Blue Liquid Seeping from Hull /Keel Joining

[dougieji]

Just inspected a Bavaira 50 cruiser with a view to purchase. Boat on hard for some time in Thailand looks well maintained overall BUT there is seeping blue fluid stain from where keel attaches to hull. Before i think about a survey has anyone an idea of what causes this and is it a problem.

Have pictures only 350 k total and have tried for last hour to upload and will not ????

[Captsteve53]

Blue or Green ? Usually means some sort of galvanic corrosion coming from the keel or keel bolts (assuming this is not an encapsulated /enclosed keel), there's been numerous discussions on this recently in a previous thread under cracks around keel,

Cheers Steve

[dougieji]

teal blue, not sure if encapsulated, what am i doing wrong to not being able to upload pics ?

[Captsteve53]

Yes i had some issues with uploading pics at first,

1) scroll down to the bottom of the page to the heading under ADDITIONAL OPTIONS then (attach files) on a lot of views it's not there until you scroll down to the bottom of your page,

try to follow the previous threads and find the same issue as yours as there's numerous posts on this subject - some helpful some not

Cheers Steve

[dougieji]

Pics downloaded, thanks, files were tooooooo big

[Captsteve53]

Bavaria's have bolt on cast iron keels as most other late model mass production yachts, here's a recent article you should read about keel failures before there's numerous posts telling you not to worry! there's a Bavaria just lost her keel as well!

Keel failure: the shocking facts - Yachting World

I always err on the side on safety as I am a marine surveyor under the IIMS and Lloyd's maritime and we need to check these issue's out before we make rash statements such as (dont worry about it) under such maritime bodies if such a thing like a keel coming off after an inspection we would be liable under the law to prosecution, some thing a lot of sailors dont realize, average insurance for this costs over $3000 a year before i set foot on a vessel!

Cheers Steve

[Captsteve53]

From your pics it certainly looks very minor, A lot depends on the age of the yacht?

If she is a more recent build it should present no real issues at all, but to be prudent just check inside the vessel inside/under the floors for any signs of movement or cracks, all these keels are bedded on some sort of sealant/adhesive such as 5200 or similar and its not un common to have a small void where sea water will ingress and cause this type of re action,

Again from the Pictures only i would say not an issue

I offer the forgoing only as advice with no preconception, with no legal implications and without prejudice.

Cheers Steve

[dougieji]

Originally Posted by Captsteve53

From your pics it certainly looks very minor, A lot depends on the age of the yacht?

If she is a more recent build it should present no real issues at all, but to be prudent just check inside the vessel inside/under the floors for any signs of movement or cracks, all these keels are bedded on some sort of sealant/adhesive such as 5200 or similar and its not un common to have a small void where sea water will ingress and cause this type of re action,

Again from the Pictures only i would say not an issue

I offer the forgoing only as advice with no preconception, with no legal implications and without prejudice.

Cheers Steve

thanks, i am just trying Bavaria forum there appears to be a copper coating on some models which could account for the colour

[Captsteve53]

Yep called Copper Coat Marine Antifoul | Coppercoat Coppercoat supposed to be good for up to 10 years!!!!

[dougieji]

Originally Posted by Captsteve53

Yep called Copper Coat Marine Antifoul | Coppercoat Coppercoat supposed to be good for up to 10 years!!!!

thanks the boat is 2006 model so 10 years is up. Time to recoat ?

[boatpoker]

why not just look in the bilge and see if someone dropped a bottle of blue stuff ?

It does not look like corrosion to me and certainly not any kind of galvanic corrosion.....
Certified Corrosion Analyst

[atoll]

as a plumber i have seen this around copper tubing,ie copper oxide
i have also seen this in cases of osmosis where the trapped liquid seeps out from the hull.

my guess would be it is trapped liquid seeping out from the keel /ballast joint that has become laden with a leeched out copper solution.

try burning some of the residue on the end of a knife,if it has a green flame it is copper.

i would also look at replacing,or at least inspecting keel bolts,due to the numerous,documented bavaria keel bolt failures.

[Captsteve53]

In reply to your question re application of the Copper coat unless evidence is available for re-coating then you should plan on the expense of re-coating (not cheap in the short term) but works out in the long term,

Just a note: If some thing blue was in the bilge how would it get through the hull with out a gallery or some form of corrosion crevis/galvanic or other, my first synopsis holds true due to the following:

1) Dissimilar metals(Keel bolts/steel &keel/cast iron) and alloys(copper coat) have different electrode potentials, and when two or more come into contact in an electrolyte (in this case sea water), one metal acts as anode and the other as cathode. If the electrolyte contains only metal ions that are not easily reduced (such as Na+, Ca2+, K+, Mg2+, or Zn2+), the cathode reaction is reduction of dissolved H+ to H2 or O2 to OH−. The electro-potential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte.

2) This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. The electrolyte provides a means for ion migration whereby ions move to prevent charge build-up that would otherwise stop the reaction.

I would never be able give a diagnostic analysis from a picture in any event,


Below if you are interested is regarding keel checks where you can form your own better informed decisions,

Keel studs and their retaining nuts and washers should be inspected visually every year for any signs of corrosion and, in particular, before and after any significant passage. Any sign of corrosion of the studs or signs of rust weeping at the hull to keel join, water ingress around the keel join, or loosening of the studs should be addressed immediately and, wherever possible, with the assistance of a qualified surveyor and/or a reputable repair yard. It is not generally necessary or advisable to draw the studs and lower the keel unless there is evidence of damage, corrosion or general loosening.

Certainly a yacht must be lifted from the water and visually inspected after any grounding, no matter how insignificant it might appear. A good insurance policy will provide cover for this and the cost will be accepted as a fair cost irrespective of whether or not damage is found. In our view, the policy excess should be waived in respect of the inspection and only applied if there is damage requiring repair. With most incidents of grounding there will be an element of point impact damage and there may be some consequential shock damage elsewhere. Sometimes the latter is the most damaging.

After a grounding and inspection of the hull, it is always prudent to check the engine and generator mounts to ensure that none of them has become dislodged or broken. In more significant groundings the rig should be checked too. The engine is often the ‘get out of jail card’ in an emergency situation.

The modern matrix design of some light-displacement yachts gives concern. We frequently encounter incidents where the keel structural matrix has been damaged and consequently moves independently of the hull skin. This is generally encountered after grounding when only an in-water inspection has taken place. When the vessel is hauled ashore and the keel inspected while still in the slings, any twist or separation of the matrix bonding becomes evident.
It is important to inspect the hull to keel join with the keel studs/bolts in tension – i.e. with the vessel held in slings, rather than resting on her keel – when any gap or movement/damage will be more appreciable. Continued use of a yacht in which the keel matrix has separated is dangerous.

I offer the forgoing only as advice with no preconception, with no legal implications and without prejudice

Cheers Steve (MIIMS-Lloyd's Maritime-NZ Eng 1)

[dougieji]

Originally Posted by Captsteve53

In reply to your question re application of the Copper coat unless evidence is available for re-coating then you should plan on the expense of re-coating (not cheap in the short term) but works out in the long term,

Just a note: If some thing blue was in the bilge how would it get through the hull with out a gallery or some form of corrosion crevis/galvanic or other, my first synopsis holds true due to the following:

1) Dissimilar metals(Keel bolts/steel &keel/cast iron) and alloys(copper coat) have different electrode potentials, and when two or more come into contact in an electrolyte (in this case sea water), one metal acts as anode and the other as cathode. If the electrolyte contains only metal ions that are not easily reduced (such as Na+, Ca2+, K+, Mg2+, or Zn2+), the cathode reaction is reduction of dissolved H+ to H2 or O2 to OH−. The electro-potential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte.

2) This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. The electrolyte provides a means for ion migration whereby ions move to prevent charge build-up that would otherwise stop the reaction.

I would never be able give a diagnostic analysis from a picture in any event,


Below if you are interested is regarding keel checks where you can form your own better informed decisions,

Keel studs and their retaining nuts and washers should be inspected visually every year for any signs of corrosion and, in particular, before and after any significant passage. Any sign of corrosion of the studs or signs of rust weeping at the hull to keel join, water ingress around the keel join, or loosening of the studs should be addressed immediately and, wherever possible, with the assistance of a qualified surveyor and/or a reputable repair yard. It is not generally necessary or advisable to draw the studs and lower the keel unless there is evidence of damage, corrosion or general loosening.

Certainly a yacht must be lifted from the water and visually inspected after any grounding, no matter how insignificant it might appear. A good insurance policy will provide cover for this and the cost will be accepted as a fair cost irrespective of whether or not damage is found. In our view, the policy excess should be waived in respect of the inspection and only applied if there is damage requiring repair. With most incidents of grounding there will be an element of point impact damage and there may be some consequential shock damage elsewhere. Sometimes the latter is the most damaging.

After a grounding and inspection of the hull, it is always prudent to check the engine and generator mounts to ensure that none of them has become dislodged or broken. In more significant groundings the rig should be checked too. The engine is often the ‘get out of jail card’ in an emergency situation.

The modern matrix design of some light-displacement yachts gives concern. We frequently encounter incidents where the keel structural matrix has been damaged and consequently moves independently of the hull skin. This is generally encountered after grounding when only an in-water inspection has taken place. When the vessel is hauled ashore and the keel inspected while still in the slings, any twist or separation of the matrix bonding becomes evident.
It is important to inspect the hull to keel join with the keel studs/bolts in tension – i.e. with the vessel held in slings, rather than resting on her keel – when any gap or movement/damage will be more appreciable. Continued use of a yacht in which the keel matrix has separated is dangerous.

I offer the forgoing only as advice with no preconception, with no legal implications and without prejudice

Cheers Steve (MIIMS-Lloyd's Maritime-NZ Eng 1)

The electro-potential difference between the reactions at the two electrodes is the driving force for an accelerated attack on the anode metal, which dissolves into the electrolyte.

This makes perfect sense to me. The electrical activity and resulting corrosion has caused the blue fluid to leak out of the space where the sea water, the electrolyte entered in the first place and from my inspection the seal was broken in many places which would indicate that the problem is quite advanced

Thank you again for your insights

[boatpoker]

I did not say there was no breech in the keel/hull joint, in fact small breeches are quite common. I said and I'll say again Galvanism will not cause any blue/green corrosion
by-products. Steel and iron "rust" (Iron oxide). Rust is a form of corrosion specific to those materials. Copper does not rust although it may corrode. More likely is is simply verdigris, a benign form of corrosion or It could possibly be "bronze disease" (possible in any copper bearing alloy) but that is unlikely.

As copper is higher (more cathodic) than steel and iron (less cathodic) on the galvanic scale, it is the steel or iron which will corrode not the copper and their corrosion by-products are not blue.