Any Surveyors? - Am I being set up? 7 photos

[Dipper]

When I bought my boat (not a Moody), some of the keel stud nuts were badly rusted due to water collecting in the bilges. I replaced all the studs with high tensile steel studs (as recommended by the designer). The original nuts were glassed in but it only needed a tiny crack to allow water in the bilges to penetrate causing rust and expansion making the crack larger etc etc.

When I renewed the studs, I painted the nuts and surrounding area with several thick layers of car body underseal - the old fashioned very cheap rubbery stuff not the modern waxy product. Twelve years later, still no signs of rust.

 

[Anonymous]

[ QUOTE ]
I am wondering if an annual job should be to slacken, grease, and tighten the nuts, with a torque wrench.

[/ QUOTE ]Now you've been through this you will always watch when she comes out and is dropped down, for any movement in the keel. That's the real guiding factor for you; if there is no appreciable movement and the keel still lines-up, no dings on the leading edge, then you are OK.

As for rust, with older stuff, already rusted, I wire-brush and apply rust converter/pickle. I've been using a cheap local Spanish product for some years (pink, looks a bit like kaolin and morphine when you shake it) and that works fine. I then spray over the top with an anti-rust spray (from RS Components) -- it's the stuff that manufacturers use to coat steel parts for storage in open areas, before they are used or treated. Pink, waxy. Comes off easily and lets a spanner onto any nuts without removing it. Most of the parts of my steering system and even the hydraulic pipe connectors are steel, and they all live under our bed so there is constant condensation down there. Using this technique I only need to do something once a year and having got it under control, this year I just touched-up the wax spray in one or two places. Very pleased with the degree of control.

I've also had great success with zinc-rich cold galvanising spray. I was using Hammerite on engine bed parts, etc., but it is messy and not that effective. Last year I sprayed a 12" section of our anchor chain that had become a bit rusty (sound, but tired galvanising leading to rust areas) with a liberal amount of Zn spray. I gave it three coats. Looked very smart and I did not expect it to hold up but it survived the whole summer mostly at anchor and is still looking good today.

Maybe degrease your new plate and protruding studs and nuts and spray over with Zn spray?

 

[Bilgediver]

"The standard Moody method of keel construction and attachment (apart from a few boats with lifting keels) is a cast iron fin keel or twin keels attached by mild steel studs and nuts resting on mild steel backing plates in the bilges. The joint between the keel and hull is sealed with Sikaflex.

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If you have an aversion to SS keel bolts there is absolutely no point in going to high tensile over mild steel . It might sound a good alternative and gain beer points in the yacht club bar but will offer no advantages on boats such as a Moody.

The reason for this is that when one looks at the whole assembly of keel to hull we see that the limiting factor in this whole assembly is the compressive strength of the fibre glass hull and that the required torque figures to reach this limit are well withing the capabilities of normal sized mild steel bolts. The only problem will be corrosion so this could be addressed by a coating of some sort such as cad plating , galvanizing, good paint preparation or even the underseal gunge you get in HAlfords which sticks like sh*t to a blanket and is often used in the offshore industry on marine riser assemblies which are exposed to all sorts of conditions.

Westely consistently used stainless steel and I occasionally draw a stud or two to see how they are doing and have yet to find a wet one let alone one which shoes any sign of distress however the tension in these studs is minimal compared to the tension that would be in them in a normal steel on steel application. I often wonder if anyone has found a broken or cracked stud on a Westerly.?????

 

[Anonymous]

[ QUOTE ]

If you have an aversion to SS keel bolts there is absolutely no point in going to high tensile over mild steel . It might sound a good alternative and gain beer points in the yacht club bar but will offer no advantages on boats such as a Moody.

[/ QUOTE ]It all comes down to what the designer allowed for. High tensile steel is stronger but more brittle. If you ding your keel you don't want the bolts to shear, so ductile mild steel is clearly a little better. A large number of mild steel bolts, sharing the load, sounds like a good engineering solution provided they are replaced every so often when they get rusty -- which they will, however they are protected.

The correct answer is to use what the designer specified -- high tensile, stainless or mild. I thought that most were high tensile, but maybe I am wrong? If high tensile was specified by the designer, for goodness sake don't replace them with mild steel as the loading calculations (static, dynamic and grounding) will have been calculated by the naval architect.

 

[Richard10002]

"I've also had great success with zinc-rich cold galvanising spray."

David,

Can you tell us the name and brand... I would like to get some, and so would my current neighbour.

Cheers

Richard

 

[Anonymous]

Richard, it is VERY buried right now under where S. is sitting /forums/images/graemlins/frown.gif But it is a local Spanish brand so I don't suppose you'll get it in Malta though there must be an alternative brand. The wording to look for is 'Zinc Rich' and 'Cold Galvanising'. There used to be a brand called 'Galvafroid' available in the UK in pots or spray and that was excellent. In Spain I couldn't get anything other than spray with is a pain on a boat as it goes all over the place outside and you have to tape papers everywhere before spraying. I much prefer to use a brush. See......

http://www.nwepaints.co.uk/acatalog/Galvafroid%20Data.PDF
http://www.zinga-uk.com/files/Competition%20Galvafroid.pdf
http://www.clearcoproducts.com/cold_galvanize_sprays.html
https://www.hygienesuppliesdirect.com/products/prod130333 -- check this first?

 

[DownWest]

A thought on high tensile steel. It is more prone to corrosion than mild. Some of you may remember Fiat's problems way back with rust (Lancia Beta esp.) Reason was they thinned down the steel in the bodys and upped the quality (higher tensile) Unfortunately they didn't improve the protection, the result was they had to buy back Lancias when the engines fell out due to rust.
A

Lemain, sorry, didn't see your earlier post on the qualities of different steels.-A