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post #1 of 8 Old 11-24-2007 Thread Starter
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Centering mast in the partners

I just tuned the rig on my 30' keel stepped sloop because the boat had excessive weather helm on Port tack. I'm replacing the wedges at the partners with Spartite, so I want to be sure the mast is placed correctly at that point. The pre existing wedges push the mast about 1/2" more to Starboard than where it sits naturally. This position (the original position)places the mast an equal distance between the outside of the port and starboard hull. One book I read claimed this is the correct position, but I have received some conflicting information. I have sailed the boat several times since the tune. Everything seems fine, however, I have not encountered strong wind. Thoughts on mast placement in the partners?
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post #2 of 8 Old 11-24-2007
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Well certainly the mast base, the mast track and the mast head should all be on vertical plane thru the centerline of the boat...generally there should be equal spacing on either side of the mast where it passes thru the partners. As the partners might not be centered, when I did my Spartite, I centered the mast in the partners, then also measured to the rails to confirm that location was in fact also on the centerline of the boat. My recollection is the instructions say to be sure the mast is set with whatever pre-bend you may use, but no backstay applied...

You comment about the wedges pushing the mast to one side is puzzling - are the wedges diferent widths, or what?
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post #3 of 8 Old 11-24-2007
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Umm... have you measured the mast partners to see that they're actually on centerline and symmetrical? If either the mast step on the keel or the mast partners in the deck is slightly off, the alignment of the mast will suffer greatly. Probably worth checking.

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post #4 of 8 Old 11-24-2007
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This can get difficult.

1) The boat has to be level. Get a spirit level. Pick a dead still day. May not be possible for your locale.

2) When level, put two pieces of heavy tape across the partners. Make sure they intersect dead center in the partners' hole. Use a ruler.

3) Drop a heavy thread with a lead sinker on it to just short of the mast step, and I mean 1/4"/0.5 cm.

4) Get someone light, like a little girl with her wits about her, to go below and put a dot with a felt pen directly under the lead sinker...BUT make sure the boat is still perfectly level, which may involve two spirit levels (fore and aft and port and starboard) at right angle (use the partners, plus a pair of opera glasses to READ the levels as you move around the boat to achieve levelness.

Then you've got to wait for the pendulum you've made to stop swinging and start just hanging.

However, if you do these things, you will have the means to determine easily how aligned your partners is to the step below.
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post #5 of 8 Old 11-24-2007
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The trouble with centering based on the hole through the deck is that the hole may be out of center. Measure the distances to the rail of the boat in all directions to find the center of the "hole" and tune accordingly. If you are not comfortable tuning, then get a rigger to tune it and then pour your spartite. The spartite sets up very fast.
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post #6 of 8 Old 11-24-2007 Thread Starter
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Yes, the wedges are different sizes, and no, the partners are not centered between the rails. According to the Spartite instructions, this is fairly common. If the mast head is centerd, and the mast is centered at the partners, does it make a differnce if the mast step is off a 1/2"? Wouldn't this be the same as a deck stepped mast which is centered? I hope so, because The step is fixed.
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post #7 of 8 Old 11-25-2007
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i would think that 1/2 inch on the mast step would be noise, i.e. not to worry abouit.
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post #8 of 8 Old 08-06-2012
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Re: Centering mast in the partners

i have seen many references to Spartite. Is the the best way to go with securing the mast at the partners? is a mast collar still necessary after using spartite?

Thanks
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