View Full Version : worn ballast hole for the rudder?
09-28-2011, 03:47 PM
Hi i have a folkboat with a worn ballast hole for the rudder
the hole in the ballast its out of round worn on the starboard side
drilled out and a pipe inserted has been suggested to me so is this
the best way to fix it?
09-28-2011, 04:54 PM
Photo? I'm curious to see what you're talking about. Ballast hole? Does your rudder have lead ballast for some reason? Is it a pivoting rudder (swings up for some reason?)
09-28-2011, 06:47 PM
The lower gudgeon, cast into the ballast, is out of round.
Iron or lead, One could temporarily align the rudder, and cast epoxy in the hole around the pintle.
Use slow hardener so the resin does not buble up.
Use WEST 404 filler. Not too much that the mixture cannot run into the hole by gravity.
Pre lube the pintle so it can "break" loose after the dookie gets hard.
If it is open on the bottom, pre smoosh some very thich dookie from the bottom up to dam it. (ha ha dam it)
I do the very same thing on my rudder every 6 or so years.
The 404,hi density, is perfect for this job. Very tough. It will isolate galvanic corrosion/electrolysis the way a pipe or metal bushing will not.
Ideally, a nylon bushing would be fit, but this is very close to that.
09-29-2011, 02:39 AM
Yep thats it ... the hole for the bottom rudder bearing in the cast iron keel is worn?
09-29-2011, 06:14 AM
http://farm6.static.flickr.com/5289/5229504757_7ab6d5da73_z_d.jpg My G n P 's are galv steel, 25years old, with lots of use.
They never had bushings, always have been metal to metal. For years , I just smooshed lanolin in there at haulout time, but eventually, there was a lot of slop, especially in the middle fitting. The "404" fix has worked out very well.
On a side note, do not let the rudder /tiller flop around, even a little bit, when anchored/ tied up. The slightest motion is relentlessly wearing away material, increasing corrosion, and just plain making a racket. Seize the tiller/ wheel with pins or line when sitting still.
09-29-2011, 04:38 PM
Seize the tiller/ wheel with pins or line when sitting still.
Yes i always do that but the guy i got it off maybe didnt!
Wizbang, in #4, refers to a "dookie." How do you pronounce that? Like, a chocolate chip dookie?
Anyway, Wiz suggests what seems to be the simplest solution. Cast a bearing in place around the rudder shaft also in place. You could probably do it with lead, maybe do it with bronze, but epoxy seems like the best solution. Filled with...what? graphite, carbon fiber, glass, etc.
09-29-2011, 06:37 PM
WEST 404 Hi Density Filler. Made for bonding stuff under load, very dense. Looks like talc, fer all i know it could be.
Dookie like kooky
09-29-2011, 08:23 PM
I might be inclined to cast in place some Babbit metal, same as an old style shaft bearing and a lot of rudder bearings.
09-29-2011, 09:04 PM
My boat's bottom shoe is removable (luckily) - so I cleaned it, partially filled it with bronze rod (welded), drilled a new hole & then built up & machined the shaft end. I added heavy waterproof grease - though we'll see how long that lasts. Bronze on bronze isn't perfect, but it has lasted 70 years......
I like the Babbit metal idea though...
As seen in this article:
The term "Babbitt Metal" doesn't mean much beyond it's what's used in plain bearings. Depending on the type of bearing, the composition might be copper/tin or lead/copper, with many other things as well.
The uniform thing about Babbitt bearings is that they're meant to be run in oil, otherwise they wear very quickly. We also don't know what the ballast keel material is. I assume lead, because iron wouldn't have worn the shaft, not visa versa. One idea that just occurred to me is that it might be a good idea to drill a small hole out through the bottom of the "rudder hole," so that any sand, grit, etc, and be washed out through the bottom, rather than being held in the cup of the foot bearing, mixing with water and making a very effective grinding paste.
09-30-2011, 08:04 AM
"because iron wouldn't have worn the shaft, not visa versa."
It may not necessarily be "worn", but electrolicized.(I know that is not a real word). Where do those freakin molecules go?
That's what happened to my bits, and that is why I like the epoxy, as much as an insulator as a bushing.
Throw a bunch of new metal in there, dang molecules might speed up even more!
09-30-2011, 08:57 AM
Babbit metal serves very well as a plain bearing in slow speed situations like a rudder stock which turns at what? Maybe 6 rpm? It has self lubricating properties and water will serve as an adequate lubricant in this situation. I have run it as an outboard shaft bearing (1800rpm, water lubricated only) and gotten a few years service with no lubricant. It is only a thirty minute job to repour it.
Agreed that there should always be a drain hole and preferably a through hole in the lower gudgeon/bearing.
from seo's link...
Babbitt metal is most commonly used as a thin surface layer in a complex, multi-metal structure, but its original use was as a cast (http://forum.woodenboat.com/wiki/Casting_(metalworking))-in-place (http://forum.woodenboat.com/wiki/In_situ) bulk bearing material. Babbitt metal is characterized by its resistance to galling (http://forum.woodenboat.com/wiki/Galling). Babbitt metal is soft and easily damaged, which suggests that it might be unsuitable for a bearing (http://forum.woodenboat.com/wiki/Bearing_(mechanical)) surface. However, its structure is made up of small hard crystals (http://forum.woodenboat.com/wiki/Crystal) dispersed in a softer metal, which makes it a metal matrix composite (http://forum.woodenboat.com/wiki/Metal_matrix_composite). As the bearing wears, the softer metal erodes somewhat, which creates paths for lubricant between the hard high spots that provide the actual bearing surface. When tin is used as the softer metal, friction causes the tin to melt and function as a lubricant, which protects the bearing from wear when other lubricants are absent.
09-30-2011, 09:59 AM
Anyone know if these cast iron keels weld ok?
A good welder can weld anything. But if your question is whether there's a rod available that is compatible with the keel iron, that would be another question.
I think that the proper solution is a epoxy dookie, just as Wizbang says. I think his reasoning in 13 is right to the point. If the keel is iron, the eating away of the keel hole would most likely be caused by disimilar-metal corrosion between the bronze rudder shaft, pintle, etc, and the iron. Simply building up the metal in the hole would not do anything to address the cause of the problem. The only addition I'd make to the "dookie" would be to put a round of super high density plastic under the lower pintle, assuming that the foot bearing is carrying the weight of the rudder. Without that, you're going to have rudder/keel contact. With the plastic bearing and the epoxy dookie, they should be pretty well isolated from each other.
09-30-2011, 04:39 PM
A good welder can weld anything...yep thats me...:)
anyone ever welded using 3 car batterys?
09-30-2011, 09:10 PM
Does 2 count? That's all I had. Wasn't a pretty weld - but it held....
09-30-2011, 11:21 PM
Two things above to worry about, welding and graphite:
Cast iron tends to crack when welded. A good welder with enough experience with cast iron to 'know' whether it should crack might succeed, but I would braze cast iron, not weld. It is an expensive mistake if the keel cracks.
Graphite is carbon, which sits all the way at the top of the galvanic series and to be a bit hard on any other metal http://www.astm.org/HTTP/IMAGES/10995.gif. It takes a lot to make the epoxy conductive, but as it wears, the graphite will be exposed and act like a dissimilar metal.
I would use filled epoxy to build up the hole. Wizbang's West 404 suggestion should make a good high strength wear resistant filler. The MSDS says it contains fumed silica and calcium metasilicate. You could cast yourself a thrust bearing with some layers of glass cloth and 404 filled epoxy squashed between some poly lined boards.
10-02-2011, 04:58 PM
IT welds better with 3 batteries apparently ill be trying it soon getting the jumpleeds and electrode holder sorted!
i am a welder so that should help![a lot]
I wanna be able to weld on site away from mains[little jobs]
so if i go with this epoxy solution i would have t0 put a temp rod into keel hole and 404 epoxy around it?...and that would be strong enough to take the forces off a rudder? they will be considerable i would of thought steel will be stronger
Epoxy with a high strength filler has a lot of compression strength. It also has the advantage of being a good insulator. And, you can probably leave your existing rudder shaft installed, with a thin liner of plastic (anti-freeze jug plastic might be about right) to give you good bearing/shaft clearance.) One thing I'd be sure to do, whatever method you choose, is to have someone work the steering through it's whole range of motion while you observe the shaft moving in the foot bearing. If the shaft is bent (I have no idea how that would happen), the shaft would not simply rotate on its axis, but would oscillate around the axis. That MIGHT be the cause of the wear. Or back to Wizbang, it's more likely corrosion. But still, worth a check.
10-04-2011, 06:40 PM
I think you would be better off just greasing or waxing the shaft. Plastic bearings are better off with tight tolerances. The bigger the clearance the higher the contact pressure because the smaller diameter shaft contacts a small area on a larger diameter hole. The compressive strength of the filled epoxy can run from 10,000 to 30,000 psi.
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