Wishbone boom

[delite]

I have seen local sailboat that is about 30 feet with a wishbone boom. It could be a Nonsuch but I am sure it also had a foresail. I am curious what advantages a wishbone would provide on a boat of this size. How about disadvantages?

[kwaltersmi]

A wishbone boom and/or cat rig are great for simplicity and ease of use. I've also been told they are great off the wind and downwind. However, they can be limited when sailing to windward.

[killarney_sailor]

Wishbone boom rig is self-vanging so the rig is very simple with only two sail controls - the sheet and a choker line which is like an outhaul in function but is at the mast. Sometimes, not often, you will see a wishbone on a fore and aft rig - often a schooner but most common on catboats.

[Jeff_H]

I keep hearing people say how easy a wishboom boom is to sail. I have sailed on several and frankly do not find them simple at all, at least if you care about sail shape. (If you don't care about sail shape then any rig is easy to sail)

Getting proper sail shape with a wishbone boom is a delicate balancing act between the snotter and the outhaul. The snotter changes the height of the of the leading edge of the wishbone as well as its fore and aft position. It effectively acts like a jib sheet lead block changing the angle between the clew and the outhaul. The outhaul acts in part like a jib sheet when going upwind pulling in and down thereby controlling the twist and draft.

The shortcoming of the wishbone boom is that it is not rigidly fixed and therefore the flying position of the wishbone (relative to the sail) changes with windspeed and angle of attack, as does its fore and aft position which effectively automatically adds or takes away twist and auto-powers up or depowers the sail. The mainsheet is typically set up so it typically only controls the angle of attack, but because the geometry of the boom end to the deck is not stable, the after end of the boom rises in a gust and so the mainsheet pulls it more toward the centerline over trimming the foot of the sail (the opposite of dropping a traveler and backwards of what you ideally want to happen).

The result is that a conventional rig has a more stable flying shape which is easier to trim and leave, and with the impact of the adjustments somewhat isolated directionally, on a conventional rig it is easier to diagnose and make small corrections than on a wishbone where every adjustment is interconnected.

Jeff