Seamanship

[Wrong]

My view is diametrically opposed to the idea striking the main is a best case scenario in most situations. The one exception is on approach to one's destination. In this case, provided the wind is not too close to maintain course and speed under jib alone, lowering the main en route is a good choice.

However, I often wonder what sailors will do in the case conditions require heaving to and the main is down... A mainsail with three reefs provides the option of reefing down and sailing under main alone on most tacks without putting excess strain on the mast and rigging. Faced with the need one can still heave to. Not so with only a headsail up...

[Rustic Charm]

Originally Posted by StuM

Specifically, it's LP (Luff Perpendicular) which is the width from luff to clew at right angles to the luff. (as opposed to at the foot which some people think.

Once again Wikipedia gets it wrong. Note that a 100% genoa overlaps the mast, contrary to what Wikipedia's definition would imply.

Doh! now I'm all confused. If wiki is wrong (which flabbergasts me), can someone sketch a rough idea of what your talking about?

[sjaversa]

Would the same principles hold true for a catamaran

[StuM]

Originally Posted by sjaversa

Would the same principles hold true for a catamaran

Yes, that is correct. (The forum software wouldn't let me just post the word 'Yes" by itself)

[StuM]

Originally Posted by Rustic Charm

Doh! now I'm all confused. If wiki is wrong (which flabbergasts me), can someone sketch a rough idea of what your talking about?

Wikipedia says "Genoas are categorized by a percentage representing their area relative to the 100% foretriangle"

It is actually LP/J expressed as a percentage.

in the drawing below, the sail (green) triangle is 100% of the foretriangle, but the LP measurement is considerably less than the J measurement, so this is not a Genoa, it is something around a 90% jib.





A 100% sail where LP = J would, of necessity, extend back past the mast.

[OldFrog75]

Originally Posted by StuM

Wikipedia says "Genoas are categorized by a percentage representing their area relative to the 100% foretriangle"

It is actually LP/J expressed as a percentage.

in the drawing below, the sail (green) triangle is 100% of the foretriangle, but the LP measurement is considerably less than the J measurement, so this is not a Genoa, it is something around a 90% jib. A 100% sail where LP = J would, of necessity, extend back past the mast.

I said the same thing in an earlier post (posited more as a rhetorical question) further up but I should have known Stu would get on the case in his usual inimitable and thorough style.

A picture is truly worth a thousand words.



PS. But I still don't understand why the industry uses this convention rather than simply dividing Foot/J. Would be a lot less confusing.

[StuM]

Originally Posted by OldFrog75

Wouldn't it be easier to just divide the length of the foot by the "J" measurement and call it a day?

No, because the length of the foot doesn't determine the total sail area, but the LP does. A high cut yankee style sail and a deck sweeper with the same LP will have the same area, but will have very different foot lengths.

Think about it. The area of a triangle is 1/2 base x height which is 1/2 luff x LP). You can't work out the area of a triangle from the lengths of two adjacent sides. (luff and foot)

[OldFrog75]

Ok. Now that the original thread has been thoroughly hijacked...

I thought the definition of a jib was 100% or less but the definition of a genoa was any overlapping headsail.

Since we've determined that a 100% sail is in fact overlapping does that mean the definition of a jib is 90% or less?

[John_Trusty]

If Wikipedia is wrong, why not change it? We apparently have some real experts on this post, so why not one of you going to WP, delete the wrong and copy in the right. I guarantee that the average page hits on a WP link is much higher than the venerable Cruiser's Forum.

Not knocking my community, just saying that we need to spread the knowledge.

[DefinitelyMe]

Originally Posted by zeehag

when picking a mooring, i double dog dare you to be able to steer a sailboat into th e position you need without the jib, so last sail down is jib.(engineless mooring pick up)

Hey Zee. I haven't yet found a boat where you couldn't sail up to a mooring under main alone, you just need a bit more room for reaching back and forth with the heavier, full-keeled variety. I approach on a reach, furl the genoa/jib and then the foredeck is free for dealing with the pickup. Then come up into the wind and stop the boat right by the mooring. The main doesn't come down until the boat is firmly on the mooring. That way, if i screw up there's still something up to bail out with!

[DefinitelyMe]

Originally Posted by Wrong

My view is diametrically opposed to the idea striking the main is a best case scenario in most situations. The one exception is on approach to one's destination. In this case, provided the wind is not too close to maintain course and speed under jib alone, lowering the main en route is a good choice.

However, I often wonder what sailors will do in the case conditions require heaving to and the main is down... A mainsail with three reefs provides the option of reefing down and sailing under main alone on most tacks without putting excess strain on the mast and rigging. Faced with the need one can still heave to. Not so with only a headsail up...

A lot of boats will heave-to very nicely under storm jib alone, with no main. Some require it in fact. I've never come across two different boats that heave-to in the same way yet.

[Dockhead]

Originally Posted by StuM

Wikipedia says "Genoas are categorized by a percentage representing their area relative to the 100% foretriangle"

It is actually LP/J expressed as a percentage.

in the drawing below, the sail (green) triangle is 100% of the foretriangle, but the LP measurement is considerably less than the J measurement, so this is not a Genoa, it is something around a 90% jib.





A 100% sail where LP = J would, of necessity, extend back past the mast.

Learn something every day!

Thanks, Stu!

[Jon Eisberg]

Originally Posted by DefinitelyMe

A lot of boats will heave-to very nicely under storm jib alone, with no main. Some require it in fact. I've never come across two different boats that heave-to in the same way yet.

OK, I'm curious...

Can you name a few?

Fore-reaching I can see, but actually maintaining a classic hove-to position under a headsail alone? That I'd like to see...

;-)

[DefinitelyMe]

Originally Posted by Jon Eisberg

OK, I'm curious...

Can you name a few?

Fore-reaching I can see, but actually maintaining a classic hove-to position under a headsail alone? That I'd like to see...

;-)

Well, mine's not too bad under jib alone but you're right, i guess it would be fore-reaching rather than heaving-to. I've also done it on a Beneteau 375, and the two are very different boats. I'm guessing you consider the 'classic hove-to position' to be going sideways and maybe a little forwards with the bow just a little off the wind? In that case no, i don't think i've ever tried that with just a jib and i don't think it would work very well as you need the strapped main to push the stern around and keep the bow into the wind. A couple of friends of mine reported having been hove-to (fore-reaching i guess you would say) in their maxi 95 off Bermuda (en route from the Bahamas) under jib alone. They liked having the beam on to the waves a bit more than the 'classic' posture would allow as it allowed them to slide down the face of the rather large swells they were encountering. It also allowed them to make way in the right direction without having to have anyone on deck.

I guess i've never really made the distinction between fore-reaching and being hove to. I started off on square-rig tallships and the term 'fore-reaching' wasn't a term we used.

[kerrydeare]

Originally Posted by OldFrog75

... Wouldn't it be easier to just divide the length of the foot by the "J" measurement and call it a day? ...

Not to risk semantics, but if all jibs were cut as right triangles, then maybe so.

High clew jibs (sometimes called "reachers") don't qualify and would not give the same arithmetic result. Also many heavy weather jibs are cut "high" to avoid catching a big sea.

Even today I still think the Wall Ross book "Sail Power" says it all very well.