A quick search for opinions...

[Dieselram94]

My rudder stuffing box is no longer bonded to the hull and has dropped a bit. So I’m planning on removing it and grinding away all the original fiberglass that wrapped it so I can reinstall it. My original plan was to cut a bucket to use as a form and after reinserting it with 5200 on the bottom flange have the cut down bucket So I could pour a gallon of seacast to fully encircle it and make it better than original. However the seacast company yelled me not to do this as it won’t bond to the metal well. So now I’m planning on scrapping that idea and after prepping and removal, reinstall using maybe biaxial cloth and west system gflex epoxy. Anyone have any better solutions? Has to do this repair as well?
Thanks!

[LopezMike]

As you might guess, the critical link is bonding to the metal. Nothing, literally nothing, bonds to rust. The trick is to somehow get down to bare metal. Grinding as much as you can will do for a start.

A: If the metal part could be removed I would strongly recommend using the electrolytical method. It's simple and cheap. Just submerge the part in a bath of water doped with washing soda, hook up one wire from a big battery charger to the part and the other to a hunk of sacrificial steel (carbon welding gouging rods are even better) and watch the bubbles. The process stops when the iron oxide is gone so no fear of decrying the part unless, of course, it's all rust! There are multiple YouTube videos covering this.

The next step is to immediately coat it with epoxy. And I mean as soon as you can get it dry. Take a propane torch to it to get it dry right away and paint on a coat of epoxy. Then you can take your time about bonding the whole assembly to the hull.

If there is any way to either remove the part from the boat or devise some way to rig up a temporary bath around the part this is a very good way to go.

B: Sand blasting is the usual industrial way but I shudder at such a thing inside the boat.

C: If you can't remove it then you will have to do the best you can with a wire wheel. Then convert the rest of the oxide to a phosphate with Naval Jelly or some such concoction. They are all just Phosphoric Acid. Then the epoxy should bond well. I recommend finding some horrid bit of scrap metal to perfect your skills.

Do it right and you can forget about it. As to how I know this stuff, you don't want to know. Bad experiences over a half century of boat foolishness.

[nebulatech]

Regarding bonding fiberglass to metal, I just glassed over a hole in my holding tank and while I was at it, I added 2 layers of woven roving across the bottom. I still need to clean it up. I will check the bond and let you know how it stuck. You can sand the metal with 80 grit sandpaper and use a wire brush in the corners. Wipe down with acetone or MEK just previous to adding resin. LopezMike is correct about wanting to get the resin on right away.

One other thought, if you had some way to add something like a collar for the glass to bite into, that would help. I'm thinking about how concrete has rebar to grab onto. I believe you can weld stuff, a skill I don't possess. Can you weld stainless?

I personally would not bother with West Systems. Regular polyester resin is what our boats were built with over 40 years ago. The testament of time counts for a lot in my book. Additionally, there are some coatings that bond well with polyester/vinylester that don't stick to epoxy. Even today's boatbuilders don't use epoxy, so consider that. Shannon Yachts uses vinylester because it is more resistant than polyester to osmotic blistering. Epoxy like West Systems is superior to polyester for wood, and is excellent for laminating. I'm not down on it. The $40 gallon of polyester at your local hardware store is what I recommend. Woven roving and a finish coat of colloidal silica for fairing is what I would use. There are fairing compounds that sand better, but I already have a bunch of colloidal silica. Here's the woven roving I purchased, which has worked great for making backing blocks and the above-mentioned holding tank:
https://www.ebay.com/itm/Fiberglass-Wov ... 3504034386

This is an instructive video my boat builder friend recommended to me, not quite what you're doing but the concepts of tapered grinding and overlapping layers is applicable. (I'm not endorsing their products)
https://www.youtube.com/watch?v=MVLRjxe_iUw

[WillieC]

Thinking out loud here...a glass tube? Then add to it all the reinforcement you want. There are fiber bushings available that should be easily modified by a machinist. Then it is just figuring out the seal portion so there is only a small metal/fiberglass interface.

This is an intriguing project. Do keep us informed.

[hetek]

A couple things come to mind. Is the tube steel or stainless? I do see the rust but am wondering if it is just from the rudder arm. Regardless, whatever it is, I'd nix the existing fiberglass tube and start from scratch. Grind a texture to the tube to give it some tooth, or "key" as Edd China would say.

Regarding polyester, epoxy, Vinylester... It is my understanding that polyester and vinylester are great for "primary" bonding, as in laminations of a hull in a mold. Epoxy is best for "secondary" bonding, as in your application. Where you are trying to bond to cured fiberglass and/or dissimilar materials.

I installed a bow thruster in my Seasport Pilot, To 'glass in the tube I used West System epoxy with alternating layers of woven roving and chopped strand mat, built up like a circular fillet. True, it was a fiberglass tube but I would do the same for the rudder tube.

And, yes, I'm a glutton for punishment.

[hetek]

Here's my bow thruster install...

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The tube is straight but you can see how it got thicker at the end with my laminations to the hull. Almost like an hourglass.

I also first put a 3/4" radius fillet of thickened epoxy as a starter to bond the tube in place before I started with the laminations. Small strips first, then built up to larger strips with each lamination. I finished just by brushing gelcoat over the thing to make it pretty.

Told you I was a glutton for punishment.

[nebulatech]

Told you I was a glutton for punishment.

You are a true craftsman

[hetek]

No, I'm a glutton for punishment!

To this day, my wife reminds me of how much time I spent installing the thruster. And not in an "admiring of my skills" kind of way.

[hetek]

Not to go OT, but to clarify my last post...

I took the family on a day trip to Connecticut. We took a ferry ride across Long Island Sound to New London, CT, and we spent the day on the Essex Steam Train ride. On the way back to the ferry we had a nice dinner at an Outback steak house. But then we made the now infamous detour to Defender Marine Suppy, where I picked up the thruster bits of kit.

No one remembers the great day we had on the ferries, the steam train or dinner. Just the stop at Defender where dad bought that darned bow thruster!

[nebulatech]

Good thing you have us to appreciate your dedication.

[Dieselram94]

Thank you for all the input! The tiller arm is off and I plan on completely removing the metal tube as well as the fiberglass tube it sits in. The matting that originally created that tube appears to be csm? But it as well is delaminating from the hull. I’m quite sure this rudder has taken a hit at some point in its life. I like the key idea, maybe a groove cut into the metal with a Grinder as well as a heavy sanding is the key. I’m just worried that the new matting will crumple up on me as I try to neatly wrap it around the metal tube. I have a hard time just wrapping a Christmas present lol. Some excellent ideas you guys have. I’m hoping to get that metal tube removed Monday

[hetek]

I wouldn't go too crazy with a grinder and a groove, but truly give it a rough surface with some coarse paper. Edd China uses the word "key" which always cracks me up - he's English which may explain that.

I find that biaxial forms better in compound surface situations, around and across, and resists lifting off the surface in the corners. Kinda hard to explain. For my woven roving layers I cut the sheet of roving at a 45 degree angle to the weave, in strips. Made it like a woven roving biaxial tape on steroids.

Chopped strand mat is a bit different. The strands are held together in the mat form with a binding agent, which is designed to dissolve in polyester resin. Once it's wet out, it makes it form nicely. The binder won't dissolve in epoxy and the mat will take a bit more coaxing. Whatever you use, lay several strips and don't try to do it all with one piece.

Nitrile gloves will be your best friend too.

Hope this helps.

[DesertAlbin736]

Would comment if I had something constructive to add other than a) that the pipe looks like stainless or could perhaps be monel? And b) rust never sleeps. Looks like some good input from others. Definitely have a bit of work to do there.

On New London, when we were back there in 2015 we missed doing the Essex steam train thing although we did get to spend a day over in Newport sailing a 12 meter race boat & another at Mystic Seaport & ran our boat up to New London & docked & stopped for lunch at a restaurant, though now I can't recall the name of it. Then went as far up as just short of the sub base (where I went to sub school in 1971, ironically the same year our boat was built). Now the Nautilus is a museum ship but when I was there in '71 it was still in commission & home ported at the sub base.

Defender is one of my favorite online suppliers.

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[nebulatech]

Reporting back with the adhesion to my stainless holding tank:

I found that I could lift the fiberglass off the tank if I tried. Maybe 20-30ft/lbs? That's seriously just a guess. I'm not concerned for my project, but for your rudder post, I think I would do a little more prep. I did my repair on my tank in 2 steps; first a patch of colloidal silica inside and out, hardened overnight and sanded with 80 grit, then two layers of woven roving in one step on top. The colloidal silica works really well and bonds better than the woven roving, likely due to the smaller particle size being able to get into the scratch pattern. Whatever you use will be purely a mechanical bond so it makes sense to make sure the fiber material gets into the scratch.

I agree perhaps taking a grinder to carve a ring around the shaft in 2-3 places. Doesn't need to be deep, maybe 0.5mm. You are making a "pipe" or a circle. The fiberglass won't be able to lift off the steel like a sheet could, but unless there is some physical obstruction, I think there is a risk of the shaft sliding up and down. I believe that is the problem you are currently trying to address, if I understand correctly. Alternatively, if you are removing the tube completely, can you find a stainless steel welder to weld a ring or other shape onto the shaft?

I would consider colloidal silica for your initial layer including going in the groove. The silica is structural, and it is intended for cramming in shall places like a keyway, cracks or grooves. Maybe a thin coat of resin thickened with silica then CSM or cloth for the next layer while the silica is still wet so the two layers chemically bond. This should provide a positive fit. I initially suggested woven roving, but I've reconsidered. You want something that will curve easily and soak up resin easily, at least for the initial layers.

Like others, I'm very interested in how you proceed.

[motthediesel]

Thinking out loud here...a glass tube? Then add to it all the reinforcement you want. There are fiber bushings available that should be easily modified by a machinist. Then it is just figuring out the seal portion so there is only a small metal/fiberglass interface.

This is an intriguing project. Do keep us informed.

I like this idea by WillieC. Just do away with the metal sleeve entirely. I don't know the diameter of your rudder shaft, but there are lots of sources for fiberglass tubes in all sorts of dimensions. Here's one for example: http://k-mac-plastics.com/fiberglass-frp-tubing.htm

Fit a stuffing box on top and bond it in with fiberglass cloth and epoxy resin and you would be all set.