Wowza ! Nice rant :) lol š Crazy !! You just canāt make that stuff up! On another note how do you like the TackTick considering this for Christmas request from Mrs Claus as I can use on both the C&C and the Etchells ! :)
John Conklin S/V Halcyon > On Dec 19, 2019, at 12:04 PM, David Knecht via CnC-List > <cnc-list@cnc-list.com> wrote: > > ļ»æ So you poked something I wasted too much time on so I am going to waste > more time venting about Sailtimer: > > I have no experience with their hardware, but I was considering purchasing > the wind instrument. It looks like an interesting piece of hardware, and I > was concerned about my TackTick wireless wind sensor being 7 years old. I > sent the Tacktick to Raymarine and they checked it out and found it good as > new, so I donāt plan to āupgradeā. In the process, I had many emails with > Sailtimer regarding how the app worked, because I am a very data driven > racer, and it looked like it might provide some interesting/useful data. I > found them to be condescending, obtuse, ignorant, confusing and many other > adjectives that I wonāt repeat. I tried very hard to get them to explain how > their algorithm dealt with wind shifts (my primary concern for a wind sensor) > and while I think I finally got them to agree that wind shifts are important > in racing, I still have no idea what the software provides in terms of useful > data on upwind performance and shifts. It seems like it might give you some > data on how to steer relative to polars, but I am not sure how useful the > implementation is in the real world. I donāt think it provides anything > useful on wind shifts. Here is a sample of the kind of gobbledygook I > received: > >>> Headers and lifts are actually another antiquated racing method, that are >>> very clumsy in the age of GPS and computers. They were great in the 1920s >>> when it was impossible to do trigonometry every second in a boat heeled >>> over and crashing through waves. But they make you choose some arbitrary >>> length of time to get an average wind direction. And they make an >>> assumption that the wind is going to go back to average later. If a lift >>> happens for 2 minutes, why call that a lift and not say that it is the real >>> wind? Too many assumptions. > > I disagree. The decision of whether a shift is 2 min or 10 min or 10 seconds > is a key decision a racer makes and calling them right is what wins races. > They seem to think it is unimportant. I sent them a pdf that showed why you > sailed lifts and not headers to shorten the distance to the weather mark. I > got this in response: > > This again is an oversimplification. All sailors know that you cannot simply > shorten the distance (otherwise you would try to go at 2 knots nearly > straight upwind). (DAK: in fact all racers know that what they say here is > wrong. This is not about trying to pinch to go straight to the mark. This > is about sailing lifts to shorten the distance while sailing optimal on each > tack. This is ABSOLUTELY about shortening the distance to the mark!) To get > to the mark fastest, the optimal tack is a balance of minimizing tacking > distance (no idea what that means) and getting the fastest boat speed from > the polar plots. The SailTimer app recalculates all of this every second (I > agree sailing fast to polars is important, but it cannot determine the > shortest distance if it cannot decide what is a lift or header and what is > not. I would want a historical (for the race) perspective on the wind angle > was 2 min ago or when I last was on that tack). > > This is just geometry and vectors really; there is no reason to use your > grandfatherās old shortcuts and rules of thumb, when there is a powerful > computer and live GPS and wind data on any smartphone now. :-) > > Also, many of the rules in the PDF are for artificial race courses, but they > do not work if the mark is not exactly upwind (DAK: untrue! Sailing lifts > and not headers works whether the mark is directly upwind or not! It only > changes the laylines and how far you are going to sail on each tack.). But > the SailTimer app calculates optimal tack headings on all points of sail. It > is also the only product that uses tacking distances (undefined) to calculate > the optimal course (no idea what that means). > > On another point: they claim that there is an optimal set of tacks to the > weather mark which their app calculates in advance and then updates as you > sail (you can see an example on their web site). I contend that there are an > infinite number of tack combinations that would get you to the mark at > exactly the same time if nothing changes during the leg. The optimal set of > tacks in a race is actually a complex combination of current, shifts, > competitor positions, land masses, tides, obstacles etc. and the software > cannot/does not determine that. They are also very confused about optimal > course on a tack (polar performance) and when you change to the other tack > (port starboard). They use the same term for both making explanations > incomprehensible. > > Bottom line: the hardware might be fine, but I would not expect much from the > software. I would be interested to hear from anyone who uses the software to > know if it is better than their ability to explain it. Dave > > S/V Aries > 1990 C&C 34+ > New London, CT > > <pastedGraphic.tiff> > >> On Dec 18, 2019, at 9:55 PM, Randy Stafford via CnC-List >> <cnc-list@cnc-list.com> wrote: >> >> Listers- >> >> Have any of you used products from SailTimer, e.g. their SailTimer App and >> SailTimer Wind Instrument? If so, Iād appreciate hearing about your >> experiences with the products and the company. >> >> The company is based in Halifax, Nova Scotia, and headed by Craig Summers. >> Anybody on this list know him, or other employees of the company? >> >> Thank You, >> Randy Stafford >> S/V Grenadine >> C&C 30 MK I #79 >> Ken Caryl, CO >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each and >> every one is greatly appreciated. If you want to support the list - use >> PayPal to send contribution -- https://www.paypal.me/stumurray >> > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each and > every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray >
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
