lets take this in parts:

can you build the hybrid shearwater from the sectional sport plans.  the short answer is  'it depends'.

the sectional sport plans is a stitch and glue hull and deck.  the hybrid shearwater has different deck sections (forms) than the stitch and glue.   so your plans will not likely have the right forms shape every 12 inches that would be required to create the forms used in typical hybrid construction.  you could buy the hybrid shearwater sport plans to resolve this porblem.  that said, some people do a 'hybrid' deck using stitch and glue technique.  they create panels of cedar strips that exactly match the stitch and glue plans....and do a hybrid that way....and depending on the design, this can look really nice.   in this case, you would stick with the plans you have.

can a shearwater hybrid be turned into a sectional.  yes.  it would basically follow the technique and plans of the sectional. but you would be adjusting it for the new deck. shape.....so basically your bukheads are going to be a different shape (assuming you has nornal hybrid plans)....but the mechanics of how to do it and bits you would need for assembling it all would be the same,

h

   Thanks for letting me think out loud.....well kinda....and coming up with the right answers. I see from the plan purchase contents exactly what the difference in the decks is. The beauty of the strip built deck curves is hard to beat. Should be easy enough to modify the sectional bulkhead to match the curve. Thanks again.