When sailing to windward with a fractional rig and full batten Main, how much of a bubble should there be on the luff of the Main. Our boat is Shoal draft so we need to sail her kind of fat, but I still want to get as close to the wind as possible. The jib we run is a 129% racing sail. Thanks for the feedback
Mainsail Bubble
- Thread starter Sail Fast 356
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Sail Fast 356: The bubble comes from the jib backwinding into the main. A lot of guys don't think it is a big deal and it probably isn't but personally I prefer to sail without a bubble. Think of the sail in a wind tunnel with smoke blowing over it. The bubble does distrupt the air flow. On a mast rig rig, the engine is the jib, which is trimmed first. When I trim the main, if the telltails are flowing, I'll tolerate the bubble because the only way to eliminate it is to trim in the main, which might distrupt the flow, so I carefully watch the telltails as I trim in. If they start to get screwed up I stop trimming. On a fractional rig, the main is the engine and is trimmed first. If it were me, I'd carefully back off the jib to elimate the bubble and see what happens. The bottom line is that if you have to sail with it, it is no big deal. If you are a purist like me, everytime I looked at it I'd want to eliminate it. My wife does not refer to me as a purist - she calls it anal!!
Sail Trim?
The pictures of a 356 on this site show the chain plates and spreaders to be quite wide, so I'm trying to figure out how you could sheet in a 129% around that spreader and be able to back wind the main. Is your main very full or the entry on the luff very full? you should be able to tighten the outhaul and with a hand tight main halyard have the max draft position in the main at about 45-50% and minimum depth. Maybe you don't have enough pre-bend in the mast to accomodate the luff curve of the main. Can you post a picture of the rig with main sail hoisted?
The pictures of a 356 on this site show the chain plates and spreaders to be quite wide, so I'm trying to figure out how you could sheet in a 129% around that spreader and be able to back wind the main. Is your main very full or the entry on the luff very full? you should be able to tighten the outhaul and with a hand tight main halyard have the max draft position in the main at about 45-50% and minimum depth. Maybe you don't have enough pre-bend in the mast to accomodate the luff curve of the main. Can you post a picture of the rig with main sail hoisted?
Main Bubble
The Jib tracks are on the cabin top which allows a narrower slot. Usually when on the windward leg we bring the jib all the way in and then ease out the main until we just get a bubble provided all the tell tales are flying. I usally try to drive by the Jib tell tales. This may be the wrong idea?
The Jib tracks are on the cabin top which allows a narrower slot. Usually when on the windward leg we bring the jib all the way in and then ease out the main until we just get a bubble provided all the tell tales are flying. I usally try to drive by the Jib tell tales. This may be the wrong idea?
Mainsail trim
With a fractional rig, I'm guessing you don't have a basckstay adjuster, so flatening the main is likely limited to progressivly tightening the outhaul and making sure you don't have too much halyard tension which tends to move the draft forward. I'd also play with the mainsheet tension and position of the traveler to get all the teltales on the main flowing. If you have a boom vang, it should be loose to allow the traveler and mainsheet to control twist. Check the leach chord on the Genoa to make sure it's not closing the Genoa leach and contributing to backwinding the main, and try moving its Genoa car back a little, if the bubble is near the top of the main. Move the car forward if the bubble is nearer the bottom of the main.
With a fractional rig, I'm guessing you don't have a basckstay adjuster, so flatening the main is likely limited to progressivly tightening the outhaul and making sure you don't have too much halyard tension which tends to move the draft forward. I'd also play with the mainsheet tension and position of the traveler to get all the teltales on the main flowing. If you have a boom vang, it should be loose to allow the traveler and mainsheet to control twist. Check the leach chord on the Genoa to make sure it's not closing the Genoa leach and contributing to backwinding the main, and try moving its Genoa car back a little, if the bubble is near the top of the main. Move the car forward if the bubble is nearer the bottom of the main.
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