Building a place to sit

The next challenge was to figure out the seating.  I wrestled a lot with the height and placement of the seats. I consulted a number of folks on the Glen-L boat building forum to get their dimensions so I had a place to start.  For the base wood form, before foam and upholstery, I settled on an 8" height at the front and 6" at the rear.  The seat depth would be about 18" with a back seat angled at 15 degrees from level.

Starting with those dimensions, I cut out frames , front pieces and stringers from 3/4" mahogany plywood to assemble two boxes that would support the seats.  Here's a picture.

The three frames sit on top of the floor battens, which run front to back.  I dadoed plywood on the front and back and then added 2" wide stringers across the bottom and the top rear where the plwood for the seat will rest.   After positioning and finishing, this will get screwed to the battens to hold it in position.  

I also fit the uprights that will support the back rest.  The seat and back rest will be upholstered 3/8" marine plywood that is removable so I can store stuff under the seats.  There is tilt to the seat and then additional angle to the uprights to give a backrest slope of about 15 degrees.  The back of these uprights on the front seat will be covered with plywood to finish off the interior of the rear cockpit.

This is the rear seat.  Essentially the same, however there is no need to finish off the back of these uprights.  The uprights aren't attached as of yet.  I plan to make the pieces removable so I can finish it all in my basement and then just mount them in the boat.  They will remain removable.
I also have to put a few more pieces on the outside edges to support the seat so it doesn't flex and probably add another back rest upright on each end.
I am not quite sure how to finish off the seating and make it easy to upholster, as well as look good. Before finalizing it, I plan to trailer my boat to the upholsterer to review options on finishing it off and making sure I end up with a nice finished product.   He may recommend some changes that will affect the final build.