Free body diagram of a sailboat

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Discussion Overview

The discussion revolves around the physics of sailboat dynamics, specifically addressing the phenomenon of a sailboat "rounding up" into the wind during high winds while heeled over. Participants explore the implications of sail configuration, forces acting on the boat, and the effectiveness of the rudder in these conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the rounding up behavior of the sailboat and questions why it occurs when only the foresail is up, suggesting that the force should not allow the boat to turn toward the wind.
  • Another participant emphasizes the importance of the relative positions of the center of pressure (CP) of the sail and the center of lateral resistance (CLR) of the boat, arguing that these positions determine the moments acting on the boat.
  • A different participant explains that the CP of a Genoa sail is typically located forward, which may not counteract the turning moment created by the mainsail, suggesting that adjustments to sail size and shape can influence the rounding tendency.
  • Concerns are raised about the adequacy of the participant's free body diagram, noting that it does not account for the rudder's effectiveness when heeled or the changes in wetted hull area and forces on the sail and keel.
  • Another participant reiterates the importance of the rudder's effectiveness and the dominance of underwater forces in the rounding up behavior, particularly in relation to different keel and rudder configurations.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the factors influencing the rounding up behavior of the sailboat. There is no consensus on the adequacy of the proposed diagrams or the specific contributions of various forces and configurations.

Contextual Notes

Participants highlight limitations in the discussion, including the need for more detailed analysis of forces acting on the boat, the effects of heeling, and the specific configurations of sails and keels. The complexity of these interactions remains unresolved.

  • #31
sophiecentaur said:
The situation as described poses a problem under really bad conditions as it implies that you need to heave to and can't run before a storm.
How so? The boat will round up. That's what you want, if you want to stop sailing.
 
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  • #32
sophiecentaur said:
I don't think the Physics approach will help too much here. After all, even with a lot of computing power and know how, there's still a need for physical testing on cutting edge hydro and aero dynamics designs. So - no shame in a practical approach here.
Well, this is what I was afeared of. See post 19. ... and post 1. You guys are expanding the scope beyond answerability.
 
  • #33
DaveC426913 said:
How so? The boat will round up. That's what you want, if you want to stop sailing.
I have heard. though, that when conditions are really bad (no personal experience) it may be better to run. But (bad metaphor, perhaps) it's a rock or a hard place.
 

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