The third and final installment from Kevin Hall and his incredibly thorough instrument analysis. Here is Part one and Part two of the series.
The target ball knows which sail we have up. If we’re on the crossover between the deep soaking A2 and the much more open A4, it doesn’t try to get us to sail a low mode with an open sail. It knows that sail needs lots of apparent. When the target ball is bigger and to windward of the boat’s ball, we know to heat. When the target ball is smaller and to leeward of the boat’s ball, we know to work on taking some of our built snowball back down toward the leeward mark. The ball glides around the screen producing sensations or intuitions which feel like the ones we get from the heel, wind pressure on our cheek, sound of the water, voice of the trimmer, view of the horizion….
It was known since the 80s that one of the biggest errors for inshore navigators was a potential or even likely difference between the virtual mark used by the software, and the actual mark used by everything else. Many approaches have been generated over the years for this challenge, but one that is becoming industry standard now is to again have the sailors on the rail help ensure the accuracy of the virtual mark by…well again, check the code yourself.
Finally, starts are kinda neat-o now compared to how we used to do them. Since the committee and pin positions are beamed into everyone’s software, teams now get to enjoy starting practice instead of colliding as they chase that perfect ping. The navigator used to announce a “time to kill” number, which assumed about six things and was remarkably similar to black magic. Now, the entire boat sees a display of the line, the boat, and a curve a bit like a polar curve which represents where the boat would be at the start gun if we sheeted on “now”. In one glance, when the isochrone marches inside the virtual pin we know that we can’t get to the pin early anymore, and when it creeps down toward the line, we know it’s time to make sure there’s enough flow on the fin to nail a repeatable acceleration.
In April of 2018, an article written by Kevin Hall and posted on Sailing Anarchy in an effort to share ideas to brainstorm a few new variables for younger sailors to use in their efforts to improve onboard technologies became the inspiration for the history you just learned. That post is here:
DOWNWIND SAILING ON A DYNAMIC “TP 52 or SIMILAR”:
Thoughts about the future use of instruments and software to get to the bottom mark sooner.
DEFINITIONS:
“Bottom Turn”: the transition from the end of a surf or soak to the next heating cycle. Has “when?” and “how big a turn?” components.
“Top Turn”: the transition from the end of a heat cycle, or the turn down onto a wave. Has a “driven by heel or by BSP or by rate of BSP acceleration?” aspect.
“BT rate”: how aggressive the bottom turn
“TT rate”: how aggressive the top turn
“OGMode”: Clear air opposite gybe in mm:ss mode: balancing all variables to have the best chance of not having the boat just behind come out of the simo gybe on your wind. Needs better name but for now let’s define the concept with two examples. 1. If we soak 30 seconds before a gybe, we will start the turn further to leward, but be slow into the gybe and will get rolled out of the turn by a boat that does a better gybe. 2. If we sail hot for 2 minutes we will extend away from the boat behind, and depending on the conditions and the shift, the apparent wind bad air wedge may be better for us than example #1. 3. If we balance these things well by the whole boat knowing how long until we hope to gybe and working together on the “no look gybe speed and boathandling”, we have the best chance. On very strong teams much of this becomes unspoken. On A- teams it is hit or miss. On B teams and worse, it is embarrassing to watch how badly it is done sometimes…
Angle Gap = TWA-AWA
Speed Gap = TWS-AWS
Building and keeping the SNOWBALL = shorthand for using #1,#2, #3, #4, to produce greater numerical average (Absolute Value)#6 and lower numerical average value #7.
DISCUSSION:
What dinghy sailors learn as they get better at downwind sailing, is that there is a tremendous finesse involved in doing the bottom turn soon enough to make the most of the new/existing speed. Most sailors have to unlearn the “milk the surf too far” tendency. It is natural to take the surf further down the wave, but then both the BT rate and time to next TT are much greater. (“Up in the lulls and down in the puffs” is this same movie, but on very low brightness and volume). On a big boat with instruments with lag and calibration inefficiencies, this lesson and tendency is hidden behind 7 tonnes and 11 bodies which may not always move as one. There is now enough good historical, VPP, dynamic VPP, “live database”, class experience, etc to use the instruments in a whole new way to help guide the helmspeople and trimmers in their choices about #1-5.
A study of the behavior of many derivative values, a few iterations of graphic representations, and some balancing of theory, sailing data, VPP, and feel, could produce a new kind of information and graphical representation of it which would behave more like a dinghy sailor’s feel and would help all but the very top teams (and, once tuned well, might even help the top team!).
