Bukashkin
22.04.2021 2:39:12
Without X-ray vision, or by cutting a sample core out of the hull, no one, not even a surveyor, can tell what's in the laminate. Boat buyers have to rely on the builder's reputation.
See full version: Stringers are the Key to Hull Strength
Without X-ray vision, or by cutting a sample core out of the hull, no one, not even a surveyor, can tell what's in the laminate. Boat buyers have to rely on the builder's reputation.
BoatTEST.com can happily report that we hear of very few cases of boat hulls delaminating – of any brand – these days. It used to happen, and occasionally still does, but it is not something that most buyers need to be worried about.
Looking at the bottom-support structure provides clues to the real quality of construction. A fiberglass laminate is very flexible, so all fiberglass boats rely on longitudinal stringers and athwartships frames and bulkheads to maintain the hull's designed shape. While it's impossible to see into the laminate, the hull support structure is accessible, and provides a clue to overall quality.
The two stringers have two layers of 1708 on each side. They are glassed too the hull with "two" layers of 1708 as shown in Travis' schematic. Bottom line, these two stringers will never crush, rot or move.
Subsequently, question is, how many layers of fiberglass do you need for a car? two layers
Just so, how many layers of fiberglass do you need for a boat hull?
Where the fibreglass of the deck has become delaminated, it’s almost certain that water will have penetrated the stringers. Whereas a deck hole can mean the replacement of just one stringer, deck delamination will usually involve putting in all new stringers. This is a major job, which will mean removing and replacing the entire deck as well as the stringers. This will not only be time-consuming but also very expensive, and keep the boat out of the water for a long time. more
Where there are instances that the stringers are regularly wet by bilge water, then they’ll certainly need to be replaced periodically. If there’s simply a gel coat protection on the stringers, that time will tend to be sooner rather than later. In this case, it’s best to assume the worst and that the stringers have rotted. [links]
If it’s been a number of years since the stringers have been replaced, then they should be inspected to judge their condition. If the boat has spent plenty of time out on the water, then there’s a good chance that the stringers will be in a bad condition, especially if the boat hasn’t received much maintenance. more
If someone has bedded something in the deck and not sealed it properly, the water will be able to get through that hole and will rot the wood stringer on the boat. When there is rot in the stringer, it’s just a matter of time before it fails, and the stringer falls apart. Whenever you discover this, the first thought should be to check the stringers if they’re not boxed in. more
It turns out there were several earlier boats made of fiberglass and various plastic resins, but most of them were too brittle for practical use. Dan says it was the development of polyester resin that started the fiberglass boat revolution. In part, this problem of terms revolves around the separate, but parallel, developments of fiberglass and plastic resins. more
Others followed suit. Dan says, "B.B. Swan made a small fiberglass catboat in1947. Carl Beetle built fiberglass boats at a GE plant in Pittsfield, Mass. He exhibited his fiberglass boat at a show in January 1947." [links]
According to Dan Spurr, editor of Practical Sailor, and the author of a forthcoming book on the history of fiberglass sailboats, Heart of Glass, "It probably was a fellow named Ray Greene in Toledo, Ohio. He built a fiberglass and polyester sailboat in 1942, probably a Snipe. So a sailing dinghy was the first fiberglass sailboat." After a pause he adds, "But you have to watch your terms." more
Back in Toledo, Ray Greene, who had studied plastics while a student at Ohio State, had been working with Owens-Corning on fiberglass composites. He had made composite boats as early as 1937, but was searching for just the right plastic to use for boats. He received a shipment of the polyester resin in 1942 and produced a daysailer. more