It seems to me there's a whole lot of well-intentioned but not very helpful speculation going on here by people who are trying to analyze the damage by looking at the posted photos. To support their conclusions, they assume that the owners neglected the maintenance of their boat, and that the technicians who worked on it didn't know what they're doing. Now they're debating among themselves the type and manner of fastenings they think were used by the maunfacturer. They want to be helpful, but you just can't do a serious analysis like this over the internet.
This is not the way to get the reliable answers you want and need, and it's only contributing to your frustration. You need to have the damage examined up close by a qualified expert, who can do whatever testing or analysis may be necessary, and can ascertain what fastenings were actually used by the builder without relying on vague memory, and determine whether the fastenings were changed by a technician. In short, you need a reliable, court-admissible analysis by a qualified expert, that tells you (1) whether the damage was someone's fault other than your own, and (2) that is sufficiently persuasive to prevail over the opposition's expert opinion to the contrary. You have to be prepared for the possibility that he might not be able to pin the responsibility on someone else. Then, armed with that analysis, your attorney can attempt to negotiate a reasonable settlement of your claim with the responsible party. Failing that, there's always court.