Nacra Mast Ball Movement

I've never noticed them moving, but it's not surprising. It's a part that should be replaced every few years, depending on usage.

They only squeak in light air.

sounds like the mast ball socket isn't smooth enough to "slide" over the slippery mast ball and is instead "grabbing" the ball

next time the mast is off why not run your fingertip around the cup and check for any burrs or roughness

if there sand it out with a dremel, (big burr) or fine wet and dry sandpaper, (slight roughness)

i wouldn't think slight turning of nylon threads is going to damage a stainless thread

it's not like the mast is going to go round and round and unscrew the ball enough to reduce the number of threads carrying the load

Get some round ball type polishers that will fit on the end of your drill motor. I got a bunch of different types from McMaster Carr. I kept getting a flat spot after one or two sails and it squeaked. After polishing no problems. It took a good amount of work, I don't think wet/dry sand paper and a finger is going to do it.

Thanks for the advice. I will look at polishing the mast base socket. As for damaging the threads on the rod that was not the concern. The concern was the ball and failure inside the ball with the threaded portion. Thanks

On my previous boat, N5.0, I had that problem, I didn't have a factory mast base but one made in a workshop, with a non perfectly spheric cup, so it would "grab" the ball instead of sliding around it. I tried tightening the ball really hard and at some point it did stay in place, but it was too much, I damaged the thread and deformed the ball, so I had to replace it. My biggest concern was that the thread would get damaged after time but it didn't happen. I still had the precaution to secure the mast base with a short line when lowering the mast, to avoid dropping it if the ball popped out. I still do that now but I probably exagerate.
On my N5.5 I don't look at that too much, I think it's okay but at some point I saw the ball rotating instead of the mast, tightened it a bit more next time and forgot about it.

My biggest concern is when I drop the mast. Will the threads in the ball fail and then pop there goes the ball when lowering the mast and it is a fire drill from then on.

Long ago there was a thread about the ball popping out, maybe at at catsailor.com. The causes of damaged or weak threads were not the point in discussion but the possibility of the ball popping out and the consecuences. I think it did happen to more than a few, so it is a possibility. The old N5.0 masts didn't have a captive system, and so was the case of my first workshop made mast base.. What happens is:
if you do nothing, the mast will drop at some point quite violently. Nothing you can do to avoid it, Newton does it all..
If you secure the base with a short line, it will pop out but you can still hold the mast if you are paying attention

Mast balls rotate on both my 5.0 & 5.7
Initially I tried turning them on a bit tighter, didn't help. Last couple years, I just quit thinking about it. The 5.7 especially, I can grab the mast & rotate, & see the ball move with the socket. It has not done anything to the threads. I am to lazy to attempt polishing the socket in the mast base.
The mast will not pop off when lowering, as long as you have the pin in place.(Or use a 1/4" bolt, pip pin, even a short screwdriver...just DON'T SAIL WITH THE PIN IN PLACE).
I suppose polishing & a bit of lube would extend the life of the ball, but really, they are a wear item. I have 120 days on a new ball, it shows a millimetre or so of wear, looks like it will last years.
All the ones I've seen do flatten off on the top. Eventually they will develop cracks, & probably fail. Once you see cracks, throw it away & screw another one on, good for another few years.

i sail nacras. in the last 2 years, i've cut a circle from the side of an empty milk container which is plastic and slip it into the mast base. i make it just large enough to fit firmly when pushed by hand so it doesn't shift around. then i apply some grease to the plastic and the mast ball and step the mast.

i figure the plastic will last one year and then change it out. i used to have flat spots on top of my mast ball from the friction of the metal base but not any more. i think hobie sells disks for just this purpose.
j

Thanks for the advice! Kevin

If you want to ensure that the ball stays connected to the striker post and that it doesn't rotate, then drill a hole through the ball and through the post and install a 1/8" diameter stainless roll pin. If you ever need to replace the ball, just tap the pin out with a drift and then unscrew the ball.

Or an even simpler solution that I don't see mentioned would be to just put a little loctite on the threads of the striker post. Then put a dab of bearing grease inside the mast step socket or on the ball to cut down friction. This would be the easiest solution and will probably take care of the problem altogether.

sm

Edited by Dogboy on Mar 28, 2014 - 10:16 AM.

If one of you are going to put a pin through the ball and striker post, make sure you lubricate the ball often too. Otherwise the pin may shear the ball apart if there is sufficient friction.

Hey Zach, I assume this has happened to you and your dad (shearing a pin)! See ya next week at the fleet meeting.

:mischuge: