Re: What is this thing?
Yep, that is just the spinner of a taffrail log. The spinner is trailed behind the boat and is connected to the log (kind of like an odometer) that records nothing but distance. By recording your time & reading the distance off the log you can calculate your speed (though the distance is all you are really looking for when navigating).
--- My guess is that the club's "Taffrail Log Trophy" is given out in conjunction with a "Predicted Log" competition, or it looks like they call it a "Taffrail Log" competition. This is a competition where power boats run around a predefined course in open water (usually some sort of a buoy to buoy course over maybe 10 - 20 miles or such). The participants of the contest are given the details of the course maybe a week before the competition and have that week to lay out their course using dead reckoning navigation (using paper charts, Eldridge tide & current tables, and weather forecasts). You also have to understand the exact speed of your boat at given engine RPM's. The object is to predict exactly how long it will take you to run each leg of the course (down to the second). It is not the fastest boat that wins, but the boat that is closest to their prediction that wins. During the running of the competition (historically) the ONLY things that may be used aboard the boat for navigation are the compass and engine tachometer (all clocks are stowed or covered etc., and I would think that today all electronics must be turned off & covered) Each boat has an "observer" aboard who has the sole timing device and it is his responsibility to record the exact time of each leg that is run, and to ensure that the rules are adhered to.
It is a good test of navigation skills in understanding and predicting how the currents & winds affect the course and speed of your boat.
