Center Board Help Needed

[Brave Dave]

I have a vibration in the center board of my 1977 DSII. Dropped the CB and found the hole around the plastic (delrin ?) bushing wobbled out. Machined new bushing of same length to fit tight in the CB, epoxied into center board with CB pivoting on the SS bolt and still had the vibration. Dropped CB again after someone told me that the CB pivots on the plastic and not the SS bolt. The original bushing I removed was only slightly wider than the CB, with some space between the bushing and the inside of the CB trunk. The advice the person gave me was that the bushing should be a snug fit to the inside of the CB trunk. I am not sure if the advice I am getting is right, having the CB pivot on the plastic bushing, rather than the SS bolt does not seem right since the CB is fiberglass coated plywood.

So, does the CB pivot on the SS bolt or the outside surface of the bushing?

How long should the bushing be?

How can I get rid of the vibration? (which only happens at low speeds on any tack)

Also, the CB is in great shape.

Any GOOD advice sought

Thanks, Dave

[Brave Dave]

I see some folks took a look at my message. Just wanted to say I talked with Rudy at D&R Marine. Rudy is worth his weight in gold. What I learned was that the CB does pivot on the Stainless Steel bolt and that the bushing should be just wide enough to not let the CB slide side to side insid ethe CB trunk but still allow the CB to pivot on the SS bolt.

Thanks to those who took a look at my message.

Dave

[DaveB]

Hi... Rudy is right when he says that the centerboard bushing pivots on the the SS bolt. The vibration could be coming from a warped board or even some damage to the board's leading edge. On my boat, I also had vibration at higher boat speeds(unlike yours). I corrected the problem by smoothing and recontouring the leading edge. This contour should be gradually tapering to a approx. 1/4" final edge(kind of like the St. Louis arch!) I also had to correct some warp by sanding aggressively using a staight edge in all directions. Hope this helps.
Dave

[Brave Dave]

Thanks DaveB.

My CB looks to be in good shape, however the leading edge is a wide (5/8 inch+) flat edge. The previous owner may have belt sanded flat to erase some damage or it may have come from the factory like that. While laying under the boat I have thought about fairing the leading edge to a more dynamic profile. Haven't seen the trailing edge yet, only blocked the boat up off the trailer high enough to get to the CB bushing. I guess I'll beach the boat and pull it over on it's side to fully inspect the CB next time out.