How Long Have Fibreglass Hulls Been Built?

[Cheechako]

There were quite a few fiberglass boats in the 60's

[noelex 77]

There was an article in PBO by Proff Pritchard some years ago looking at the long term durability of GRP.

The shear strength of GRP showed this performance after immersion in water:

[oleman]

From a practical stand point the blow fab into a mold, plastic boats took over the small boat industry around 1955 era. They were relatively cheap, places like Sears and Montgomery Ward sold them on the extended credit plan and the lakes and waterways of the South Eastern USA were awash with them by 1962 or so. In the late 50's I watched the boats go by with their tall Mercury motors screaming. By the late 60's the fad was gone and they had gone off to the dis-use or scrap pile and the small boat industry was also gone. To this day the percentage of families with boats has not returned.

[Bikini Blues]

We have a 1967 Chris Craft Cavaliar 33' all wood boat. I think they also made a few in 1968. That info might help you date the change over in manufacturing.

[zeehag]

hank mckune was building fiberglass dinghies and sloops (marque named victory 21, still a one design)in mid 50s. hand layups with extra thick fiberglass, not plastic, hulls.
my son owned a 1958 cal , errrr, jensen wenk ( pre-cal) 24 ft sloop, built in 1958. bulletproof hand laid fiberglass.

there are others.
chris craft commander 38 were later--1967 build for 1968 sales. i had one of the first 18 laid up in glass when i was in marina del rey, 1992.
i had a 1965 built 35 cavalier in 1994. cool boats with twin 283... vroooom love that sound. only problem was th e build was fiberglass over wood.

[cal40john]

Some polyesters are thermoplastic. The unsaturated polyester resins that use an initiator (not a catalyst, look up free radical chemistry) that are used in boat building are thermosetting.

Epoxy is much less permeable than polyester, but it is not waterproof. Look at Interlux's barrier coat. It is an epoxy that forms microplateletes to greatly increase the travel path of water through the epoxy.
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http://www.yachtpaint.com/Literature...tb-usa-eng.pdf

Originally Posted by mstrebe

Polyester and Epoxy are fundamentally different materials. Firstly, polyester is a "thermoplastic", meaning that if you heat it up, it will return to a moldable plastic state. Epoxy, on the otherhand is "thermosetting", meaning that once it hardens, it's not going to become formable ever again.

Like most (but not all) thermoplastics, polyester tends to be quite a bit more deflectable than epoxy before it breaks. It's use in fiberglass boats is not to provide strength, but rather to hold the strength members (the fiberglass) in place without movement so that they can provide the strength. You can think of it as a high quality glue in this application. Polyester is not waterproof, and old fiberglass hulls eventually become saturated with water. However, this is such a slow process that it doesn't really matter.

Polyester releases volatile organic compounds and gasses off for quite some time after production, which leads to "new boat smell". These VOCs are smog gasses, and this has led to the regulation of polyester boat production in California, killing the boatbuilding industry here.

Epoxy is quite a bit stronger than polyester and (unlike polyester) is impermeable to water. Unlike polyester, it is a strength component along with the glass in hull production and allows boats to be made to the same strength with fewer layers of glass. It also has considerably less outgassing, and because it's impermeable to water it doesn't have problems with blistering. Its considerably more expensive (5X) than polyester however, and only recently has it become competitive to build hulls out of it.

Epoxy is strong enough to hold carbon fiber in place and allow it to be rigid, Polyester is too deformable to rigidify carbon fiber (which is strong in stretch but breaks easily in deflection).

New vacuum-bagged injection moulding techniques for Polyester have extended its life in boat building, as VOC outgassing can be controlled and a finished gel-kote (pure polyester) layer can be applied to both sides, creating a finished hull that requires no liner. Finishing both sides of carbon fiber is still quite difficult.

Big manufacturers like Beneteau and Catalina have doubled down on Polyester for cruising hulls, and are moving to carbon/epoxy for their performance racing lines, putting them in position to exploit carbon/epoxy when the market will bear it while retaining the low cost advantages of polyester for as long as possible.

[Cheechako]

Originally Posted by noelex 77

There was an article in PBO by Proff Pritchard some years ago looking at the long term durability of GRP.

The shear strength of GRP showed this performance after immersion in water:

Thanks, that's interesting. I've long suspected The Glass layup deteriorates over time. Seems to get brittle. I once pulled a free fiberglass dingy that was overgrown with grass and weeds out. Pieces broke out of it. Dry and brittle. I suspect sun does the same thing as water.

[zeehag]

the first fg boats were , until mid 1970s of epoxy, not polyester, which was not used until the mandate by epa to change way of boat building with fg. that is when the blisters became frequent and prolific, and the other changes--chopperguland vacuum sealed layups of matte, no roving , became popular, and when they learned thet matte and choppergun layups ar enot strong, they need the woven roving to succeed.
so. fiberglass layups began in 1950s, polyester layups began in mid 1970s.

[Scout 30]

Originally Posted by zeehag

the first fg boats were , until mid 1970s of epoxy, not polyester, which was not used until the mandate by epa to change way of boat building with fg. that is when the blisters became frequent and prolific, and the other changes--chopperguland vacuum sealed layups of matte, no roving , became popular, and when they learned thet matte and choppergun layups ar enot strong, they need the woven roving to succeed.
so. fiberglass layups began in 1950s, polyester layups began in mid 1970s.

That's the first time I've ever heard that. Can anyone verify this? It's my understanding that epoxy wasn't used in boat building until the Gougeon brothers refined the formula & it's never really been used in production boats.

I think the most important point to be made here is that polyester resin does not form an adequate secondary bond. When polyester resin is first laid up the molecules of the separate layers interlock. After the resin has completely cured this no longer takes place. As a result layers or repairs done later are likely to delaminate. Repairs made to fiberglass boats, whether above or below the waterline, should be made using epoxy resin due to it's superior adhesion. I'm amazed at how many people, including professionals, ignore this rule.

[ZULU40]

Originally Posted by Scout 30

That's the first time I've ever heard that. Can anyone verify this?

the first epoxy patents go back to the late 1920s
I only know the russians history with boating
they were more interested in polyester and had nothing I recall about epoxy

[Blue Stocking]

Originally Posted by Dsanduril

Epoxy is an adhesive, it has bonding capabilities with different materials that are entirely absent in polyester resin (some simplification, but not much). Entirely different chemistries.

Glass hulls, especially solid glass, and especially from the 60s through 80s are almost universally built with polyester - no epoxy anywhere (unless a post production barrier coat of some form of epoxy was put on the bottom because of blisters).

Epoxy was also used during the same period, but mostly in cold-molded and similar construction techniques. Very little was used in glass layup.

In the modern era, with many different fiber materials, many different core materials (far fewer solid glass hulls than in that heyday), and way more choices in resins it is much harder to make blanket statements, but in that era glass lamination was done with polyester. Epoxy was for specialized and custom boats. (Generalities, but I'd guess they apply >90%)

My Rhodes Reliant 41 Yawl, built in 1965, has hull and deck connected with 36" laminations of epoxy fill mat and woven roving.

[Scout 30]

Originally Posted by Blue Stocking

My Rhodes Reliant 41 Yawl, built in 1965, has hull and deck connected with 36" laminations of epoxy fill mat and woven roving.

The Rhodes Reliant is one of the prettiest boats ever built, wood or fiberglass. Was the hull to deck joint originally glassed with epoxy or is that an improvement that you made? Either way it's a smart move.

[zeehag]

Originally Posted by Scout 30

That's the first time I've ever heard that. Can anyone verify this? It's my understanding that epoxy wasn't used in boat building until the Gougeon brothers refined the formula & it's never really been used in production boats.

I think the most important point to be made here is that polyester resin does not form an adequate secondary bond. When polyester resin is first laid up the molecules of the separate layers interlock. After the resin has completely cured this no longer takes place. As a result layers or repairs done later are likely to delaminate. Repairs made to fiberglass boats, whether above or below the waterline, should be made using epoxy resin due to it's superior adhesion. I'm amazed at how many people, including professionals, ignore this rule.

you might wanna follow th ehistory of the blister problem a lil closer.
you will read that which was told me in person by a notorious boat builder and which i have read in various boatbuilding publications. the compounds changed in mid 1970s, causing uniflite and all other production boats many problems with osmotic blistering. the method of use as wellas th ecompounds were changed at same time.
most of us have known this since mid 1970s, as well. as we have been old enough to remember these changes in our searches for proper cruisers.

[Scaramanga F25]

Henry Ford made automobile parts using hemp fibers and resin made from soya. 1940 + -

[Shimraise]

All Hatteras boats have been fiberglass since their beginning with Knit Wits in 1959. Don't know if anyone else was doing it prior.