Sea cock bolts??

Caer Urfa

Caer Urfa

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During a recent survey the surveyor was not to happy about 'possible 'rust showing on the four through hull bolt nuts
holding the sea cocks in and wants the bolt nuts replaced or worse the complete bolt.
At this point the hull is 25mm thick so they will take some getting out!
Question is what are the bolts made of? if they are bronze why would they rust? if not what do members think the bolts are made of?
DSCN1093_edited.jpg
 
They should be bronze. It is possible in some cases that someone has fitted brass, which is a separate issue that shouldn't concern you but is worth knowing about.

Looking at your photograph, one bolt, partly hiding behind the black pipe seems to show a bit of rust staining. It also looks a bit silvery, could it be stainless steel? Or is there a nut on there that is stainless?

Stainless steel and bronze are close enough together on the galvanic scale to be considered compatible, but stainless steel, even 316 (A4) should not be used in this position as it may start to crevice corrode, particularly on the thread. The first visible symptom will be rust staining.

The boat is unlikely to sink in the next 5 years, especially if it is only one bolt. You will need a hammer and a long pin punch, but it shouldn't be difficult, and I'd replace it on the next lift out. I'd probably look at all the other bolts as well while I was at it, for peace of mind. If they're ok, coat them with mastic and replace them and that will be that. Otherwise, replace them. I got my replacement bronze bolts from Classic Marine, they're expensive wherever you get them from.
 
They should be Silicon Bronze which of course does not "rust" but can de-zincify - usually turing pink and crumbly. First thing is to clean them thoroughly on the inside to see if they are "pink". However, the only way of really checking is to knock them out, take out a mortgage and buy some new ones.
 
[ QUOTE ]
During a recent survey the surveyor was not to happy about 'possible 'rust showing on the four through hull bolt nuts
holding the sea cocks in and wants the bolt nuts replaced or worse the complete bolt.

[/ QUOTE ]

How is he going to make the decision as to whether it's the nuts, or the whole bolt/s? or has he left that up in the air for you to decide.

I dont know the answer to your questions but:

Having just replace 13 keel bolts at tremendous cost, due to a bit of rust, the lesson to be learned is that if a surveyor is coming anywhere near your boat, you need to get rid of all "possible" signs of rust, or at least leave some for him to find on something that is easy to replace.

I'm not knocking surveyors... they have a job to do and, if they didnt give the advice, and my keel fell off, or your seacock leaked and sank your boat, they would be in trouble - it's for us to give them little to find where we can.
A few hours of wire brushing /forums/images/graemlins/smile.gif, (drill assisted where possible), would avoid many of these things
 
Last time I replaced a Blakes seacock the bolts came out easily enough but it then took several heavy blows with a lump hammer to release the fitting from the Sikaflex!
 
Yes, thats the problem. Had the same thing happen many moons ago but fortunately while ashore. Put a spanner on the nut an the bolt snapped like a carrot. Why I suggested any doubt have them out. If they are sound it is obvious and they can be replaced. Equally obvious if they are not - once you have them out!
 
Thanks gents for the info,
I am really looking forward to getting the bolts out! I have a feeling I will end up having to get both sea cocks out to re-seal them as all the knocking out required to get the bolts out will break any seal.
Regards
Mike
Colvic Watson Owners Group
 
Do not look very robust in your pictures, I would suspect some dezincing has taken place on a least a couple. Should be marine grade bronze but whos knows whats been changed over the years. A good long correct dia pin punch (Snap On) will tap the bolts out but best to draw off the valves as well to check the bronze on the body itself if you are going this far

Brian
 
Just a thought.

They may be bedded on cut outs made of marine ply or similar.

Might be an idea to scrape a bit gently just to see what's there.

On the other hand, might be part of the moulding.

Often they are bedded on ply when there is a large turn of the bilge.

Best of luck
 
Hi Snowgoose
Yes they are mounted on raised pads which are all part of the hull mould, the hull at that point is 20mm thick plus the mounting pads making 25mm thickness.
We do not call Colvic Watsons little tanks for nothing!
Thanks all for your comments
Mike
 
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