Usher, what is about the Hubb that leads you to say its design is faster at the expense of 'turning' than others,e.g. MND? The aspect ratio and dims are close except for the WP being further forward.
Following is my attempt to pull togeather some things we have been talking about. I hope I am not just repeating myself.
Yes, there are details of BBs to consider but the essence of those descendants of the Boogie (e.g.Mach 7-7) foam boards is that they are planing hulls with aspect ratios reflecting the science of Linsay Lord and are right sized so that the rider can readily weight fore and aft for trim and turning without having to slide up and back on the board itself. Only leaning fore and aft is required.
Usher expressed the aspect ratio of his board as equal to Length / Width, i.e 2.05 is his reference board example. Linsay Lord and followers express the aspect ratio as W/L which is .49 for the reference board and .50 for the MND and Hubb boards we have looked at.
Lord's test results show a .4 ratio as the ideal for rough water and the ability to go wider in smooth conditions. (
https://mypaipoboards.org/pubs/LordLind ... _ratio.pdf) In this article, John Elwell mentions .5 as a target. (
https://mypaipoboards.org/interviews/Jo ... 0823.shtml) Of course there are design attributes to consider but the main Boogie board linage is right in line with Lord's science perhaps explaining the stability of the design over the years.
Noses complicate the comparison of BBs to paipo boards with extended nose features. In reviewing Lord' science (
https://mypaipoboards.org/pubs/LordLind ... _ratio.pdf) I noticed his discussion of adding displacement bow- noses to otherwise planing hulls to smooth out water entry. When calculating aspect ratio he excludes the bow (nose) from the dims used to calculate the aspect ratio. Usher's rolled nose serves the same purpose as Linsay's bows especially at slow speed before planing.
A couple of weeks ago I stumbled upon and watched the bodyboard movie on Amazon Prime, Holding On - The Skid Kids Story. They rode conditions that were too intense for other craft and thought using a BB in weaker conditions was not a good application of the BB design or their interest. The shortness of BBs do seem optimal for intense conditions where you need to 'hold on' above all else and just do not want any excess out front to jam in. Likewise, once planing speed is reached the nose is not engaged so will not drag. But how about smaller conditions or places that have slow sections that peak back up?
I do see that as downside to be addressed. Usher added a couple inches to his reference design in his SDF board and used it for a belly in the nose to displace water prior to hitting planing speed. He felt he could get going sooner. He did not feel he sacrificed his ability to pivot fore-aft. Any surface area is gave up in the main planing area was not missed. However, He also used a conventional BB with a wider nose for slower summer surf.. more surface area and float up front to get and keep planing upon.
I now see why the BB community will tell you to go wider rather longer if you need more float or planing surface beyond the right sized length. You do not want to sacrifice the fore-aft pivot ease with more length. However, Lord points in his test results that in rough water that at a point, width will create more drag then help. See chart 7 in the article.
Concaves seem to be just a refinement of the basic BB planing surface. John Elwell (
https://mypaipoboards.org/interviews/Jo ... 0823.shtml )talks about Simmon's concaves and touches on the Bournouli Principal science that explains it. Those who have gone to quad concaves cite the same principals.
From
https://bodyboardking.com/p/9419012/nmd ... model.html:
"The QuadConcave can be broken down into two parts:
1. Central Double Concave - Tracks laminar (water) flow through the centre of the board keeping you higher on the wave face, which allows you to generate more speed into your bottom turns.
2. Outer Venturi Channels - Draws the laminar flow from a wider entry point into a narrow exit through the tail. Based on Bernoulli’s principle, the laminar flow increases in speed as it progresses through the channel, giving you more drive. "
There are some actual references to Bournouli somewhere on one of the sites if you are looking for connection to science. However, whether quad concaves are any better than a single concave is up for debate. Quads might be the breakthrough for stagnant BB design or just the latest fad.