Author Topic: Keel Bolt / Stud Leaking (Read 11706 times)

Harry Brown · « **on:** January 27 2016, 07:51 »

Hi Guys,

I have a 2007 Bavaria 39 Cruiser.
I'm looking for some guidance for stopping an intermittent leak from the aft keel bolt / Stud. (confirmed, definitely not leaking from anywhere else).
Has anyone had experience with this? Can I just re-torque the bolts or is removing / installing the keel the way to go?
I would assume removing the keel, to check everything is OK would be the best option, but if someone knows better, I would consider that!

Depending on the best solution, would anyone have or be able to explain the procedure / equipment needed please? i.e. keel trolley, compound used between mating faces, torque settings etc, etc.
I am capable of doing the job and looking forward to rectifying ASAP. The job would be carried out using a boat lift.
If no one has the procedure for Bavaria, maybe they know of a different type of vessel, that the procedure is similar?

Many thanks in advance for your help with this matter.

Yngmar · « **Reply #1 on:** January 27 2016, 11:00 »

That's a serious issue, especially on a boat that's not even 10 years old. Just re-torquing the bolts is definitely not enough - you'd have salt water trapped around stainless bolts, which leads to crevice corrosion. I would haul out, find the source of the ingress and get an expert (in my case it would probably be a surveyor) to confirm.

If the boat hasn't suffered any groundings or other accidents (e.g. sling failure during lifting), it's hopefully just the seal, which can be repaired without dropping the keel (3M 5200), after flushing with fresh water and drying out thoroughly. You can then withdraw the affected bolts one at a time for inspection (best done in the water) - to see if they've already been damaged.

It could also be something really bad, like damage to the keel matrix or a failed bolt that causes a gap to open at the aft end of the keel.

Dropping the keel is a huge effort and logistical nightmare. You need to build a frame to hold the keel, then lift the boat off it and figure out how to support its weight without resting on the keel, so you can access both sides of the joint. Alternatively a trolley that can be jacked up to receive the keel and haul it away, but that is tricky as the boat needs to be suspended above with enough room to maneuver the trolley out from underneath. This is made more difficult by the relatively thin hulls of Bavarias, which make it hard to suspend their weight when not resting on the keel - supports must be well placed at bulkheads and stringers, else they'll come right through the hull.

Once you've hauled out, share some photos and hopefully a positive diagnosis. Good luck!

Harry Brown · « **Reply #2 on:** January 27 2016, 11:32 »

I agree with you about not just re-torquing.

Could you please expand of the repairing of the seal and flushing in situ?
Also, they are studs and not bolts, so I can only take the nuts of and not withdraw, if that makes sense?

Harry Brown · « **Reply #3 on:** January 27 2016, 11:35 »

FYI, there is a good discussion taking place at present at the link below, with picture and video, that may help explaining.
http://www.ybw.com/forums/showthread.php?448651-Keel-Bolt-Stud-Leaking

Yngmar · « **Reply #4 on:** January 27 2016, 13:33 »

Quote from: Harrry Brown on January 27 2016, 11:32

I agree with you about not just re-torquing.

Could you please expand of the repairing of the seal and flushing in situ?
Also, they are studs and not bolts, so I can only take the nuts of and not withdraw, if that makes sense?

If the research I did for my boat was correct, they should be studs that are screwed into steel fixtures which are cast into the lead/antimony alloy that forms the keel. If it's an iron keel it may be differently made but should be functionally equivalent. You should be able to withdraw them using lock nuts. You'll definitely need a large size box spanner (size 36 on mine for M24) on an impact driver to get the nuts off in the first place.

When you're in the slings, grab the keel and try moving it sideways as hard as you can. It shouldn't wobble one bit. You'll also see if there is a crack in the seal. This may open or close when the boat is sitting on the keel, as that deforms the hull (so a flexible sealant should be used). If there is a crack and no other concerns (no wobbling and keel bolt inspection ok), you can wash it out (fresh water in the crack - not too much pressure) to get rid of the salt and then after drying squirt in sealant as far as possible and build a nice thick seam of sealant all around the keel/hull joint. Do check on the existing sealant and if it's peeling off easily, replace it all instead of just fixing the crack.

The Other Woman · « **Reply #5 on:** January 27 2016, 13:37 »

Hi Harry,
Just a suggestion
I had the same water coming round the keel studs so i checked the tightness of the nut it was OK. So after pondering what to do and thinking it would cost mega money i decided to slacken of the nut

to my supprise no water came in

.
the water was coming out the box section but were from? as it was salty i tasted it

it was coming from the vetus exhaust pipe there was a pin prick in the pipe spraying down to the hull and slowly it had crept its way down the box channel. new pipe job done.

Mick

Craig · « **Reply #6 on:** January 29 2016, 05:12 »

Leaking water around a keel bolt is a possible Major issue, even if it is a small amount of water at the moment.

You only have to look at the Cheeki Rafiti MAIB report to see the problems in identifying keel attachment issues and their repair. In this case, 3 of the repairers had different methods of determining the severity of keel damage and different methods of repair.

Merely seeing if the keel has any movement while in a sling is not enough. Banging the hull to identify delamination can not be done while the boat is on the hard, it needs to be done, either in the water or with the hull suspended in a sling with no support on the keel.

I noted from this report that my Bavaria 38 ( 2009) has much better keel boat washers than Cheeki Rafiti but don't know about earlier Bavarias.

I would strongly recommend getting "proper" professional help in determining if you have a major issue.

It would be great if you could let us know what the professional reports showed and how they did their investigation.

Craig
"Shirley Valentine"
Gold Coast Australia

Harry Brown · « **Reply #7 on:** January 29 2016, 10:44 »

At this stage what I am looking for is someone who has experience of removing a keel that has been bonded to the hull, at assembly. Ideally someone with Plexus MA310 experience.
This is the beginning of the leak, I'm going to gather as much information as I can, and then make an informed decision on what to do next. It may come to professional help after all but I'm keen to learn about this anyway.

Thanks for all replies.....

Ziffius · « **Reply #8 on:** January 29 2016, 15:07 »

Hi Harry, I have a 2005/6 bav 39. I looked at the video you posted on the ybw forum. At the bottom of the hull cross member right beside the keel bolt is the link drain hole that allows water to pass from the forward bilge compartments into the rear keel bolt compartment where your bilge pump is. That cross member is hollow and allows water from other parts of the boat to reach the bilge pump, not just the next compartment - areas like the rear of the boat eg under the calorifier. To me the water in the video is coming from the cross member and wicking round the keel bolt sealant. I have had water appear here from al sorts of places - it can be bone dry for ages then suddenly starts appearing particularly after being in bumpy seas. The water from other places gets held back by the geometry of the construction which means it can take some time and motion to eventually get to the bilge sump.

I would really be careful in your diagnosis to triple check where the water is appearing from.

Harry Brown · « **Reply #9 on:** January 29 2016, 16:54 »

Hi Ziffius, it does look like that doesn't it. Thinking about it now I wish I did a quick shot of the otherside of that bulkhead to show. It is completely dry. $:-\$

Harry Brown · « **Reply #10 on:** January 29 2016, 17:14 »

Just for an update:

There has been an awful lot of discussion over on YBW and Cruisers Forum. Its a bit to much for the to copy and paste over here but you guys might want to check it out when you have time.

http://www.ybw.com/forums/showthread.php?448651-Keel-Bolt-Stud-Leaking

and

http://www.cruisersforum.com/forums/f47/keel-bolt-stud-leaking-160134.html

Bavaria have suggested that if it is only 1 bolt leaking, to carry out a clean and reseal of the stud inside the bilge and the keel to hull interface. Detailed information at the link above. They also attached a Keel Installation Manual that is applicable to all Bavaria Yachts (attached to this post)

Ziffius · « **Reply #11 on:** January 29 2016, 22:30 »

Harry, just because the other side of the crossmember is dry doesn't mean that water isn't coming from the crossmember itself. On mine the flood from my calorifier found its way to the bilge sump via this crossmember. However, once the bulk of the water was mopped up it would seep out of the hole to the compartment forward whilst the sump was completely dry. That was due to the balance of the boat being a bit forward heavy. Try poking some rag into the crossmember to see if it comes out wet.

Ziffius · « **Reply #12 on:** January 29 2016, 22:51 »

I noticed near the end of the cruiser forum you say
"It leaks during and after a sail. Stood in the slip it was leaking slowly for about 2 days (1 quart), as the keel settled down. No staining or rust as its only just happened. Boat is 2007."

That sounds more like water inside the various voids below the cabin sole finding its way towards the sump - if the boat is on the slip I wouldn't expect water to be still coming up from the keel For 2 days.

Yngmar · « **Reply #13 on:** January 29 2016, 23:02 »

Just shove a wad of Blu-Tack into the limber hole to temporarily seal it. That'll let you rule it out.

Trundletruc · « **Reply #14 on:** January 30 2016, 16:46 »

I had a number of occasions when water appeared round the rear keel bolt in my 2002 B36.
The first time it appeared when we had friends on board and whilst washing up the splatter went down the cracks in the floorboards!!! Initially I thought we had a slight leak.
The second time it was caused by a leak on the rear shower with the water running down through the locker and into the fiberglass frames.
The third time I occasionally noticed water appeared from the bilge pump. On examination I found out that the pipe from the bilge pump to the rear of the boat did not have a U bend so rain water and hose pipe water, when cleaning off the boat,was running down to the one way valve situated just before the pump. Unfortunately, the one way valve was leaking slightly. One can imagine that the pipe could hold quite a lot of water.
This just goes to show that you need to check very carefully that it really is the keel stud that is leaking.
I would be inclined to build a dam of sealant or something round it to make sure it really is the keel stud.
I have to add that in my cases the water was not particularly salty but it is difficult to say when wet overalls have dripped water onto the floor.

Impavidus · « **Reply #15 on:** January 31 2016, 16:28 »

Hi all. A word or two of caution when playing with you nuts

Keel studs and nuts are typically 316 stainless steel they should be kept dry to prevent Crevice Corrosion (or in an environment that has a ready flow of oxygen such as flowing water or open air). They must be lubricated before tightening or undoing to prevent Galling.

Corrosionpedia explains Crevice Corrosion

Crevice corrosion refers to the attack of metal surfaces by a stagnant solution in crevices, for example in nuts and rivet heads. When dust, sand and other corrosive substances are deposited on surfaces, they create an environment where water will accumulate and corrode the part. It can happen between two metals or between a metal and a non-metal. This causes damage to the metallic part, which is initiated by the concentration gradient in chemicals.
Oxygen causes an electrochemical concentration cell outside the crevice. This is a differential aeration cell where the air present is oxygen. In the crevice (the cathode), the pH and the oxygen content increases. However, this is the opposite for the chlorides; they are lower.
For chlorides, the electrochemical concentration is higher on the inside, which worsens the corrosion. When a ferrous metal is present, the ferrous ions react with the chlorides to form ferric chloride, which attacks stainless steel. This makes the concentration of both the oxygen and the pH remain lower in the crevice than the concentration in the water solution that forms on the metal. The propagation mechanism is similar to that of pitting corrosion.

Galling. (from bolt depot)

Thread galling occurs during installation when pressure and friction cause bolt threads to seize to the threads of a nut or tapped hole. It is also known as "cold welding".
Once a fastener has seized up from galling it is typically impossible to remove without cutting the bolt or splitting the nut.

What Bolts Are Susceptible To Galling?

Galling is most often seen in stainless steel (especially when using lock nuts), aluminum, and titanium. Fasteners with damaged threads and fine threads are particularly prone to galling. Hardened steel bolts, especially when zinc plated, rarely gall.

Galled bolt with removed nut
Bolt showing light thread galling after the seized nut was removed.

What Can I Do to Prevent Galling?

Slow Down Installation Speed

Because heat generated by friction is a contributing factor in galling, slowing down the installation speed can prevent galling. It is recommended that power tools not be used for the installation of stainless steel or other fasteners prone to galling. This is especially important when using nylon insert lock nuts as these nuts significantly increase the chance of galling.

Hope this helps.

Best regards Ant.

Salty · « **Reply #16 on:** January 31 2016, 17:50 »

Thanks Impavidus, your comment backs up my reply to a previous posting under the heading of leaking rudder from 2015. In that posting I attempted to draw the readers attention to stainless steel immersed in stagnant seawater. For many people, stainless steel seems to be an almost perfect material, but it has some very serious and significant drawbacks that need to be considered carefully in order to get the best out of the material. The following is part of an article that I referred the readers to at the time, and it's inclusion here is, I think timely, and confirms your comment:-

"Stainless steel: The most common keel-bolt material in America is stainless steel. This is dismaying to many, because stainless steel suffers rampant corrosion when immersed in stagnant seawater. Using it for keel bolts anticipates that the bolts will remain dry?which is optimism bordering on delusion. The good news is that if they do remain dry, they have proven to last for half a century or longer."

The problem of course is if they don't remain dry, and will tend to be concentrated in the area between the top of the keel and the point just below the washer inside the bilge where the securing nuts are tightened, as this is where the seawater is most likely to remain stagnant. Water within the bilge area itself is not normally stagnant because it remains continually on the move with the boat pitching and rolling. In consequence of that movement the water remains aerated, oxygenised and therefore not stagnant.

On boats where the hull seal has starting to leak is the situation I believe, where there is the most risk of stagnant water being present, and hence the need to maintain that hull seal in very good condition.

Referring to the MAIB report on the loss of the Cheeki Rafiki, and the photo of the upturned hull shows significant rust staining around at least one of the holes for the keel bolts. Sadly with the keel in place, being able to see that staining is not at all easy.

Another problem I personally have noticed is that there are some grades of stainless where a process takes place resulting in the nuts beginning to crumble. Whilst at sea onboard Liquefied Natural Gas tankers, many parts of the ships were constructed from stainless steel on account of its ability to be able to handle the extremely low temperatures involved in the handling of LNG and also of Liquid Nitrogen where nitrogen vapour was used within the seals for gas compressors and in inerting the interbarrier spaces.
Parts that needed to be made removable for reasons of access, and largely located on deck where they were open to the sea air, were secured with stainless nuts and bolts that in a relatively short period of time began to crumble and had to be replaced with a better material. Despite the hundreds of millions of pounds those vessels each cost to build, some of the grades of stainless steel used weren't always the very best, though as far as I can recall the problem was limited to just nuts and bolts.

tckearney · « **Reply #17 on:** February 02 2016, 07:56 »

Hi a very simple and cost effective way of checking for keel bolt leaks is to get a piece of 3" plastic drain pipe cut it into 2" length's and then silicone them around the bolts and nuts, one per bolt. I had this problem and thought the worse and the water did taste slightly salty, but it was a leak elsewhere in the boat coming through the voids in the hull construction. To test for sea water get a sample of the water along with one of fresh water and rain water then put them in a small pan and reduce the water slowly on the cooker. You will see the salt deposit is different on the seawater. I did this and it gave some but not complete assurance. I therefore bought a test kit from the pet shop for testing freshwater and salt water fish tanks. That confirmed my thoughts that this was definitely not seawater. It ended up being the calorific pressure release valve

Harry Brown · « **Reply #18 on:** February 24 2016, 09:10 »

UPDATE:

Guys,

I was at the boat this weekend.
I need to eat some humble pie!!

I was 100% wrong, you guys were right. The keel bolt is not leaking, it is from elsewhere, (yet to be tracked down, fresh water leak slightly tainted with salt).
This is obviously good news but I am very sorry for wasting everyone?s time and appreciate all the help /advise that I was given.
When I first saw the water around the bolt, I panicked and talked myself into the worst, it really did look like it was coming from the bolt, further investigation proved otherwise.

I also apologize to every other Bavaria owner for muddying the already dirty waters regarding Bavaria keels!

The boat is sound, the keel is sound, and 39 Cruiser is still an amazing yacht!

Thanks again, I?m going to go finish my pie now!!

The Other Woman · « **Reply #19 on:** February 24 2016, 09:52 »

Hi Harry,
Thanks for the update,

Good luck in finding the leak, hopfully it wont cost as much as you first thought.
There are a few good places to start looking as have been posted but please try the exhaust pipe and water baffle .

Keep us informed of your progress.
Thanks
Mick

Ziffius · « **Reply #20 on:** February 24 2016, 19:26 »

And calorifier, sink drain. Old water spillages. Rain water ingress through screw in the toe rail. Leaks from shower drains. All possibilities for water ingress that might take some time to reach the bilge. Last year I put a water melon on the galley top which rolled as we sailed along and hit the galley tap turning it on with the sink cover in place. Most of the aft water tank (luckily half empty) ran out over galley top and down over oven and into bilges and other places. Took quite some time to finally get a dry bilge again as more water kept appearing with boat motion. If your lucky you might eventually get a bone dry bilge after mopping out every time water appears.