JEM Watercraft

I am setting up forms for a Northwind. It looks like they are designed to be spaced on 1 ft centers with the outside edge on the station line from both directions so the center space would end up about 1 ft minus two times the thickness of the form material. Correct? For instance I am using 1/2 in MDF for forms. Each space would be 11 1/2 in between stations but the middle one would be 11 in +/-. Correct?
And since the bow and stern pieces are so short could they be butted into the end station and just screwed in place?
And if I am going to use an internal stem do I cut back the bow and stern pieces to net out the same length with the stem pieces fastened on to the ends? or are they designed to have a stem added as they are? Maybe I am not figuring right but adding up 1' x # of stations and the length of the bow and stem pieces I am not coming up with 17' 2".
You can probably tell I have been watching Nick Schade videos. What a gift! It is a free and fairly comprehensive tutorial with some good music to boot. Unlike some other bloggers my taste in music lines up pretty close with his. A lot of work to give away to DIYers.

I used 5/8 mdf for my forms. I fastened the bow form to the first form and spaced the rest of the forms 12" front to front. Then I fastened the stern form to the last form which made the forms total length 17'-0 5/8". When the stripping was complete I had an overall length of 17'-2". The dimensions are of the finished craft. The internal stems are cut into the forms, just like Nick does it on his videos. If you notice the widest form width is 28" and after 1/4" strips are added on both sides the boat will be 28 1/2".