Old vs New Fiberglass Sailboats Hulls

[capnorv]

That's one beautiful boat!

[sailronin]

There is a lot of variation in construction of '60s glass boats. Better builders hand laid up the hulls with mat and roving; others used chopper guns with higher resin to glass ratios and often uneven distribution of material. As there was random alignment of short fibers from the chopper gun the builders tended to make the hulls thicker and heavier, but not necessarily stronger.
As has been pointed out, cored construction has potential for for problems if care was not taken with installation of through-hulls and deck fittings.

Probably the best new 'glass construction technique is the resin infusion method which ensures precise resin to glass ratios and even distribution throughout the structure.
Dave

[easterly38]

Just curious. I have a hand laid glass hull. Many say it is very strong. Some other guys I know have hulls that were chop-gun constructed. I have yet to see either break in half or sink. In the real world, does it make a difference? They both seem plenty strong to me. Of course, there may be some issues with bedded wood in the glass. But so far as fiberglass goes, that stuff is seriously tough no matter how it is done.

[minaret]

Originally Posted by smurphny

Sure, if you have owned the boat and have taken care of it, no problem. But, many boats have been transferred lots of times and are unknown quantities. An unsuspecting guy where I found my Alberg bought this really sleek looking 40' space-shippy sailboat only to find out that the entire (very thin) core was rotten. It eventually went to the dump.

I spent a month replacing deck core, which is a messy but fairly easy job. Balsa is still the best core material. The main problem with most rotted core is that it was never saturated properly. Boats like Pearsons were mass produced and filling the core was apparently not on the agenda.

Having repaired acres of rotten balsa core in decks and hulls over the years, I would never own a boat that had any balsa in it anywhere. It is absolutely the worst of all core materials. They still use the stuff at some manufacterers because it's light, but if you do some panel testing you will find that if you actually fill the gaps between balsa blocks with resin it's substantially heavier than a foam core, and still dramatically less rot resistant. If you do an actual layup on a curved surface, which causes the blocks to splay on the weave, you'll see that it takes many gallons of resin to fill the gaps. Straight resin is very heavy and brittle. This is why most cored boats have gaps in the core everywhere, which turn into natural channels for water. You can go to great lengths to avoid this, but youre still putting spongy wood below your waterline. Never a good idea.
When we built Carl Schumacher's last design, the 77' VLDB "Cascadia", they spec'd balsa core for the whole boat, deck and hull, below the waterline as well. I fought them tooth and nail on this, but noone would listen to the lowly guy who actually builds the boats, only the NA and chemical engineers. We bagged all core in epoxy, and bagged all laminate in carbon fiber and epoxy. 12.8 million dollars later, the owner took her for trials in Prince William sound and got 4 days aboard her before the hired skipper put her on a rock at 17 knots. We had to cut out the entire outer skin below the waterline and recore the entire hull from WL down, at a cost of over a million dollars. I laughed a lot...

[felixqld66]

Originally Posted by minaret

Having repaired acres of rotten balsa core in decks and hulls over the years, I would never own a boat that had any balsa in it anywhere. It is absolutely the worst of all core materials. They still use the stuff at some manufacterers because it's light, but if you do some panel testing you will find that if you actually fill the gaps between balsa blocks with resin it's substantially heavier than a foam core, and still dramatically less rot resistant. If you do an actual layup on a curved surface, which causes the blocks to splay on the weave, you'll see that it takes many gallons of resin to fill the gaps. Straight resin is very heavy and brittle. This is why most cored boats have gaps in the core everywhere, which turn into natural channels for water. You can go to great lengths to avoid this, but youre still putting spongy wood below your waterline. Never a good idea.
When we built Carl Schumacher's last design, the 77' VLDB "Cascadia", they spec'd balsa core for the whole boat, deck and hull, below the waterline as well. I fought them tooth and nail on this, but noone would listen to the lowly guy who actually builds the boats, only the NA and chemical engineers. We bagged all core in epoxy, and bagged all laminate in carbon fiber and epoxy. 12.8 million dollars later, the owner took her for trials in Prince William sound and got 4 days aboard her before the hired skipper put her on a rock at 17 knots. We had to cut out the entire outer skin below the waterline and recore the entire hull from WL down, at a cost of over a million dollars. I laughed a lot...

a lot to be said to listening to the experiences of those who actually "do" love the technical thoerists...I laughed alot at that as well

[daddle]

Laughing at a guy who's boat is wrecked on some rocks? Sad. Overall, balsa cores have performed very well over many years. Also performing very well are Lapworth's 1960's fiberglass Cal boats. Lapworth realized that fiberglass boats did not need to be built thick like wooden planked boats. The Cal 36/40/48 hulls are quite thin in most places, often only 9 or 12mm. That they raced very well and that almost all are still sailing is proof that there is no need for wasteful heavy slow-sailing layups.

[sarafina]

Honestly, except for the case by case argument, looking at an individual boat and determining her hull quality, I don't think it makes a rat's ass difference...

Puts me to mind of a quote from an long time USCG guy...

something like;
"Every day wooden boats die premature deaths from carelessness or neglect, while FRP boats that should die a decent death have to be forcibly put down."

Lots of things cause boat failure, but it seems that rarely is catastrophic hull failure, due to condition of the 'glass, the cause of the failure. Stringers and interior structure supports, chainplate beddings, core failure due to bad bedding (not general 'glass failure), collisions, hatch failures etc all seem to account for the failure of a boat far more often.

[minaret]

Originally Posted by daddle

Laughing at a guy who's boat is wrecked on some rocks? Sad. Overall, balsa cores have performed very well over many years. Also performing very well are Lapworth's 1960's fiberglass Cal boats. Lapworth realized that fiberglass boats did not need to be built thick like wooden planked boats. The Cal 36/40/48 hulls are quite thin in most places, often only 9 or 12mm. That they raced very well and that almost all are still sailing is proof that there is no need for wasteful heavy slow-sailing layups.

I wasn't laughing at the poor owner. Although he's one of the wealthier men in America and can certainly afford it, there were two serious injuries in this wreck, one of them to the owners daughter. It wasn't a funny situation. What was funny was the fact that the chem. engineers swore up and down to everyone involved that using balsa wouldn't be a problem, just like you. They sure were wrong...
I'm not arguing for "wasteful heavy slow layups", just that balsa is an ignorant core material. See any really reputable manufacturers still using it? Why is foam core an often mentioned marketing point? And why use a biodegradable material to build a boat when you can make a lighter stronger, completely rot proof panel with foam core for less money?
Please explain...

[felixqld66]

Originally Posted by daddle

Laughing at a guy who's boat is wrecked on some rocks? Sad. Overall, balsa cores have performed very well over many years. Also performing very well are Lapworth's 1960's fiberglass Cal boats. Lapworth realized that fiberglass boats did not need to be built thick like wooden planked boats. The Cal 36/40/48 hulls are quite thin in most places, often only 9 or 12mm. That they raced very well and that almost all are still sailing is proof that there is no need for wasteful heavy slow-sailing layups.

Daddle I am laughing at the folly of people who don't listen to practical experience...anyone losing a boat or anything they treasure is a shame regardless

[minaret]

Originally Posted by felixqld66

Daddle I am laughing at the folly of people who don't listen to practical experience...anyone losing a boat or anything they treasure is a shame regardless

The "pro" skipper was worth laughing at too. Hit a clearly charted rock in Prince William, one of the most heavily traveled bodies of water in AK. We installed one of the earlier model FLIR/ Fwd. looking sonar units on this boat, as well as a deploying anchor arm, dinghy transom garage w/dinghy on deploying rail, etc. etc. The FLIR was in a glass tube that deployed out of the forefoot of the boat and retracted to flush mount when not deployed. It cost over 100k for the unit and installation was epic. It was the first thing to hit the rock.

[Tynesider]

Hi Gents

An interesting post with even more interesting replies!

During my 5 years research for my paper The History of The Colvic Watson Motor Sailer I spent many hours talking to old workers of Ardleigh Laminated Plastics Ltd later becoming Colvic Craft Plc.

Although my main interest was in the Colvic Watson we should not forget that Colvic Craft built some fine much larger yachts (and motor boats) such as famous the 60's Clipper Class and many Blue water yachts up to 65' over the 30 years they were in production.

We have all seen the description "heavy layup‟ but what does that mean?
It‟s a technique and part of the mould process when constructing a mould in GRP (Glass Reinforced Plastic) and G L Watson and Colvic were very careful on this point when designing the hulls, as all the hulls had a very heavy layup where the hand layed polyester resin reinforced woven matting used was from 24.5oz, 20.5oz, 16.5oz and 10oz per sq/ft used from the keel upwards to form a rigid bonded hull and coach roof.
The hulls were then heavily further constructed and strengthened with side and bottom transverse bearers also bonded into the hulls for extra strength and the moulds were manufactured at the time by Colvic in a special temperature controlled moulding building to ensure the correct mould process was carried out making the hulls far in excess of Lloyds specifications for the hull design at the time.

Again a major factor not mentioned in other posts is the design of the boat and 'who' designed it, fortunately in the case of the Colvic Watson design there is no boat around today with a better pedigree second to none than a design by G L Watson.

I also do 'Pre -Buying Inspections visits' of Colvic Watson's for new buyers many which were built in the 70/80's and in say over 80 boats I have inspected I have found only 3 with minor signs of Osmosis (and they were in both built in 1984).

Gelcoat 'Spider' cracks or 'Star cracking as we call them in the UK rarely has anything to do with chemical issue between glass layers but is normally caused by stress points or Impact by an object (or boat) to that area, the proof of this is if 'correctly repaired' it very seldom re-occurs.

The Colvic Watson Motor sailers hulls were built up to 34'-6" and it is not unusual to find hulls up to 1 1/2" to 2" thick in places, even my small CW 24' hull area is mainly 3/4" to 1" thick.

Yes GRP technology has moved on but when inspecting some of the more modern yachts of today that surprisingly have sometimes only 1/4" thick hull on 34/45' yachts I would have no hesitation in buying a 70/80's GRP hull boat.

Hope this might help

[smurphny]

Originally Posted by Tynesider

Hi Gents



Gelcoat 'Spider' cracks or 'Star cracking as we call them in the UK rarely has anything to do with chemical issue between glass layers but is normally caused by stress points or Impact by an object (or boat) to that area, the proof of this is if 'correctly repaired' it very seldom re-occurs.

You may not have seen any of these on your side of the pond. During the '60s when U.S. companies were experimenting with polyester resins, a number of large boat builders like Pearson and Pacemaker produced many boats that suffer from this spider-crack condition. It occurs universally over the entire gel coat surface and has nothing to do with flexing of the hull. It was some sort of chemical dissimilarity, creating differentials in expansion between the underlying glass and the gel coat. Short of entirely sanding off the gelcoat, it is impossible to fix. Overcoating with epoxy primer and Awlgrip only delays its eventual reappearance.

[smurphny]

Originally Posted by minaret

Having repaired acres of rotten balsa core in decks and hulls over the years, I would never own a boat that had any balsa in it anywhere. It is absolutely the worst of all core materials. They still use the stuff at some manufacterers because it's light, but if you do some panel testing you will find that if you actually fill the gaps between balsa blocks with resin it's substantially heavier than a foam core, and still dramatically less rot resistant. If you do an actual layup on a curved surface, which causes the blocks to splay on the weave, you'll see that it takes many gallons of resin to fill the gaps. Straight resin is very heavy and brittle. This is why most cored boats have gaps in the core everywhere, which turn into natural channels for water. You can go to great lengths to avoid this, but youre still putting spongy wood below your waterline. Never a good idea.
When we built Carl Schumacher's last design, the 77' VLDB "Cascadia", they spec'd balsa core for the whole boat, deck and hull, below the waterline as well. I fought them tooth and nail on this, but noone would listen to the lowly guy who actually builds the boats, only the NA and chemical engineers. We bagged all core in epoxy, and bagged all laminate in carbon fiber and epoxy. 12.8 million dollars later, the owner took her for trials in Prince William sound and got 4 days aboard her before the hired skipper put her on a rock at 17 knots. We had to cut out the entire outer skin below the waterline and recore the entire hull from WL down, at a cost of over a million dollars. I laughed a lot...

As stated previously, I think putting a wood core below the waterline is inherently a bad idea. Regardless of the relative strength issue, sooner or later it is going to absorb water because balsa can't be totally saturated with resin and the prospect of recoring a hull is almost unthinkable.

In recoring my decks last year, it was apparent that Pearson had not adequately sealed the balsa. Nevertheless, IT LASTED 40+ YEARS and failed only because the previous owners let it drastically deteriorate. If the boat had been maintained, as many are, there would have been no problem. IMO the workability and light weight of balsa makes it a great material for deck construction. It is not possible or even advisable to totally saturate 3/4" balsa because it would require thinning the epoxy and, as you say, increase weight. It just needs to be encased in resin with no voids. If you're careful in filling the area with balsa there is not much left to fill. A balsa cored deck composed of two layers of glass and 3/4" core is well over an inch thick, very light and very strong. No other material I know of can achieve this kind of strength to weight ratio. I investigated other synthetic core materials before doing my decks and found they were all subject to a host of strength and delamination issues and were mostly experimental products.