I recently hauled my boat and after few days I noticed allarming coloured streaks oozing out of the thin crack (very thin and of little concern by itself) between the keel and the hull. The colour of the streaks is green-blueish, something that suggests copper sulfate, and sort of shiny that suggests micro-cristals.
According to the boat makers the keel bolts are AISI 316 SS and the keel is of lead. The boat was made in 1978.
Do you have any suggestion? Do I have to drop the keel and check the bolts? I would rather avoid it, if not really necessary.
Daniel, There have been a lot of discussions about using SS below the water line as well as using SS with other metals in an electrolyte solution (salt water). The arguments boil down to the susceptibility of SS corrosion. In the absence of electrolysis, SS protects itself by using excess oxygen in its environment to create a thin skin of corrosion, which prevents additional corrosion. If abrasion through mechanical movement abrades the skin and additional oxygen is available, it self heals. If the surrounding environment is oxygen depleted because of the lack of air or water flow around it and mechanical abrasion occurs, corrosion is very rapid and severe. This is commonly called crevice corrosion. In addition to this is electrolytic corrosion, the first mentioned case. This is where the dissimilar metals in an electrolyte create an electric current which erodes the most anodic metal at a rate according to their difference in the periodic element table.
Now, in your case, you know nothing because you did not build it yourself. You observe a staining which could be corrosion. You have been told your keel is lead and the bolts are 316. You have the prime ingredients of both corrosion cases. You have no peace of mind here without keel removal. Can you afford the loss of the boat or possibly even the loss of life? Your call. Steve
"Daniel" <daniele.fua@unimib.it> wrote in message news:l7Hke.24543$795.759388@twister1.libero.it...>I recently hauled my boat and after few days I noticed allarming coloured >streaks oozing out of the thin crack (very thin and of little concern by >itself) between the keel and the hull.> The colour of the streaks is green-blueish, something that suggests copper > sulfate, and sort of shiny that suggests micro-cristals.>
According to the boat makers the keel bolts are AISI 316 SS and the keel > is of lead.> The boat was made in 1978.>
Do you have any suggestion? Do I have to drop the keel and check the > bolts? I would rather avoid it, if not really necessary.>
The one way to tell if there's a problem is to remove a couple of bolts.
"Daniel" <daniele.fua@unimib.it> wrote in message news:l7Hke.24543$795.759388@twister1.libero.it...> I recently hauled my boat and after few days I noticed allarming> coloured streaks oozing out of the thin crack (very thin and of little> concern by itself) between the keel and the hull.> The colour of the streaks is green-blueish, something that suggests> copper sulfate, and sort of shiny that suggests micro-cristals.>
According to the boat makers the keel bolts are AISI 316 SS and the keel> is of lead.> The boat was made in 1978.>
Do you have any suggestion? Do I have to drop the keel and check the> bolts? I would rather avoid it, if not really necessary.>
Jim, Normally the keel bolts will be cast into the leadballast and are not removable without recasting the keel. They will appear as long studs and fasten thru the floors with nuts and washers. Steve
"Jim Conlin" <conlin@comcast.net> wrote in message news:0MKdnRZtVJAEZg7fRVn-gw@comcast.com...> The one way to tell if there's a problem is to remove a couple of bolts.>
"Daniel" <daniele.fua@unimib.it> wrote in message> news:l7Hke.24543$795.759388@twister1.libero.it...>> I recently hauled my boat and after few days I noticed allarming>> coloured streaks oozing out of the thin crack (very thin and of little>> concern by itself) between the keel and the hull.>> The colour of the streaks is green-blueish, something that suggests>> copper sulfate, and sort of shiny that suggests micro-cristals.>>
According to the boat makers the keel bolts are AISI 316 SS and the keel>> is of lead.>> The boat was made in 1978.>>
Do you have any suggestion? Do I have to drop the keel and check the>> bolts? I would rather avoid it, if not really necessary.>>
I've no idea if it's applicable to ss keel bolts in a lead keel, but it's certainly possible to detect loss of bolt thickness caused by corrosion for steel bolts in concrete foundations - as used in chair lifts, power wire towers etc. Ring a few local non destructive testing companies, it's reasonably specialised but you might find someone with the right equipment, experience, and an interest in boats ... Has to be better than taking off the keel! David "Steve Lusardi" <stevenospam@lusardi.de> wrote in message news:d713kc$1so$02$1@news.t-online.com...> Jim,> Normally the keel bolts will be cast into the leadballast and are not > removable without recasting the keel. They will appear as long studs and > fasten thru the floors with nuts and washers.> Steve>
"Jim Conlin" <conlin@comcast.net> wrote in message > news:0MKdnRZtVJAEZg7fRVn-gw@comcast.com...>> The one way to tell if there's a problem is to remove a couple of bolts.>>
"Daniel" <daniele.fua@unimib.it> wrote in message>> news:l7Hke.24543$795.759388@twister1.libero.it...>>> I recently hauled my boat and after few days I noticed allarming>>> coloured streaks oozing out of the thin crack (very thin and of little>>> concern by itself) between the keel and the hull.>>> The colour of the streaks is green-blueish, something that suggests>>> copper sulfate, and sort of shiny that suggests micro-cristals.>>>
According to the boat makers the keel bolts are AISI 316 SS and the keel>>> is of lead.>>> The boat was made in 1978.>>>
Do you have any suggestion? Do I have to drop the keel and check the>>> bolts? I would rather avoid it, if not really necessary.>>>
Steve Lusardi wrote:> Jim,> Normally the keel bolts will be cast into the leadballast and are not > removable without recasting the keel. They will appear as long studs and > fasten thru the floors with nuts and washers.
They can be removed. That's what the threads do.
You might have a really tough time getting them to turn... if you put a slugging wrench down onto the nut, then put on a lock nut over that, you should be able to get it started.
"DSK" <dsk@dontbotherme.com> wrote in message news:6g%ke.20287$8S5.9853@bignews3.bellsouth.net...> Steve Lusardi wrote:>> Jim,>> Normally the keel bolts will be cast into the leadballast and are not >> removable without recasting the keel. They will appear as long studs and >> fasten thru the floors with nuts and washers.>
They can be removed. That's what the threads do.
I believe he means from the keel itself.
Steve
You might have a really tough time getting them to turn... if you put a > slugging wrench down onto the nut, then put on a lock nut over that, you > should be able to get it started.>
Doug, On all the lead keels that I have seen, the bolts are held in the keel by anchors, because the lead is too soft for threads to hold. Very often a frame is constructed of steel and the the bolt pattern in the frame is used to drill the mounting holes in the floors for alighnment reasons. This frame is then cast into the keel. Alternatively, a wooden frame is made to suspend the bolts head down with large washers and then the keel is cast. In all cases the bolts cannot be removed without recasting the keel. I suppose one could use a threaded anchor, but I have not seen that. Steve
"DSK" <dsk@dontbotherme.com> wrote in message news:9o1le.28087$CR5.17414@bignews1.bellsouth.net...>>>They can be removed. That's what the threads do.>>
Steven J. Ross wrote:>> I believe he means from the keel itself.>>
Steve Lusardi wrote:> Doug,> On all the lead keels that I have seen, the bolts are held in the keel by > anchors, because the lead is too soft for threads to hold.
Really? I suppose if you're casting a lead fin around bolts held in place by some kind armature, maybe you're right.
In my experience, cast lead keels are alloyed with antimony, which makes it take a thread very well. The place for the keelbolts are drilled & tapped (using a jig), then the bolts put in.
I have also seen conventional bolts put up through the keel stub via recesses molded into into the keel, the recesses are then filled with putty. Then there's the technique (used in a couple of the lower priced mass-produced boats of the early 1970s) of welding the keelbolts in a 'T' and casting them into the keel. The method you describe is sort of a variation, I can easily believe it's done but haven't seen it myself.
They better not be able to be removed. All keel builders either weld a cage, or J-hook the bottom of the bolt to lock it in the lead. Only older iron keel are not done this way. There was a few cases of keels falling of because the forgot to bend the bottom of the bolt. The lead/antimony will not hold a straight bolt. Most keel builders tack the bottoms together to prevent them from floating away during the lead pour.
"DSK" <dsk@dontbotherme.com> wrote in message news:6g%ke.20287$8S5.9853@bignews3.bellsouth.net...> Steve Lusardi wrote:>> Jim,>> Normally the keel bolts will be cast into the leadballast and are not >> removable without recasting the keel. They will appear as long studs and >> fasten thru the floors with nuts and washers.>
They can be removed. That's what the threads do.>
You might have a really tough time getting them to turn... if you put a > slugging wrench down onto the nut, then put on a lock nut over that, you > should be able to get it started.>
DSK wrote:>>> They can be removed. That's what the threads do.>>
Steven J. Ross wrote:>
I believe he means from the keel itself.>>
So did I> ;)>
Regards> Doug King>
If the bolts were bent and cast into the molten keel, you will not remove them. You should find out the breaking strength of the bolts and then do not exceed this torque when trying to remove the nuts or bolts. If you get up close to breaking torque for your bolts and they don't come out and they don't break they are ok. Hell, If they get up to 75% and don't give, I'd trust them.
If you break one, you've got to do them all.
If they need to be changed, you might cut them out with a torch or saw, and re solder the keel top sections around the replacements, which you will position with very carefully crafted jigs tack soldered on, then cut off afterwards.
Should keep you busy for the weekend. Older bodymen and plumbers have experience with lead filling, using a naptha blowtorch. Old cast iron pipes were often caulked with molten lead.
Daniel, If you decide to remove the keel and inspect the bolts, I for one would be very interested in their state. I personally believe that malleable iron or manganese bronze is the keel bolt of choice and that the use of SS is very dangerous for the reasons stated in my other thread. However, there are many others that don't feel this way. Your inspection could go a long way in determining which school of thought is correct. Steve
"Daniel" <daniele.fua@unimib.it> wrote in message news:l7Hke.24543$795.759388@twister1.libero.it...>I recently hauled my boat and after few days I noticed allarming coloured >streaks oozing out of the thin crack (very thin and of little concern by >itself) between the keel and the hull.> The colour of the streaks is green-blueish, something that suggests copper > sulfate, and sort of shiny that suggests micro-cristals.>
According to the boat makers the keel bolts are AISI 316 SS and the keel > is of lead.> The boat was made in 1978.>
Do you have any suggestion? Do I have to drop the keel and check the > bolts? I would rather avoid it, if not really necessary.>
On Thu, 26 May 2005 00:41:47 -0300, Terry Spragg <tspragg567nospam@rogers.com> wrote:
If the bolts were bent and cast into the molten keel, you will not >remove them. You should find out the breaking strength of the bolts >and then do not exceed this torque when trying to remove the nuts or >bolts. If you get up close to breaking torque for your bolts and >they don't come out and they don't break they are ok. Hell, If they >get up to 75% and don't give, I'd trust them.
///>Terry K
This certainly sounds like uncommonly good advice. Unfortunately, it is not practical - something of a day dream in fact.
Engineers find great difficulty in relating tightening torque on a well-characterized fresh nut and bolt to its allowables or breaking strength - but when it comes to a submerged, possibly corroded fastener, you will be hard pressed to compute a torque value that is within a factor of three of the actual value which snaps the shank.
On Thu, 26 May 2005 00:41:47 -0300, Terry Spragg> <tspragg567nospam@rogers.com> wrote:>
If the bolts were bent and cast into the molten keel, you will not >>remove them. You should find out the breaking strength of the bolts >>and then do not exceed this torque when trying to remove the nuts or >>bolts. If you get up close to breaking torque for your bolts and >>they don't come out and they don't break they are ok. Hell, If they >>get up to 75% and don't give, I'd trust them.>
///>
Terry K>
This certainly sounds like uncommonly good advice.> Unfortunately, it is not practical - something of a day dream in fact.>
Engineers find great difficulty in relating tightening torque on a> well-characterized fresh nut and bolt to its allowables or breaking> strength - but when it comes to a submerged, possibly corroded> fastener, you will be hard pressed to compute a torque value that is> within a factor of three of the actual value which snaps the shank.>
Brian Whatcott Altus, OK
Well, let's presume a non-corroded bolt, then. If it breaks, it was corroded. Surely, the fact that it is submerged doesn't matter much.
Daniel wrote:> I recently hauled my boat and after few days I noticed allarming > coloured streaks oozing out of the thin crack (very thin and of little > concern by itself) between the keel and the hull.> The colour of the streaks is green-blueish, something that suggests > copper sulfate, and sort of shiny that suggests micro-cristals.>
According to the boat makers the keel bolts are AISI 316 SS and the keel > is of lead.> The boat was made in 1978.>
Do you have any suggestion? Do I have to drop the keel and check the > bolts? I would rather avoid it, if not really necessary.>
Thank you> Daniel
Thankyou for all your kind replies. Just to add a little more information: 1) the hull is fiberglass 2) still according to the manifacturer, the bolts are fixed in the lower part with a washer and a nut embedded in the keel lead. It should be possible to unfasten them.
I agree with dbohara: the colour of the ooze is quite puzzling: SS 316, fiberglass, lead... where do copper cristals come from?
Anyway, my first try is going to be some inspection in the crack; this weekend I will chisel off the outer layers of paint, putty end whatelse on a limited zone to have a closer look at the interface between the keel and the hull.
The ballast would be much safer if it were well up in the middle of the boat.
<dbohara@mindspring.com> wrote in message news:1117163568.283981.191940@o13g2000cwo.googlegroups.com...> Your problem got me curious so I did a search on keel bolts and there> is a plethora of info on the subject of inspecting and replacing keel> bolts. Owning a 28' boat, I have never had this problem because my> ballast is internal to the hull of my S2. Considering the difficulties> with bolt-on keels, why do they seem favored over good internal> ballast?> Now I cant stop and will become obsessed with finding a way to inspect> keel bolts...>
IF it were MY boat, and this critical of a structure {with regard to the results of a catastrophic failure}. . . I literally wouldn't trust MY eyes, library research, and any non-viewers comments.
This may be one of those cases where the few dollars to hire a TRUE expert, would be well spent. I would do a bit of research and find a GOOD, WELL RECOMMENDED, local sailboat surveyor. Hire his expertise, and listen to his opinion.
Regards & Good Luck, Ron Magen Backyard Boatshop
"Daniel" <daniele.fua@unimib.it> wrote in message news:eLAle.28893$795.894204@twister1.libero.it...> Daniel wrote:> > I recently hauled my boat and after few days I noticed allarming> > coloured streaks oozing out of the thin crack (very thin and of little> > concern by itself) between the keel and the hull.> > The colour of the streaks is green-blueish, something that suggests> > copper sulfate, and sort of shiny that suggests micro-cristals.> >
According to the boat makers the keel bolts are AISI 316 SS and the keel> > is of lead.> > The boat was made in 1978.> > SNIP
