Is this really repairable?

I'm curious what the story is here, surely the insurance would have written it off as an uneconomical repair (if it was insured) which means someone has likely bought with a view to repair and given up, or it wasnt insured and the owner is trying to get something back on his loss. Either way i would have thought it would be worth more sold for parts.
 
JumbleDuck said:
What's a latent stress?
Click to expand...

Latent stresses are stresses that have yet to manifest themselves. IE a given material or part can be severely stressed as a result of impact or other force beyond its design capability and not show any signs until it is stressed again. The resulting failure can be instantaneous and catastrophic.
 
mrplastic said:
Latent stresses are stresses that have yet to manifest themselves. IE a given material or part can be severely stressed as a result of impact or other force beyond its design capability and not show any signs until it is stressed again. The resulting failure can be instantaneous and catastrophic.
Click to expand...

I'm sorry, but that doesn't make any sense at all. A stress is an internal force; you seem to be describing damage, which is completely different.
 
JumbleDuck said:
Though they presumably come with keels, rudders, electric, engines, intact hulls and things like that.
Click to expand...

But there is a £55k difference. impossible to say whether it is worth it without having a real close look. Sort of in your part of the world so you could check it out if you are curious.

No need for me because I have a similar one (with all the bits together) already.
 
JumbleDuck said:
I'm sorry, but that doesn't make any sense at all. A stress is an internal force; you seem to be describing damage, which is completely different.
Click to expand...

That is what I thought I had said.....Stresses generally occur in materials as a result of external forces generating internal forces. Just because stress is an internal force does not mean that it cannot be caused by an external force such as impact. Damage occurs because the given material or part is simply stressed beyond its physical limits, you seem to be suggesting that damage could not cause latent stresses because the force was external? That doesn't make any sense to me, Forces are absorbed and released at some later point (latent stress) resulting in structural failure, damage is the result but is often also the root cause,
 
mrplastic said:
Damage occurs because the given material or part is simply stressed beyond its physical limits, you seem to be suggesting that damage could not cause latent stresses because the force was external? That doesn't make any sense to me, Forces are absorbed and released at some later point (latent stress) resulting in structural failure, damage is the result but is often also the root cause,
Click to expand...

Sorry, but I still haven't a clue what you mean by "latent stress". A stress is an internal force. It's either there, in some quantity, or it isn't.
 
JumbleDuck said:
Sorry, but I still haven't a clue what you mean by "latent stress". A stress is an internal force. It's either there, in some quantity, or it isn't.
Click to expand...

I think that he means damage caused by stress to the structure that has weakened it and may manifest itself later.To my latent stress is what is found in welded structures for example.
 
JumbleDuck said:
Sorry, but I still haven't a clue what you mean by "latent stress". A stress is an internal force. It's either there, in some quantity, or it isn't.
Click to expand...
Ok let's substitute the word stress for defect...it amounts to the same thing.

But to further clarify, take a piece of material let's say extruded acrylic. Now the extrusion process is highly stressful ( as opposed to casting) and as a result the material is stressed and retains that stress. it copes because it is within it's design parameters, however if you drill it, cut it or machine process (damage or thump it) in anyway you stress it further, this may not have any apparent effect during the operation and the additional stresses may never show but on many occasions cracks will start to appear around drilled holes or cut apertures and these can occur a long time after the processing or impact damage occurred these are latent stress cracks, IE delayed as in.....latency.....you may not understand that or agree with it but it's a fact, it happens..... in all sorts of materials.

Stress can be nullified or reduced by annealing and this can completely remove internal stresses, you can't do that with a 42ft Bavaria! Maybe there is a marine structural engineer out there that can shed more light on this and answer my original question?
 
mrplastic said:
Ok let's substitute the word stress for defect...it amounts to the same thing.

But to further clarify, take a piece of material let's say extruded acrylic. Now the extrusion process is highly stressful ( as opposed to casting) and as a result the material is stressed and retains that stress. it copes because it is within it's design parameters, however if you drill it, cut it or machine process (damage or thump it) in anyway you stress it further, this may not have any apparent effect during the operation and the additional stresses may never show but on many occasions cracks will start to appear around drilled holes or cut apertures and these can occur a long time after the processing or impact damage occurred these are latent stress cracks, IE delayed as in.....latency.....you may not understand that or agree with it but it's a fact, it happens..... in all sorts of materials.

Stress can be nullified or reduced by annealing and this can completely remove internal stresses, you can't do that with a 42ft Bavaria! Maybe there is a marine structural engineer out there that can shed more light on this and answer my original question?
Click to expand...
I don't think you can induce latent stresses on a Bavaria by bashing it on the rocks.You can weaken the structure invisibly but that's not the same.If you were for example to twist the boat by force and then lock it in that shape by laminating over then you'd be inducing stresses.
 
30boat said:
I don't think you can induce latent stresses on a Bavaria by bashing it on the rocks.You can weaken the structure invisibly but that's not the same.If you were for example to twist the boat by force and then lock it in that shape by laminating over then you'd be inducing stresses.
Click to expand...

That makes some sense to me, but you would also be containing that stress and strengthening the structure at the same time. My experience is that you can stress a material, leave it on a bench top and for several weeks it will show no signs of that stress and yet one day it will be cracked and crazed without any additional external force acting upon it. In my industry that is called stress cracking and the delay defines it as latent.
 
Last edited:
Delamination may be the term to use, it's latent to the extent that impacted areas may appear to look OK but will in fact be weakened. Delamination can be cut away and rebuilt. It will still be pretty strong overall and you'd have a hell of a job to weaken the boat to the extent of it being dangerously weak.
 
savageseadog said:
Delamination may be the term to use, it's latent to the extent that impacted areas may appear to look OK but will in fact be weakened. Delamination can be cut away and rebuilt. It will still be pretty strong overall and you'd have a hell of a job to weaken the boat to the extent of it being dangerously weak.
Click to expand...

My understanding is that a bermudian sloop rig constantly stresses the hull which is fine all the time that stays within its design parameters. Add in the external forces encountered in big weather and that adds up to a whole lot of stress.
Fine on standard undamaged boat, but this has been seriously damaged and how could you ever really know it would ever be as good as the day it was built? Recent events clearly demonstrate what can happen in the event of a serious structural failure and that on an apparently sound boat! No one has any real idea what happened to that but whatever it was involved a structural failure at some level. "Pretty strong overall" ?

I wouldn't bet my life on it.
 
It probably could be repaired and be adequately safe, but the problem would be that it would be impossible to re-sell at a sensible price reflecting the work involved. Any surveyor would no doubt advise walking away, as there are loads of perfectly good versions of the same boat available on the market.
 
pvb said:
It probably could be repaired and be adequately safe, but the problem would be that it would be impossible to re-sell at a sensible price reflecting the work involved. Any surveyor would no doubt advise walking away, as there are loads of perfectly good versions of the same boat available on the market.
Click to expand...

Nuff said!
 
mrplastic said:
But to further clarify, take a piece of material let's say extruded acrylic. Now the extrusion process is highly stressful ( as opposed to casting) and as a result the material is stressed and retains that stress.
Click to expand...

That would be a residual stress. I think you are getting confused between residual stresses and hidden defects.

In twenty five years of researching and teaching in solid mechanics (stress and strain) I have never seen the term "latent stress" used.
 
Last edited:
You must log in or register to reply here.

Share this page

Top