Looks very niceThat is simple tongue and groove strips available from timber merchants and DIY stores. Just google tongue and grove strips for a whole range of choices of types and suppliers. I am just doing this job on my own boat using some 40 year old strips that used to be my kitchen ceiling. Most are attached to battens glued to the GRP with CT1, but in some cases where there is not much curvature it makes sense to build panels and glue in place. Photos show what it looks like.
OK the Robbins Elite Cabin Line is close, but if you are painting then relatively simple to route 2mm grooves into plain ply and paint. That is what some production builders such as Cornish Crabbers do. There also white plastic panels moulded in grooves such as used extensively in Bavaria yachts, but not sure of the source. However T&G glued together in a panel and painted will achieve much the same - they are 6mm thick and both lighter and cheaper than ply.Its not strips im afraid and as a race boat iim looking for 6mm machined panels with a facing veneer.
Used to get them from Latham's but no longer doing pre machined.
Thats perfect thank you!