That’s pretty amazing! Joel
On Fri, Apr 5, 2024 at 8:11 PM Dreuge via CnC-List <cnc-list@cnc-list.com> wrote: > Hi, > > Just for the fun of it, I entered the text of your email into ChatGPT4. > > > You: > I have a set of polars for my C&C 34+ (below), but I am unsure of how to > interpret the downwind data. There is no information I have found on how > the angles were determined. I am interested in best angles for downwind > work without a spinnaker going wing on wing with a whisker pole. I am > guessing the data is with a spinnaker and I am not sure if that matters. > The issue is whether to go wing on wing direct to a mark and go a shorter > distance vs. wing on wing or not on a lesser angle according to the polar > chart. I have tried to measure this on my boat and have not found a big > enough difference to convince myself I should tack downwind. > > ChatGPT: > Interpreting the downwind data from the polar diagrams of your C&C 34+ > requires understanding a few key points about these diagrams and how they > relate to sailing without a spinnaker. Polar diagrams are typically > generated with a spinnaker, especially for downwind angles, so the speeds > shown might be higher than what you can achieve wing on wing with just a > mainsail and a jib. > > Here’s how you can approach the interpretation and application of this > data for wing on wing sailing without a spinnaker: > > Understand the Polar Diagram: The polar diagram shows boat speed at > various wind speeds and angles. If the data is indeed with a spinnaker, the > speeds at downwind angles will likely be optimistic for wing on wing > sailing. > > Determine Best Angle for Wing on Wing: Without a spinnaker, your best > downwind VMG (Velocity Made Good) might be at a different angle than what's > optimal with a spinnaker. Wing on wing is most efficient when the wind is > directly behind, but if the polar diagram suggests a slightly off-wind > angle is faster, it may be due to the spinnaker's influence. > > Experiment and Record: Since you’ve mentioned not finding a significant > difference in speeds when testing different angles, it’s essential to > conduct more trials under various wind conditions and record your boat’s > performance. Accurate and consistent data can help you understand your > boat's behavior better. > > Consider the Course and Conditions: The choice between going straight > downwind (wing on wing) or jibing downwind at angles suggested by the polar > diagram also depends on the course and sea conditions. If the direct > downwind route is shorter and the speed loss is minimal, it might be the > better choice. However, if off-wind angles significantly increase speed, > the extra distance might be worth it. > > Adjust for Non-Spinnaker Performance: Since the polar diagrams are likely > based on spinnaker performance, you might need to adjust the expected boat > speeds downwind. You can do this by reducing the speed values slightly or > by using performance data from similar boats sailed without spinnakers. > > Software and Tools: Consider using sailing software that can adjust polar > diagrams for different sail configurations. Some programs allow you to > input your data and conditions to simulate the best course and sail setup. > > Ultimately, the decision to go directly downwind or jibe at angles > according to the polar chart should be based on a combination of empirical > data from your own experiences, the specifics of the course and conditions, > and adjusted expectations from the polar diagrams. Continuous recording and > analysis of your sailing data will help refine your strategy over time. > > > - > Paul E. > 1981 C&C Landfall 38 > S/V Johanna Rose > Fort Walton Beach, FL > > http://svjohannarose.blogspot.com/ > > On Apr 5, 2024, at 3:18 PM, Bill Coleman via CnC-List < > cnc-list@cnc-list.com> wrote: > > > > On Fri, Apr 5, 2024 at 2:44 PM Bill Coleman <colt...@gmail.com> wrote: > >> I anguish over this nearly every race, and one thing I can tell you is >> that whichever choice you decide, you will wish you did the other! >> >> Bill Coleman >> Erie, PA >> >> >> >> On Fri, Apr 5, 2024 at 1:48 PM David Knecht via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >>> I have a set of polars for my C&C 34+ (below), but I am unsure of how to >>> interpret the downwind data. There is no information I have found on how >>> the angles were determined. I am interested in best angles for downwind >>> work without a spinnaker going wing on wing with a whisker pole. I am >>> guessing the data is with a spinnaker and I am not sure if that matters. >>> The issue is whether to go wing on wing direct to a mark and go a shorter >>> distance vs. wing on wing or not on a lesser angle according to the polar >>> chart. I have tried to measure this on my boat and have not found a big >>> enough difference to convince myself I should tack downwind. Dave >>> >>> >>> S/V Aries >>> 1990 C&C 34+ >>> New London, CT >>> >>> Please show your appreciation for this list and the Photo Album site and > help me pay the associated bills. Make a contribution at: > https://www.paypal.me/stumurray > Thanks for your help. > Stu > > > Please show your appreciation for this list and the Photo Album site and > help me pay the associated bills. Make a contribution at: > https://www.paypal.me/stumurray > Thanks for your help. > Stu
Please show your appreciation for this list and the Photo Album site and help me pay the associated bills. Make a contribution at: https://www.paypal.me/stumurray Thanks for your help. Stu
