Centerboard pivot hole

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Bilgemaster
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Re: Centerboard pivot hole

Post by Bilgemaster » Tue Jan 03, 2017 10:40 am

...And further to Boat's last comment, even I can see from the visible play between the swingkeel's hole and that pin that some kind of bushing mod like Newell's described above might be a good idea...even if the centerboard's designed to be "sacrificial" in the event of a grounding. Maybe a Delrin or even PVC one? And caps on the ends of that pivot pin couldn't be a bad idea either.

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Cougar
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Re: Centerboard pivot hole

Post by Cougar » Mon Jan 09, 2017 12:34 pm

How often do you guys renew the pivot pin? Last weekend I checked the pin on my '99 :macx: and found it to be in a very decent condition, pretty sure it has never been renewed by the previous owner. Where the keel rotates around the pin, the latter is in excellent, shiny condition. AFAIK the boat has been in the water every year from April through October. The previous owner used it mainly on fresh water. We keep it on fresh in the marina, but sail on the salt almost every weekend during the season.

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BOAT
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Re: Centerboard pivot hole

Post by BOAT » Mon Jan 09, 2017 12:40 pm

Cougar wrote:How often do you guys renew the pivot pin? Last weekend I checked the pin on my '99 :macx: and found it to be in a very decent condition, pretty sure it has never been renewed by the previous owner. Where the keel rotates around the pin, the latter is in excellent, shiny condition. AFAIK the boat has been in the water every year from April through October. The previous owner used it mainly on fresh water. We keep it on fresh in the marina, but sail on the salt almost every weekend during the season.

That's a good question - It would be nice if one of the really smart guys on the site who knows about metal corrosion could give us a lesson - my understanding was that the corrosion stops when you remove the metal from the salty environment thus making the problem less pronounced on boats stored on the trailer - but I could be wrong.

There are guys out there that are experts in this corrosion stuff - engineer guys - we would need them to tell us.

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Tomfoolery
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Re: Centerboard pivot hole

Post by Tomfoolery » Mon Jan 09, 2017 1:05 pm

Cougar wrote:How often do you guys renew the pivot pin? Last weekend I checked the pin on my '99 :macx: and found it to be in a very decent condition, pretty sure it has never been renewed by the previous owner. Where the keel rotates around the pin, the latter is in excellent, shiny condition. AFAIK the boat has been in the water every year from April through October. The previous owner used it mainly on fresh water. We keep it on fresh in the marina, but sail on the salt almost every weekend during the season.
When I dropped the CB a couple of years ago, the pin was in excellent condition, as was the hanger. And I do believe mine has spent its whole life in fresh water.

There's play, but making a tight fit to the pin will only overload the tiny contact areas of the CB pin hole, which will enlarge them (mash them) to where the CB can slobber back and forth anyway. The CB is prevented from moving/angling by contact between the CB and the trunk (very large areas with great mechanical advantage), not by reacting against the pin (very tiny areas, and very poor mechanical advantage).

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BOAT
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Re: Centerboard pivot hole

Post by BOAT » Mon Jan 09, 2017 1:15 pm

So maybe it's all about salt water - salt is the key. (?)

K9Kampers
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Re: Centerboard pivot hole

Post by K9Kampers » Mon Jan 09, 2017 3:23 pm

BOAT wrote:So maybe it's all about salt water - salt is the key. (?)
But I thought you said traction was the key?! :wink:
How many keys are there?! :D

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BOAT
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Re: Centerboard pivot hole

Post by BOAT » Mon Jan 09, 2017 5:24 pm

Your Right! Too many keys!

Lethamae45
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Re: Centerboard pivot hole

Post by Lethamae45 » Sat Jun 02, 2018 6:34 pm

I was looking at the swing keel from the diagram, last week my keel came loose, luckily was still attached to the lowering line and able to save. macgregor 26sx 1990. Got it on the trailer, went underneath and this is what I saw, in the keel well are two grooves on each side of well, (grooves for pivot pin) At the very top above the groove I see the head of a bolt, no brackets, no holes nothing. Looking at the drawing with the metal bracket that attaches to the top bolt I think that is exactly the set up I have. So with that, my question is where can you aquire that bracket and pivot pin and how do you install it? Guess if I had a manual it would help....don't have one. Any help would be appreciated....Thanks!

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sailboatmike
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Re: Centerboard pivot hole

Post by sailboatmike » Sun Jun 03, 2018 4:53 pm

Salt water shouldn't make much difference to a 316 stainless steel pin, the issue for stainless is lack of oxygen which causes crevice corrosion because the oxide coating can't form / renew itself. Boats stored on trailers shouldn't have issues with crevice corrosion.

We took the keel bolt out of my old JOG boat which was built in 1977 a couple of months ago, the bolt itself was fine even after 40 odd years of salt water use, alas the hole in the steel keel it went through was about now about 30mm (1 1/4") which isnt exactly snug on the 1/2" bolt anymore.

Just as a side note, when we fixed the keel we took the JOG boat out for a sail, it was a totally different experience to sailing the Mac, I would think mainly due to the complete opposite in hull shape concepts (the JOG boat is a true full displacement rounded hull), The JOB boat felt more comfortable, a bit like sailing on a feather bed, the Mac was more brutal but seemed to accelerate through the gusts far better and was overall faster. It was just conformation to me that we did the right thing selling the JOG boat and buying the Mac.

vizwhiz
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Re: Centerboard pivot hole

Post by vizwhiz » Sun Jun 03, 2018 5:18 pm

Lethamae45 wrote:I was looking at the swing keel from the diagram, last week my keel came loose, luckily was still attached to the lowering line and able to save. macgregor 26sx 1990. Got it on the trailer, went underneath and this is what I saw, in the keel well are two grooves on each side of well, (grooves for pivot pin) At the very top above the groove I see the head of a bolt, no brackets, no holes nothing. Looking at the drawing with the metal bracket that attaches to the top bolt I think that is exactly the set up I have. So with that, my question is where can you aquire that bracket and pivot pin and how do you install it? Guess if I had a manual it would help....don't have one. Any help would be appreciated....Thanks!
A 1990 Mac S has external access ports to the bolt holding the swing keel. Check on Sumner’s purpletradingpost webpage to find his very thorough explanation of how he accessed them, dropped his keel, made a special wrench, etc.

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