lapping the jib

[Brian Wood]

what are the advantages or disadvantages of the jib overlapping the main?

[Ian McColgin]

The overlapping jib creats somewhat better velocity in the slot and, since the rating rules do not count the extra sail area, is "free" whether particularly efficient or not.

If not trimmed correctly, especially in combination with a baggy main, it may slow the boat more than it's smaller lockermate.

Most sloops are served well in light and moderate air by a jib that's 120% or so of the foretriange area. You'll go faster in light air with bigger but it may or may not be worth the work for you.

You should also have a jib a bit under 100% if you expect to sail with speed, grace and comfort in a fresh breeze - Force 5, average wind about 19 knots - or more.

[Bruce Hooke]

On an existing boat it's a way to get extra sail area without making major changes to the rig like lengthening the mast. On the other hand, it's a lot more work to come about with a big overlapping genoa because all that overlap has to get past the mast, so for leisurely sailing on a boat not intended for racing, designing the boat so that it does not need a lot of overlap in the jib to get enough sail area for light air sailing has some real benefits.

While we’re at it, let’s cut the clew fairly high so that we can get a good view forward under the sail. Deck sweeping genoas make sense on a racing boat because of the way the rating rules work and as a result they seem to have become standard on non-racing boats where they make much less sense.

[ahp]

The area of the jib that overlaps is about half as effective as that foreward of the mast, but the handicap rules don't measure the overlap, thus you get more area for "free".

Can you think of any strict one design class with any significant overlap? I can't.

[rbgarr]

The Flying Dutchman class comes to mind. http://www.sailfd.org/50thanniv.htm

Technically, sailing to windward with an overlapping jib, in combination with the mainsail, enables the boat to sail closer to the wind's direction by increasing 'upwash' on the headsail and allowing the mainsail to be trimmed to a higher angle of attack (i.e., to windward).

An overlapping jib actually decreases any 'slot velocity change' compared to a non-overlapping jib.

[ 01-27-2005, 12:39 PM: Message edited by: rbgarr ]

[johnw]

Most rating rules do count the overlap, but not all of them. None count overlap area as much as they do foretriangle area, which is a shame. If they did, the winches on our boats would be smaller and our boats would be easier to tack.