# High Tech vs traditional-Comments?



## TSOJOURNER (Dec 16, 1999)

Anybody care to comment on high tech vs early construction methods?

Dennis


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## davidk (Feb 1, 2002)

It might not be everybody''s cup of tea but we have just launched our second new classic shape wooden yacht built by craftsman using traditional skills and techniques except for all the fastenings and coatings. Essentially every face is covered with epoxy and every joint is glued with epoxy (usually as well as bolts, screws etc.). Even the teak decks are ''caulked'' with epoxy impregnated with graphite for the dark stripe effect. The epoxy type has some flexibility so the timber construction can still flex as it was designed to do.

Our first boat has been in the water for some 13 years and has not gained any weight. The danger of our methodology is that any deep gauges to the timber going into fresh wood can allow moisture to be sucked into the timber at an alarming rate. We have never had a problem but are just aware that if we did have a scrape we would need to get it fixed. in our view epoxying wooden hulls is great provided it is done comprehensively from new. This is the case with the second boat.

The first boat was essentially a rebuild/renovation. All the original timbers were disassembled and the moisture content was reduced to a consistant 5% before each timber was encased.

It just suits those of us who like traditional wood (for its strength as well as its beauty) but dislike the maintenance normally assoviated with it.

I''ll tell you about the carbon fibre spars coated in two colour clever clever paint to look like spruce another time.


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## Jeff_H (Feb 26, 2000)

That all sounds very interesting. I do have a number of questions and comments. Am I right in interpreting that the first boat was carvel planked and you simply(disassembled and) surface sealed all of the frames, timbers and planking with epoxy then reassembled the boat with a form of edge glued construction? And that the second boat was constructed the same way but from scratch? Was the second boat conventionally framed? How big a boat are you talking about and what sort of design? 

I too am a big fan of wooden construction having owned a number of wooden boats over the years, oddly enough each with a different construction technique. During my most rabid wooden boat days I had considered just the technique that you are using. From the research I had concluded that you did not have enough gluing surface area in the plank seams to develop the full stength or the wood over a long period of time. This is the reason for example that ''cove and bead'' strip planking works so well. The cove and bead, besides helping to align the planking, increases the surface area of the joint. When I had looked into the glued seams it looked like scarfed edges or splined edeges would have been required. 

For myself I am a fan of a number of wooden boat building techniques which would include cold molding (perhaps over a strip planked core), glued modified ashcroft and to a lesser extent, glued double planking. With all of these I would epoxy saturate the wood all sides, even if it is only a surface saturation, and sheath in a glass/epoxy or kevlar/epoxy laminate for abrasion and impact protection of the surface. 

I do beleive that if done well this would produce an extremely low maintenance boat that would offer a lot of strength for the weights involved. Certainly it would be one of the least expensive ways to build a one off. 

Jeff


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## davidk (Feb 1, 2002)

Jeff, firstly please understand I am not the expert boatbuilder. The first boat is a 20ft half deck centreboard dayboat of carvel construction on frames and ribs. Yes everything was disassenmbed, dried out where necessary and planks which could be re-used were entirely coated. The planks were fastened and glued to the new ribs, frames etc and I believe these joints to be the main source of strength. The Epoxy between the plank edges was effectively caulking.

The new boat is a 42 ft yawl (technically she is a rebuild but only the lead and keelsom were retained). It started with the old boat, and the original plans which were found in a maritime museum. The old boat was checked for shape ref the plans and jacked back to her shape (some sag removed) - this was all measured with laser levellers. New frames were laminated up to fit the shape as old frames were removed one by one (for the order think like you were tightening down a cylinder head). Only when the old boat had new frames was the old planking removed and discarded. I have wondered if it wouldn''t have been easier to loft new frames from scratch since everything was being checked against the plans anyway (and the new boat is infact much closer to the plans than the old was anyway ... not just in hull shape). Whilst the carvel construction is edge to edge planking (i.e. no gaps designed-in unlike the first boat) of course the main strength must come from the plank/frame type bonds. These are all bolted as well as glued. Being a traditional shaped ''metre'' rating boat her wine glass shape is more white wine glass shaped than red wine glass!


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## Jeff_H (Feb 26, 2000)

Thank you for the additional information. Your construction technique on the second boat sounds almost like the Traditional New England rebuilding techniques from the early 20th century by which every other plank was removed. The remain planks were used as ribbands and then new frames were steam bent into place. Once the new frames were in place new floor timbers were constructed. Then working from the rail down and the garboard up the boat was replanked over the new frames. At the end of the planking the old frames were removed and you had a new reframed and planked hull. The problem with this technique in your case would be getting proper epoxy encapsulation. 

Jeff


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## Jeff_H (Feb 26, 2000)

(This is a very long one- For those whose eyes glaze over, you might as well skip over this.) 

We actually had this discussion a few weeks back but since I could not find it in the archives, here''s how I see this question.

Obviously, one of the most obvious differences between early fiberglass boats and more modern fiberglass construction is sheer weight and how it is distributed. There is a very popular myth that early fiberglass boats are as heavy as they are because early designers did not know how strong fiberglass actually was. That''s bunk! 

During WWII the US government had done a lot of research on fiberglass composites and that information was pretty readily available. The properties were really pretty well understood. Carl Alberg was working for the Government designing fiberglass military gear when the Pearson''s hired him to design the Triton. He knew how fiberglass worked. What he knew, and as most designers of that era and as we know today, is that while fiberglass reinforced polyester laminates are pretty strong in bending, they are not very stiff. This means that when loaded like a beam, fiberglass laminates can with stand a large loading and bend without breaking but will bend farther than other materials such as the same weight piece of wood with the same loading. (That is why fiberglass fishing rods became so popular in the early 1950''s) 

But they also understood that fiberglass is a pretty fatigue prone material and that flexing greatly weakens fiberglass over time and so building a flexible boat will greatly reduce the laminate''s strength over time. 

Early designers understood stood all of this about fiberglass. In order to try to get fiberglass boats with close to the same stiffness as wooden boats, fiberglass hull thicknesses were increased beyond what was needed strictly for bending strength. That is why they were as thick as they were. 

What was not understood very well was how to handle the raw materials, resins and fabrics, during construction to maintain the Fiberglass''s inherent strength. To achieve the full inherent strength of the various materials in fiberglass used in a fiberglass hull requires:
-Careful mixing of the resins, 
-A surprisingly long cure time, 
-Careful handling of the reinforcing fabrics (For example folding fiberglass mat or cloths weaken the individual fibers)
-And a proper proportion of resin to reinforcing fiber. 

The difference in strength and durability between an ideal laminate and one that was laid up less than ideally can be enormous, especially if allowed to flex a lot over time (perhaps as much as 50% on a unit basis). The extra thickness in the hull might add as much as 30% to the overall bending strength of the hull but substantially less (perhaps between 5% and 10%) to its resistance to puncture (sheer). 

One of the really striking things about early fiberglass boats is the almost total lack of internal framing compared to more modern design. Early fiberglass boats were a wonder in their simplicity of design and construction. Early designers viewed the fiberglass hull and deck as a monocoque structure and so really did not try to brace it with a systematic layout of longitudinal or athwartships framing.

Whatever internal framing there was used on these early boats was not tabbed into the hull with the same attention that was given to tabbing by the 1970''s. When I worked in boatyards in the 1970''s it was not all that unusual to see these 60''s era boats come in ''banana''d'', (as it was called which meant flexed until the tabbing on bulkheads, flats and risers had been loosened) by the extremely high rigging loads of that era. I spent a lot of times re-tabbing boats in those days. 

Also when you work on these boats it is not unusual to find very resin rich laminations. Resin really adds almost no strength to fiberglass. It is really there to hold the fibers. In early boats, lots of resin was used because it made it easy to wet out the cloth and to get compartively smooth surfaces for layup to layup bonding. These resin rich laminates results in lower initial strength and a more fatigue prone laminate. In the 1970''s this became better understood and today even pretty inexpensive boats are careful to use better ballanced resin to fiber contents. It is quite routine to see vaccuum bagged (or injection/ vaccuum techniques like Scrimp) that produce very light, dense and strong parts within the industry. 

While there were some internal elements glassed to the hull they occurred where convenient to the design and allowed shockingly large unsupported panels. When you sailed these older boats and a wave hit the hull, you would feel the vibration of the panel flexing. While this flexure does not equate to weakness, it does equate to the likelihood of more fatigue over time. 

On a point by point basis I would compare early fiberglass to newer fiberglass this way:

Resins: Early boat builders tended to use a lot of accelerators in an effort to decrease curing time. The use of accelerators tends to produce a more brittle and fatigue prone laminate. In the Mid-1970''s and early 1980''s resin formulations changed producing resins that are especially prone to osmotic blistering. By the mid to late 1980''s resins were changed again reducing the likelihood of blistering. Today, it is not unusual to find more exotic resins (vinylester and epoxy) used in even mass production boats. Vinylester in particular offers a lot if used in outer laminates. Vinylester is nearly as water impermeable as Epoxy but is far less expensive. VE offers superior fatigue, and blister resistance. When used with higher tech fabrics (even higher tech fiberglass fabrics), VE dramatically increases the strength of lay-up. Boats like the new C&C 99 are using epoxy resins as well. 

Reinforcing fabrics:
Early fiberglass fabrics have comparatively short fiber lengths and lower fiber strengths than current materials resulting in less strength. Beyond that they were often handled poorly (folded and stacked) so that the strength of the fibers were reduced further. In the 1970''s as better stress mapping was understood, directional fabrics were developed and even conventional materials were more properly oriented to improve their load capacities. 

Today, we use higher strength conventional laminates, and have an arsenal of higher tech fibers range from Bi-axial and Tri- axial oriented fiberglass fabrics, to higher strength fiberglass fibers due to improved fiber manufacturing techniques, materials like Kevlar and Carbon fiber. (Even value oriented builders like Hunter and Beneteau are employing Kevlar in its newest boats for increased strength, stiffness and abrasion resistance.) 

Framing, liners and Coring:
Early boats rarely had cored or framed hulls. They also rarely had either structural or cosmetic liners. This is an area that is a bit more complex with good and bad aspects to each of these options. To breifly touch on each type of construction, there is cored and non-cored and framed and non- framed with specialized types of each. You often hear people use the term ''Solid Glass Construction''. This is actually a very vague and not a terribly precise description of the structure of a FRP boat. As the term ''Solid Glass'' construction is typically used it means a boat that does not have a cored hull. A non-cored hull can be monocoque (the skin takes all of the loads and distributes them), like many small boats today and larger early fiberglass hulls. They can also be framed as most modern boats are constructed today. 

A cored hull is a kind of sandwich with high strength laminate materials on both sides of the panel where they do the most good and a lighter weght center material. Pound for pound, a cored hull produces a stronger boat. Cored hulls can also be monocoque or framed construction. While cored decks are almost universally accepted in one form or another, cored hulls tend to be a very controversial way of building a boat. Done properly , pound for pound there is no stronger, stiffer, more durable way to build a boat. It''s the "done properly" that mekes coring so controversial. Ideally a hull is cored with a closed cell, non-out-gassing, high density foam, that is vacuum bagged into place. Thru-hull orface and bolting areas are predetermined and constructed of solid glass or reamed out and filled with epoxy. All of that makes proper coring expensive to construct. There is almost nothing better than a properly cored hull, and almost nothing worse than a poorly constructed cored hull. 

Decks are typically cored with end grain Balsa. End grain balsa offers excellent sheer resistance for a given weight and cost. The orientation of the cells theoretically promote good adhesion with the laminate and also resists the spread of rot. Early boats often had plywood decks with glass over. This is the worst of all worlds. Because of the orientation of the cells plywood tends to distribute rot very quickly once rot starts. Plywood tends to be heavier than other deck cores and does not have as good adhesion to the laminate as other core choice. Plywood was a cheap but not very good way to go. 

Framing helps to stiffen a hull, distribute concentrated loads such as keel and rigging loads, and reduce the panel size which helps to limit the size of the damage caused in a catastrophic impact. Framing can be in a number of forms. Glassed in longitudinal (stringers) and athwartship frames (floors and ring frames). Used in combination, all of which combined provide a light, strong and very durable solution but one that is expensive to manufacture and require higher construction skills to build precisely. 

Molded ''force grids'' are another form of framing. In this case the manufacturer molds a set of athrwartship and longitudinal frames as a single unit in a mold in much the same manner as the rest of the boat is molded. Once the hull has been laid up the grid is glued in place. The strength of the connection depends on the contact area of the flanges on the grid and the type of adhesive used to attach the grid. This is a very good way to build a production boat but is not quite as strong or durable as a glassed in framing system. 

Another popular way to build a boat is with a molded in ''pan''. This is can be thought of as force grid with an inner liner spanning between the framing. This has many of the good traits of a force grid but has its own unique set of problems. For one it adds a lot of useless weight. It is harder to properly adhere in place, and most significantly it blocks access to most of the interior of the hull. Pans can make maintenance much harder to do as every surface is a finished surface and so it is harder to run wires and plumbing. Adding to the problem with pans is that many manufacturers install electical and plumbing components before installing the pan making inspection and repair of these items nearly imposible. 

Glassed-in shelves, bulkheads, bunk flats, and other interior furnishings can often serve as a part of the framing system. These items are bonded in place with fiberglass strips referred to as ''tabbing''. Tabbing can be continuous all sides (including the deck), continuous on the hull only, or occur in short sections. Continous all sides greatly increases the strength of the boat but may not be necessary depending on how the boat was originally engineered. The strength of the tabbing is also dependent on its thickness, surface area and the materials used. When these elements are wood they can often rot at the bottom of the component where the tabbing traps moisture against the wood. 

Most early boats were non-cored hulls with minimal framing, this allowed a lot of flexure and really put a lot more stress on the minimal framed connections within the boats. Most had balsa or plywood cored hulls. 

Hull to deck joints:
Early boats typically had a number of hull to deck joint. Most simply had an inward turning flange on the hull and that was bolted through the deck and toe rail. These thru-bolts were seen as the primary bond and varied widely in size and spacing. They rarely had backing plates even from the best builders of the era. Between the hull flange and the deck was either some form of bedding compound, such as polysulfide (like Boatlife) or organic compounds (like Dalphinite) or more commonly a polyester slurry. All of these are comparatively low adhesion and lifespan solutions. 

In the 1970''s some offshore intended cruisers started glassing the joint from the interior but the big change was to higher adhesion caulking/ adhesives in the joint. 3M''s 5200 became a common adhesive for this purpose. Bolt spacing was increased as builders often considered the 5200 to be the primary connection. Outward facing flange connections became more popular because they permit quicker turn around time for the molds and less labor to prep the mold for the next boat. They are inherently weaker and more vulnerable. 

Today, most manufacturers seem to be using any one of the earlier techniques with the ''Big Three'' using extremely high adhesion adhessives engineered for the aerospace industry. These produce extremely sturdy joints that should outlive most of the other joint types that have preceded them. You never hear of hull deck failures any more which back in the 1970''s seemed to be a fairly frequent occurance.

Rigging:

Early glass boats tended to use extremely stiff spars and extremely high rig tensions. Without adjustable backstays these high loads were imparted into the hull on a routine basis. They really can take a toll on a boat. It was not unusual to find these early boats so distorted by rigging loads that doors in passageways would not close on a beat. 

In the late 1970''s and into 1980''s there was a real shift in turnbuckle design. Some of the more popular turnbuckle designs really had comparatively short life spans and resulted in lost rigs and rigging. By the 1990''s turnbuckle design had changed yet agaib and seemed to have moved toward a more durable engineering.

Over time rigs got lighter and more flexible. This is a mixed blessing. A slightly flexible rig imparts less load into the hull and deck and bend can be increased to depower sails. Taken to the extremes seen in late 1970''s through early 1990''s race boats, they make a rig that is hard to keep in the boat. In the early 1990''s IMS recognized this problem and shifted the ratings a bit to encourage stronger rigs and so rig losses in newer IMS type race boats are compartively uncommon these days. Some of this improvement is the use of Carbon Fiber spars. Carbon Fiber makes a really stiff and shocking light spar material but is very expensive and the jury is still out on the long term life expectancy of carbon spars. 

In conclusion: 
Early fiberglass boats were really engineered as if they were a wooden boat built out of fiberglass. They ended to be more flexible and although heavy, the poorer strength of materials that came from material and handling choices meant that they had very high stresses but they were not as sturdy as they appear. By the 1970''s designers better understood how to engineer fiberglass as fiberglass, but were faced with historically poor resins that resulted in real blister problems. By the 1980''s resins improved, as did fiberglass material handling techniques and rigging design and strength of materials. The blister problem was better understood and higher tech resins and fibers entered the industry. Today''s baots tend to be lighter and stronger than earlier boats. This weight savings is used to produce higher ballast ratios and to produce greater stability or carrying capacities. Hull deck joints have improved in some ways, but I hate the fact that outward flanges are becoming popular again. Blister problems have been reduced greatly and rigs are becoming easier to operate. That said I see popularity of inmast furling mainsails to be a serious negative trend. 

At least that is how I see it. 

Respectfully
Jeff


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## paulk (Jun 2, 2000)

Long, but succint and a pleasure to read. Thank you, Jeff H.


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## thomasstone (Dec 21, 2001)

Still not following you on this one.Are you still saying some of the early glass boats that have very thick hulls are not as strong as they appear to be.I dont think my boat (1965 )was a wood design built out of glass. It also seems to me being in a yard right now all of the boats with the blisters were built in the eighties. I just dont see how a 3/4"glass hull is not strong.Im sure glass building techniques are way better than they were in the sixties, but I also dont think thier is a strenghth issue with the overbuilt boats of the sixties. I would imagine with better engineering of today the glass does not need to be as thick.
thomas


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## DuaneIsing (Jul 10, 2001)

Jeff_H,

Thanks for the detailed explanations - always appreciated.

Your point about some builders making the wiring and plumbing inaccessible is important to me. Who wants to have to rip a boat apart to find and repair a system problem?

What is it about external flanges on the hull/deck joint that is inherently weaker?

Duane


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## Jeff_H (Feb 26, 2000)

In the part of the posting that I believe that you are referring to, I said something to the effect that, while early fiberglass boats appear to be very strong because of their thicker hulls, in reality they are not as strong as they appear. The basis for this is that most people assume that fiberglass is uniformly strong and so if it is thicker it is also automatically stronger. What I am trying to explain is that in developing the strength of a structure there are a lot more factors than simply the thickness of the fiberglass. These factors include the strength of the actual laminate, the thickness of the laminate and composite section, and the spacing, method of connection and stiffness of the frames. 

When you look at early fiberglass boats you typically find substanially weaker laminate and much more widely spaced framing (or no framing at all). This combination would lead to fatigue issues which further weaken the laminate. 

So while most people generally assume that the thicker hulls of early boats have substantially greater strength than lighter modern boats that is not really the case. I know that intuitively most of us would say as you have "I just dont see how a 3/4" glass hull is not strong". Perhaps if we use this model it might help to explain my point. Visualize two beams that are equal in cross section and one is made of oak and one of cedar. Obviously, if you wanted both beams to be of equal stength the oak which is substantially stronger will need be reduced in thickness. But if you didn''t know that the cedar was not as strong as the oak you would assume that the cedar being substanially thicker must be stronger. 

Similarly, assume we had these two beams set up so that the oak beam also spanned a substanially shorter distance than the cedar. Well if you wanted both beams to support equal loadings you would further need to reduce the thickness of the oak beam. Again if you did not take into account the smaller spans that the thinner beam had to bridge intuitively you could also assume that the cedar being substanially thicker must be stronger.

Whether your hull is not strong enough is not something that I can answer, but in my life I have seen hulls that have failed due to fatique, and if you look at modern boats and automatically say that they are not strong enough for your tastes than I am pointing out that since the thinner hull of a modern glass boat may have similar or greater strength to an earlier glass boat (even with the early boats 3/4" thick hull), perhaps that early glass boat may not have enough strength for your needs either. 

To explain my point about early fiberglass boats originally being engineered like wooden boats built in a different material (and that would probably include your 1965 boat). In the 1950''s and early 1960''s wooden boats were designed using a number of different empirical scantling rules (Herreshoff and Nevins being quite popular). These rules established empirically the thickness and spacing of the various parts of a wooden boat structure. During the period of early fiberglass boats these formulas were simply adjusted for the relative strength properties of wood vs fiberglass. But fiberglass and wood have such different properties that by the 1970''s a different understanding of how to engineer fiberglass began to be developed to take advantage of its strengths and overcome its weaknesses. It is partially the evolution of that understanding that resulted in today''s lighter stronger boats. 

Respectfully
Jeff


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## TSOJOURNER (Dec 16, 1999)

Hi Jeff,
I want to know the truth but I have a real hard time believing what you''re saying about this fiberglass thing...you may not care. But if you do, can you give a number of examples? Years, brands and failures?
Thanx

Dennis


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## Jeff_H (Feb 26, 2000)

Dennis:

To give you some specific examples of the boats that I referred to that I worked on that I saw banana''d or with poorly installed bulkheads:

A mid-1960''s Islander about 32 feet. The owner had raced it and managed to pull the hull deck joint apart at the transom when the knee at the backstay tang broke loose from the hull and the bolts cut through the transom. This knee was plywood and was glassed in with a single layer of cloth onto the hull. This boat also had dislodged the main bulkhead. This resulted in the cabinetry across from the head being pulled loose. There were large spider cracks on the outside of the hull at the main bulkhead which were clearly flexure cracking and pushing on the hull you could see some ''hinging'' at the bulkhead.

Worked on a early 1960''s Paceship Eastwind (roughly 25 footer). This boat had a partially molded fiberglass interior that had shifted and had damaged the deck structure above when it had rotated out of position. The surveyor was the person who taught me the term "Banana''d".

Helped a guy working on an early Columbia approximately 31 feet which had bounced off a dock and dislodged some of the glassed interior components. I helped him glass in a plywood bulkhead that had shifted. It had originally only been only spot tabbed into place on one side.

I have mentioned the Morgan IO with the hull deck joint problem.

I had a 1965 Grampian Classic 22 that had flexed and broken the joint between the aft bulkhead of the cabin where it met the cockpit seats. I reglassed that area back together.

To answer Duane''s question about why I consider external flange hull to deck joints weaker:

The bolting, caulking or adhesive surfaces on an internal flange hull to deck joint don''t show and so can be thicker in depth and have a much larger contact area. Outward turning flanges are a bit more limited in size because if constructed as solidly as an internal flange they would look very clunky. 
When you think about how an internal flange hull ot deck joint works, the joint really is not in bending. It is subjected to sheer and to tension trying to pull the joint apart. But external flanges often occur below the deckline and so are exposed to a greater likelihood of damage in a boat to boat or boat to dock accident and are exposed to large hinging forces that create bending loads within the joint.

In an on-the-internet question and answer session with Hunter that I moderated a few years back, Hunter was asked about Hunter''s outward facing flange hull deck joint.

The Factory Representative answered,

"[Hunter''s] Hull/Deck joints are outward lapped flanges. The joint is prepped and then filled with 3m5200 and bolted on six inch and 8" centers (depends on the size of the boat) using 1/4" SS aircraft style nuts and bolts 360 degrees around the perimeter of the hull. It is then capped with a heavy-duty vinyl rubrail. No it might not be the best hull/deck joint but it ranks right up there with them and provides some unseen benefits. It does provide a strake for protection of the hull side and it does place hundreds of potential leak points outside the hull. This joint has been in use for 20 years and has stood the test of time. Surveys of damaged boats from Hurricanes and collisions indicate the strength is substantial, durable, and easily repaired. We do two leak tests of the boat one is done in an enclosed spray room for 4 hrs and the other is a pressure test and soap spray to pinpoint any leaks prior to shipping."

"We do use outboard lapped flanges because they are easier to construct than inboard flanges. We cycle tooling at a rather high rate and to obtain that rate sometimes we need two to four sets of identical tooling. That adds up fast because tooling is the major investment in FRP construction. I don''t argue that an inboard lapped flange is better. But I will argue that an outboard flange for the reasons mentioned earlier is more than adequate and is construction friendly. It is certainly better than a shoe box joint that provides none of the benefits of either and is more prone to leaking and harder to repair if damaged. But then so would an inboard lapped one be even harder to repair and harder to access it''s fasteners [Than an external flange]."

I suppose that the rep from Hunter is right that a damaged outward flange joint is easier to repair but I still think it is inherently weaker and more prone to damage.

Jeff


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## Jeff_H (Feb 26, 2000)

Dennis, I just looked at your question again. If you are talking about the material layup issue, my sources come from a number of sources. 

For example I compared the glass in a coring (depthsounder installation) from my family''s 1965 Pearson Vanguard to a plug that I had from a 1980''s era Pearson (Fuel Tank Vent). Sanding both with 220 grit paper and then putting motor oil on the same I was amazed at the clear difference in spacing of the laminations with much fatter resin lines. 
After that I began to pick up samples of corings as I walked around boat yards. (They make good backing plates under a washer) When ever posible I try to identify the boat that the plug came from. It became clear that early boats generally had visibly more resin rich laminates. I had the chance to discuss this observation with a marine surveyor/ yacht designer, who was with Bristol in the 1960''s and into the early 1970''s, he basically confirmed that to be his experience as well. 

Jeff


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## TSOJOURNER (Dec 16, 1999)

Hi Jeff,
Yeah, thats one of the things I was wondering about. The other things are colisions, grounding dammage (not keel) stress failures...stuff like that.
I want to be educated on all points not just the kind of boats (traditional, heavier,higher D/L) that I am used to. I will never shun these boats( T,H,HD/L). I just like to know whats going on and your brain seems ripe fer tha pickin''.
Thanks alot.

Dennis


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## thomasstone (Dec 21, 2001)

Im not saying that early glass boats are stronger than todays boats,(thier are probally alot though). I just dont agree with you when you say some of the early boats with thick hulls are not as strong as they appear to be and the extra weight is just causing more stress. It also appears to me the eighties boats are the ones with the blister problems.Thier is an eighty something endeavor behind me full of blisters and two eighty something union 36s in front of me covered with blisters.Also I dont see an early glass boat taken from drawings of a wooden boat as a negative thing either.I would imagine alot of new boat design has evoled from the past.In my case I am doing a pretty major re-fit and I have not seen any signs of stress due to my thick hull. I am also not sure of my builders rep(chris-craft) during that time.(1965).With out getting techincal how do you explain so many old boats on the water?You would have to agree they did something right to have this kind of longevity?
thomas


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## TSOJOURNER (Dec 16, 1999)

What thomasstone said.

Dennis


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## TSOJOURNER (Dec 16, 1999)

Jeff_H,
Thank you. How wide spread where these types of problems?
I know what I think but what do you think some of the big changes where from the sixties through the seventies?

Dennis


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## paulk (Jun 2, 2000)

Longevity may be due to things entirely unrelated to fiberglass layup schedules and glass/resin ratios. Improved navigational tools like depthsounders, Loran, GPS and the ever more popular radar are keeping people in old fiberglass boats from finding as many rocks as they used to. Plastic (fiberglass) left to float in the water doesn''t deteriorate much - just look at all the clorox bottle lobsterpots. If they can keep from hitting anything, no wonder there are so many old boats around. 
To the point about possible "under- engineering" of fiberglass contstuction, you can read just about any old boat review in Practical Sailor. Wobbly bulkheads, flexing topsides, delaminated tabbing, and crazing gelcoats due to overbending abound. Sometimes the items are fixed "after the first 50 or so hulls...". Sometimes the "factory fix" is installing a heftier backing plate. Sometimes it''s: "many owners have replaced..." Of course the marketing departments don''t call this "under-enginering" -- they call these things "improvements" in the proud history of their company and product. Have fun sailing, and don''t hit anything no matter what your boat''s made of!


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## Jeff_H (Feb 26, 2000)

I guess "how strong they appear" is in the eye of the beholder. Most people equate the extra hull thickness with proportionately greater strength. All other things being equal, that would be true, but with all of the variables it is just not the case as I tried to point in my early posts on this string. 

Blisters still occurs in boats built today, but by the early to mid 1980''s most quality American boat builders had dealt with the blister problem and had changed resins, and layup practices to combat the problem pretty successfully. 

I never said that glass boats were literally built from woodenboat drawings. What I said is that they were engineered using wooden boat engineering interprelated to glass construction and the properties of glass were sufficiently different to wood which resulted in designs that did not use fiberglass very well. This approach to the fiberglass engineering did not necesarily place material where it was needed and had too much material where it was not. 

Chrris Crafts were considered to be extremely well built boats for their day. They were designed by Sparkman and Stephens who were the leading yacht designers (probably world wide) during that era. S&S probably had the absolutely best engineering information that was available and their boats from that era have held up exceptionally well. 

Lastly, to address your question about the number of older boats on the water somehow showing that they were well constructed. If you sailed in the 1960''s, the popular sail areas were no less crouded with boats than they are today. Huge numbers of fiberglass boats were constructed in the 1960''s and 1970''s. (In 1968 something like 10,000 new sailboats over 30 feet were constructed in the US while just over 3,000 were constructed in the year 2000 up from a low of 2200 boats in the early 1990''s.) But when you are out on the water early fiberglass boast represent a small percentage of the boats out there. Over the years I have seen or heard of a fairly large number of these older boats going to the landfill. While many of these boats died of economic rather than structural problems, there has been a significant reduction in the number of older boats out there. 

Jeff


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## TSOJOURNER (Dec 16, 1999)

Jeff, Are you saying that if you took a new Hunter (thin and light) and an old Alberg (thick and heavy)of similar lengths and did a sort of nautical ''demolition derby''with them, the Hunter would be left standing, or floating???


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## TSOJOURNER (Dec 16, 1999)

It would''nt have to be just a Hunter. I could name at least ten.
Although I like to hear both sides of the story... I still don''t buy it. I''m not even close to buying it.


Dennis


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## TSOJOURNER (Dec 16, 1999)

Hey Snicklefritz, 

I believe you stumbled on a great spectator sport. The Sailboat Demolition Derby. I saw *******/NASCAR types doing it with old school buses on TV, why not derelict old sailboats? Count me in.....


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## Jeff_H (Feb 26, 2000)

I am saying that here in Annapolis a few years back a 4100 lb Laser 28 and an Alberg 30 bounced off each other (topsides to topsides) in a thunderstorm and it was the Alberg that suffered the stress cracks and damaged hull/deck joint. Of course that is a too small a sampling for a fair example.

But if you consider your Hunter example, there is nothing especially thin about a Hunter as compared to a Alberg of equal length. If you compare an Alberg 35 at 12500 lbs to a Hunter 35.5 at 13,000 lbs of which the Alberg also has 500 lbs more ballast and a heavier rig, that suggests that the Hunter''s hull is actually heavier. And if you consider the Hunter''s framing system and higher density laminates, what ever else you can say about Hunters, I would suspect that the Hunter would do quite well relative to the Alberg in a similar impact. 

Jeff


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## obiec (Sep 26, 2001)

It dose seam that the boat produced today are of a much heavier lay up than those produced just say 8 years ago. I could be wrong on this, But it seams that a 95 Hunter or Catalina was not a very good heavy whether boat. How ever it seams that the ones today are incredible. All you have to have are deep pockets. Is it possible that the up tern in the economy has allowed the population as a whole to afford better boats and the manufactures can now sell a much nicer boat. And the population that can now afford it is Evan demanding it. This makes me think that 10 years from now I might be able to afford a very well built 2000 boat, that will sail for many years to come.


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## windship (May 4, 2002)

obiec,
Why do you say these boats are incredible heavy weather boats?

Dennis


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## obiec (Sep 26, 2001)

As I stated I don''t know, I was more thinking out loud with a question to those whom might have a good response. This is why I was thinking that they might be good heavier whether boats. First of all It seams that there displacement has gone up quite a bit, and I am relating this back to being thicker glass better bulk heads and a generally stiffer frame. So I think they are going to flex a lot less? Secant with so many having roller furling as well as roller mains it is going to be very easy to select the right sail combo. Third It seams to me that there rigging is heavier also. And last the open sterns with the swim steps to me seams grate if you are knocked down or pooped there could be no better way to drain that cockpit that quickly. It dose seam like you would get your feet wet a little more often in following seas.


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## windship (May 4, 2002)

obiec,
Yeah...cool. I was just wondering. Thanx for the reply.

Dennis


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## Jeff_H (Feb 26, 2000)

obiec

While I am not sure that I disagree with your conclusions, I do disagree with your reasoning why the newer Hunters might be better seaboats. If you look at 40 to 41 foot Hunters for example from the mid 1980''s (Legend 40), mid 1990''s (Passage 405) and today (410), you will see that the 410 is indeed about 1600 lbs heavier than the mid-1980''s Legend 40 but is virtually the same weight as the mid 1990''s Passage 405. The mid-1980''s Legend 40 also had 500 lbs more ballast and so was more like 2100 lbs lighter when the keel is subtracted. But when you look at the details, the 410 and 405 have substanially larger tankage (fuel, water and holding) they carry an extra battery bank and an larger engine. Newer boats tend to be designed to have a lot more small built in items ,as well as, alot more heavy stuff on board. Cumulatively items such as, inverters, bigger and an increased number of battery banks, heavier and duplicate ground tackle, multiple bow rollers, electric windlasses, arches, rigid vangs, corian counter tops,innerspring matresses, standard (vs optional) refrigeration, bigger engines and larger capacity alternators, larger capacity hot water heaters and such popular options as watermakers and built in auxilary gensets, really can add a lot of weight to a boat that has nothing to do with the boat''s actual strength.

When you add to that the fact that displacement on boats was generally cited as completely stripped out in the 1980''s and cruising boat weights today typically are typically cited as with a reasonable compliment of gear, I don''t think that we can assume that the hulls are heavier or have more bulkheads. 

Roller fuling mainsails are fine for coastal cruising but are a really bad idea for offshore work. (They have a lousy record of jambing at the worst times and also over time when reefed, they tend to power up as the sail cloth creeps down toward the gooseneck. One thing that I applaud about Hunter (unlike Beneteau and Catalina) is that they have tried to direct potential buyers away from in-mast furling. 

Then there is the heavier rigging. From my experience, I am not sure that is really true, but even if it is, newer Hunters are designed without backstays. This enormously increases the loadings on the upper shrouds as they now bear the brunt of maintaining headstay tension and aft loadings. They could easily have two or three times the loadings that they previously had to withstand and so would need to get significantly larger.

Which only leaves the open stern and given that the lip of the companionway is below the height of the cockpit seats, you really need to have an open transom to prevent downflooding. 

Jeff


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## seabreeze_97 (Apr 30, 2006)

"When you look at early fiberglass boats you typically find substanially weaker laminate and much more widely spaced framing (or no framing at all). This combination would lead to fatigue issues which further weaken the laminate."

Here we go again. Jeff H., you have stated on another thread that the rumor of why the early fiberglass boats were built so thick (because the engineers under-estimated the strength of fiberglass) was false, and that they did know exactly how strong it was. Are you now saying that they over-estimated the strength of fiberglass and should've framed and braced more heavily? The reason they had little or no framing is because they didn't need it. That's why fiberglass boats took the boating world by storm when they were introduced. They didn't need all the space-consuming framing support, thus, it made for much roomier boats within the designs of the time. Cabins interiors could be built right up against the hull.

"Over the years I have seen or heard of a fairly large number of these older boats going to the landfill. While many of these boats died of economic rather than structural problems, there has been a significant reduction in the number of older boats out there."

Sorta like old cars, and most of them aren't made of fiberglass. Hmmm.
Any boat, regardless of hull composition eventually faces extensive refit or scrapping. Most people, in this disposable world, opt for something new. 

Kevlar (for example) reinforced hulls can be thinner than fiberglass hulls for a given strength requirement, but, as with most things these days, the boats are built to certain limits of strength, where older products tend to have excess strength to deal with situations outside what some engineer thinks might happen. It's not that they planned to have all that excess strength, it is just one of the more pleasant side effects of the construction methods of the time. Cost constraints play a bigger factor today, causing those strength margins to be cut even closer. Overbuilt is the term most often associated with older boats, where newer things, all too often, are just good enough for the averages.


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## sailingdog (Mar 19, 2006)

Some of the newer GRP boats are built ridiculously light, some are built reasonably heavy, with proper respect to design constraints and laminate thicknesses.

Older boats often didn't use stringers, as the heavier layup was stiff enough to not require their use. The lighter laminates used by some modern designs often requires the use of stringers or framing to make the hull stiff enough to be safe. However, the laminate itself is often not thick enough to really be safe, even though the engineering analysis of it says that it has enough strength.

Dave Gerr, in his book _The Nature of Boats_, 
has a great example, where a boat manufacturer talks about how stiff and strong a laminate being used is and demonstrates by hitting it with a hammer, which bounces off. A naval architect takes the hammer and reverses it and easily drives the claws through the laminate.

*There are good boats, both old and new, and there are bad boats of all ages*. A badly designed boat, even using the newest, high-tech materials and techniques, is still not going to be seaworthy or durable. Some of the older designs were made without the full understanding of the material limitations-and may have more resin and chopped strand mat than would make a durable, strong boat.


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## seabreeze_97 (Apr 30, 2006)

. By the 1980''s resins improved, as did fiberglass material handling techniques and rigging design and strength of materials. The blister problem was better understood and higher tech resins and fibers entered the industry.

http://yachtpuff.com/pages/14/index.htm
An 80's era boat with a horrid case of the blisters. So much for "improved" materials and handling.


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## Newport41 (Jun 30, 2006)

Boats are now days a commercial product. They're designed to sell to the largest market and I think the design changes over time go hand in hand with construction methods. Now days the market is going for space, comfort, and to a lesser extent, speed. The seaworthy designs of the past are out of style and the wide, light and complicated are in. There's pluses and minus' to this. Cruising appeals to more people now but finding what some would call a "real,seaworthy" boat is getting difficult. I think the real loss in the high-tech construction and design is the fact that there's so redundancy. There's no room for error. Take the Mumm 36 or any other high tech racing sled. Aspects of them are stronger than anything we've seen. But if something happens that wasn't planned on or calculated in the design phase, then they're so fragile.


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## luckyjim (Jun 2, 2007)

Newport41 said:


> Boats are now days a commercial product. They're designed to sell to the largest market and I think the design changes over time go hand in hand with construction methods. Now days the market is going for space, comfort, and to a lesser extent, speed. The seaworthy designs of the past are out of style and the wide, light and complicated are in. There's pluses and minus' to this. Cruising appeals to more people now but finding what some would call a "real,seaworthy" boat is getting difficult. I think the real loss in the high-tech construction and design is the fact that there's so redundancy. There's no room for error. Take the Mumm 36 or any other high tech racing sled. Aspects of them are stronger than anything we've seen. But if something happens that wasn't planned on or calculated in the design phase, then they're so fragile.


I could not agree more. There is no room for errors when sailors lives are on the line. The failure patterns in epoxy vs polyester are very different indeed. As the life-cycle of a boat goes from being a polyester hull with AL stick to an epoxy hull with epoxy stick all of a sudden the designer could place the centerline of the hull below the waterline as the weakest part of the system. Think I am exaggerating? Read on...If you look at the materials and the way the shop floor has to handle them during the layup you will see that the market and certain designers are about to or may have already set themselves up for a major fall.

Just last year a 2005 Tartan 3700 hull split clean open 30 inches under the forward bulkhead some distance from the mast step. The incident involved a delivery from NJ to MD. The hull split allowing water in up to 3' above the cabin sole. The USCG came to the rescue and thankfully no lives where lost at sea. The boat was then whisked away from a yard in the NE and repaired.

The owner was quickly blamed for over tensioning the rig. No notice was ever supplied, or has been supplied to owners on rig tension, or hull inspection procedures. It is a shocking way for a manufacturer to allegedly conceal relevant safety data from the market.

Do a Google search for 'split hull Tartan 3700' and see what you come up with


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## sailingdog (Mar 19, 2006)

Jim-

There's actually a thread on this issue, which was started a day or two ago by Camarderie IIRC.


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## camaraderie (May 22, 2002)

Original thread...2002...last post 2006...welcome Jim but be aware of the dates and if you would like to start up an old thread again that is fine...just acknowledge the fact to save the rest of us from reading a lot of old stuff again! Thanks. 
As an aside I posted some links to the Tartan problem you cite and others under Buying a Boat last night! Small world!!


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## sailingdog (Mar 19, 2006)

It was your thread from last night that I was referring to.


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## Giulietta (Nov 14, 2006)

I like Hi tech...but old thread suck


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## camaraderie (May 22, 2002)

Dawg...your post was being composed at the same moment as mine. 

I like older designs with new materials...except foam cores in hulls!!


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## sailingdog (Mar 19, 2006)

Yeah, those Divinylcell foam-cored, carbon fiber and kevlar boats are really pure junk.


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