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Hobie 16 main sail luffing
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=59714		 Page 1 of 2
Author:  jonathan.olivier [ Tue Jan 03, 2017 1:20 pm ]
Post subject:  Hobie 16 main sail luffing
Hi Guys

We have noticed that on a close haul our main sail starts luffing (see image). This while the jib is not. All telltails on jib are fine and we are pointing more or less as high as others around us. Why would this be doing this? I've been trying to read up about the slot between the jib and mainsail, although this seems more like a black art. Its either right or not.

Is it the jib causing this? It feels to me that we are losing a lot of power because of it (and it just doesn't look right). Has anybody experienced this before?

Thanks


Imagepost images
Author:  Matt15 [ Tue Jan 03, 2017 2:40 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Looking at your photo you can see the creases in your mainsail which tell me you don't have enough down haul tension.
Author:  mmiller [ Tue Jan 03, 2017 4:22 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Agreed... needs more downhaul and at some point in wind speed... some travel the jib out a bit. The "slot" should be a curved match to the main luff and jib leech. Sit to the lee side and view. Adjust the clew block attachment up or down to adjust the shape. Up on the clew blocks pulls down on the leech tightening the slot at the top and opens the bottom.
Author:  srm [ Tue Jan 03, 2017 6:44 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Hard to tell for sure, but looking at the picture (the mast head particularly) it almost looks like the mast is counter-rotated. If that is the case, then you will definitely have performance issues.

Otherwise, more downhaul, sheet harder, and get out on the wire.

sm
Author:  MBounds [ Tue Jan 03, 2017 7:02 pm ]
Post subject:  Re: Hobie 16 main sail luffing
I have to agree with sm - the mast looks counter-rotated - not just in the masthead, but in the way the mast is bending and the gooseneck appears to be on the windward side of the mast.

If you do that enough, you're going to break your mast.

Counter-rotating is a problem in heavy air when the jib is sheeted in tight before you get the main in. The back pressure from the jib causes the "bubble" in the main and prevents the mast from rotating properly.

When powering up from a standing start or after a tack, sheet the jib in tight to help bear away, then loosen it a bit (about 6" - 12") until the main is fully sheeted and mast rotated properly. Then sheet the jib in tight.
Author:  AntonLargiader [ Wed Jan 04, 2017 6:27 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Is your main halyard hooked at the top? If not, it will probably loosen over time and contribute to the loose luff, as well as giving you mast rotation problems.
Author:  HobieMarty [ Thu Jan 05, 2017 10:15 am ]
Post subject:  Re: Hobie 16 main sail luffing
When I try to zoom in on that picture, I can't tell anything? How do you all see the details of mast rotation and all? I do agree, if the halyard is not hooked at the top of the mast and the down haul is not tightened down, the you will indeed have wrinkles. Looks like you are hauling ass though. Lol!!!!!
Author:  jonathan.olivier [ Thu Jan 05, 2017 10:39 am ]
Post subject:  Re: Hobie 16 main sail luffing
Thanks for the response guys. Really helpful. I can definitely confirm that the mast was counter rotated in that picture. The reason being that the mast bush was incorrectly placed, but this is easily solvable. I will try out some of the suggestions this weekend and get back to you. Hopefully with some good results
Author:  srm [ Fri Jan 06, 2017 8:06 am ]
Post subject:  Re: Hobie 16 main sail luffing
HobieMarty wrote:
When I try to zoom in on that picture, I can't tell anything? How do you all see the details of mast rotation and all?


Look at the mast head pulley. From the camera angle of the picture, if the mast were properly rotated, you would be able to see the broad side of the pulley. Instead, what you see is the narrow edge of the pulley which indicates that the luff track on the mast is pointing almost directly at the camera - mast is counter rotated.

sm
Author:  MBounds [ Fri Jan 06, 2017 10:15 am ]
Post subject:  Re: Hobie 16 main sail luffing
I can tell the mast is counter-rotated from the mast bend. It should be a concave bend away from the camera - the lower part of the mast flexes to leeward, while the part above the shrouds flexes to windward - like this: )

In the photo, the lower mast is flexing to windward, like this: (
Author:  HobieMarty [ Fri Jan 06, 2017 5:26 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Good eye, I see it now. Looks like a lot of stress on the mast.
Author:  AntonLargiader [ Fri Jan 06, 2017 9:44 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Jonathan,
When you cleat and uncleat the main halyard, is there tension on it? If so, then you're not engaging the tang at the top. The halyard should not need any tension in it while sailing if the slug on the top of the halyard is engaged in the tang. Halyard tension (if you have the main halyard on the right) will help invert the mast on a port tack.
Author:  HobieMarty [ Sun Jan 08, 2017 5:56 pm ]
Post subject:  Re: Hobie 16 main sail luffing
Is the "mast bush" another name for the Teflon mast cup bearing?
Author:  MBounds [ Sun Jan 08, 2017 6:27 pm ]
Post subject:  Re: Hobie 16 main sail luffing
HobieMarty wrote:
Is the "mast bush" another name for the Teflon mast cup bearing?
I'm pretty sure that's what he meant. Bushing > bush, although the definition of a "bushing" is a cylinder with a hole through it. The "official" part name is "mast bearing chip."

However, misplacing the bearing chip shouldn't prevent the mast from rotating, at least when the rig's not loaded up.

Bottom line - make sure the mast has rotated - and held in rotation by good mainsheet tension - before sheeting in the jib on the new tack.
Author:  smattie [ Mon Jan 09, 2017 8:56 am ]
Post subject:  Re: Hobie 16 main sail luffing
AntonLargiader wrote:
Jonathan,
When you cleat and uncleat the main halyard, is there tension on it? If so, then you're not engaging the tang at the top. The halyard should not need any tension in it while sailing if the slug on the top of the halyard is engaged in the tang. Halyard tension (if you have the main halyard on the right) will help invert the mast on a port tack.


I don't think you'd get very far without having the swagged stop engaged in the tang. When I first started sailing my H16, I could NOT get the stop engaged and desperate to sail, I simply tied the halyard off on the mast cleat. It nearly tore the cleat out in a very short amount of time. I never tried it again. That just my observation.
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