Rudder rebuild?

[OneBoatman]

With age there has been osmosis, there also appears to be voids from water entry and freezing damage over the years. As long as the rudder post itself and gudgeons on your boat are solid and they are not weakened by corrosion you can re-build your rudder with good success using layers of glass and epoxy. You already have the post and the rudders basic shape. Your first step is to drop/remove the rudder. You should ask the marina owner to put her up on soft ground and see if its ok to dig a temporary hole to drop it while she is on the hard. If she's already resting on pavement you will likely have to pay him to lift the boat to drop the rudder assembly. Water entry usually begins where the post enters the rudder, but that of course was many years ago. Probably good to cut about a half an inch off the bottom of the rudder to expose the core and allow moisture to escape. Dry the rudder assembly thoroughly and vertical in a warm place. Drying may take several weeks. Once dry, Grind or belt sand until you are happy keeping in mind the original skin thickness as you remove residual paint and the outermost layers of glass. This will ensur after re-skinning it will be smooth and close to, or perhaps a bit thicker just so as not to cause any interference in use. Don't worry about appearance. Pre-fill and fair any voids with a filler paste, then you want to re-encapsulate the entire rudder with at least 2-3 layers of medium wt glass and another of two lighter weight layers using West System or a similar two part epoxy resin system such as Maas. Target adding 3/16 to 1/4" of glass all over. Take care to pre-clean and achieve a good seal where the post enters the rudder. Take your time and be sure to mix properly following the pot-life, gel, and cure guidance. Once re-encapsulated and sanded smooth, paint the entire rudder with a final mix of epoxy resin or barrier coat to seal any areas of exposed glass. Test fit it if you have any concern about clearances before readying it for bottom paint. For a smooth epoxy finish you only need break the shine before re-painting, however if you chose to re-build with polyester resin as (likely the original build was) you will have to de-glaze the surface and apply several coats of epoxy barrier coat before you apply your anti-fouling paint.

[boatpoker]

Originally Posted by OneBoatman

With age there has been osmosis, there also appears to be voids from water entry and freezing damage over the years. As long as the rudder post itself and gudgeons on your boat are solid and they are not weakened by corrosion you can re-build your rudder with good success using layers of glass and epoxy. You already have the post and the rudders basic shape. Your first step is to drop/remove the rudder. You should ask the marina owner to put her up on soft ground and see if its ok to dig a temporary hole to drop it while she is on the hard. If she's already resting on pavement you will likely have to pay him to lift the boat to drop the rudder assembly. Water entry usually begins where the post enters the rudder, but that of course was many years ago. Probably good to cut about a half an inch off the bottom of the rudder to expose the core and allow moisture to escape. Dry the rudder assembly thoroughly and vertical in a warm place. Drying may take several weeks. Once dry, Grind or belt sand until you are happy keeping in mind the original skin thickness as you remove residual paint and the outermost layers of glass. This will ensur after re-skinning it will be smooth and close to, or perhaps a bit thicker just so as not to cause any interference in use. Don't worry about appearance. Pre-fill and fair any voids with a filler paste, then you want to re-encapsulate the entire rudder with at least 2-3 layers of medium wt glass and another of two lighter weight layers using West System or a similar two part epoxy resin system such as Maas. Target adding 3/16 to 1/4" of glass all over. Take care to pre-clean and achieve a good seal where the post enters the rudder. Take your time and be sure to mix properly following the pot-life, gel, and cure guidance. Once re-encapsulated and sanded smooth, paint the entire rudder with a final mix of epoxy resin or barrier coat to seal any areas of exposed glass. Test fit it if you have any concern about clearances before readying it for bottom paint. For a smooth epoxy finish you only need break the shine before re-painting, however if you chose to re-build with polyester resin as (likely the original build was) you will have to de-glaze the surface and apply several coats of epoxy barrier coat before you apply your anti-fouling paint.

How do you know if the rudder stock is sound if you don't fully expose it for close examination ?

[OneBoatman]

True boatpoker, you are correct for absolute certainty the rudders internal support structure should be exposed or at least be spot checked since one doesn't actually know how its doing. In a foam rudder I suppose corrosion could be quite advanced without almost any external evidence. The amount of rust bleeding from the lower section in his picture is somewhat concerning. If his rudder has encorporated mild steel that would be pretty bad. There a few things that make it less likely than not. Most rudder posts are made of relatively passive metals such as stainless steel, silicon bronze or Monel. Rudders somewhat in their favor, as far as their galvanic exposure are generally stand alone and thus less subject to galvanic corrosion than if they contained mixed metals while "sitting in seawater". If the rudder post is bonded to a protected system (not very common) then it should enjoy at least some galvanic protection. So what's left? Well, if there is internal welded structure it is possible the welds are weakened from acting anodic. And there is some risk from the acid formed during osmosis and over time this too can weaken even thicker metal sections or the welds as similar to what happens with chainplates. I've seen wood core rudders blow up and yet their internal stainless steel was in fine condition and to be honest I'm not really certain how well the foam may limit or not protect supporting metals. In the end you are correct without inspection before jumping in one one could fully dissect, choose to spot check or some variation of salvaging just the main post, or buy a post and fabricate a new rudder.

[boatpoker]

Originally Posted by OneBoatman

True boatpoker, you are correct for absolute certainty the rudders internal support structure should be exposed or at least be spot checked since one doesn't actually know how its doing. In a foam rudder I suppose corrosion could be quite advanced without almost any external evidence. The amount of rust bleeding from the lower section in his picture is somewhat concerning. If his rudder has encorporated mild steel that would be pretty bad. There a few things that make it less likely than not. Most rudder posts are made of relatively passive metals such as stainless steel, silicon bronze or Monel. Rudders somewhat in their favor, as far as their galvanic exposure are generally stand alone and thus less subject to galvanic corrosion than if they contained mixed metals while "sitting in seawater". If the rudder post is bonded to a protected system (not very common) then it should enjoy at least some galvanic protection. So what's left? Well, if there is internal welded structure it is possible the welds are weakened from acting anodic. And there is some risk from the acid formed during osmosis and over time this too can weaken even thicker metal sections or the welds as similar to what happens with chainplates. I've seen wood core rudders blow up and yet their internal stainless steel was in fine condition and to be honest I'm not really certain how well the foam may limit or not protect supporting metals. In the end you are correct without inspection before jumping in one one could fully dissect, choose to spot check or some variation of salvaging just the main post, or buy a post and fabricate a new rudder.

As a retired Certified Marine Corrosion tech, I disagree.
Monel is relatively unheard of in this application and bronze is rare. Stainless steel is by far the most common rudder stock material and is the material used on the subject vessel.

The passive film created by the addition of chromium to stainless requires oxygen to regenerate, it will readily corrode particularly at welds due to crevice corrosion if deprived of said oxygen. The stagnant water trapped inside a foam cored rudder is by definition de-oxygenated

[Fore and Aft]

BoatPoker is right you need to expose the core. This is such an easy job; one you could even take home and do at night in your garage. Just drop the rudder, with a grinder split the rudder down the fore and aft edges, remove the core, inspect the shaft, dry the rudder out using a household fan heater that is blowing directly on to the rudder halves, new core, glue the two halves back together, fix the bad fiberglass areas, sheathe the outer rudder with two layers of say 450gm double bias with epoxy resin, some builders leave a channel at the top of the rudder/shaft area so they can fill that area with Sikaflex (dissimilar materials potential area for leaks), fill and fair and reinstall. The hardest part of the whole job is to make sure you have not increased the thickness of the rudder blade so much that it rubs on the hull.
Cheers

[boatpoker]

Originally Posted by Fore and Aft

BoatPoker is right you need to expose the core. This is such an easy job; one you could even take home and do at night in your garage. Just drop the rudder, with a grinder split the rudder down the fore and aft edges, remove the core, inspect the shaft, dry the rudder out using a household fan heater that is blowing directly on to the rudder halves, new core, glue the two halves back together, fix the bad fiberglass areas, sheathe the outer rudder with two layers of say 450gm double bias with epoxy resin, some builders leave a channel at the top of the rudder/shaft area so they can fill that area with Sikaflex (dissimilar materials potential area for leaks), fill and fair and reinstall. The hardest part of the whole job is to make sure you have not increased the thickness of the rudder blade so much that it rubs on the hull.
Cheers

This ... plus review post #25

[gordonhinds]

It’s a rubbish rudder. Make/get a new one. It will transform your boat and the ‘feel’. There would be plenty of second hand ones in yards if you look for them.

[boatpoker]

Originally Posted by gordonhinds

It’s a rubbish rudder. Make/get a new one. It will transform your boat and the ‘feel’. There would be plenty of second hand ones in yards if you look for them.

Please tell us of a yard where one could pick up a gudgeon/pintle, semi-hung rudder that would fit this boat of which only approx. 240 were built ?

[davenrino]

Originally Posted by SailingHarmonie

The first picture told me all I needed to know. The internals of your rudder are now full of water. The danger here is corrosion (especially of the welds). There is an internal web of metal attached to the rudder shaft that actually transmits the turning torque to the outer shell. If that web breaks off the shaft, the rudder is useless because the shaft spins and nothing happens.

How likely the damage is to be serious depends on many variables. Quality of the metal alloy used. Skill of the welders. (If it was welded. I have seen the web made of rods that were threaded into the shaft.). If you patch the holes and leave it like that with salt water inside… it will fail at some point. Maybe sooner, maybe later.

I can honestly say if it was my boat, I would drop the rudder and split it in half to get a look at the condition of the internals. I can say that, because I did exactly that on a similar boat.

If you are a bay sailor, close to help, and in water rarely too deep to anchor, risk of loss of steering might not warrant the work. If you are crossing oceans, this should be looked at closely. This is not a young boat, and stuff happens…

It is not a very complex job to open the rudder and have a look. If repair of the metal internals is needed, that can be a bigger deal, but if it is needed, well, it is needed.

This would be my concern. My boat is 53 years old and it is a big ocean out there so I had Foss Foam (Finco) in CA build a new one. It is also a much better design than the original.

[Ballsnall]

Originally Posted by davenrino

This would be my concern. My boat is 53 years old and it is a big ocean out there so I had Foss Foam (Finco) in CA build a new one. It is also a much better design than the original.

Almost all 30, 40 and 50 year old rudders will have water intrusion yet rudders falling off doesn't seem to be a common occurrence. The failure mode doesn't warrant a new rudder, though if you have the bucks and the boat warrants it then best solution is to just replace the rudder, otherwise dry the rudder, fill the voids with thickened epoxy then re-laminate and go sailing is a good alternative.

[GILow]

Originally Posted by Ballsnall

Almost all 30, 40 and 50 year old rudders will have water intrusion yet rudders falling off doesn't seem to be a common occurrence. The failure mode doesn't warrant a new rudder, though if you have the bucks and the boat warrants it then best solution is to just replace the rudder, otherwise dry the rudder, fill the voids with thickened epoxy then re-laminate and go sailing is a good alternative.

I disagree. Rudder failure comes up quite often in boat rescues.

The dry it and fill it approach is not much different to sticking your head in a bucket of sand.

[Nicholson58]

Go to see my photos on this forum about my rudder rebuild. Use 3M micro balloons with US Composites 635THIN epoxy resin to make the filler. Very light, strong, waterproof. Slow cure resin, hours, no blush, low heat for thick pours. Mix in balloons till it looks like Kraft marshmallow cream.

Your rudder is a train wreck. Lucky it didn’t leave you stranded.

[Bigjim]

Originally Posted by Searles

Yep stale or highly saline salt water will do this every time ,same with encapsulated chain plates ,it never stops .⛵️⚓️

I am located in Lake Michigan, so no saline water at all.

[GILow]

Originally Posted by Bigjim

I am located in Lake Michigan, so no saline water at all.

I’m pretty sure you can still get crevice corrosion in fresh water.

[SailingHarmonie]

Three pages of comments and you are back to where you started. Cut it open, inspect, and repair if needed; or patch and hope.

Before taking a 40 year old boat on a 2500 mile ocean passage, I cut mine open to look. There were no issues, and I had one less thing to worry about. It was a good investment in better sleep. If you were crossing oceans, this would be the only smart thing to do. Despite what some people seem to think, rudder failure most certainly IS a thing. The attached photo is the first step of opening the shell of the rudder.

If you are day sailing locally, and your rescue towing subscription is kept current, you might very well rationally decide the risk isn't worth the cost and just patch it up and hope. In this case neither choice is "bad" they just balance issues in different ways.