Rust on keel bolts- should I be worried?

[seabreez]

Originally Posted by Michael Cobbe

There are two problems if you use a wire brush to remove the rust it will leave tiny bits of metal which will increase the rust. The other probem is I had a steel boat and rust converters don't work. The only way to fix it and stop it coming back is to sand blast it and paint it with Zinc rich epoxy. There are small sand blasters for yachts. https://www.google.com/search?client...ster+for+yacht

Had this before... First I would take a maker and mark the bolt forward and aft. Next I would tackle, loosen one "nut" at a time and see if the stud or bolt move in the keel. If the bolt moves... it means the nut and bolt is seized. This is caused by the stainless not being lubricated when it was assembled at factory. I would wait for a haul out to tackle this.

If the bolts is stationary and the nut can be loosened... you are in luck! (DO ONLY ONE AT A TIME). Take the nut off and remove the washer. If you clean with a wire brush, make sure the wire is stainless and not steel. I would clean this with sandpaper and check to see if the bolt has been sacrificed by rust. Vacuum the dust out. If the bolt is good... lubricate the nut with anti seize compound and reinstall and tighten very tight of with a torque wrench to make sure all bolts are tighten evenly. I would not paint, or epoxy. I would spray with Fluid Film or some other rust preventer.

After reinstallation I would mark (with a marker) the nut in relation to the bolt, just for reference until the next time you go down there and check. I my opinion, the rust shown is not much and easy enough to clean. I also hate rust with a passion...

[Searles]

With respect to Jim ,all 304 ss is slightly magnetic ie bolts and nuts ,washers con be fished out with a good magnet 316 ss if true to code is non magnetic ,I would dought that the plates are 2205 ss but in America it’s possible ,I still would not advise playing with keel bolts in the water .⛵️⛵️⚓️

[Jim Cate]

With respect to Jim ,all 304 ss is slightly magnetic ie bolts and nuts ,washers con30 be fished out with a good magnet 316 ss if true to code is non magnetic

With all respect to you, sir, this is incorrect for any of the 300 series stainless alloys, UNLESS they have been cold formed, as in rolled threads, cold-headed bolts and so on. for such items, 304 will become slightly magnetic and 316 is less likely to do so.

But for raw plate s/s, such as backing plates are made from, they are non-magnetic.

One of very many references:

"The 300 series of stainless steels contain sufficient Nickel to render them non-magnetic. As 316/L & 304/L are the most common stainless steel grades used, they are the grades that most people are familiar with. All the stainless steels from the 300 series are non-magnetic.

The Metallurgy of: "Is Stainless Steel Magnetic?" - Metal ...www.malabou.com › "

Jim

[wingssail]

Personally I would not be casual about the rust around these bolts. Given the age of the boat I would perform a thorough examination.

Haul the boat and ensure that it is blocked with the keel thoroughly supported, then remove the nuts and steel plates, individually where possible.

If any doubt remains about the source of the rust then dropping the keel (lifting the boat off of the keel) and dye testing the exposed portion of the bolts may indicate the condition.

In any case, we don't want to hear of keel failure, the catamaran guys would never let you forget it.

[ChrisseH]

I would not do anything. And definitely DO NOT cover these with any kind of paint! In many older yachts the plates and nuts were covered with topcoat and looks now awful. If the surface rust on the plates disturbs you whipe most of it away with a cloth dipped in oil or a rust removing agent.

The situation would be quite different if there would be any signs of a grounding in the blige.

[kavu]

I'm overwhelmed with the responses! Thank you to everyone, I am glad to hear that it is better than feared, but will definitely inspect further. We plan to haul out again in a couple of months time, I will wait until then and once on the hard remove the nuts and backing plates (one at a time) to check if there is any corrosion going on further down. If so, we'd have to drop the keel and do further inspections from there. If not, change backing plates and washers to 316SS.