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Keel Trunk Flex

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JoergK
Navigator

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USA
140 Posts

Initially Posted - 06/14/2004 : 13:34:44

Yesterday, the first time that I was belowdecks when underway at a good pace with the keel banging around (it has been doing this, probably because the pin hole is a bit worn out and I have no disk shims to stabilize the keel side-to-side). To my horror I saw the wooden box around the keel trunk flex sideways when the keel banged inside the trunk!! I couldn't sleep last night, thinking of the keel and imagining catastrophic failures like suddenly loosing the keel or the trunk breaking off and water pouring in. How serious is this situation? Has anyone experienced such trunk flex and continued sailing? I'd hate to have to end my season already now - it's only June.

Joerg
2002C250 WK "BerLyn"

Edited by - on

svmoxie
Past Commodore

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USA
331 Posts

Response Posted - 06/14/2004 : 14:25:47

Joreg,

I have never seen this in my boat but I haven't looked for it either. My keel does not make any noise (other than cable hum) when sailing unless I hit something!

If your keel is moving enough to "bang around" just from sailing I think that you need to address this issue right away. I would think that your fears are justified and if it was me I would not be able to sail with the keel in that condition.

Depending on the condition of things it might not be more that a delay to your sailing season but regardless I would suggest that you haul out now and at least take a look.

I see that you are in Bridgewater, NJ which is a little far for me to visit but maybe someone else on the forum is closer and could come by and take a look with you?

Let us know how things turn out.

Edited by - on

Bill Holcomb
Admiral

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USA
769 Posts

Response Posted - 06/14/2004 : 16:49:56

Hi Joerg,

I agree 100% with Clif. Your keel should not be banging in the trunk. AND, the trunk should NOT be flexing. Your worries are justified. Get the situation fixed pronto.

Bill Holcomb - C25 Snickerdoodle #4839

Edited by - on

megrier
1st Mate

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USA
55 Posts

Response Posted - 06/14/2004 : 16:53:39

Joreg, you might want to take the wood cover off from the trunk and have a look while sailing next time. Maybe what you saw was the same effect that see with one of those table top games with the steel balls. You know, when you pull the one on the end back and let it hit the others, the last one will bounce off while the rest stay still.

I still do think that it is not good to let that keel bang though. I sailed all last summer with the banging

and decided to add the shims this year and it is much better. I also replaced everything else while at it, keel cable, ball, keel pin, keel casting, keel winch. I bought all of the parts and took it to the local sail boat repair shop. Ya it wasn't cheap at about $1000 plus cost of parts to have them install but I feel better with everything new and in good condition. I just am not in a position to do the work in my driveway.
Greg

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 06/14/2004 : 20:45:10

Another voice in agreement... banging keel = bad... very bad.
It needs a 'hand in glove' fit to the keel trunk.

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JoergK
Navigator

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USA
140 Posts

Response Posted - 06/14/2004 : 21:44:26

Thank you guys all for your advise, even though its not what I want to hear. But I hear you loud and clear - do something!
For a first step I'll pry the wood cover off and take her out next weekend and have a close look while underway. That'll help me decide what's next. Maybe shims would tie me over until the MAJOR (proper) job? From what I read, if I want to keep the swing keel I would have to (a) fix the keel (i.e. remove it and get it somehow to a machine shop, to be drilled out and fitted with a bushing - and probably sandblasted etc etc because it looks quite ugly), (b) put in a new hanger kit plus shims, and (c) probably have the keel trunk rebuilt. (b) is the only thing I trust myself to do, for the rest I would have to pay others. That brings up the question, how much would all this cost? And would it be cheaper to order a retro-fit wing, plus shipping cost, and having a marina install it - if I can find a place that would do a job like this??? Probably have to pay for disposal of the old swinger as well - like I said it looks like it belongs on one of those superfund sites.
That said, the first part of Sunday's trip was wonderful, it was the first time that I used my new main (if you see my thumbnail picture you notice why I needed one) and the wind was strong and steady. The water was churning aft as if I had an engine running - no stink, though. But, alas ...

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 06/15/2004 : 01:53:12

Joerg,

I agree with the others who have said that a clunking keel is not a good thing. Swing keel clunks, trunks, and pivots have been discussed here in the past. If you haven't already done so, I suggest you search on "swing keel trunk" (all words, any order). When I first sailed my C-25, I also noticed the trunk squirming relative to the hull. I have since "tightened up" the whole swing keel system, and no longer loose sleep over it.

-- Leon Sisson

Edited by - on

dbehling
1st Mate

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USA
68 Posts

Response Posted - 06/15/2004 : 02:51:14

Leon,

How do you mean "tighten up" We also have a swing, coming from a fin keel to a swing was a big difference. First we heard the hum, found out what to do about that, now once in a while if a powerboat comes across our bow in an akward manner, we might feel the keel move slightly. We just might be hearing creeking coming from the whole boat for how old it is. Last weekend we we're sailing along nicely and felt something realy strange, the only thing we felt could of happen is a big fish was in the way of our keel. Ouch for the fish.

I like the idea of the shims. Everything seems to be fine when we pulled, but all ideas are helpful. Until we have the boat pulled and th keel dropped to completely check out the keel bolt, etc. We have a new keel cable, winch etc.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 06/15/2004 : 23:47:09

dbehling,<blockquote id="quote">quote:<hr height="1" noshade id="quote">How do you mean "tighten up" ...<hr height="1" noshade id="quote"></blockquote id="quote">Even as I was typing that, I had a feeling that someone might call me on my vague and lazy wording. Well, I'm still feeling lazy, so here are some reruns from the archives of my previous posts on the swing keel pivot and trunk topic:

[url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=4530"]Posted - 09/12/2003:[/url]<blockquote id="quote">quote:<hr height="1" noshade id="quote">I installed a pivot bushing in my keel to eliminate sloppy movement, and thus shock loads in rough water (a.k.a. "keel clunk"). I also reinforced the hull around the pivot area, at the aft end of the trunk, and along the length of the trunk where it meets the bottom of the hull.<hr height="1" noshade id="quote"></blockquote id="quote">

[url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=4973"]Posted - 11/07/2003 :[/url]<blockquote id="quote">quote:<hr height="1" noshade id="quote">I installed a pivot bushing in my 1979 swing keel several years ago using methods similar to those described by tojohnso and GeorgeB. I installed a 1.50" O.D. bronze bushing using WEST epoxy reinforced with powdered metal as I recall. The machine shop part is non-trivial -- be sure to get firm estimates from shops that understand what they're getting into. I'm pleasantly surprised to hear that someone had success with the mag drill approach. Yes, cast iron is scary to drill -- it sounds crunchy.

Damage to the swaged keel cable end can occur if a C-25 runs hard aground with the keel almost fully retracted. The slack cable can pivot away from the "to-hull" pipe where the turning ball is, and get bound up in the top of the aft end of the swing keel trunk when the keel is forced all the way up. This would also put large loads from unintended directions on the keel lifting eye-bolt, and could damage the keel trunk too.

The stock pivot pin is 1.00" in diameter. The four pivot bearing mounting bolt holes in the hull are 3/8-NC lined with stainless steel. The tapped hole in the keel for the lifting cable attachment is 1/2-NC. The newer cable attachment fitting assembly is a much better design than the old one piece eye-bolt.<hr height="1" noshade id="quote"></blockquote id="quote">

[url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=5292"]Posted-12/19/2003:[/url]<blockquote id="quote">quote:<hr height="1" noshade id="quote">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!

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".

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.

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

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.<hr height="1" noshade id="quote"></blockquote id="quote">

[url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=6230"]Posted-04/06/2004:[/url]<blockquote id="quote">quote:<hr height="1" noshade id="quote">Here's a rerun of a message I've posted before in response to a similar inquiry. I hope you find it helpful. Let us know if you have additional questions.

I've reconditioned two iron swing keels so far. The first was for a Venture 22, the most recent my 1979 Catalina 25. Here's what I did to them:

Forget grinding down the rust as a viable permanent solution. It's a waste of time and effort. There's no way to grind down into all the pits, and any remaining rust will spread like cancer. Sandblasting is what works. After removing the keel from boat, I had it sandblasted to "bright" metal. This is so not fun that I cheerfully paid someone else to do it, even though I own a sandblaster and two compressors. This vital step is a huge amount of work by anyone's definition of the word. Don't underestimate it. And don't even think about quick and dirty compromises at the rust removal stage. Getting rid of absolutely all the rust is key to only having to do this job once.

As soon as I got the keel back from blasting, I etched it with hydrochloric acid (a.k.a. industrial strength toilet bowl cleaner - be careful!) to remove the rust remaining in tiny pores, and the rapidly occurring surface oxidation. I then rinsed it with lots of water, and treated it with two applications of phosphoric acid (a.k.a. "Ospho"). After that was thoroughly dry, I used a stiff nylon scrub brush to remove any dusty residue. Keep a garden hose handy when working with strong acids. Don't let acid spills remain on concrete that you care about. Don't wear clothes that you care about for any of this work.

Next, I applied two coats of WEST epoxy. Then I made up fairing putty from WEST with (#407?) filler additives, and rough faired the keel.

After rough fairing, I wrapped the keel in two layers of 14oz. fiberglass cloth and WEST epoxy to protect it from misc. abrasion in the future. At this point I also added a bronze shoe where the keel runs aground, and piled on several more layers of cloth and epoxy in that area, and along the leading edge. It's vital to bury the entire surface of the cast iron under epoxy prevent rust from getting a foothold again.

I did another round of final fairing on top of the fiberglass (with #410? filler additives), followed by several last coats of epoxy resin as a barrier to protect the soft fairing compound from future bottom paint sanding.

I then applied ablative copolymer bottom paint and reinstalled the keel.

Regarding the pivot bushing issue.

On the Venture keel, I put a greased wooden dowel inside a thin-wall hard rubber sleeve (to keep it straight), taped the sleeve in position in the keel hole, and poured reinforced WEST epoxy resin around it. After the epoxy cured, I drove out the dowel, and left the sleeve in as a bushing. (That's a much lighter keel than a Catalina 25, and the head of the keel trunk is intended to provide more side thrust support.)

In the case of the Catalina 25 keel, I installed a bronze bushing (1"ID, 1-1/2" OD, 1/4" longer than keel thickness).

I got my C-25 bushing from the local marina that did the sandblasting, Banana River Marine Service, Merritt Island, Florida. I'd expect that any bearing house would have catalogs of bushings to choose from. There's not necessarily one correct bushing. Rather, you'll need to evaluate the condition or your keel's pivot hole after sandblasting to determine what outside diameter bushing you need, and are prepared to enlarge the keel hole enough for.

Obviously, if you can't find exactly the bushing you're looking for, get one with too much metal, and have it machined down to fit. Worst case, a chunk cut from the end of a really big damaged bronze prop shaft out of a motor yacht could easily be machined to fit on a lathe. I had a machinist set the pin-to-bushing clearance at about 0.025" to 0.030".

The original 1.0" hole in my C-25 keel was worn and rusted in a jagged hourglass shape, just under 1.5" at the waist, and around 2.0" at the widest.

After the flat sided head area of the keel was faired, I used that surface as an alignment reference. Using a hand-held die grinder (heavy duty version of a Dremel), I ground the narrow center area of the hole into alignment. That was the only area where the bushing touched the walls of the worn hole. I made up a wooden alignment jig (using scrap plywood & 2x4 bored in a drillpress) to hold the pivot pin and bushing straight in the hole. After roughing up the outside of the bushing and the inside of the hole, I cast the bushing in place with WEST epoxy reinforced with powdered aluminum and milled fiberglass lint. I used duct tape dams to form pouring funnels, and to contain the epoxy while it hardened.

After the C-25 keel was installed in the hull, I measured the alignment. At a point 7 feet from the pivot, it was within +/-3/16" of dead straight in the keel trunk. I was grinning.

This repair has now been in service for several years. I can say with confidence that the keel has been reliable, quiet, and trouble free. If there can be a good side to all this work, it's that if you do it right, you don't have to do it again.

Good luck with whatever method you decide to use. <hr height="1" noshade id="quote"></blockquote id="quote">

And here's a link to a long discussion of C-25 keel dymanics [url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=6288"]Posted-04/11/2004:[/url]

Sorry I'm too tired and lazy to compose an original answer to your inquiry. Let me know if you have more specific questions.

-- Leon Sisson

Edited by - on

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