Centerboard clunking, anyone with any experience?

TomY

Alden Forum Moderator
Jun 22, 2004
2,768
Alden 38' Challenger yawl Rockport Harbor
This fall, I had the yard raise the board enough to lower the centerboard to inspect the SS pendant connection. After 3 seasons, the nicro press fitting, SS thimble and the wire itself looks brand new. I had some concern about corrosion after I removed the bronze bar and installed all SS wire.

But what I was really after was how to address the clunking I get from the board occasionally. Usually off the wind in quieter condtions is when I can hear it. I should note that the clunking may be louder now with the bronze bar removed, I can't be sure of it as it still clunked with the bar but I think a little less. Also, the noise stops with just a couple of turns on the lifting gear, it is only when fully extended.

Up in the lift, I had a few of the yard guys look at it. This is Rockport Marine in Maine which builds alot of large wooden boats as well as maintaining to a high degree, many classic wooden boats. Many of these wooden sailboats have large bronze centerboards.

All agreed the Challenger has alot of room between the board and the slot in the lead keel. Boats they deal with(I have rattled many a bronze board in the yard there) have much less side to side play.

The design may have called for the extra room to keep growth from freezing it? Doesn't make sense, I leave mine raised at the mooring and the heavy weight will always lower I believe. My board hasn't been painted in 3 years and had little or no growth on it. BTW, they present alot of area and you can see how they have a huge effect on performance especially to windward.

Pushing the board back and forth in the slings, I decided I will simply build it up somehow and decrease the play. Quite simply, this will silence it and only help its performance. The question is with what and how?

I had them block the boat higher this year and leave the slot open underneath to lower the board somewhat. Alittle digging should get it low enough. They suggested simple bronze plates or cheeks on each side. Alden once suggested Derlin. The problem is how to fasten either material
as it is not likely to be even a 1/4" thick(I estimate the play at close to 1/2"!) Once I figure that out it will be quite simple.

Another thing Rockport Marine added was the pins on these boards last a long time. The reason being that they(and the board) just sit there and the only wear they recieve is raising and lowering which amounts to nothing. I haven't removed this pin but taken the covers off to see a castlenut on the ends.

Anyone with any experience improving the centerboard?
 
A

Anonymous

Tom,

As you know, I don't own a very large bronze or fiberglass centerboard (lots of little wood or fiberglass ones, though). However, I corresponded for several years on Sailnet's Morgan-List. Lots of these old boats are centerboarders and while most later ones were 'glass, the earlier ones were bronze. None had that bronze bar arrangement of the Challenger, rather they all have sliding sleeves and stainless pennants travelling horizontally under the sole (!). Many correspondents grumped about the clunking. Many folks had problems with the stainless components corroding, often in as little as 3 years in the tropics. Some reported significant wear in the pins and adjacent board and, as the Morgans' pins were fiberglassed in, repair was more difficult. Some folks report that their boards can be immobilized by marine growth relatively quickly; getting 'em freed is a chore. None wrote about adding shims. More experienced folks wrote about how to drop a bronze board w/o damage to self or board.

Were it me, I'd consider adding large 'washers', simply pinned in with the centerboard pin. These washers could be any handy material that isn't corrossive as compared to the bronze or brittle. I might make up a bit of fiberglass, cast on plastic on window glass, laid up to the desired thickness, sawn to an appropriate diameter. You should be able to get something in there as big in radius as the pin is above the bottom of the keel.
 

Whit

.
Sep 13, 2004
93
Hunter 30_88-94 New Orleans LA
Clunking Board

On a previous vessel, I used Plastic (Durlon) blocks, aprox. 2” X 2” X 2” on either side of the board. These were replaced as they wore. I filed out slots on the inside of the centerboard trunk at the bottom to hold them. This worked well. The plastic was easy to work with and closed the tolerances enough to lessen the banging while allowing the board to move freely.
 
A

Anonymous

Starboard type washers

Just a guest enjoying the board (and a Challenger fan).

As it happens I was perusing an Allied Seabreeze site just the other day and one member said that he had made giant "washers" for his centerboard (~350 lbs bronze) out of Starboard-type material. I forget the thickness of the material (that would vary according to the amount of free space anyway), but I think he said that the "circles" were about 20" in diameter. He sounded happy with the results.