Have recently acquired a 34ft catamaran. Have some basic sailing experience but a lot to learn.
Was sailing today in 15-20knot winds and when just had the jib up (no main) was getting a lot of weather helm and was ending up in the irons. The jib is a bit over 100% and was on a beam reach.
I know the basics of weather helm but have no idea what is going on here. With just a jib up shouldn't I be pushed to leward?
Gday Magic
Yeah with that boat it must be you - Margic Carpet sailed around the world fine with Chris and he could sail well (I raced against him back in the 90s). She is based on a Crowther 10 which also sail well - so the problem is you.
One of the strange things about cats and weather helm comes with the boards. IF you go on a reach and you don't put the boards down the boat slips sideways. The only thing stopping the boats leeway are the rudders which then get pushed by the leeway and get loaded up with weather helm. I am guessing you did not put the boards down when sailing. In fact using weather helm is not a bad way to trim the boards - leave them up but when you feel slight weather push them down more. Actually just put them down when sailing any close than a broad reach - you only need them half down for beam reaching but go full down for anything closer to the wind. For the jib to do its normal thing and balance the boat you need something for it to pivot around. Keelboat sailors never have this issue because they don't pull up their keels but cat sailors can't get the jib to make them bear away if the boards are not down to pivot around. Now if the boards were clean and fully down then I am stumped - actually ensure the hulls and rudders are clean - nice cats don't do dirty bottoms - they don't sail well at all with any growth. BUt Magic is easy to clean - float her in 4ft of water and scrub away - you will be done in half an hour.
So if you did have the boards down a bit, there is another possibility - you were going too slow. Cats don't like having only a genoa up - the sailplan is not setup that way. Masthead monos can but 3/4 rig fractionals don't like it. The boat will stall and the foils won't work well. I often sail under genoa only when on a square run, but a beam reach is asking for the main to be up too. I reckon if you put the main up, the foils will start producing more lift and the rudders will work nicely - in 20 knots you really want to be sailing along at 7-9 knots on a beam reach. Your boat will need a certain speed before it can work in a 20 knot breeze. Here is how I like to sail a fractional multi on a reach. Pull both main and jib on and have the main and jib luffing a little. AS the boat speeds up the apparent moves forward - you wind the jib on more and more till the luffing stops. Travveler down the track 70cm or so, then you pull the main on. The boat speeds up and then genoa luffs so you click it on a few cm. Then the main luffs but you DON'T trim to stop the luffing. Look up at the leech telltale on the third batten (Put on there if you don't have one). Pull the main on till it hides behind the sail half the time. Feel the helm - if there is too much weather helm drop the traveller some. Don't worry about the telltale now - drop the traveller a cm or two till you have comfy weather helm - just find the balance between helm and main trim. She should glide along at 9 knots or so in a 20 knot beam reach - hitting 12 in the gusts. She should feel GREAT on the helm. Trim the jibs luff, trim the main for helm once she is moving - its the only way to sail.
cheers
Phil
Hi Phil,
Yes I was definitely clear that it was not the boat - she is far more capable then we are :-D.
That information is excellent. Was sailing with the boards up and just didn't understand the forces at play.