How Long Have Fibreglass Hulls Been Built?

[lateral]

Originally Posted by 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.
Page 3:
http://www.yachtpaint.com/Literature...tb-usa-eng.pdf

I thought the "micro platlets" were overlapping so as not to let water through? Why would a barrier coat be designed to let water through?

Not that I am a fan of interprotect, apart from its ease of use. I use 100% solids epoxy as per GBros (MEE test) permeability test of the 90's. Interlux barrier is solvent rich.
.....hijack end.

Moisture Exclusion Effectiveness - WEST SYSTEM by ATL Composites

[cal40john]

Originally Posted by lateral

I thought the "micro platlets" were overlapping so as not to let water through? Why would a barrier coat be designed to let water through?

Not that I am a fan of interprotect, apart from its ease of use. I use 100% solids epoxy as per GBros (MEE test) permeability test of the 90's. Interlux barrier is solvent rich.
.....hijack end.

Moisture Exclusion Effectiveness - WEST SYSTEM by ATL Composites

Well you should show them how to design an epoxy where all the platelets are joined together to make a perfect seal. The point was epoxies are permeable, if you add something that lays down flat that water can't get through, the water has to travel a much greater distance through this low permeable substance to get where you don't want the water.

Everything is permeable on the graph you linked even West to some extent. If West thought their product were perfect why do they make their 422 Barrier Coat Additive to increase water exclusion effectiveness?
West System International - WEST SYSTEM 422 Barrier Coat Additive

The Interlux with barrier coat and West with barrier coat isn't listed on this graph so we don't know how effective it is or where they are relative to each other.

[Scout 30]

Originally Posted by zeehag

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.

Here's an easy way to prove you're wrong. Up until recently there was no way to gelcoat over epoxy. Even now there are only a couple of types of epoxies that are compatible with gelcoat. All production fiberglass boats are gelcoated & they always have been proving that no production boat builder has ever laid up hulls using epoxy resin. At 5 times the cost it's just too expensive. Some builders are using vinylester resin but it's usually just in the first layer due to cost.

Here's a David Pascoe article that explains why it appears that there was an increase in osmotic blisters in the 70's. In my opinion what happened in the 70's was that builders realized that fiberglass hulls did not have to be nearly as thick as they were building them. Combine this with a crappy economy & then throw in the oil embargo & you can see why some builders turned to cheaper polyester resins that ended not holding up as well over time. David points out that quality builders like Hinckley that did not cave to economic pressure & move to cheap resins have not had blister problems.

Boat Hull Blisters: Blisters Again?

[Blue Stocking]

Originally Posted by Scout 30

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.

Phil's original drawings from June '63 specified all secondary bonds, bulkheads, hull-to-deck, etc, all to be epoxy.

[Hard Rock Candy]

I had a 54 Vet that was made out of what I thought was epoxy. It could have been Polyester. It did start to come all apart by 62. Mac

[Scout 30]

Originally Posted by Blue Stocking

Phil's original drawings from June '63 specified all secondary bonds, bulkheads, hull-to-deck, etc, all to be epoxy.

That is simply proof of a very high quality boat. It's also proof that as early as the 60's boat builders knew that polyester resin provided an inadequate secondary bond but most used it anyway & still do to this day.

[Eumelia]

When I was a high school kid in 1966 I had a part time job building fiberglass Snipes. Always have loved that sweet smell of polyester resin...

[roverhi]

Some of first polyester resin boats used cotton as a substrate, not fiberglass. Some of these boats were still in use in the '60s. Polyester resin was invented by Dupont in the '30s but perfected by the Germans. The Brit's stole the formula for the improved Polyester Resin from the Germans and gave it to the US who began manufacturing it in 1942. Fiberglass was also invented in the '30s with Owens Corning filing the first patent for fiberglas in 1938. Fiberglas reinforced polyester plastic parts soon went into production for aircraft parts after 1942. There were many pioneers in fiberglass boat production and date from the late '40s. by the '50s, fiberglass outboard boats were beginning to replace wooden runabouts. Our neighbor bought a fiberglass boat with an unheard of powerful 35hp Johnson outboard around 1956-58. We used to scrape up all the nickels we could to buy gas and ski befhind the boat. Our 18hp Mercury powered wood skiff that we bought in '57 had the bottom sheathed in fiberglass by the builder, but was marginal for skiing. Mercury and Evenrude/Johnson were soon in a hp war breaking the 50hp barrier by the end of the 50's.

Blisters became a problem with the OPEC fuel embargo in 1973-4. The boat builders became desperate to get resin and began importing a lot of it from the far east. That resin had issues with blisters. Remember seeing a boat in around 1975 that almost totally blistered below the water line. Uniflite built river boats for the Navy out of a fire resistant resin. They put their FRP boat production expertise to work making civilian powerboats as the Navy contracts began to dry up in the early '70s. They made a big deal about the fire resistant qualities of their boats and the hulls and decks they layed up for Valiant. Severe blistering problems of that fire resistant resin soon raised it's ugly head and put Uniflite out of business. Valiiant lived on after dropping the Fire Resistant Resin for standard Polyester Resin. About the only real fix for boats built with that resin was to grind the below water line hull down to a thin male mold and laying up a new hull on to it.

[mstrebe]

Originally Posted by 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.

Page 3:

http://www.yachtpaint.com/Literature...tb-usa-eng.pdf

Oh, good to know that the polyester resins used in boat-building are actually thermosetting. I wondered why they didn't deform eventually under heat and stress as a thermoplastic would. Thanks for the info.


Sent from my iPad using Cruisers Sailing Forum

[Bluebeard]

Originally Posted by Scout 30

Here's an easy way to prove you're wrong. Up until recently there was no way to gelcoat over epoxy. Even now there are only a couple of types of epoxies that are compatible with gelcoat. All production fiberglass boats are gelcoated & they always have been proving that no production boat builder has ever laid up hulls using epoxy resin. At 5 times the cost it's just too expensive. Some builders are using vinylester resin but it's usually just in the first layer due to cost.

Here's a David Pascoe article that explains why it appears that there was an increase in osmotic blisters in the 70's. In my opinion what happened in the 70's was that builders realized that fiberglass hulls did not have to be nearly as thick as they were building them. Combine this with a crappy economy & then throw in the oil embargo & you can see why some builders turned to cheaper polyester resins that ended not holding up as well over time. David points out that quality builders like Hinckley that did not cave to economic pressure & move to cheap resins have not had blister problems.

Boat Hull Blisters: Blisters Again?

Hanse were offering epoxy hulls about ten years ago, at a premiun of course. I've no idea how many they made. If I'd coincidentally won the lottery that is what I would have bought.
I'm also curious about your statement that you can't gel coat over epoxy. I've made several damage repair to GRP ( polyester ) hulls always with epoxy, and finished with gel coat for cosmetic reasons. Never had any problems.

[Scout 30]

Originally Posted by Bluebeard

Hanse were offering epoxy hulls about ten years ago, at a premiun of course. I've no idea how many they made. If I'd coincidentally won the lottery that is what I would have bought.
I'm also curious about your statement that you can't gel coat over epoxy. I've made several damage repair to GRP ( polyester ) hulls always with epoxy, and finished with gel coat for cosmetic reasons. Never had any problems.

This has been a hot topic for years so you can google it & find a ton of info on it. The 2 major problems are adhesion & curing. Gelcoat is a polyester resin that creates a chemical bond to the fiberglass layers that are laid on it before it cures. When applying it over epoxy that's not possible so you need a mechanical bond which gelcoat is not very good at. It's the same as using polyester resin for a repair. Sometimes it works but don't count on it. The second problem is that gelcoat often won't cure over epoxy. When that happens it's a mess. West system has a vinylester additive that's supposed to make this work & system 3 has an epoxy that they've developed that gelcoat is supposed to work with. Ofcourse neither of these options were available in the 60's. You can find anecdotal evidence of gelcoat over epoxy working sometimes for repairs but I can assure you that cold molded & stitch & glue boats are always painted. Why would you risk a big mess when awlgrip works so well

[Scout 30]

Originally Posted by Bluebeard

Hanse were offering epoxy hulls about ten years ago, at a premiun of course. I've no idea how many they made. If I'd coincidentally won the lottery that is what I would have bought.
I'm also curious about your statement that you can't gel coat over epoxy. I've made several damage repair to GRP ( polyester ) hulls always with epoxy, and finished with gel coat for cosmetic reasons. Never had any problems.

I stand corrected regarding production boat builders using epoxy. Hanse does in fact build with epoxy. The exception that proves the rule? They're not common in the US so I was not familiar with them but they appear to be very high quality boats. However, it should be noted that they are painted boats. No gelcoat.

There are other builders, like Tartan, using vinylester resin which I believe is a modified epoxy that appears to be quite superior to polyester resin. But again, this is a relatively new process. No vinylester in the 60's.

[Don C L]

Aeromarine in Sausalito built the Bounty II in 57 I believe and then the west coast Triton appeared in 59, but the Columbia 29 beat it into the SF bay. My '62 Columbia 29 remains solid as a rock, no blisters etc. The early boats are worthy of restoration. Google "Lawrence Walters memories." He built the first Columbia 29 and got it to the boat show at the Cow Palace in SF just ahead of the Triton. He talks about copying the lay-up schedule of the Bounty from the folks in Sausalito.

[Yeti]

The group of people that eventually became Yacht Constructors (Cascade Yachts) started building fiberglass boats (Chinook 34) in the Portland area in 1955.

Cascade Yachts

http://sailboatdata.com/viewrecord.asp?class_id=3656

[Don C L]

Originally Posted by Yeti

The group of people that eventually became Yacht Constructors (Cascade Yachts) started building fiberglass boats (Chinook 34) in the Portland area in 1955.

Cascade Yachts

CHINOOK 34 sailboat specifications and details on sailboatdata.com

That's a beautiful boat! And I was wrong about the Bounty II, it came out in 1956