Building wood board

[EastcoastJoe]

Hi folks,
My son and I are making our first wooden board. The best fit for us was to build it out of solid planks. Watched alot of vid's and decided to chamber the boards to lighten it up. Thinking about filling the chambers with foam to help her float better also. We have a nice template for an 8 ft long board. Gonna leave 2 cedar stringers solid with no chambers along with 2 more cedar planks on each side for color and strength. Any ideas about adding the foam to the chambers? Any input or thoughts would be appreciated. I will show pics of progress.

thanks!