H26 keel knocking

Fred

.
Sep 27, 2008
493
Catalina 28 mkii 745 Ottawa, Ontario, CA
weve been anchored out a few nights now and if the water is not completely still the centreboard tends to knock around somewhat and the sound reverberates through the hull. I’ve tried both lowered and raised positions. Any ideas out there about how to quiet it down?
 
Jan 19, 2010
12,362
Hobie 16 & Rhodes 22 Skeeter Charleston
Have you tried putting the lift line on the winch and put a little tension on the line?
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Have you tried putting the lift line on the winch and put a little tension on the line?
I am assuming it’s rocking side to side, which Keel position wouldn’t affect.
 
Jun 2, 2004
649
Hunter 23.5 Calgary, Canada
I'm on a lake with a lot of power boats and skiers on weekends. There's only one protected place to anchor so otherwise I'm exposed to the wakes. My H 23.5 knocks in the same way as you described, whether in the up or down position.

Years ago I think I read here that somebody inserted shims on both sides on the centerboard to make it quiet.

Once, just as a test, I swam under the boat and tied a light line around the bottom of the centerboard and ran it up over the side of the boat and tied it off on a stanchion or cleat. It worked, but is a goofy thing to do.

Maybe there's a way to insert a shim(s) without removing the entire center board bracket?
 
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Nov 26, 2017
64
Hunter 260 Mille Lacs
With the centerboard up, get a piece of line long enough to go under the boat and up to the deck on both sides and back again. Run the line under the boat from the bow, with both ends on one side of the boat and the middle of the line on the other. tie off one of the ends and loosely tie off the midpoint on the other side of the boat, with the line running at about the middle of the CB. Now with the remaining loose end, tie a giant loopy knot around the other line. It needs to be a big knot and tight within itself so that it won’t come undone, but loose enough to slide on the other line that it’s tied around. I don’t know the name of the version of this knot I’ve used, but doesn’t really matter. You could even thread a small float onto the line if you want to get fancy with it. Now, go to the other side of the boat again and tighten the end of the line that’s tied off to the boat, so that that end of the line is tight and pulling up hard on the centerboard. Finally pull the other end of the line (from the loop side of the boat) so that the knot slides down the taut line and under the boat. When you feel the knot come up against the CB, pull just a little more to put some sideways tension against the CB, but not enough to pull the knot over the CB. Tie off and you are done. The CB shouldn’t wobble back and for the anymore with thebknownpuahing it to one side...

When ready to sail again, just untie and remove the line, drop the CB, and you are good to go.
 
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Fred

.
Sep 27, 2008
493
Catalina 28 mkii 745 Ottawa, Ontario, CA
Jeff... I tried a variant of your approach and even though the boat is bobbing around quite a bit in the wind theCB is quiet! Thanks!
 

Fred

.
Sep 27, 2008
493
Catalina 28 mkii 745 Ottawa, Ontario, CA
I changed the upper centreboard line with some (12 ft) new double braided dock line (nylon). This rope has some stretch in it so when pulled up tight it seems to hold the centreboard snug and it only knocks a bit with severe waves but is otherwise quiet.
 
Jun 2, 2004
649
Hunter 23.5 Calgary, Canada
If the boat wakes are large enough such that the rocking back and forth makes the centerboard knock, then they're too big to have the centerboard in the up position. When up, the boat rocks a lot more than when it's in the down position acting like a big damper to the side-to-side motion. For me, the bobbing can be worse than the knocking! I'd prefer a solution for when the CB is down.

Is the centerboard solid? I wonder if I could attach a small pad eye to the bottom of the CB, and then run the line up to the side like I described above. I can't imagine that a little 1/8 inch line dragging through the water would slow me down much. Besides, on my 1x7 mile lake, the faster I go the sooner I just have to turn around when I get to the other end.
 
Jun 2, 2004
649
Hunter 23.5 Calgary, Canada
Further to the above, this string idea would work with the CB up or down, not that I want to use it when it was up as I mentioned. Also, when sailing, I could pull the string around to the stern to tie it off such that the string is trailing the centerboard rather than remaining sideways up and over the side. There are no weeds in my lake, but for some people when positioned sideways I suppose it could pick up some floaties.

I just don't know if putting a couple of screws into the centerboard is a bad idea!
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
I made a set of nylon washers for the previous boat and they were slightly thinner than the space between the board and the trunk. When they got wet they swelled just a bit and you could tell by the little bit more effort to raise the board. It's cut the banging by about 1/2. They were untouched for about 8 years, so wear was not an issue.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
I made a set of nylon washers for the previous boat and they were slightly thinner than the space between the board and the trunk. When they got wet they swelled just a bit and you could tell by the little bit more effort to raise the board. It's cut the banging by about 1/2. They were untouched for about 8 years, so wear was not an issue.
This is a great solution if you can figure out a way to make it work as an add-on. The First 210 and 260 keels have these delrin 'pucks' bolted to the side of the keel head that rotates in the housing. It is a precision fit that allows for no slop. But part of this scheme factors in that the pin has no slop as well. If the keel was engineered to sway in the well, the pivot bearing is probably oversized and it will swing from there.

pucks.jpg
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
The Mac keel assembly had a bolt hole that required turning a nylon tube to insert into it. I suspect that some of the wear was the outer ends where the keel was trying to rotate on it. The washers were no more than bushings and i thought about a solution like your pucks. That's a great way to do it, if you have the tools.
 
Jun 8, 2004
10,027
-na -NA Anywhere USA
On the Hunter water ballast centerboard brackets are two white plastic Derwin sheaves that are designed to snug the centerboard from slapping sideways. If that is happening I would suggest inspecting the centerboard housing. I would not run any lines secured to the lower section of the centerboard thru the centerboard housing.

I remember seeing advertised a long handle with brush for cleaning the hulls with boats in the water. Not sure how long but if long enough to go completely under the hull with centerboard up, could you attach some messenger line attached to a larger line from one side of the boat to other side? If so that might be an option
 
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Fred

.
Sep 27, 2008
493
Catalina 28 mkii 745 Ottawa, Ontario, CA
On the Hunter water ballast centerboard brackets are two white plastic Derwin sheaves that are designed to snug the centerboard from slapping sideways.
I don't see that on the H26 centerboard bracket drawing, unless you are referring to the "chafe blocks" which would indeed limit some lateral motion (not sure how much). When the boat is out of the water again I will inspect to see if these are visible and undamaged.
 
Aug 22, 2017
1,609
Hunter 26.5 West Palm Beach
When setting up clearances on a swing keel, a balance must be struck between having it snug enough for good performance & loose enough so that barnacles and other marine crud. will not jam up the works. If the boat is not left in the water for more than a day or two at a time, then often the clearances can be much tighter.