Hi guys .. just wanted a clarification on reply from Mark last year that it's normal for some looseness at the boom front clamp leading to the clew end up and down a couple of inches if adequate up/down force applied. Is that really normal - else I will have to open the damn clamp up and shave off some plastic to make sure the clamp does not rotate around the boom front end. Tks.
Yep, both my bigger booms the clamp fitting rotates around the boom end (to allow the boom to align with the clew fitting at the clamped height)
I have a north carbon boom (an older model) that doesn't rotate at all though.
If you're talking about a "pivot head" then yes some booms have them some don't. I think the recent trend is for most booms to have them
Yes - it 'rotates' but somehow I can't tighten the two screws holding the clamp enough to prevent rotation, e.g. if its supposed to be adjusted to a certain angle to match the clew and then secured. I guess it's just busted - will try to see if I can open the thing up (involves punching out the long pins that holds the two wrap-around plastics) and shim it. Tks guys ..
If its designed for it, it is not busted and there is no way tightening it will make it stop. But I would like to know why you would want it to not rotate?
^^^^^^^ There is no reason to screw up a perfectly good boom. If the head didn't rotate, to would put undue pressure either up or down, at the clew end of the sail, deforming the natural shape of the sail. All sails have different clew heights, there is no other way to compensate for that.
Ah ok. I will 'adapt' to it then. Must be my crap riding skills .. like after a hard jump landing, the boom goes lower and I will then hanging with my ass even closer to the water. I just push it back up .. no matter, its just a hassle - as long as I know it's supposed to rotate when sailing. Will not be screwing up that boom .. no worries. Thanks.
Now you're making it sound like the boom is sliding down the mast, that's different, and it's not supposed to happen.
If it's a boom rotation at the head, as you originally said, it always instantly goes back to the neutral position due to the sail forces, so your butt shouldn't be dragging.
But if it's sliding down the mast, then you need to tighten the clamp around the mast, not the boom arms.
Yes you're not making sense.
Booms are designed to:
1) clamp onto the mast and stay where they are while sailing,
2) maintain an orthogonal relationship with the mast with almost zero rotation in yaw,
3) rotate up and down at the clew to suit different mounting heights but not to swing up and down while sailing.
What exactly is your boom doing that is contrary to any of those articulations?
Sorry for the confusion. A picture is better. The boom rotates up and down like shown .. especially after a hard landing. Should it be fixed in position or allowed to rotate up and down under strong force?
Select to expand quotestanley71 said..
Sorry for the confusion. A picture is better. The boom rotates up and down like shown .. especially after a hard landing. Should it be fixed in position or allowed to rotate up and down under strong force?
Booms typically rotate in that direction somewhat stiffly. They are held in place by the clew of the sail.
It's good form to rig the sail with minimum distance between the sail clew and the boom end. If its rigged like that it moves very little.
If it is rotating down with mast bend and not coming back up the rotation joint is too stiff.
Get the opinion of an experienced sailor next time you rig. You may just need to back off some bolts a 1/4 turn.
Or you want to make sure that the boom end is quite close to the outhaul of the sail. Max of 2 cm will give a more solid feel.
I have this often with my race sails when I'm leaving the beach without proper wind and I loose up my outhaul for a better drive. I hate the feeling of the boom getting up and down to much. On the outside the outhaul is set to spec and the feeling gets much more compact and direct.
Enjoy jumping
stanley - i know what you mean. i have the same problem with a recent naish carbon wave boom and severne carbon boom. the head section that clamps around the monocoque arm section is really sloppy. the constant wiggling is wearing away at the carbon arms but at least they haven't snapped yet. I have to open the head and put a roll of ice cream or margarine container plastic around the arm to pack it out and then clamp the head back on. booms and i don't get along very well. i only weigh 70-ish kg and i'm lucky to get much more than a year out of any type/brand of boom. the alloy np boom heads don't get sloppy and feel great while in one piece but the arms would usually break somewhere near the head. ive never tried a full carbon np or north boom
I think that must be it, the clew is too far away from the boom. It's the sail that should stop the clew moving up and down, but it can only do that if it's within a cm or so.
Select to expand quotedecrepit said..
I think that must be it, the clew is too far away from the boom. It's the sail that should stop the clew moving up and down, but it can only do that if it's within a cm or so.
Thanks guys! Will try that ... just in time too ... dusting off all the gear now
