Re-hanging 400#/180kg Cast Iron Keel

[Spot]

I just completed framing repairs to my Luger Southwind 21 (6.4m).
The next step is going to be removing the external stub keel with a swinging cast iron centerboard to re-seal and re-bolt.

-The keel is held on by (8) 1/2-13 UNC SS bolts (strong 12mm)
-Local adhesive/sealant 'sauce' is Loctite/Henkel PL Marine Fast cure polyether rated for below waterline. Application procedure for impermeable surfaces is to apply, separate to allow atmospheric moisture to help cure, mate and adhere for final cure min 24 hours before painting.
-The currently installation of the keel is flat to the bottom but there were a couple keel bolts that seemed to be leaking from outside in. The new bolt holes are over-drilled, filled w/ epoxy, and redrilled for the bolts.

I have never done a re-hang. Lacking torque specs for the bolts and sealant manufacturer's minimum thickness...how would one go about this? Does it make sense to O-ring between the keel and the hull at the bolts and/or add some spacers in non-critical sealing areas to prevent excessive compression/squeeze out? I will be removing the cast iron and prepping the mating surfaces before any sealant application. I have also ordered new hardware for the keel bolts and centerboard pivot bolt and can replace the lifting cable bolt with parts sourced locally.

Appreciate the input, thanks!

[nelly]

One comment is I would not trust the red epoxy fill. Personally, I would drill this out and use G10 tubes, epoxied in place with thickened epoxy. I would be concerned about water ingress into your core with the above setup if the epoxy cracks at all under the weight of the keel - but maybe that is overkill, hopefully someone here with more knowledge can chime in.

[Spot]

Originally Posted by odonnellryan

One comment is I would not trust the red epoxy fill. Personally, I would drill this out and use G10 tubes, epoxied in place with thickened epoxy. I would be concerned about water ingress into your core with the above setup if the epoxy cracks at all under the weight of the keel - but maybe that is overkill, hopefully someone here with more knowledge can chime in.

Thanks. The red fill has glass fibers and the new capping covers it too, in spite of the way I drew it...

[JPA Cate]

If you were having water come from the outside in, you should make sure you drain out all the salt water from the iron keel. If there is water in there, some of the iron has expanded from rusting, and getting rid of any salt water in there is really important, because you risk having to hire a jackhammer, and open up the side of the keel to get in there and remove all the rusty iron, then you have to decide what you're going to use to re-fill it. It's a hard, heavy work sort of job, very hard if it is hot and humid. Rust never sleeps. Sorry, I don't know if you can safely use rust converter in this circumstance.


Ann

[Spot]

Thanks Ann. Previous owner's solution to water ingress was to smear some orange RTV 'gasket maker' goop around the outsides of the offending lock nuts and washers...

The boat has spent most of its days on a trailer and the sailing has been in fresh water so I am hoping for the best. I will certainly inspect the iron for defects. I ordered some wire brush attachments and paint removal disks online.

[Spot]

What do we do with the rusty centerboard...so early in the evening?
Removing the trailer, pivot bolt, and centerboard was relatively uneventful and the pieces do not look so bad.
New bolts/washers/locknuts ordered and received along with some wire wheels and paint removing disks. Thinking it might be a good time to change the wire to the winch as well.

[Spot]

Keel stub is off and seems to be in pretty good shape. Cable was also pulled and measured and dimensions sent out for quotes. Cleanup and repaint to begin this weekend.

Current plan is to clean up iron (pressure wash, sand, wash, paint) and hull and line up some help for the re-install. Apply sealant to keel, to hull, add spacers, and snug up keel to hull. Let cure, remove spaces, fill holes, let cure, install cable, go sailing

[GordMay]

Check with the boat builder, or designer, for the design torque values, which can vary wildly [see links], for the same bolt size.
To calculate a correct bolt tension [to achieve a desired bolt tension, but not shear the bolt, crush the laminate, or strip the threads in an iron keel] we’d need to know the strength of everything, which may be tricky for the bolt and keel, and near-impossible for the laminate.

➥ https://j109.org/docs/keel-bolt-torque-table.pdf
➥ Keel Bolt Torques
➥ https://www.catalinadirect.com/image...CF85CB2A3F35B5

[s/v Jedi]

The little machinist handbooks have tables for torque that include both dry bolts and using different kinds of thread locker etc. which lube the thread and require different torque.

I am not a mechanical engineer, but I think that may be stainless steel isn’t the best material for keel bolts?

I think the rubber O rings simply get crushed but they may form a better seal. The way ai have seen keels bolted back in was with 5200 and initially just taken up enough for squeeze out all around the keel and equal space between keel and hul all around. More torquing was done later of course but I don’t remember how much time in between and in how many steps etc.

[Spot]

Thanks for the links and thoughts GordMay!
The boat manufacture Luger has been out of business for many years.
The links you provided gave boat-specific guidance from 20 to 80 ft/lb with the 20-somethings from Catalina using 1/2"x 13 being 39 ft/lb.
The link below from Fastenal shows low 40's ft/lb depending on dry or oiled.
Various websites mention a risk of galling with prevention being clean hardware, going slow, and adding a lubricant.

https://www.fastenal.com/content/mer...ce%20Guide.pdf

Thanks Jedi!
I read somewhere that 5200 is a day to skin over but 7 days to cure. I have also read enough stories that make 5200 seem like something you never want to have to take apart yourself. I pinged both 3M and Henkel (Loctite PL Marine) about my application. 3M I asked about 3/4/5xxx product selection and Henkel if there were tips beyond their published technical data sheet.

PS Wondering if a simple chamfer on the hull's outer holes would be easier and effective versus adding the O-rings.

[s/v Jedi]

Originally Posted by Spot

Thanks for the links and thoughts GordMay!
The boat manufacture Luger has been out of business for many years.
The links you provided gave boat-specific guidance from 20 to 80 ft/lb with the 20-somethings from Catalina using 1/2"x 13 being 39 ft/lb.
The link below from Fastenal shows low 40's ft/lb depending on dry or oiled.
Various websites mention a risk of galling with prevention being clean hardware, going slow, and adding a lubricant.

https://www.fastenal.com/content/mer...ce%20Guide.pdf

Thanks Jedi!
I read somewhere that 5200 is a day to skin over but 7 days to cure. I have also read enough stories that make 5200 seem like something you never want to have to take apart yourself. I pinged both 3M and Henkel (Loctite PL Marine) about my application. 3M I asked about 3/4/5xxx product selection and Henkel if there were tips beyond their published technical data sheet.

5200 is slow to cure but for this application worth it I think. I wouldn’t go for slow cure products.

I also recommend to read this thread: https://www.cruisersforum.com/forums...st-156846.html

[Spot]

Progress Report:
Keel stub is off, stripped, and coated, waiting for full epoxy cure before paint.
Hull is cleaned off but showing some defects.
Do these small blisters and eyelashes need to be dug out and filled or let the 5200 sort it out?

[s/v Jedi]

Originally Posted by s/v Jedi

5200 is slow to cure but for this application worth it I think. I wouldn’t go for slow cure products.

I also recommend to read this thread: https://www.cruisersforum.com/forums...st-156846.html

Typo, I wouldn’t recommend fast cure products. The reason is that they are weaker.

Originally Posted by Spot

Progress Report:
Keel stub is off, stripped, and coated, waiting for full epoxy cure before paint.
Hull is cleaned off but showing some defects.
Do these small blisters and eyelashes need to be dug out and filled or let the 5200 sort it out?

That looks good, yes, grind out and fill with epoxy that is thickened with a high density filler. Then I also recommend to paint it with an epoxy barrier coat before attaching the keel with 5200.
I think I see barrier coat already in the last picture… what is that, the keel?

[Spot]

Originally Posted by s/v Jedi

Typo, I wouldn’t recommend fast cure products. The reason is that they are weaker.

That looks good, yes, grind out and fill with epoxy that is thickened with a high density filler. Then I also recommend to paint it with an epoxy barrier coat before attaching the keel with 5200.
I think I see barrier coat already in the last picture… what is that, the keel?

Yes , the coated piece is the keel stub that through-bolts to the boat and provided the pivot point for the bolt for the swinging portion. I used a poly-carbide sanding pad/disk to remove the old finish (smelled like poly resin) and then treated the surface with a rust-buster type spray (phosphoric acid). After talking to tech support at West System Epoxy, I ended up sanding back to clean metal and coating with epoxy and scrubbing the wet epoxy into the surface with a wire brush. The next coating was epoxy with West's 422 barrier coat additive. The jury is still out whether to paint the keel something flashy or use the can of Rustoleum that I already have that approximates the hull color. Talking with my work's 3M rep confirmed the sealant choices for this application to be either 5200 or 4000UV.

Thanks for the prep advice Jedi. I have fumed silica and glass spheres and more of the barrier coat additive. I had a good result using the formula 1 part mixed epoxy with 2 parts spheres and 1 fumed silica. I saw this recipe in an old MAS epoxy video and used it for fillets when I redid the framing that will support the keel.

[s/v Jedi]

Originally Posted by Spot

Yes , the coated piece is the keel stub that through-bolts to the boat and provided the pivot point for the bolt for the swinging portion. I used a poly-carbide sanding pad/disk to remove the old finish (smelled like poly resin) and then treated the surface with a rust-buster type spray (phosphoric acid). After talking to tech support at West System Epoxy, I ended up sanding back to clean metal and coating with epoxy and scrubbing the wet epoxy into the surface with a wire brush. The next coating was epoxy with West's 422 barrier coat additive. The jury is still out whether to paint the keel something flashy or use the can of Rustoleum that I already have that approximates the hull color. Talking with my work's 3M rep confirmed the sealant choices for this application to be either 5200 or 4000UV.

Thanks for the prep advice Jedi. I have fumed silica and glass spheres and more of the barrier coat additive. I had a good result using the formula 1 part mixed epoxy with 2 parts spheres and 1 fumed silica. I saw this recipe in an old MAS epoxy video and used it for fillets when I redid the framing that will support the keel.

In this case you need to leave out the spheres and just use the silica. The spheres are not crush proof. Work as clean as possible because itis much harder to sand.

Paint the keel? No antifouling paint? Don’t use Rustoleum as it isn’t for under water use.

The problem I have with the barrier coat additive is that is results in a thick, not so smooth layer, which requires more work. I prefer to use Interprotect 2000 or TotalProtect barrier coat instead. When using those, you let it cure a little (until no paint sticks to your finger when you touch it, but the paint still shows your fingerprint) then put on the first coat of antifouling to get a molecular bond.