I have a 2008 Jeanneau 39i. Today, while sailing in 18 to 20 kt winds, with the boat doing around 7 kts ( not racing just mucking about ) I noticed the head stay "bouncing" a bit in the strong wind.... I don't recall ever seeing a head stay that was ( my words: looking a bit loose ) moving this much. Any thoughts? is this normal on a 7/8 fractional rig. I've never owned a fractional rig before.
roller furling. no electric winches, was just up the mast for inspection a week ago.. no issues.
back to the question. head stay "bouncing " a bit ... never saw this on my other boats. this is the first time i've owned a fractional rig. and I don't see any adjustment options on the head stay. is there an adjustment I'm not seeing on a Selden mast, 2008 Jeanneau 39i , and how much lateral movement under sail do you see in your head sail?
How firm is your leeward shroud in 20 knots wind? If it is loose the shrouds may need tensioning. With swept back spreaders, the shrouds are most important on forestay/headstay tension. Selden do have a a very good manual on mast adjustment on their website. Alternatively get a rigging specialist to check the rig over, very good for peace of mind
What point of sail were you on and what was the sea state?
All masts pump when going to weather in steep seas. On some boats you can counteract this somewhat by increasing backstay tension. A lot of Jeanneaus don't have backstay adjusters and in any case there's a limit to what you can do with a fractional rig. If you're beating in 20kts you probably want the backstay hard on in any case.
Do you have video? This is a matter of degree. If it's pumping a little bit then it's normal, if it's an excessive amount then you have a problem. It could be anything from problems at the step to rigging tension or even a failing shroud swage. Take a good hard look at your rig and if you aren't confident in what you see then it's definitely worth getting a rigger to do an inspection. But I'd start with video, if nothing else you can show it to a rigger and get an expert opinion.