Looks like you should do a partial seam on the first strip of little boats with the skinny navy blue strip under them as one piece. This will have the corner stones attached. Then add the blue triangle and boat/triangle piece. Then you are ready to attach the next long strip of boats and continue all the way around.

Wow, that will be gorgeous

it looks like a lot of partial seams will be needed as you go along. You designed it, so it can be done. Just take it slow and give it a try perhaps with scraps that are the same size as the pieced areas. Good luck.

I would foundation piece it. I would start with an oversize piece of navy fabric, probably a piece of 108" backing. Create your center applique. Mark the surrounding octagon stitch line. Extend the octagon lines so they form the 2 squares for the boat border. I would use matching navy thread and stitch on the marked stitch lines. This will create a permanent guide and stabilize the portions of the octagon that are on the bias. This is called 'stay stitching' in garment construction. Chalk will just wear off as you are probably going to be handling this a lot. Next, paper piece all your little boats, INCLUDE the narrow navy band in your paper piecing pattern. Remember to include seam allowances. Piece full boats for ALL the boat segments with the exception of the solid portions that go underneath the other border. Make the 8 anchor blocks. The anchor blocks should be the same width as the boat segments (which is why you want to include the navy border in your PP). Join all your boats and blank filler for the top border. (boat, filler, 5 boats). No anchors. Press the seam allowance over on the outside (top) edge. Using the 'stitch & flip' method, sew the top horizontal boat border. Use a 2.5 stitch length. Do the same on the horizontal bottom,pressing the outside (bottom) border over. Now create the vertical side strips, and add the anchor blocks to both ends, press the outside seam allowances. Stitch them on. The inner edges of the square will be stitched and the outer edge will be loose, but the seam allowance will be pressed under. Now do the 45 degree borders. Start with the NE one. Create the border with the boats and blank. Press the seam allowance over on both long edges. Position this on your quilt. You will need to unpick the top border where the 45 degree one goes underneath. Pin securely. Next do the SW one (no anchors), then add the anchors to the SE & NW ones. You will need to finagle these in place, so I wouldn't stitch them down until all four are laid out to your liking. You can now top stitch all the loose edges really close to the edge, or hand applique them. To reduce bulk, turn the piece over and cut out the backing under the boat borders, leaving about a quarter inch. You can also carefully cut out the portions of the borders that go underneath the others. Trim the backing to desired size.