1990 26S centerboard slop

[My Mistress]

I recently replaced the centerboard on "Mistress" due to an unfortunate accident. The hole for the pin seems to be larger than on the old centerboard, and the CB moves around significantly.

I've been searching these boards for a method to take up some of the slop without compromising Roger MacGregors original design parameters. I have seen suggestions to replace the SS pin with sched. 40 PVC ; the addition of cheek blocks and bearings to the CB; and epoxying furniture slides in the CB well to lessen the banging while at anchor.

Does anyone have a tried and true solution? I have considered rubber bushings or PVC/delrin washers between the CB and angle brackets which will flex or compress and allow the CB to move as designed while at the same time tightening up the loose play.

Item 2 is the pivot pin itself. The ends bear directly on the fibreglass hull, and they are rough. Has anyone adapted a wear plate between these two or is this something that I shouldn't be bothered with?



- James

[Interim]

James--

I haven't experienced this, but would the method that people use on rudders work? They seem to drill out a larger bolt and wedge it into the rudder, and then put the pin through that bolt (sort of a bushing).

The difference would be that you don't have a ready-made bracket holding it in place as you do with the rudder, but something could be rigged I imagine.

Just an idea.

--john

[Tomfoolery]

Any chance the existing hardware is mismatched? Apparently, there were two CB styles for the 26 classic with swing CB: large hole and small hole, with different hardware to support it. Screen-grabbed from BWY:



I would call BWY and ask them, armed with pictures you could email them in case they ask. Rough ends on the pin suggests (to me) that it was replaced, and just saw cut. The stuff I've gotten from BWY in the past, and the (assuming original) CB pin on my X, was nicely finished, not just rough cut chunks of metal. While anything is possible, it doesn't sound like original.

[grady]

Here was my solution to the excessive amount of slop in the S model center board. I do not have any pictures so I will try to explain as best as possible.

My center board always banged at anchor and made a lot of noise. So when I removed it to check it had a very large hole in the center board and a small bolt. The bolt that I removed was bent also. First thing I did was to go up one size on the pivot bolt. I believe it is 1/2 inch now. Second I glassed in the hole that was there and then drilled it just a touch larger then the bolt. After that I painted the entire center board including the hole with VC performance epoxy. Then sanded the hole to make a perfect fit to the bolt. Then I took some 1' by 1' square Kydex and bonded them together to make the trunk where the center board pivitoted square. After that the entire trunk and bottom was painted with VC performance epoxy. Verified the center board fit in the trunk with almost no play. I glassed in 10lbs of lead shot in the bottom of the board just to make sure it would swing down with everything being tight. I also changed the centerboard line to a 2 to 1 to make it easier to raise. After all that I can leave the center board down with no banging and also I can point almost as high as a D model.

[nprbill]

91 M26S ! Painted the inside of the center board trunk and the center board with 4 coats of ablative bottom paint. That decreased the clearance so much that the CB stuck. I took it back out and sanded the top, head, so that the board moved easily.
When I was painting the center board, I wrapped up a bolt the same size as the pivot bolt in packing tape and kept it in position in the pivot hole. This allows some paint build up in the hole but not to have to redrill it.

If this doesn't work, go to Walmart and buy some roll up cutting boards. Cut them, drill for the pivot pin and use on each side of the CB for shims. If you are worried about them falling out use some non permanent 3m to hold them in place. The size should be big enough to reach the top and front of the center board trunk to back past the pivot bolt as far as you like.

[My Mistress]

Any chance the existing hardware is mismatched? Apparently, there were two CB styles for the 26 classic with swing CB: large hole and small hole, with different hardware to support it. Screen-grabbed from BWY:

That may be a possibility. I recall the ad at the BWY website stating the CB was the "large hole" type.

I would call BWY and ask them, armed with pictures you could email them in case they ask. Rough ends on the pin suggests (to me) that it was replaced, and just saw cut. The stuff I've gotten from BWY in the past, and the (assuming original) CB pin on my X, was nicely finished, not just rough cut chunks of metal. While anything is possible, it doesn't sound like original.

The hardware seems to be original. I merely reutilized them. I cancelled my order for replacement hardware from BWY. They didn't have it in stock and the sales rep stated that it would be a couple weeks until it was available. Way too long to wait! I'm anxious to get on the water.

[My Mistress]

Here was my solution to the excessive amount of slop in the S model center board. I do not have any pictures so I will try to explain as best as possible.

My center board always banged at anchor and made a lot of noise. So when I removed it to check it had a very large hole in the center board and a small bolt. The bolt that I removed was bent also. First thing I did was to go up one size on the pivot bolt. I believe it is 1/2 inch now. Second I glassed in the hole that was there and then drilled it just a touch larger then the bolt. After that I painted the entire center board including the hole with VC performance epoxy. Then sanded the hole to make a perfect fit to the bolt. Then I took some 1' by 1' square Kydex and bonded them together to make the trunk where the center board pivitoted square. After that the entire trunk and bottom was painted with VC performance epoxy. Verified the center board fit in the trunk with almost no play. I glassed in 10lbs of lead shot in the bottom of the board just to make sure it would swing down with everything being tight. I also changed the centerboard line to a 2 to 1 to make it easier to raise. After all that I can leave the center board down with no banging and also I can point almost as high as a D model.

I don't have a pivot bolt, but a pin ~ 1" diameter. IIRC, the hole in the CB is ~ 1 1/4 inch. I had thought of glassing the hole, but I also read somewhere that the CB is meant to be loose fitting so it transfers forces to the CB well, and not the hardware, which would bring up my next question:
Have you had any stress issues with the mounting hardware since you tightened up your CB? It's only the 2 bolts that hold the whole shebang to the boat.

[Tomfoolery]

Be careful when it comes to reducing the clearance on the pin. The leverage on that pin could easily spall or crush the FG in the area of the pin. I would think the CB is intended to react against the inside walls of the trunk, with the pin there only to locate the CB and act as a hinge for retraction.

Notice the relatively long lever arm above and below the pin on the right side, with the CB pushing against the walls. Contact pressure (force divided by area) at the top and bottom would be relatively small as the force is relatively low, and the area relatively large.

If the pin were trying to do that, the lever arm is the thickness of the CB, though maybe reduced when the CB slides over to one side when pushed on by the water. But the reaction forces, which would be relatively huge, would be taken out only through the surface where the pin contacts the CB at the ends, which is relatively very small, so the contact pressure would be extremely high compared to the previous case.

But either way, I'm guessing the pin was not intended to take any real load, especially since it's only passing through unreinforced FG.

Left side - CB hanging on the pin, with large clearance hole.
Right side - CB canted from lateral force, hole/pin not taking any load.



Disclaimer - I have no idea what the geometry actually looks like inside there, so I just made this sketch up to demonstrate the principle.

[My Mistress]

Be careful when it comes to reducing the clearance on the pin. The leverage on that pin could easily spall or crush the FG in the area of the pin. I would think the CB is intended to react against the inside walls of the trunk, with the pin there only to locate the CB and act as a hinge for retraction.

That's what I got from reading through past posts, that the CB load bears against the walls of the trunk.

But either way, I'm guessing the pin was not intended to take any real load, especially since it's only passing through unreinforced FG.

I have a 1990 26S. The pin is held by two "L" shaped steel brackets, not un-reinforced FG. All the load would be concentrated at the attaching points of the two bolts holding the brackets to the hull.


Presently, I am considering using heavy rubber washers between the CB and the mounting brackets; hoping that the rubber will give enough to reduce the load, yet be firm enough to reduce the slop.

[Sumner]

Just a quick note and that is that I always pull the centerboard up on anchor so no banging there and also non when underway. I don't want it down on anchor just in case the boat swung into shallower water or swung and the CB struck a submerged object. In both cases since the CB was striking something with the boat swinging sideways I don't think it would retract upon impact as it does with the boat moving forward.


http://purplesagetradingpost.com/sumner ... de-39.html

Also after putting the barrier paint and the bottom paint on the bottom and in the trunk (not on the CB as it is from ruddercraft) it fits very tight when up in the trunk,

Sumner

1300 miles to the Bahamas and back -- 2015

The MacGregor 26-S

The Endeavour 37

Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[My Mistress]

I got back under "Mistress" and pulled the whole shebang again. I just wanted to show you all what I am describing.
There is 3/8 - 1/2 inch of free space between the CB and the brackets on both sides; and the CB pin is 1" OD while the hole in the CB is 1-1/4 ID; quite a lot of play there.
In the picture, my fingers are physically touching the CB pin.

My plan of action is one of two:

1. Insert the CB pin in a piece of 1" PVC tubing and press fit that into the CB (almost a perfect fit, BTW).

2. Make a pair of large washers/bushings out of a piece of delrin to take up the majority, but not all the space between the CB and the CB brackets.

Either course of action should eliminate a lot of the CB slop, but still leave the CB free to rotate and move side-to-side. I am leaning to using the delrin due to it's flexibility and durability over PVC.
The hull is ~ 1/2" thick here, so it should handle the stresses well.

[My Mistress]

OK, here's how it went:
I added a hard rubber bushing one either side of the CB. There is enough room for it to rotate freely.

We went out for a shakedown cruise yesterday and I over-nighted on her last night. The CB works like a champ, dropping down and coming back up easily. Last night, the only sounds I heard were on water in the ballast tank, and water against the hull while she was at anchor!