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I don't think you are understanding my point. So here's a more scientific explaination. Almost all plastics are low-modulus and therefore are very "stretchy". Fiber reinforcement will reduce the ability to deform and of course if you build a hull that is mostly fiberglass with minimal resin it will be stiffer and less flexible. But the matrix material is still plastic; and will respond as a plastic does especially when under constant load. When you place a plastic under constant load generally it will slowly deform until the plastic has minimized the stress load. Think of a rubber band. If you stretch it and keep it stretched; at some point the rubber band gets longer semi-permanently and the strain in the band gets lower. The same thing can happen with a fiber reinforced plastic. It's a good reason why you should not over-tension your shrouds and leave them taught; the boat will deform to minimize the stress.
Under normal circumstances the hull is stiff enough to withstand short term bending stresses and bounce back to it's original shape. When subjected to long term stresses the plastic will undergo what is known as stress-relaxation (explained in laymans terms in the previous paragraph); where the polymer bonds actually stretch and change shape to reduce the strain on them. When this happens the fiberglass will slowly become loaded and also stretch enough to elastically deform and the result is a shape change in the hull. It might not be permanent; remember these deformations are largely elastic in nature. Some polymers can stretch up to 50% in length elastically due mainly to stress-relaxation. When the force is removed it will shrink back to it's original length. If you stretch the same plastic more quickly it will yield (plastically deform) and break with the same amount of strain. The rate of strain is a critical factor in the deformation of plastics.
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This sounds entirely logical to me, and I believe that it is consistent with what I was saying. Over time it is entirely possible that the hull will morph to accomodate the jackstand.
My concern would be the initial impact that occurs when the boat is lowered onto the stands and one of them is too high. The concern is magnified because the
possibility exists that the boat was not lowered nice and slowly, but dropped on in a hurry creating a very similar impact to the boat hitting a rock, dock or similar. I think that we are in agreement that this impact is not healthy for boats, and that permanent damage can result.
Now this may be a concern that some would equate with 'Well gee, a hurricane could hit when I'm out there sailing so I can't be concerned about a whole bunch of things that I can't control...'. As well, there are many who mention that they have seen, bought and sailed boats with this issue and have not noticed any problems.
If I am looking for a boat for myself my standards are a bit lower than they are if I am offering advice to someone else. I have no way of knowing whether someone asking a question on the internet has been around boats for a long time, understands anything about the boats they are looking at or can afford to deal with anything that might come up.
As well, I believe that people are a bit more intuitive than they give themselves credit for. Frequently, the posts or questions on here are from people with a nagging little sense of doubt in the back of their minds. Because they may be new to sailing, and because they are looking at a boat that embodies all of things they fantasise about on long cold nights, they sometimes discount these doubts and tell themselves that it's not serious - everything will be okay.
I don't think they should. If there are problems that are obvious enough to be apparent to a neophyte - the possibility exists that those problems are big ones. So if someone sounds like they are wavering - I will discourage them from buying. If they sound confident, but want an answer to a technical question and if it is something that I have any experience with - I will offer whatever advice I can to the limit of my experience. (You'll never find me advising people on their recalcitrant diesels as I don't really understand much about their innards
) If they are on cloud nine because they have just closed on the 'dreamboat' - I offer congratulations and keep any negative thoughts to myself.
So - to get back to the original situation...
The OP wanted some reassurance. My recollection of the post is that he is looking at a 30 plus year old boat that has a nice, thick hull. The boat is sitting on a jackstand and has a dent in the hull that is noticeable by a newbie.
If it was my boat - I would be in the yard looking at it regularly to make sure it was okay. I'd specifically be checking the jackstands because they settle quickly at diffferent rates depending on the composition and moisture content on the ground they are on. They almost always need to be adjusted over a season.
Apparently the owner of the boat was not doing this. This sets off
alarms for me. If they can't take care of such an obvious issue - what else are they neglecting ???
Finally - the newbie is looking for a boat to sail - not a boat to fix, and may well be on a budget that would preclude major repairs to a hull or the innards. So I say keep looking for one of the thousands of boats out there that have been taken care of nicely.
On a tangent... there has been some discussion on this forum regarding the longevity of fibreglass hulls. It is possible that we are starting to see them deteriorate through these examples of dents and deformation ????
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