Surface Rust on Keel bolts: any sense in replacing just the nuts and washers?

[Phoenician]

G’day All

Would welcome advice on whether regalvanizing just the nuts, washer and backing plates on my 12 year old Jeanneau is a useless exercise if not removing the bolts as well.


Here’s the background:

The keel is fixed to the boat with 11 bolts. 6 of them are located in the central sump, and those exhibit significant signs of surface corrosion, even though – at this time – there doesn’t appear to be any structural damage to the bolts or the nuts. There is no water ingress from the keel bolts, everything else appears quite ok. The corrosion is most likely galvanic, the central sump on the Jeanneau is poorly designed: it is flat, so it lets water (whether fresh or saltwater) from other sources sit there. (finally found a way to fix this problem, this will happen next)

As I’m about to go on the hard - in a well-equipped, competent boatyard- one of the techies suggested to remove the 6 central bolts, washers and backing plates, replace and/or re-galvanize them. Replacing the actual bolts is not an easy option at this time, ( J bolts sunk into the lead of the keel). However, removing the backing plate will allow us to have a closer look at the bolts and take it from there…

I’m wondering if replacing just the nuts/washers and backing plate is a useless exercise so long as the original bolts are in place?

I have pondered other considerations such as knowing that keel bolts are overdesigned anyway (Casey), and that if I fix the problem of water in the sump, it should make the source of galvanic corrosion go away, and I should be fine just sanding and epoxying the bolts and nuts (did it once before, lasted barely 2 years before corrosion set-in again). Or that I’m just another sailor overly stressed out by his/her keel bolts!

So the collective wisdom of Cruiser’s Forum will be much appreciated

[a64pilot]

First I’d guess it’s not galvanic corrosion if the nuts and washers etc are all galvanized steel.
However in my opinion I think that replacing the nuts and washers one at a time and applying the proper torque to be something that should be done, if you have a loose bolt or other problem it may show itself by not torquing up properly.
However I think that I would also apply Par -al -ketone or “BlackBear” to the exposed metal. If you have ever seen Cosmoline it’s very similar to that, and or similar to the wax like grease coating you will see on steel cable.
It’s very good at preventing rust

[model 10]

If a keel bolt is going to fail, it's not going to be the nut that fails, but why not replace them anyway? New fresh parts look better than old rusty stuff.

[dfelsent]

In a previous boat I had stainless keel bolts and nuts and washers with carbon steel 4”x3” plates to spread the load.
The plates were severely rusted around the edges. By edges I mean everywhere except the bits clamped by the nuts and washers.
For very short money I had a local shop waterjet cut new plates.
Made me feel better at least.

[Phoenician]

Thanks for the replies, all pointing in the same direction

@A64 Pilot: + 1 for Black Bear. I will look into it. I'm surprised that this compound so clearly effective on airplanes hasn't migated to the marine world, but it sounds incredibly effective, will procure.

On "applying the proper torque": any advice on how to determine the proper torque value?


I'm also curious in if your experience heat must be applied to the bolt/nut combination to remove the nut? (presuming they must have applied glue of some sort upon the original installation)

[Tillsbury]

Re-galvanise? Surely they’re stainless aren’t they?

I had very slight surface rust on keel bolts when I bought the boat, surveyor pronounced them good but recommended they be cleaned up thoroughly, covered in tefgel/lanocote and re-torqued. The boatyard who did this also checked all the correct torques with the manufacturer, checked the exposed parts of the bolts, and insisted on putting two nuts on each keel bolt. This is just a data point of course — your experience may vary but both places seemed to me to know what they were doing.

[GordMay]

Keel Bolt Torque Spec’s:
➥ https://j109.org/docs/keel-bolt-torque-table.pdf
➥ http://www.j24class.org/news/keel-bo...ance-bulletin/
➥ Keel Bolt Torques

➥ https://www.pbo.co.uk/expert-advice/...el-bolts-28039
➥ https://www.sailmagazine.com/diy/how...e-is-your-keel

[a64pilot]

I would not expect any king of sealant requiring heat to remove.
Doesn’t mean some nut didn’t use red loctite, but I wouldn’t expect it.

[Cheechako]

Sure, I'd remove them, inspect the general area, clean or replace them and coat everything with something. CRC 5-56 (like cosmoline) is great.

[TheThunderbird]

The bolt is due to fail, not the washer nor the nuts.
Alas a poor bothered uses as 304 and not high grade ss316 (A4 v.A3)

I changed my nuts (two!) And connected metal parts to earth,

You galvanize iron, not steel, did jeanneau produce also Viking boats?

Lanocote? This is a caress on an elephant back! BWHUAHAHAH.

Use bloody GREASE please, a pound of it

Btw, 6bolts only is good on a 33'

[Cheechako]

Lanocote far better than grease. Been there done that. You cant wash lanocote off even if you try.

[Alita49DS]

"the central sump on the Jeanneau is poorly designed: it is flat, so it lets water (whether fresh or saltwater) from other sources sit there. (finally found a way to fix this problem, this will happen next)"

I have a 49DS and the same problem. Actually, it is worse. The design is so poor that the limber holes leave water trapped in the cavities either side of the central "sump".

I would be very interested in what your plan is to cure the problem. Perhaps you would be good enough to share it.

[ReneL]

Replacing with new galvanized washers ,nuts
will protect the bolts,almost as much as galvanizing the
bolts,just as the original galvanizing sacrificed itself keeping bolts safe.
They can be replaced again
when their zinc is sacrificed.
Stainless steel may look nice
but I don't think they will
protect the bolts(metallurgists,correct me?)
Of course keeping bilge dry
and additional surface protection can only help!

[sailorboy1]

surely regalvanizing can't save much over just getting new ones

[a64pilot]

If you chose to reuse, it’s going to be a problem, cause your going to have to remove them all and send them off, you can’t do one at a time.

If you chose to though I think I would cad plate, I used these people to re cad plate aircraft hardware for when I would rebuild an engine etc. they do a good job
http://www.adc-ga.com/index.html