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SK pivot replacement

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steephen
Navigator

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100 Posts

Initially Posted - 12/17/2003 : 21:15:07

My brother and I just dropped the swing keel (C-25) carriage in prep for replacements; we used the threaded rod system and it worked fine. We found the pin to be bent a quarter inch...
Cat Direct said the new bearing blocks were "a little wider" than the originals. My originals are about 1-1/4" wide, while the new ones are 2" wide, thus making installation possible; bolt holes all seem okay; pin itself is the same size.
Anyone else run into this? Am I not understanding something? CD says the replacements are all the same size. If I install these pin-holders, though, I'll have to run my keel through a thickness planer or a bread slicer...

Stephen Z on "Little Wing"

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 12/17/2003 : 21:21:39

Why can't you use he old holders?

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John V.
Admiral

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USA
559 Posts

Response Posted - 12/17/2003 : 22:17:33

when I replaced mine last season I took the new castings to a machine shop and had them milled to the correct width. No big problem, it cost me $25 for both. I took the whole works to parker marine in Vermillion. They took care of some modifications to the keel to remove some protrusions that prevented the keel from fully extending.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 12/18/2003 : 11:52:19

Stephen Z,

John V has it right. The new keel pivot hanger castings are deliberately made too wide. The intent is that you will carefully measure, and have a machine shop trim the new parts to exactly fit your hull and keel. When I went through this, I installed a bronze pivot bushing in the iron keel using reinforced epoxy. Before installing, I had the new keel bushing machined to protrude maybe 1/8" or so on each side of the keel casting with 0.030" radial clearance on the 1.00" pivot pin. I then had the pivot hanger castings machined to leave maybe 1/16" axial (side-to-side, athwart ships, whatever) clearance. No more keel clunk!

-- Leon Sisson

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Steve Kostanich
1st Mate

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88 Posts

Response Posted - 12/18/2003 : 12:03:09

Steephen,

I have replaced my hanger brackets twice, and each time they required machining each face to allow the keel to fit in between them. I think the last time I did it (2001) the brackets came with instructions stating that the machine work had to be done to make things fit,(it said grid to fit NO way there is too much to be removed) and that the clearance on each side between the bracket and the keel should be no more that 1/32". I am a retired high school machine shop teacher, and have my own shop at home so it was no problem to do. I would think a commercial shop should be fairly reasonable to have the work done, as long as you can tell them exactly how much to taken off of each bracket. Here's how you do that; bolt the brackets in place and measure the space between them, prefereably with a dial caliper, and then place something solid on one side of the pin hole in keel and use the depth function on the caliper to measure the thickness of the keel thru the hole. Now subtract the space between the brackets from the thickness of the keel and divide by 2. That is how much needs to be taken from each bracket for a zero clearance fit. Add .031 to each amount and that takes care of the needed clearance. For example, if the keel is 3" thick and the space betweem the brackets is 2.750", the difference between the two is .250", divide that by 2, and that is the amount to remove from each bracket (.125") plus the .031 clearance and the total is .156" from each bracket. Hope this all makes sense.

Steve Kostanich C-25 1119 sr/sk

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rclift
Navigator

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USA
152 Posts

Response Posted - 12/18/2003 : 20:21:39

Steve, John, Leon have it right. One slight problem I had with this method was lining up the bolt holes. I didn't take into account the 1/16 inch gap between the mounting bracket and outward most part of the mounting hole. When I put everything together It fit more snug then I had intended. By the way I had 5/32 taken off each although I know that it varies from boat to boat. Use a machine shop close to home, you may be making more then one trip.

Ray Clift
Buzz 1361

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/19/2003 : 10:00:44

The keel pin was bent 1/4" ?? Does it fit snugly in the keel or is the hole in the keel wallowed out a bit? The reason I'm asking is that a keel pin with a good snug fit in the keel should be very hard to bend short of a major "event".

Also, does the keel fit snugly into the trunk when in the down position? A tight fit between the keel "head" and the keel trunk is necessary to take the side loading without overstressing the keel pivot. Catalina direct offers a 'fit kit' to achieve the proper clearances. If you've got the keel out, it would be a good time to check that aspect of the keel assembly.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 12/19/2003 : 15:14:45

ClamBeach and others,
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">The keel pin was bent 1/4" ... is the hole in the keel wallowed out a bit? ... should be very hard to bend short of a major "event". <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I suspect that by now all C-25 keel pivot holes that haven't had a repair bushing installed are considerably wallowed out. When I first removed mine for reconditioning, the 1" pin was bent about 1/4", and the hole was hourglass shaped, almost 2" at the widest. My forward dinette bench shows some telltale spiderweb gelcoat crazing from a possible keel drop in the past.<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">... does the keel fit snugly into the trunk when in the down position? A tight fit between the keel "head" and the keel trunk is necessary to take the side loading without overstressing the keel pivot<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">This was debated in some detail a few years ago, both on the forum in use at that time, and via e-mail to me. There were two schools of thought -- either the pin or the head of the keel trunk were originally intended to take the side thrust created by heeling. I started out in the head of the keel trunk camp, but ended up talking myself over to the pin & bearing side. As built, the keel head is much narrower than the trunk head. To believe that the trunk was intended to take heeling loads is to say that "keel clunk" was a deliberate feature of the design. I think the keel head shim repair kit (combined with the plastic thrust washers on the pin) is an attempt to solve a wear and tear problem as inexpensively as possible. (I have yet to hear anyone who installed a repair bushing describe that job as trivial.) It doesn't look to me as though the trunk head was originally designed to transfer heeling loads to the hull, particularly in the earlier boats. While bringing my 1979 C-25 home in the ocean the week I bought it, I watched in fascination as the head of the keel trunk squirmed visibly in moderately large waves.

Since then, I've reinforced that area, as well as installing a fairly tight pivot bushing (as previously mentioned elsewhere).

-- Leon Sisson

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/19/2003 : 15:29:25

IMHO... (4) 3/8" bolts bedded in fiberglass aren't adequate to take the sideload generated by a 6' long 1500 lb chunk of iron without some 'help' from the keel trunk itself.

My thinking on this comes from my experience as a Mac owner... where the keeltrunk was the major player in restraining keel side motion... the keel pin was mostly just a 'hanger'.

Good idea about beefing it up either way...

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steephen
Navigator

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100 Posts

Response Posted - 12/19/2003 : 17:11:29

Thanks for all the info, folks. True, the keel is much narrower than the trunk it goes in to, so in this case the heeling load must go directly onto the bronze pin assembly.
I have a machinist brother who is going to trim the bearing blocks for me, and make a 1" pin with a fatter middle, so I don't have to deal with installing a bushing.
Next trick: mag drilling the keel itself.
Is there a thread in these pages by anyone who has beefed up the hollow of the trunk to take up some of that heel load?

Stephen Z.

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Doug L
1st Mate

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27 Posts

Response Posted - 12/21/2003 : 07:26:11

I used a floor jack to lower the keel just enough to remove the old castings and pin, and yet keep the keel up in the trunk so it couldn't fall sideways. I then used my Delta combination belt/disc sander to slowly remove enough material from the castings until they fit. It took quite a few trials of slowly raising the keel back into the trunk until it fit. I found on my boat, to fit correctly, the amount of material to be removed was slightly different on each side. I didn't bother calculating clearances. When the assembly first fit back up in the trunk, I left it. I figured a few up and downs of the keel, with its tremendous weight rubbing against the soft bronze castings, would make the fit just right. Having the sander close at hand made this method possible.

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