a lot of cutting power and it is fully straight and even in what it produces along a long surface.  

hope this helps others. it took me a bit to work it out fully before I started. not sure I would have wanted to try and make those long cuts without support under the saw base. would suggest that the manual might make this suggestion. what is in there right now would not convey this without some thought.