View Full Version : oselver verkstaden wild jib wing on wing?
01-22-2010, 12:30 PM
i was reading wooden boat mag march/april 2002 and came upon the piece on this revived viking craft now being raced in norway. the photo on top right of page51 shows the boat on a run with the clew of the 95% jib brought into midship right in front of the mast, a boom brought up and yoked to the mast, the tack of the jib attached to the boom and both released from the boat's stem and swung out to windward. the article never mentions this strange arrangement which i had never seen before.
has anyone any info on this type of sail set for reach or run sailing? i'm dying to try this on my jordan footloose to spice up next summer's sailing. straight sprit sailing gets a bit drab particularly on light wind days.
need help with understanding the technique, calculating the sail size and shape and anything that might make it successful.
01-22-2010, 03:45 PM
Acutally, I've explained it and shown pictures a few times recently on the forum. Can't quite recall which topics, but probably in one of them about færings.
The jib on an oselver is flown off a boom. The front stay is attached to jib boom. It is tensioned in the bow with a downhaul - usually attached to a small 4 spun block & tackle leading back to the mast or that area. The mast and stays are tuned to have full tension and stand upright when the jib boom is drawn completely down and settled in a notch in the bow.
In upwind work, the front stay is drawn tight and the jib is controled with the sheets as any jib.
In downwind work like a broad reach, the jib boom can be released in the bow and swung out into clear air. The sheets are then used to get a good shape to the jib in that position. This allows the jib to fly with the same kind of laminar flow over both sides usually only possible in upwind work ... the jib can continue to pull as an airfoil many degrees more than a regular jib system - where the jib becomes something more of a 'sack' to collect wind on one side only.
Running directly before the wind, the jib is swung out to 90 degrees and is given only a slight shape by letting the sheet out enough to allow a little wind to reach around the back side - which I expect generates a bit more power than a simple wind catching bag the normal jib becomes in the same situation. The main is swung out to the other side, bringing the jib into clear air.
The jib boom is controlled by the downhaul and a port & starboard outhaul. Swing it out to where you want it, tension the outhauls and then the downhaul. In effect, the mast has no forestay - but the wind is from behind and it isn't needed. When you tack upwind, the first thing you haul in and tension is the jib boom. That must be in place before rounding, because it is impossible to haul it into its seat if you are slow.
The jib in a oselver is a standard jib in all other respects. Same sheeting and uphaul. Downhaul/cunningham runs from the sail, through a ring or block near the forestay bracket and back along the jib boom to a clam cleat. The racing oselvers use exclusively high-tech fibers - mylar-kevlar and such, but any jib will fly.
Found the post with a picture.... http://www.woodenboat.com/forum/showpost.php?p=2425133&postcount=26
Post 27 also.
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