Join Date: Mar 2006
Location: Cape Fear, NC, USA
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Assume common flex/stress cracks => What is good enough?
While cracks are not a good thing you can find many OLD neglected glass hulls that have cracks, BIG CRACKS for years and they still hang togeather. Don't misunderstand me, they are not a good thing but they are seldom if ever, life threatning. IF you live in the north coutry where freezing is a common occurance it is much more of a problem as the ice expansion increases the size of the cracks every year. So, don't panic but anything you do to dry out (could of hot days in the summer) and seal up (putty, paint, or full blown expensive repair) is a good thing. However, most of the goodness is asthetic, and economic(resale) rather than life saving.
Having said all that I am assuming the cracks are the rather common flex/stress cracks that you will see on most all production boats aroung the corners of hatch openings etc. where it is hard to keep the structure from flexing at least a little bit. You should do an informal survey of boats of a similar vintage and function to see how they look. Sometimes it can happen that the builder makes a mistake or leaves out a backing plate or does a poor job fitting a bulkhead and the cracks are the first clue. In that case..... Good job sherlock, continue the investigation.
For more info one of the best texts is:
by Hugo du Plessis
Since its first edition in 1964, owners and professionals have relied upon this classic reference to understand the many facets of fiberglass boat construction. Now completely updated, it is an invaluable, nontechnical resource for expert information on the principles of fiberglass construction, as well as sound practice. Author Hugo du Plessis focuses on the kind of boats that dominate the used market, examining fiberglass's durability, weaknesses, effects of use, and the latest research into causes of blistering--or osmosis. His advice will help owners extend the life of their fiberglass boats and prevent would-be owners from purchasing craft that are soon to fail.
About the Author
Hugo du Plessis has spent a lifetime with fiberglass. Forty years ago he was one of the pioneers, starting as a moulder and boatbuilder with a special interest in sheathing. Later he became a surveyor specializing in fiberglass boats, so gaining experience in the common defects as well as the elusive ones. He has, he says, learned something from every boat he has surveyed.
Hugo du Plessis has owned boats for 60 years, including a small charter fleet. This new edition was written on his yacht (fiberglass of course) while cruising in the West Indies
Available on Amazon used for aboutr $24 + ship. (new $40)
It is my fiberglass design/repair bible. It does not focus/dwell on mixing resin and laying fiber but on the design/stucture issues.
NOTE: Chapter 42 => "Every crack tells a story"
Last edited by sailandoar; 05-03-2006 at 11:02 AM.