Macgregor 25 1981 Knockin Keel

[patrickfarley]

I cleaned the keel 2 years ago. The keel had 4" of growth on it.
I cleaned the keel, went down to metal and then high pressure kind of material for removing rust. Then I covered it with a metal paint to keep the water and rust off of the keel.
The keel has stayed the same for the last two years. It has a few rust lines but nothing important.
My only problem in the knocking noise I get from the keel. I was thinking about taking it out again and then glassing the upper part of the keel so it will fit the gap perfectly. However, I worry about making it too wide.

My current thought is to use the plastic from a kitchen cutting board. If I place a cutting board on each side and glue the boards to the sides of the gap I would reduce the amount of moving sideways space of the keel in the gap. The plastic is not as hard as fiberglass and if something gets into the space it will cut right through the plastic and not freeze the keel. I can replace the extra liner space each year and end up with a keel that will not make noise as pressure hits from different directions. Plastic can be purchased at different sizes and it can be shaped to fill the gap space appropriately.

Is there a problem with this idea?

What glue would you use to hold the plastic in place?

 

[centerline]

why dont you just tighten up on the keel bolt and squeeze the trunk a bit closer to the keel?.... its a much easier fix to the problem of too much slack in the trunk.

is the keel locked down?.... the keel will have a lot more side to side movement (and noise) when hanging from the cable, but not so much when its in its proper lowered position and resting on the inserted lock bolt.

 

[patrickfarley]

The keel trunk cannot be shrunk. It is made of fiberglass and the keel bolt area would be broken by the squeezing. Locking the keel in place will tighten it up a little and reduce the noise but it will not stop the noise.

 

[centerline]

shrinking is not necessary......fiberglass is rigid, but has a lot of give in it... and the way the trunk is built, it can be squeezed considerably.
Ive "tuned" the keel trunk on both of the macgregors ive owned after changing the keel bolt....
I am sure if you were to remove the keel from the boat and inspect the trunk, you would not find any excessive wear in the trunk.....
another way to do it if believe your boat was built with a wider than normal trunk, is to get an 1/8" sheet of plastic (nylon, delrin, uhmw, ect) and build a large washer to slip up in the trunk beside the keel.... then reinsert the bolt thru it and snug it up. and although my keel did shift when the boat rocked pretty hard, I never found enough tolerance in mine to add any shims.... somewhere between a half turn and a turn and a half on the keel bolt nut is all you need.
and it will NOT lock the keel in place, but only remove the slack between the keel and the sides of the trunk...

there is no better way to do it for ease of solving the keel shifting problem... there are a lot of swing keel boats (not just macgregors) and the shifting keel is common. sometimes its not bothersome, but some times it is. so when the problem needs to be addressed, an inspection to insure nothing is failing, and then tightening the bolt a bit more is the usual remedy... no slack, no movement, no noise, no thumping feeling...

 

[Benny17441]

"Keel Slap" The problem rests with a worn pivot bolt/keel assembly. To fix properly, as needed, install a sleeve on the keel hole, spacers in the trunk and do replace the pivot bolt.

 

[patrickfarley]

The keel is worn at the pivot bolt. The pivot bolt looks brand new. The hole for the pivot bolt is worn and will allow more movement. This pivot bolt is the larger size and was replaced before I owned the boat.
This type of job would take a shop for completion. I do not have the materials to make it done perfectly.
I worry about putting a sleeve in the hole because it was not done this way from the beginning. Do you know someone who has done this and had it work out perfectly?

 

[patrickfarley]

This is what the keel looks like. Only now it is all painted.

 

[jjsbiggs]

After I sandblasted my keel on my 25 I put on four or five coats of epoxy filler to bring it back to the correct shape and to make it smooth again. If you did that you might take up some of the space in your keel trunk.
http://www.defender.com/product3.jsp?path=-1|2259972|2259995|2260005&id=2487285

 

[patrickfarley]

I think that you are correct about making it larger. However, I would have to remove the keel, build it up and then paint it. I am hoping my idea will do the same thing with just a small job of putting some plastic in place.

 

[Piotr]

My keel have been knocking ever since I bought the boat 5 years ago. The knock is not that bad once you lock it in. It's not getting worse, and it stops the moment boat starts heeling. So, you need to heel more.