Jib pulsing.

[Quoddy]

How do I keep the jib from pulsing?
The situation. The wind was moderate with minor gusts. We are going upwind. The boat is a fractional rig without a backstay. We had the 110 factory jib on roller fuller fully deployed and a reefed main about half the square footage of the jib. The fairleads are not movable, but with the jib fully deployed the sheet points directly at the half way point of the luff. This is not luffing or flogging but a rhythmic pulsing with enough pressure to be putting obvious strain on the rig. What’s going on?

 

[SamLust]

Check your rig tension. It sounds like "pumping" to me. I know you have had issues with rig tune and my thought is you simply don't have the rig snug enough or bent properly. It requires and will take more tension than you think to bring the head stay tight enough to prevent sagging which leads to pumping. Get a loos guage. I don't care what the tune it by sound or feel guys think, unless you have been tuning the same boat for 80 years you can not do it by feel. No half way decent mechanic would tighten down a cylinder head by feel and mast rigging is no different. I set my H 260 rig with a Loos guage and did not have the problem you describe. Drop a line from your masthead to your gooseneck. There should be 3 3/4" from the line to the mast at the deepest point.

 

[Quoddy]

Forestay problem.

Thanks for that forestay idea. I have a Loos gauge and was at around 15% .I haven’t checked since early summer so I will. I thought I noticed the forestay flapping around a bit much but I thought it must be right because I believed I was at 15%. Would going to 20% or higher be in order?

 

[kloudie1]

Tighten the jib leech line a smidgen??

 

[RobG]

SamLust has it pegged

I had the same issue when I got my prevoius boat ( a fractional also) tuned to the PO's marks. Once I re-tuned, problem solved. The forstay tension will be high but I suspect your rig has stretched or the boat bent since you tuned up at the beginning of the season.

 

[SamLust]

I can't remember what exactly my setting was. I had the gauge marked with a piece of tape so I could see the tension as I tightened from the bow. I would imagine it was right up there. I had very little head stay sag.

 

[Barnacle Bill]

Well, I hate to say it, but it makes sense to have a boat with a backstay and adjustable jib/genoa tracks. If you have roller furling and bring the sail in and out at various stages, the only way to get a real good trim on the headsail is to be able to move the genoa/jib lead to a location where the luff breaks up the entire leading edge of the sail when you gradually point the boat into the wind. This is basic rigging stuff. If you have only one headsail, then one point for the lead will get you by. But, if you have more than one headsail or use a roller furling unit to increase or decrease the size of the headsail, you really need to be able to move the car on a track to obtain the best sail trim. Of course there are a few other tricks where this is modified, say in extra heavy air, where you move the lead aft a bit to spill wind off the head of the sail to depower the rig, but for the most part you want the luff to break all the way up the leading edge of the sail at the same time for best performance. Too many manufactures are building boats to make sailing so easy that you don't have to use your brain to sail. But, some sail adjustment ability makes sailing so much more fun and enjoyable and it doesn't hurt to grow more knowledgeable about the sport you love.

 

[rfrye1]

i get some "pulsing" when going hard to weather on my Hunter. Without a backstay what are your recs for adjustments, if any with the B&R rig?
Thanks. Bob.

 

[Joe]

Check your rig again... here's a guide... no loos guage required. If you trailer you boat and take the mast down alot the loos guage is handy.

http://www.cncphotoalbum.com/doityourself/masttuning/tuning.htm