Recurring theme. Securing the nuts on keel bolts

[jssailem]

I was exploring methods today and came across the “Nord-Lock” washer. This was a new discovery for me. It appears to be an idea that meets the functional requirements of bolt on keels.
What are your thoughts?

Wedge-Locking Technology | Nord-Lock®

Prevent bolts from loosening with cams and radial serrations, tension instead of friction, and a wedge-locking technology. Learn more.

www.nord-lock.com

 

[dLj]

I was exploring methods today and came across the “Nord-Lock” washer. This was a new discovery for me. It appears to be an idea that meets the functional requirements of bolt on keels.
What are your thoughts?

Wedge-Locking Technology | Nord-Lock®

Prevent bolts from loosening with cams and radial serrations, tension instead of friction, and a wedge-locking technology. Learn more.

www.nord-lock.com

I can't seem to get into any section where they give specifics on the materials they are made from. I've used these in the past, but in high vibration applications. I don't think I'd want them on my keel bolts. It would just be an added complexity in a location that doesn't need it.

dj

 

[Richard19068]

I can't seem to get into any section where they give specifics on the materials they are made from.

Is this it?

Five different materials - steel, stainless steel, 254 SMO, alloy 718 and alloy C-276

 

[Davidasailor26]

Do keel bolts really back themselves off though? I know they need to have their torque checked periodically but I thought that was more from material deformation than the nuts turning. Also checking the torque seems like a good inspection / preventative maintenance thing even if you could guarantee the nuts weren’t backing off.

 

[dLj]

Is this it?

Five different materials - steel, stainless steel, 254 SMO, alloy 718 and alloy C-276

Yeah I saw that. Obviously steel would probably not be a good choice, however, I don't know what steel they are using - couldn't find that. Then they list stainless steel - well there are hundreds of those, which one or ones do they offer? Couldn't find that info.

The other three are excellent alloys to be used but I bet they are at a price level that would cause a rather significant pucker factor... Any of those would certainly work but why would you need them? The 254 is a super austenitic, nice but really? Then the other two are nickel based alloys. I quite like them but again - for a washer on a keel bolt?

These washers are designed for very severe service, way beyond what a keel bolt needs...

dj

p.s.I misspoke above, it's not that I wouldn't want them on keel bolts, it's just that there is no functional need. Now if you gave them to me, sure I'd put them on. Especially the nickel based versions!

 

[dLj]

Do keel bolts really back themselves off though? I know they need to have their torque checked periodically but I thought that was more from material deformation than the nuts turning. Also checking the torque seems like a good inspection / preventative maintenance thing even if you could guarantee the nuts weren’t backing off.

It would be rare to have them back off. If they do, it's more likely from thermal cycling. You sure hope it's not from material deformation. that would mean your keel bolts are failing - albeit slowly...

dj

 

[Davidasailor26]

You sure hope is not from material deformation.

I was thinking more deformation of the laminate, which is probably also not great but not as bad as the bolts stretching? I know at least some people have reported getting a Little more turn when they check their torque. I presume that’s the laminate changing over the decades and not the steel bolt or the nuts.

 

[High Current]

It would be rare to have them back off. If they do, it's more likely from thermal cycling. You sure hope it's not from material deformation. that would mean your keel bolts are failing - albeit slowly...

dj

I remember reading somewhere that the J bolts can creep slightly in the lead.

 

[Project_Mayhem]

I'd hate to have to remove those!

 

[dLj]

I was thinking more deformation of the laminate, which is probably also not great but not as bad as the bolts stretching? I know at least some people have reported getting a Little more turn when they check their torque. I presume that’s the laminate changing over the decades and not the steel bolt or the nuts.

I remember reading somewhere that the J bolts can creep slightly in the lead.

I'm sure in both of these cases it can happen. I don't think either should. It may depend upon in what time frame. New boat, there could be some reason to have to re-torque after a time period – not sure what that would be but I'd guess something like possibly a year. I used to have a sailboat with a lead keel with the J bolts – they never moved but I didn't have the boat since new. In fact the only boat I've ever owned since new is my dinghy so perhaps my perspective is a bit slanted. But it would seem to me that once your keel boats are settled, so to speak, there should be no further loosing from those causes. But if your laminate is crushing, or your J bolts are creeping – I'd say there is a fundamental design issue with your keel structure.

Time, vibrations, thermal cycling can all work to loosen keel bolts/nuts so checking them periodically is a good idea. But if they are loosing due to creep or laminate crushing – something is wrong – seems to me anyway....

Of course none of this is talking about if you smash you keel into something...

dj

 

[American_Mainsail]

I don’t feel that there’s any major reason to use lock washers on keel bolts. Check the torque of the nuts occasionally when the boat is on the hard and call it a day. If there’s extra concern, maybe use some blue Loctite, but again, this isn’t something to stress about.

 

[thinwater]

I was exploring methods today and came across the “Nord-Lock” washer. This was a new discovery for me. It appears to be an idea that meets the functional requirements of bolt on keels.
What are your thoughts?

Wedge-Locking Technology | Nord-Lock®

Prevent bolts from loosening with cams and radial serrations, tension instead of friction, and a wedge-locking technology. Learn more.

www.nord-lock.com

Wouldn't a second nut be simpler? No reason to back the existing nut off, and very secure even if the load cycles outside the acceptable range for a lock washer (they only function within a limited range of pre-load).

 

[capta]

It seems to me, if this is a reoccurring problem, drilling a hole through the bolt and tightening the nut then putting in a cotter key, will stop the undoing of the nut, or at least inform you of movement.
However, if you are talking about the keel bolts coming loose from the keel itself, you are going to want to remove the keel and address the problem at its source.

 

[colemj]

Not sure of the applicability of Nord-Lock's for keel bolts, as they don't seem necessary for that, but I use Nord-lock's on our battery terminals and they are fantastic there. Torque them to spec and that bolt (nut in my case) will hold that torque forever and never loosen.

Our battery consists of 20 cells, so there are 40 terminals that need to be torqued and stay torqued. I very much trust the Nord-lok's here over any other type of lock washer.

Mark

 

[nowhereman]

I had mentioned in a post that the ground in my 1993 33.5 was atrached to my keel bolts and causing galvanic corrosion. Any one have a solution? I’m going to install a shower sump box to help keep things dry(er). Anyone else have this problem with keel bolts corroding? Thx in advance.

 

[Don S/V ILLusion]

First and most common cause is bad bilge pump connection. The bigger issue is - If the exposed portion of a keel bolt is corroded, it’s a safe assumption all of it is.

 

[jssailem]

the ground in my 1993 33.5 was atrached to my keel bolts and causing galvanic corrosion.

That is not the cause. What you are stating is, “if I attach the keel bolts to my battery then they will corrode.”

That is not the case. Some where on the boat you have a stray electrical current. The bolts are being subjected to the water in the bilge and the water is medium that is transferring the electrons of your bolt metal. You see the corrosion. Stop the electrical current, put a zinc in your bilge, or get rid of the water ( medium = electrolyte) and the bolts will stop corroding.

 

[jssailem]

Don has identified one of the usual suspects.

 

[American_Mainsail]

First and most common cause is bad bilge pump connection. The bigger issue is - If the exposed portion of a keel bolt is corroded, it’s a safe assumption all of it is.

Hi Don,

Respectfully, I'm not sure I agree with this assessment 100%. Galvanic corrosion and/or stray current corrosion is an event that happens locally at the site of contact with the electrolyte. The voltage source can be located in a remote location that is wired to the metal that is immersed in the electrolyte, but the corrosion event will occur where the metal is in direct contact with the electrolyte (in this case the bilge water).

Assuming that the keel connection was in reasonably good shape (there isn't a significant gap in the joint, the keel isn't moving relative to the joint, there isn't some other evidence that the joint is failing, the joint itself isn't leaking water into the bilge), this stray current event that (I'm assuming here) is causing some surface corrosion on the exposed faces of the bolt and nuts and was (again assuming) caught early on by an owner that's paying attention isn't necessarily reason to immediately drop the keel for a full keel bolt inspection. If OP is seeing very significant corrosion that is actually starting to cause serious degradation of the bolts, nuts, or washers, I would feel much differently.

The big thing I'm trying to convey to OP here is not to panic. When in doubt, have a surveyor take a look at the full picture to make an honest assessment of the keel connection. In the meantime, install a new bilge pump and float switch if you haven't already done so. Use marine-grade heat shrink connections and try to keep the butt connections hung up out of an area where you will have standing bilge water. If you you need extra wire, use marine-grade wire.

Another thing to note is that this discussion ties in well to our dry bilge discussion we were having recently. I think that drying your bilge enough to get bilge pumps, float switches, and keel bolts out of constant bilge water immersion solves a lot of these potential problems all at the same time. Minor stray current events originating from bilge pumps aren't uncommon and the affect is compounded by bilge pumps usually being wired as always on, directly to the battery, bypassing any switches.