Physics of Sailing - Steering with CE and CLR

This video is a screen recording of part of a webinar delivered in Spring 2020 to a class of new sailing instructors.

Topics covered in this video include:
- Forces, and the centre (location) where forces act
- Steering moments and the effect of multiple forces on the boat
- The effect of sail trim and boat heel, and other actions on the location of the Centre of Effort and Centre of Lateral Resistance (and associated steering effects)

[howarthsailing]

Hi Everyone,
I made some changes to my channel this winter that resulted in YT deleting all of my comments/replies on these videos. It's really a shame, because I feel like I have answered quite a few theory questions in the comments section over the years. If you have a question, even if it looks like it's been asked before, please don't hesitate to post a comment, I'll do my best to get back to you.
Cheers,
JH

[lamorimferreira]

Very interesting video, congratulations!

[robinj]

Really good instruction, well instructed, I understand everything of your content. What confuses me is the info from the Naval Architects. Much of the boat building literature talk about a lead of how many percent forward is CE should be of CLR. If you have a 2% lead, it would mean that the boat has a slight lee-helm when upright, and when healing into the lee-side it will counteract into a weather-helm?
I'm aware that CE and CLR are geometrical values. And that the true hydrodynamic CLR and aerodynamic CE will be somewhere different. But then what's the reason of the CE lead? Is it just an empirical method of achieving a as low of a weather helm as possible? Since a 0% lead will have more weather-helm and more counter steering.

[moarefk]

Hi there,

I love your videos ... truly rare information explaining the physics of sailing... but when watching this video, I was thinking it must be very different with a catamaran since you have two foils but one sail and CE and CLR is always apart, .. could you make a video for this topic for catamarans ?

[robdarby]

Hi Julian, I'm trying to solve a weather helm issue in a Flying Fifteen, which is an early Classic fleet boat so doesn't have a particular set of dimensions, the Classic boats all seem to be dimensioned and rig a little differently. The mast foot has 3 positions, the forward and aft positions being about +/-40mm from the central position. I currently have the mast foot in the forward most position and I'm still experiencing weather helm. Previously I extended the shrouds to get the mast rake as far forward as possible. This did produce a neutral helm, however other aspects of the rig were stupid, the boat looked awful with the boom climbing to aft and the gib clew way above the deck. So I have now reverted to a more normal geometry. I believe I cannot sensibly get the CE further forward than the current set up. Neither is it an easy task to move the keel on a Flying Fifteen, well pretty much impossible! I am wondering whether the rudder itself may not balanced. I'm not sure this is a thing in sailboats (but I believe it is in power boats). The Flying Fifteen rudder is very raked backward with the pivot point close to the top leading corner. This suggests to me there is potential that the rudder itself could have a CLR to aft of the rudder pivot point. If so, this would effectively make the rudder bear down and produce a weather helm effect on the tiller, the tiller being on the opposite side of the rudder pivot point. Does this make any theoretical sense?

[daio]

how did you do it can you share with me, thank you

[ME-rvpw]

Your arrows throw me off with some starting at the point and some terminating at the point of force

[jillgouhin]

how did you do it can you share with me, thank you