Thursday 26 February 2009

...and they're off!

The boat is in the works - well, it's kind of taken up one end of the works really - man these boats are big! First thing to do was strip her down and carry out a thorough inspection.















When inspecting carbon or glass composites, the key features to watch out for are the same whatever the project. Here're the main things to look out for:

Cracking. Get a bright torch and slowly, deliberately inspect the surface, particularly around high load areas. You're looking for hair line cracks - and open cracks, and star crazing and anything you don't like the look of. A bright torch means you won't confuse a crack with flaking paint or a pencil mark or something innocent like that.

Delamination. Take a coin between your thumb and index finger and lighty tap with the edge of the coin all over the surface, working in a methodical sweeping pattern. Solid structure will sound errr solid! - in fact it should almost 'ring' on carbon (depends on the thickness of paint more than anything). Delamination or core failure will sound dead or hollow. When you find something, work around it to find the edge of the delamination and circle with a marker pen and write a D in the middle. This technique takes a bit of practise, but after a short time it becomes pretty easy - and is a quick way to check large surfaces.

Flexing. All of the surface needs checking over for internal failure - and the best way to do this is a solid thumb push all over the structure. Sometimes a push with a thumb isn't enough and the heel of the hand and a good bit of body weight is needed. Unless you are dealing with super lightweight thin stuff, don't be scared to really test the surface - try to emulate the loading that the surface will get. Anything that moves more than you would expect is bad - but I bet you'll find cracking and delamination in the same area on most of them! Don't forget to mark what you find.

Key point damage. Fixing points and mountings get damaged very easily - especially if the part has started to flex or crack. You don't want to find the threaded inserts all need changing after you thought you were finished and the final coat of paint is drying, or that a hole for a bolt is elongated when it needs to be a close fit! A good inspection with a bright light and and test with a bolt or fastener to prove the thread or size of hole takes just a few minutes but can really make a difference.



Some damage is obvious though as this shark bite out of the deck edge shows!! Next time we make.... a list!!



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