YM Dec 2011: 11 Ways ... "Weather Helm"

[nigelmercier]

There is a very interesting article Yachting Monthly Dec 2011: "11 ways to make upwind sailing more fun". However, I'm confused over the box at the bottom of Section 4, Page 24: "What is weather helm?"

The text above the first picture (see attachment) says "lt happens when the sails' centre of effort [COE] the 'middle' of their power - is behind the boat's centre of lateral resistance [CLR], referred to here as water resistance, which is pretty much the keel..."

I'm quite happy with that, but why does the picture below (captioned "Good balance. Just a touch of weather helm") show the COE that is forward of the CLR?

 

[sighmoon]

It's in front of the centre of resistance, but to the left of it, so it is still creating a clockwise couple, which is why it's worse as the boat heels.

I take your point that the text and the diagram are not singing from the same hymn sheet.

 

[rob2]

Yes, the explanation given is an over-simplification of the couple. Anyone who has fallen off a sailboard will have discovered that instead of moving the rig forward, you can lean it out to windward for the same effect.

I was also reminded of the rooster tail form surface props - in my case it was my tail throwing up the spray!

Rob.

 

[Billows]

Would not the position of the centre of gravity of the boat influence the behavior also as the couple will try to rotate the boat about this point. Putting weight at the front of the boat is often the cure for boats difficult to tack.