I'm not totally sure, but I think my original intention behind getting rail rocker numbers was for handshaping purposes. The thought being I would replicate the rail rocker using a planer across the entire bottom curve first and then add the concave later.
Either that or I was just taking as many relevant measurements I could think of after going down a deep dive on how different shapers obtain rocker numbers.
I still haven't taken the time to dive into S3D that much so I still don't have a very good handle on which numbers are useful and how to use it.........but I've decided I'm going to try handshpaing a board here at some point (hopefully soon).
jkb, I think you should follow whatever process you feel comfortable with. Having said that knowing some pro tips does make things a lot easier and more enjoyable. I think every shaper would think that it is an advantage to have hand shaped before trying the computer. I don't think we have many (if any) notable computer shapers who have never picked up a planer, so that point could be considered debatable. Anyone know?
Are you planning on glassing it yourself?
Although the numbers range for putting together say a thruster are now well understood, it's a long road to being able to make oneself a good board, let alone a magic one. Being able to produce magic for others across a range of varying designs is another level of attainment which I am not aiming for.
By all means aim for a good board, but getting one on first build is not realistic. However creating a bad board and riding it is very instructional. For me some of the enjoyment of surfing is not just owning a good board, but trying to understand why it is good.
Unexpectedly I have deemed this years build magic! Since last writing on this thread I have taken it out in the open ocean twice and also ridden my perfect local custom HPSB in a sheltered spot which gives a reference for comparison, so I don't think I am deluding myself. It just felt so good the last 2 days. Resting today, but day before yesterday mixture of wind and groundswell started to build and by the evening the open ocean was a messy overhead on the outside and not looking attractive enough for anyone else. However, there was an almost mirage like left breaking down the side of a particularly big channel, bowling with a short, but defined wall. It really stood out amongst the mess although I knew from experience, that this sort of setup can be near impossible to ride - can't catch the shoulder, bowling face pitching over sand and being able to sit in one place waiting for the wave not possible with the currents. However I got a few and made some to close to shore, some entries into the wave made possible with white water takeoffs and the board just felt great, no feeling of any adjustment being needed.
Yesterday similar conditions, but the channel had disappeared overnight, so I chose another channel, not as good waves as day as before. In conditions like this I sometimes need to abandon my board instead of duckdiving when drifting out on the current to a crunching bar or in the case of yesterday some of the inside waves were unexpectedly crashing onto a shallow sandbar - no one else in the water so bailing board not an issue for others safety. I do a fair bit of this which is why I have been putting carbon on the underneath of my previous pu/pe annual builds - Brett Barley does this with Superbrand step ups. However it does detract from the ride and I glad I left it off this year and learned the importance of flex.
One of the things I got right this year was the fin positions. I could just use the thruster positions McKee publishes, I also have Dave Verrall's positions for his flagship HPSB "Garden Variety" range, but instead I measure the positions of the boards I am riding and make a judgement based on how they are feeling - it is more instructive this way.
Chilli Grom+ is 10 3/4" and 3 5/16" at 1 3/16" from rail - feels perfect.
Local Custom HPSB 10 1/2" and 3 1/4" at 1 1/8" from rail - feels perfect although I was surprised to find out how far back the front fins were.
Mini Bird - 3 7/16" 10 7/8" - feels perfect.
Diverse Garden Variety 10 7/8" 3/18" - on the drivey side but feels good
V1 of my annual build 10 3/4" 3 1/4" at 1 1/4" in - should have been fine but too stiff, although drivey. I had however pointed the fins 2 1/2" from nose and extra 1/2" on say Dave Verrall's 2". Nothing extreme - Rusty reckons can go up to 3" on high rockered boards. This was a moderately rockered board which maybe combined with the extra distance from rail conspired to produce the poor behaviour. Maybe things not right with the shape not helping. So it seems combinations of parameters within the normal range can go wrong.
Last years round tail build perplexing. I chose the exact same positions as the Mini Bird - short round/thumb tail grovel shape. This should have worked I reasoned, because the round tail likes the rear fin a bit further up to compensate from the stiffness of the lost surface area - it still looked rather far up at 3 7/16" on the other hand my round tail was narrower so that would have required the more forward position anyway. I also decided to be conservative with toe in and move it back to 2" and put it a more conservative distance from the rail at 1 3/16". However it was terrible - felt too far forward. This year I chose 10 7/8"and 3 3/16", 2" toe in and the same 1 3/16" from rail and it feels perfect
These positions are for Griffin fins, they don't need to work for any other fin and I am not sure they will - the Griffin rear fin has about 1/4" narrower base than the front fins. AM size small are all the same size.
Not sure what to do with next years build apart from make a slight adjustment to the nose rail apex. I could be brave and try a straighter toe in as per Rusty's suggestions for high rockered boards - don't think I would be prepared to try as much as 3" from the nose though.