thanks henny! very nice to see the whole boat for such a long time. an observation and then three quick questions:
at 8:07 you show the front rudder is angled so as to turn the boat right. one continuous pan around to the stern rudder and we see it is angled to turn left. you are in effect then crabbing to windward, perhaps accidentally as there were two people helming, one on each wheel.
judging by the boom angle you were close reaching at that time, which is consistent with your GPS track and reported wind direction. with an edit clip in the video, we then see the GPS reading 12+ knots. the boom appears to be at roughly the same angle. there was a gust then? the rest of the time you're only doing 8-10 kts.
my question is, how big an angle are the rudders at when maintaining a steady course? in other words, are they big enough such that they can compensate for the weather helm and still be at the AOA which gives the optimal L/D?
relatedly, do you have any feel for how much sideslip there is? there is a tradeoff in the fore-aft position of the rudders between compensating for weather helm and compensating for sideslip. the further apart they are (towards the bows) the more a given AOA will turn the boat and the less it will counteract sideslip. the optimal fore-aft position will vary with wind strength and sailing angle of course. but is it in the ball park?
i know you've had limited time on the boat, and that these rudders are new to you. but i would value your thoughts.
ben
weta tri #358
crew on a corsair 28cc
dreaming of a harryproa
ithaca, new york
--- In harryproa@yahoogroups.com.au, "Henny van Oortmarssen" <henny@...> wrote:
>
> As promised I have made a video of Blind Date, now sailing with her renewed "old" rudders, sailing last Sunday September 11 under the lee shore of the dyke between Lelystad and Enkhuizen, wind from S to SW Bf. 4 to 5, max speed 12.8 kn, see
>
> http://www.youtube.com/watch?v=wftyqI2aJlo
>
> On my blog you can also find an image of the track and speed. Unfortunatly I cannot figure out yet how to show this in Google Earth (to be continued)
>
> http://framsblog.wordpress.com/2011/09/12/sailing-with-blind-date-a-harryproa-visionnary/
>
> Not to bad compared with BD's second generation rudders. My experience with BD so far was with these second generation rudders. They just didn't work. With the latest modifications, reinforcing the original rudder sleeves by Rudolf and Nol to replace the original rudders and removing these second generation rudders by Nol and me, BD is now reborn and healthy again.
>
> Only for remembering purpose, and only for that ;-) below is a short video of the second generation rudders (they now RIP)
>
> http://www.youtube.com/watch?v=bSnrijWJ5Pk