How to make patterns for boat seats?

[Peppy]

Correct. I pattern to finish size. The way Darren says you'd be patterning to cut size. Which is why I have a problem with that way, when it gets to be more than a couple pieces the seam allowance gets in the way and makes it very hard to 'see through' that mess. Also one sewer has a 9/16" 'half inch' and the other has more like a 3/8". When I give them a finish size pattern it doesn't matter they just do their own thing.

[SoInTrouble]

If the cushion is boxed all around I forget about the old cover altogether and cut the face 1/4" larger than the board all around. New foam cut larger than the board all around gives the best results, but if the old foam is still in good shape it can be re-used.
Rich

Great thread, It answered a few questions I had.  I have done all car stuff and am doing my first boat.  One more question... How much wider do you cut the foam?  I am doing 3" thick box cusions 36" by 36"  I was guessing 1/2" on both sides, but it would be better not to guess and use the trial and error method..  ;D

[MinUph]

37x37

[SoInTrouble]

37x37

Thanks Paul.