Centerboard Klunk Revisited, plus cable idea ... ?

[Login3]

There are threads about the klunk. I've perused most, if not all of them. It concerns me both when sailing, but also, likely more importantly, at anchor.

A fairly common mention is that play is to be left to keep the various twisting forces from being transmitted to the hanger bolt and the fiberglass through which it depends.

When you see these photos, know I have not bedded anything in 5200 yet. I plan to take it apart. Putting it in was easy, and I wanted to test the feel of it, and make sure my knot (double overhand) and its melted end cleared as it should. It does.

However, I noticed a new thing: The board is actually harder to pull up, and I think I know why: The previous owner had put a bowline loop in, and the board was being raised from a center position, hanging straight down. With the new line in from the stbd side, the first motion the board exhibits when the line is pulled taut is to twist the centerboard to the side, rotating it clockwise. This causes friction against the inside of the well, and makes it more difficult to raise. There are marks on the centerboard and the inside of the well that suggest this was the case (before the bowline install, which didn't fully work for obvious reason)

So I'm revisiting the cable idea. I've got a spool of 3/32 stainless downrigger rope. I love this stuff. Super duper strong, and I've never broken it. The idea here would be to insert a stainless bushing into the hole of the centerboard, and run a loop of the stainless wire rope through it, and swage it together just above the centerboard. The two bitter ends would then be passed up through the tube and exit cabin top, over what should be a block, around the block 90 degrees horizontal to a loop termination, where a nylon line is attached to pass through to the cockpit. This would make the centerboard not twist when being raised.

I'd like to know the potential reasons for failure ... it has been mentioned that the cable was not as reliable as the all-rope version. Was this for boats that spend most of their time in the water by any chance? Or on land?

To fix the klunk I've done a couple things, easily undo-able, and plan to do one more ... that being the most risky, since I can't test it until on the water, I say to you this: Similar to the person who put furniture slider pads on the inside of the trunk ... but in my case I've got two hard rubber furniture "feet" and I think they would be attached to the forefoot of the centerboard (with GFlex Epoxy), just below the jutting out snout stopper that keeps the board from overextending.

These rubber pads would combine with the PEX bushing on the pin (I clearanced some 1/2" PEX) as well as the two spacers I made for the "cheeks" that ride on the pin. By themselves, the bushing and the spacers allow considerable slop .... from what was previously unbelievable ... there is still quite a lot of play. The bushing is not tight on the pin, nor is it tight in the centerboard. The spacers are not tight between the hangar and the centerboard sides. Pics below.

But together with the furniture pads (or something else if I find the better right thing in my junk stash) I think they would spread the leverage and force.

Or would I just break my boat?

Not looking for "You can't do that" unless there is a real reason. For both of these ideas. But I'm listening!

Thanks for the eyeballs and time. : )

Centerboard spacer washers and bushings.jpeg

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Centerboard hanger pin with bushings and spacers installed.jpeg

Furniture feet antiklunk things.jpeg

[Login3]

Just back in from checking the clearance for the furniture foot things. Looks like I'd have to take off about 1/8". Easy. I would of course leave a decent gap for some movement ... so instead of a KLUNK I'd be OK with a "thunk".

A klunk in the trunk ... who woulda thunk?

Yeah.

[Gotro]

I have a 26x and dont realy notice the klunking thing on my centerboard . But i wanted to say i have replaced my center board line . Heres how i did it . I used 1/8 inch dyneema line tied a bowline at the center board then ran that line up through and on to the deck then ran that line outside the starboard stantion back towards the cockpit. The 1/8 inch dyneema line terminates just maybe 6 or 8 inches after it rounds the stantion and then i tied it to a larger diameter dyneema line that travels back to the cleat. The reason i ran the line around the stantion was this small line would get pinched under the original roller pully .works well now held up for 3 years

[pitchpolehobie]

I only get CB klunk when I leave it down at anchor or the dock and its a reminder to pull it up. I was advised to never leave it down at anchor or marina and I think thats fairly standard practice now.

Early this year I replaced my stainless steel CB hanger and pin and studied the system for awhile. I had bought 8mm thick rubber rings to put on the side of the CB pin however I do think that the CB should have a bit of rock/flex into the CB trunk to disperse force into the trunk rather than just on the CB pin which means a lot of force right around the fiberglass pin hole on the CB. Picture from bwyachts edit...
basically i think you want all the pink spots pressing against the CB trunk to disperse forces when the CB is down not all the force directed on the red pin. I ultimately decided to not put the rubber rings and dont really regret it.

The one mod I kind of liked someone put furniture glide pads inside the CB trunk a few feet to the stern of the pin to stop swinging at anchor but mine was minimal.

I replaced my CB hanger w the one recommend by dyneema. I tied a double stopper knot on it and applied the weight of the CB after install to make sure it was snugged and tensioned. No issues and I feel like there is no friction or rough spots. The knot fit nicely in the groove where the knot is supposed to be.