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 don’t plan to “upgrade”. 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 won’t 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 don’t 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 grandfather’s 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 > 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, I’d 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
