Stress Crack

[kaptin kod]

Have a small section on the bow where I seem to have a stress crack, the picture below may not be to clear, but if you can see wha I mean any ideas how I can remove it, have tried using a fine rubbibg compound but it seems a little to deep for that to have any effect.

 

would I be better attacking it with a fine piece glass paper?.

 

Did it a while ago managed to hit a lock wall wasn't looking where I was going.

[Afishionado]

That is an impact radial star crack but it looks to me that the impact may have been from the inside.

 

Any way the crack will be right through the gell coat and there are two ways of dealing with it. The proper (expensive) way which will end up with an invisable repair or a decent job that you can do yourself but will be visible if you look closely.

Way No 1 Get a professional to do it and part with

[Paul D]

Interesting seeing an article on stress cracks. Now Neo is sitting on her new trailer I can see all the chips and chunks which the last 3 years of use have inflicted to her hull.

 

One long scrape where the edge of a keel roller had gouged a 2 foot line of gel coat out

 

Worst, I had two cracks with holes in the gelcoat towards the front which I think were caused by the old rollers on the front of my old trailer, where she was not sitting on the keel rollers properly. Either that or I had managed to do it with the new trailer ( worrying ! ).

 

Filled both these using Mike's method - can't be bothered to do the hard part yet ( well it is on the bottom of the boat after all )

 

The strakes each side of the bottom of the hull are also prone to being chipped.

[toerag]

Be careful repairing stress cracks - if they're from a one-off impact (dropping an anchor, twatting a lock etc.) then feel free to repair them as detailed above. If they have appeared with no apparent cause then they're almost certainly due to the glass stucture underneath flexing, in which case you have to stiffen the laminate as well as repairing the gelcoat or they'll simply re-appear. I have loads of 'flex cracks' on the gunwhales/cabin of my boat, it was simply not laid up thick enough when she was moulded.

[Mike Fox]

My previous boat had extensive stress cracking both sides of the bow, and the price had fallen to come into my price range. I got a local fibreglass specialist to check it out, and his advice was invaluable.

 

We bought the boat, contracted him to perform the repairs (externally was just cosmetic), but most importantly, to stiffen the interior moulding by the addition of foam stringers, which were glassed in using overlapping "tapered" glass cloth. The stiffening was therefore applied progressively, which was designed to prevent it repeating (it worked over then next 11.5 years!).

 

The two starting points for the stress crazing were stiff spots on the inside of the hull where a cross-brace had been glassed in. This had stopped the hull flexing at this point, and flexing both sides of the stiff spots had started the cracks there. Apparently gel coat is slightly less flexible than fibreglass.

 

Could I suggest that you check for stiff spots round the crazing area by tapping gently on the hull? The dull thud of a stiff spot is a real giveaway, and if this was the cause, can be cured relatively easily, by spreading the load via tapered patches.

 

Mike

[duncan]

Mike, as you imply the addition of stiffening to a flexing panel can be a cause rather than the solution to cracking - this really is an expert issue!

 

As Mike (the other one) points out the OP is an imact cracking not a stress crack and it's a matter of evaluating the full damage and reparing appropriately.

 

Stress cracks associated with flexing need expert evaluation

 

The stress cracks associated with 90 degree radius mouldings under tension are generally cosmetic (well apart from the waterproofing I supose all the gell is cosmetic!) and are often sucessfully removed for good when properly repaired after the mouldings have settled with time.