Sailing Theory Tutorials - Sail Trim, Separation, and Stall

This video introduces the concepts of angle of attack, flow attachment and separation, and the stall condition.
Trimming the sail in is related to increasing the angle of attack, and it is mentioned how angle of attack can affect the lift and drag forces generated by the sail.
Trailing edge separation and stall are treated with reference to the leech telltale, and laminar separation bubbles are discussed with reference to their effect on the luff ticklers.

[@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

[@stevekirby4874]

Many thanks for your videos Julian. I’m learning so much 😊⛵️

[@algotrader8677]

Excellent ! Love the combination of theory and practice explained visually in simple terms.

[@DavidHarbinson]

Julian, I have just discovered your tutorials on Utube. I am
reasonably new to sailing so on a big learning curve. Your video on Sail Trimming Separation and stall is excellent. Really starting to understand what is happening with tell tales, why and what corrective action you need to take. Really appreciated thanks so much.

[@jamesa1116]

Superb, simply superb. Erudite, deals with the subject matter very efficiently, clear presentation with concepts building on one another and a summary. Doesn’t it make you heart sing when you find someone who is such a class act at their chosen task?

[@benmonette7593]

Just discovered your lessons, thank you for making all this public and making it so clear.

[@yachticus]

Julian - well done - excellent delivery - and a good concise explanation

[@freddyrassinger8198]

Thanks Julian. Beautifully illustrated. Well paced and the length was perfect 🇬🇧

[@g.gordonwoody645]

Julian - thank you for putting this together. You hit all the marks for content, organization, illustration, and narration. I'll never look at the head sail again without thinking about separation. I'm pretty sure the main sail gets involved with the flow as well, do you cover that in any of your lessons? Thanks again - subscribed!

[@backwaters3660]

Well explained, thank you!

[@fredericl6190]

Hello Julian, you have done some of the best explanations about sailing. But your last ones were made almost two years ago... are you going to produce some more? Thank you really much.

[@AndyMillerPhotoUK]

Very good thanks -- I need to watch it a couple of times to work out how to apply.

[@kimchambers6685]

Excellent!! Thank you!

[@cjmac8233]

Great explanation

[@liasxtube]

Very helpfull. Just bought a boat and relearning.

[@steeniversen6768]

Really good go at a thorough explanation of it. Even if I think you may have time to think some things through.

[@Argo_III]

Nicely done

[@JSBax]

Are you sure about your high/low pressure areas over a sail?
I would have thought the area behind a stalled sail would be low pressure, hence why the telltales get sucked back.
Which is basically what a spinnaker does, right? It's a permanently stalled sail.
I can't see any way to interpret the wind lines separating than to say it's lower pressure because there are clearly less air molecules in that area.
I think the lift perp to wind is better illustrated by the net flow of air downward (opposite action), as a result primarily of the windward lines being pushed down by the sail angle

[@shuajackson615]

I believe you're essentially right. As I understood, it's not that there is less air in that zone, but rather fast/turbulent currents of low pressure circulating in that area. The streamlines just don't seem to reflect that aspect. Check out actual wind tunnel videos and images and you'll see what I mean. If it were high pressure then that would not create the pressure drag that we see, since the windward side of the foil would be high pressure as well

[@FernandoLXIX]

Awesome

[@user-cs5hv3eg2i]

the best

[@triton20101]

Test

[@BrooklyFire]

why am i waching sailing theory than my course chemestry theory?

[@sissycrystobal2632]

Redo vid edit out pen selection - ask your mommy what a centroid is - moment arm too - then leave her basement