Rusty Keel Bolt

Jan 7, 2014
395
Beneteau 45F5 51551 Port Jefferson
Working on my boat the other day I discovered a keel bolt I didn't know I had and wish I didn't. The boat is a '93 Beneteau 45F5 and is on the hard for the winter, the other bolts look fine and appear to be stainless in an iron keel. This bolt was hidden under a floor board near the mast and was under a couple of inches of water. Apparently rainwater from the mast collects in this area. I was thinking of replacing it before it gets worse. I generally do all work on my boat myself but I am afraid of rounding the head and creating a bigger mess. Should I take it on, leave it alone or hire a pro? Any advice appreciated, thanks.
 

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SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
You don't through Chlorine into your bilge to clean the "smell" out?

If you take a steel brush and gently scrape the bolt head, is it just surface scale?
 
Jan 7, 2014
395
Beneteau 45F5 51551 Port Jefferson
I'll use fresh water and heavily diluted bleach in the bilge but not there. The only water in there is from the mast. It's probably dry in the summer when the motion of the boat helps to empty it through the limber hole. The rust was flaking off with my finger nail. I tapped on it and it sounded like the rust on the head will flake off.
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
I'd suggest you contact Beneteau. I'd start with "I've got a problem, and I need your help." Then send them the photos, describe which of the keel bolts it is, etc, etc
 

RitSim

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Jan 29, 2018
406
Beneteau 411 Branford
A stainless steel bolt generally shouldn't rust like that. Is this the only bolt that has a bonding wire? Maybe, take a magnet and see if the magnet is strongly or mildly attracted to the bolt. A stainless bolt is mildly magnetic. It is possible that the bolt is steel.
If you use a 6-side socket you will have the maximum connection to the bolt head. I would use steady strong force on the bolt. I would not want to be loading/unloading the force on the bolt or do a lot of reversing. I think my keel bolts have a sealer on them - this would tend to be stiffer and offer more resistance the colder it is. I agree with talking to Beneteau.
 

dLj

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Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
Looking carefully at that bolt and surrounding area, I think you should clean it first. The photos don't look as though it is rust, looks more like a deposit. Clean it up and see what it looks like.

dj
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
I renew the comment on using, gently, a steel brush. I hope you find it's scale from, say, draining down a hot water heater or a chain locker, or...
 

dLj

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Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
I renew the comment on using, gently, a steel brush. I hope you find it's scale from, say, draining down a hot water heater or a chain locker, or...
Use a stainless steel brush.

dj
 
Jan 19, 2010
12,362
Hobie 16 & Rhodes 22 Skeeter Charleston
Looking carefully at that bolt and surrounding area, I think you should clean it first. The photos don't look as though it is rust, looks more like a deposit. Clean it up and see what it looks like.

dj
+1
I was going to suggest something similar. I’d take a pneumatic needle gun and chip all of the scale off... then reassess
 
Jun 2, 2007
403
Beneteau First 375 Slidell, LA
If your boat really does have an iron keel, then it left the factory with mild steel keelbolts for compatibility with the keel material. Are you sure the other bolts are stainless? FYI, these are actual bolts, that is, capscrews, inserted from inside the boat into tapped holes in the keel. They can be removed (one at a time) with the boat in the water, for inspection or replacement. Replacement bolts are available from Beneteau.

All that being said, I don't think the bolt in the picture looks bad at all. Mild steel in the bilge will always develop a little rust, you just don't want it to get out of hand. What I usually do with mine is periodically clean them up a little if necessary, hit them with rust converter (phosphoric acid), and paint them with something like Rust-Oleum. I wouldn't even consider pulling that particular bolt. IIRC, a single bolt is strong enough to support the weight of the entire keel.
 
Mar 29, 2017
576
Hunter 30t 9805 littlecreek
There's pleanty of bolt there just paint on a little naval jelly or phosphorus acid and paint. When you look down and find half a bolt that's when u worry
 

dLj

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Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
I haven't seen iron bolts as keel bolts in modern boats. I'd hesitate to paint stainless steel bolts. You'd be asking for problems you don't need.

dj
 
Dec 25, 2000
5,702
Hunter Passage 42 Shelter Bay, WA
This bolt was hidden under a floor board near the mast and was under a couple of inches of water.
Hi Tim, is your mast deck stepped or keel stepped? If deck, no rain water should be coming down the mast and into the bilge, as you say, if the mast was stepped properly. When we took possession of our boat, we had a similar situation. The only permanent fix was to step the mast correctly. No rain water in the bilge ever since and I did that in 2002. Wrote an article about the repair here. Hunter 42 Owner Modifications and Upgrades
 
Dec 31, 2016
319
Beneteau Oceanis 351 Charlottetown
I went through that a couple of years ago, mine looked worse. The bolts aren't stainless, except for the very front one,they are more of a galvanized looking bolt, called Dacro . I'd say ,like the others, clean the head off and then fit a 6 point socket over the bolt head, Mine was 30mm, I bet it'll turn out no problem.
 
Jan 7, 2014
395
Beneteau 45F5 51551 Port Jefferson
Thanks for all the advice. I'll clean it up and scrape away the rust and then decide. From what I've read iron keels use galvanized bolts but the others sure look stainless and good as new. Maybe the magnet test will tell. The only reason I lean toward replacing it is that I'm afraid if it get's worse it will be tougher to remove down the road. I will reach out to Beneteau and see about a replacement bolt before I attempt to loosen it.
 
Jan 7, 2014
395
Beneteau 45F5 51551 Port Jefferson
Well the bolt head is 56MM and on the advice of another beneteau owner, I was thinking of replacing them all just for peace of mind until I got the price. $1050 plus shipping and tax.
 
Dec 31, 2016
319
Beneteau Oceanis 351 Charlottetown
Well the bolt head is 56MM and on the advice of another beneteau owner, I was thinking of replacing them all just for peace of mind until I got the price. $1050 plus shipping and tax.
From Beneteau that sounds about right. Fastenal is another choice, likely about 6 bucks each.
 

dLj

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Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
Sobering price for sure. If you can take one out, or get the specs for the thread type, length and bolt type, you may be able to source them elsewhere.

Extreme-bolt.com makes bolts in a lot of different high strength alloys. I'd do a hardness check on the bolt that you take out as well as a quick chemistry. For the chemistry, you might be able to find a metals junk yard near you that has a hand held XRF gun. They use them to identify the metal alloys coming into their junk yard. The test only takes about 30 seconds and can tell you what the base alloy is. I'd do that first because if the bolts are simply 316 stainless steel, that is available many places. But they may be 17-4 PH or, I don't know, possibly some other alloy.

If the junk yard is close by, maybe you could get the person to come to your boat and use the gun on the head of the bolt in place and you wouldn't even have to take the bolt out.

If the bolt is 17-4 PH, you'll need to know the hardness. That will then tell you the heat treated condition the bolts are in. Anyway, good luck.

dj
 
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Oct 22, 2014
20,994
CAL 35 Cruiser #21 moored EVERETT WA
Couldn't he do the test on the nut he removed? Unless that assumes Beneteau used dissimilar metals or their bolts and nuts.
 

dLj

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Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
Couldn't he do the test on the nut he removed? Unless that assumes Beneteau used dissimilar metals or their bolts and nuts.
John,

I didn't see where he removed a nut? I thought these were keel bolts that he's thinking of replacing. Wouldn't make sense to use different bolts and nuts if both are structural. If a nut is being used for locking or some other function, it could be a different stainless. Better to check the bolts.

dj
 
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