i don't see a problem with that. 

i have done the same with chesapeake kayaks which have the same kind of deck construction.   

i think its very smart to position pieces and work in a way that gives you visibility and helps avoid the, "i can't believe i just did that!",  kind of mistakes.

my only other tip is i would still cut a little proud of the final line and use a block plane or a sanding block with 80 grit to bring it to its final position.

some saw blades will flex and drift a bit so unless i know the material very well,  i like cutting a bit proud and making the final trim with something that i have a lot of control over.

hope that helps

h

  Thanks h - 

It is my intent to cut close to the joint but leave a little bit to clean up with a plane and/or a sanding block, probably both. I just wanted to be sure I wasn't overlooking something that would make upside down trimming unworkable. When I built my Chesapeake 17 and my Sport Tandem I trimmed the decks with the boats right side up - so it's only taken me two boats worth of practice to come up with an idea that seems obvious now - I never claimed to be a quick study - 

John

Hi John, 

the only thing i would share, in addition to what i put above, is that when you work with it turned over, the blade cutting into or needing to work around your saw horse or whatever you are using to support the boat is increased.

but cutting into a sawhorse is a lot less painful then cutting into your hull :)

h

   I did trim the outer edge of the deck with the boat upside down - worked great. Started with a pull saw, finished with a block plane and sanding block. Now on to fiberglassing the deck.