Corrosion/ Zinc problem- thru hull and keel bolt...

[reserche]

Hello Hunter Owners!

Okay..here's the issue of the day - before imminent disaster, i.e., losing a keel - I wanted to ask you some advice... My diver had noted on the last report- that he saw corrosion on the keel area. My friend and I looked about the boat inside- saw some corrosion on the thru hull by the engine..also on one keel boat.

This seems to be a zinc related issue. Any suggestions? An additional large zinc? Zinc is in the wrong spot? My friend talked about running a wire to these various items... I'm just not sure what the right solution could be. Would like to hear some preliminary diagnoses.. It just appears the zinc configuration I have now is not alleviating the corrosion issue... and this is something I want to nip in the bud here.

Thanks!

 

[allend]

Apparently, if the zincs are not properly attached they do not work. Sometimes corrosion in their bolts can insulate them from the metal to which they are attached.

 

[reserche]

Apparently, if the zincs are not properly attached they do not work. Sometimes corrosion in their bolts can insulate them from the metal to which they are attached.

Hmm.. interesting. Well, I will mention this then to the dive company owner as a possiblity as well then - I put a call in to him today, but got a voicemail.. Thanks for the tip on that.

 

[allend]

My friend and I looked about the boat inside- saw some corrosion on the thru hull by the engine..also on one keel boat. This seems to be a zinc related issue.

Always a good idea to make sure the zinc bolts are not corroded, but what you mention is inside the boat. I'm no expert, but I am not sure that would be zinc-related. My understanding is that the zincs keep stray currents from eating away your exterior metal items like the prop, etc.

If you are just seeing a little surface rust or tarnish and not pitting or erosion, this means that you have some salt water in the bilge.

I would think and that a little salt water in the bilge is not abnormal -- assuming you have a prop shaft running through a non-dripless seal. Shaft seals are designed to drip a bit for lubrication.

 

[Allan Frey]

>he saw corrosion on the keel area.
We don't know what he is seeing, its vague.

>My friend and I looked about the boat inside- saw some corrosion on the thru hull by the engine..also on one keel boat.

This may or may not be serious, depending what it is that you are actually seeing.

Since you don't seem to be familiar with boats, maybe you should have a surveyor look at it.

Allan

 

[reserche]

This may or may not be serious, depending what it is that you are actually seeing.

Since you don't seem to be familiar with boats, maybe you should have a surveyor look at it.

Allan[/quote]



Allan- thanks for the note - I guess you didn't understand that this is MY boat. I already had a surveyor look at it when I bought it- he noticed some corrosion on a thru hull by the engine, told me to clean it off. I've had the boat dived every since, twice a month - this is the first note I've received that the diver is seeing corrosion on the outside.

And p.s. - I was the Commodore of a yacht racing club- I know a *liittle bit* about boats... Still - there's always new things to learn.

 

[reserche]

By the way - here's a discussion on the various causes of corrosion I've been reading, and how to remedy it... http://books.google.com/books?id=TZ...=X&oi=book_result&resnum=7&ct=result#PPA82,M1

I may also have some stray current from the bilge pump.. it seems to be shorting in and out a bit - not a great wiring job in there, so - methinks I'm going to have to have that redone. Anyway! Just some more thing to think about re: corrosion causes/ remedies.

 

[Allan Frey]

The context of your posting, Julie...
was the metallurgy and electrical systems of boats and the technical knowledge of them. I was talking in that context. That is unrelated to ownership and and running a racing club.

My interest was in keeping you safe. The phrasing of your postings indicates that you don't have the technical knowledge, in that context, to provide the information necessary for a remote diagnosis to be done accurately (eg >he saw corrosion on the keel area.) The same is the case with many, if not most boaters. Thus, I suggested that you have a local surveyor see and make the assessment.

Allan

 

[kloudie1]

Julie, your boat has a cast iron keel so any minor scratch in the paint would start a corrosion trail.. At the top of the keel however, where it intersects with the hull, sometimes there will be a minor looking crack that will weep rust. If this crack is deep enough, the seawater can get to a keel bolt and start a rust trail from there into the bilge. This requires attention, because that is the one that can corrode the keel bolts. Typically the boat would be pulled out and the keel-to-hull intersection would be ground back and re-sealed and then faired or re-fiberglassed depending on how much work had to be done. Rust at the top of that joint is something to be addressed.. Rust on the faces of the keel can wait ..

 

[allend]

I may also have some stray current from the bilge pump.. it seems to be shorting in and out a bit - not a great wiring job in there, so - methinks I'm going to have to have that redone. Anyway! Just some more thing to think about re: corrosion causes/ remedies.

Hmmm. If you have live bare wires or wires with insulation breaks or connecters together with water in the bilge, you could get some rapid electroysis. 12V can transfer quite a bit if metal quite quickly if the conditions are right. (The zincs are outside, so have little to do with electroysis inside the boat).

The warning about the keel bolts is a wise one. Once even a little slack develops in the keel attachment, the condition can progress rapidly.

 

[reserche]

Hmmm. If you have live bare wires or wires with insulation breaks or connecters together with water in the bilge, you could get some rapid electroysis. 12V can transfer quite a bit if metal quite quickly if the conditions are right. (The zincs are outside, so have little to do with electroysis inside the boat).

The warning about the keel bolts is a wise one. Once even a little slack develops in the keel attachment, the condition can progress rapidly.

This is what I'm concerned about inside... The wiring to the bilge pump seems to sort of short in and out- it doesn't seem firmly connected, and the wires look like they've dipped into the water in the when there is water...

The owner of the dive business is going to come out and test the various areas with his meter - he did say he thinks there are enough zincs, and they are properly placed for the boat... My other friend said we may want to run a wire throughout from the various thru hulls, etc. I guess we'll know more after this diagnosis with the meter.
The dive guy also said that it could also be that paint is peeling off (its time to haul and paint the bottom) - so this is also what the diver could have seen and called "Corrosion." But that doesn't explain the corrosion on the interior keel bolt. So..we'll see....

 

[reserche]

Julie, your boat has a cast iron keel so any minor scratch in the paint would start a corrosion trail.. At the top of the keel however, where it intersects with the hull, sometimes there will be a minor looking crack that will weep rust. If this crack is deep enough, the seawater can get to a keel bolt and start a rust trail from there into the bilge. This requires attention, because that is the one that can corrode the keel bolts. Typically the boat would be pulled out and the keel-to-hull intersection would be ground back and re-sealed and then faired or re-fiberglassed depending on how much work had to be done. Rust at the top of that joint is something to be addressed.. Rust on the faces of the keel can wait ..

I appreciate this Claude- this is the kind of thing I am concerned about...I appreciate you bringing this to my attention. I want to know what to look for and ask about as these various people are looking at the boat to assess it. Thanks much....

 

[reserche]

The context of your posting, Julie...
was the metallurgy and electrical systems of boats and the technical knowledge of them. I was talking in that context. That is unrelated to ownership and and running a racing club.

My interest was in keeping you safe. The phrasing of your postings indicates that you don't have the technical knowledge, in that context, to provide the information necessary for a remote diagnosis to be done accurately (eg >he saw corrosion on the keel area.) The same is the case with many, if not most boaters. Thus, I suggested that you have a local surveyor see and make the assessment.

Allan

Well, I can appreciate that Allan - but the thing was - in this case, it wasn't my lack of technical knowledge - I was reporting exactly what the diver wrote on the report "corrosion on the keel area." We didn't get any more info than that to go by... A visual inspection inside lead us to notice some interior corrosion - these two things may or may not even be related. Having a lack of information, and not being able to reach the owner of the dive firm- I thought perhaps you all might be able to consider what the possibilities were.... so I could ask whomever is going to take a look at this situation. I like to do my homework. Anyway.. thanks for your advice.