Ken Van WagnenóIíd like to thank the Detroit Express 27 Fleet and North Sails, Detroit, for inviting us down. It was nice of you guys to put this thing together. So, letís let Terry Alsberg tell us about the boat.
I was going to have a nice long discussion about the construction here but I donít want to bore you guys to death so I thought Iíd do a real quick slide presentation that I did a couple years ago Ė just some slides I had lying around and tell you a little bit about how the boat got started and how we tooled the original one Ė kind of like home movie type of stuff.
And, I have some samples of some materials we used to build the boats with because I know the construction is on peopleís minds when they hear the boats are light they wonder, ďGeeze, does that mean weíve left something out or are they flimsyĒ which in my opinion, and most peopleís opinion, is not the case. We sail in some real heavy air in Santa Cruz and San Francisco and they donít seem to fall apart very easily. Anyway, Iíd like to talk about that a little bit, too.
The idea of light weight wing boats is not new. Itís been around for a long time. I think the first people that built them were the Indians when they figured out you could build canoes out of birch bark instead of digging them out of logs. And everybodyís always wanted lighter boats Ė boats that could go faster. Boats around the 1400s or so like Columbus sailed Ė they had displacement/length ratios in the 800 numbers, and then as boats progressed about Captain Hookís era, his boat was about 600 displacement/length ratio. And then they got into ultralight boats like Colin Archerís Ė you know, thatís a West Sail 32, and theyíre about a 400 displacement/length ratio. And, boats started progressing down from there when the first Cal boats came out, everybody thought that they were radical light, you know, the Cal 40s, they were around 250 or so. And, then they got into boats like the Express which is a 71 displacement length ratio which is what you call a serious ultralight.
But, we didnít invent them in Santa Cruz. Actually, where they came from Ė the specific ancestor of the Santa Cruz ultra light came out of a book called ďCommon Sense Yacht DesignĒ by L. Francis Herreshoff. And thatís the drawing of it. This is a drawing Ė I donít know exactly when it was drawn. The book was a collection of articles that were in Rudder magazine I think written from about 1920 to 1940. And, this is a lines drawing that was just in the book, and didnít have any particular dimensions on it. Nobody knows how long it is except that if you do look at an Express, youíll notice a lot of similar shapes to it. Itís got a little bit of a V transom to it, fin keel, spade rudder, very straight rocker to it. Rocker is the curvature this way in a boat. Itís relatively narrow, relatively low freeboard, itís got a little bit of hollow at the waterline, and itís very, very much like an Express, and most of the Santa Cruz ultralights have some relationship to this drawing.
L. Francis Herreshoff and his father, Nathaniel Herreshoff, were doing ultra- light boats back before they had materials to build them out of, and the biggest single reason why you see them today and you didnít see them earlier was not because they are any smarter today than they were before, itís just that we have materials now that we can build very light weight things out of. And probably the biggest thing that our company has done beyond the people that came before us in Santa Cruz is trying to push the technology a little bit further by using better materials like the modified epoxy type of resins and uni-directional glass cloth and that sort of thing and some things weíll talk about some more. Anyhow, let me show you some graphs here that show how to help materials perform better.
This is a graph that I got out of Yacht Racing and Cruising that I handed out to you guys Ė itís preprinted and you all have copies of it. It shows how different glasses and fibers perform and also how different resins perform. Youíll notice a couple of unusual things. For one thing, glass is stronger than carbon fiber. How high this graph goes here tells you how strong the material is Ė at what point itís going to break. And even though people think of carbon fibers being a very strong material, actually S-glass is a stronger material than carbon fiber. What it isnít though, it isnít as stiff as carbon fiber. The steepness of the slope tells you how stiff the material is Ė how much stretch it has for how much load it carries. You can see carbon fiber at the steepest curve, Kevlar after that, S-glass is less stiff, and E-glass is the least stiff. And so when you build boats out of E-glass or S-glass, you have a less stiff hull than carbon fiber or Kevlar but itís not Ė its ultimate strength which is what you think of as seaworthiness is not less, itís actually greater. And, of course, the cost-benefit ratio is much, much greater to use glass than carbon fiber for more people like us who arenít going to maxies and arenít millionaires. We have to build boats that are still affordable, so we try and keep the cost-benefit ratios in mind too. Although the Expresses are not cheap, theyíre not ridiculously expensive either.
One of the important things about it is how the glass works in a composite. All fiberglass is what they call a composite. What you call fiberglass is what we call a laminate which is resin and glass together. Fiberglass is just the cloth or the material that reinforces a resin system. And most boats are built out of polyester resins which have about 2.4 percent elongation. That means that if you were to take a piece of fiberglass a hundred inches long and stretch it to be 102.4 inches long, it would start breaking. And as soon as that resin started breaking down, the rest of the laminate would go to hell real quickly because itís the weakest link theory and a composite Ė whatever breaks first, the other material will break shortly thereafter because itís no longer supported in the way it needs to by both materials.
Epoxy and vinylester and A and E 4000 which is the resin we currently use Ė itís sort of like using vinylester which is what youíd call a vinyl modified epoxy Ė we now use an acrylic modified epoxy Ė very similar chemically, itís just a newer material that came on the market a few years ago. It has a couple of esoteric characteristics that we like better that wonít interest you but these are the Ė the physicals are about the same as for epoxies and vinyl esters. And they have about 5.5 percent elongation.
Now you can look at the elongation of glass fibers and you see that they have about 5 percent elongation also before they break which means that the two materials are matched well. So that if you take the same composite and you wet it out with an epoxy resin, youíll come up to this strength here, letís say if itís E-glass like most boats are, which means itís going to be able to break at a little over 100,000 psi. But if you wet it out with an epoxy or vinylester itís going to go up to about 200,000, 250,000 Ė almost twice the strength. So just by picking a better resin, you can almost double the strength of the laminate. Thereís other nice things about these resins. They have better peel resistance which means if you are trying to peel two layers apart of glass that are glued together with that material, it has five times the peel strength of a polyester so thatís resistance to delamination. Because it has 5 percent elongation, itís more resilient. You run into buoys and other boats on the starting lines, docks and things like that, itís a tougher and more resilient resin.
Whatís the price?
Itís about twice the price. But that doesnít mean that your boat is double in price because resin is not the most expensive thing in the boat. In fact, the actual increase in price on an Express 27 is about $300 more if you use that resin. Now a lot of boats Ė you sometimes wonder if theyíre designed by the accounting department instead of engineers because in a lot of factories, they figure most customers are not interested in the resin, they just look at the shiny glass and figure if itís shiny, itís good, if itís not shiny, itís not good. They donít go any further into it than that. They donít care whether itís a better performing laminate. But, I figure $300 Ė that wonít Ė I donít know, can you buy a #4 jib for $300 here? Maybe, Iím not sure.
Yes, close. So for maybe the cost of a #4 jib you can use a better resin and itís the glue that holds the boat together; itís what keeps the water out. I canít believe that people would save you that amount of money. Itís beyond me that they would even consider using a lower-performing resin. We use it because it has better engineering numbers. All these things that we know about.
But I also found some other nice things about Ė about vinylester resin. Thatís the same basic graph, itís another way of looking at it. Tells you what elongation does. It shows you how the laminate goes to about twice the strength.
This is a chart that I copied from some Navy studies. Vinylester resins versus polyester resins. This shows just the straight engineering of it. Do you see the vinylester has got a slightly higher short-beam shear. Thatís an engineering number Ė unless youíre engineers, I donít want to go into details on it but itís what this resin here is about, this is the modified epoxies, this is the polyester here Ė a littler higher there. The shear, however, after youíve done an aging test on it, which means they raise the temperature and boil it for a while and find out what happens to it, that simulates aging according to the navy. You can see that now the numbers are really dramatic. In fact, the retention is Ė they say that a modified epoxy boat will be at 98.3 percent of its original strength after aging, and polyester dropped to 41.9 percent of its strength, and this is the reason why some hulls go Ė get soft after a while, they donít hold headstay tension anymore. The reason they oil-can more going through the water is because as the resin ages, itís lower in strength. Another thing that happens is as the resin ages, it tends to be a little more brittle and so it cracks and you can see little microscopic cracks through it. Those little microscopic cracks also mean more oil canning and less headstay tension, less shroud tension, all those sorts of things. So you find that not only do you get a higher strength initially out of these materials, but the life expectancy of the boat is high and one of the nicer things Iíve heard at the Nationals last year is some of the rocks stars that show up at Nationals that go from class to class, they were saying that they were really impressed with the fact it didnít matter how old the boat was as to how competitive they were. The first place boat was hull #95, the second place boat was hull #1, they were real close. The third place boat was hull #35 and the fourth place boat was me at #7. So, there seems to be no correlation with the age of the boat and which one performed better. Of course we hope that the boats will last at least 25 years. They were engineered and designed to do so. When we say we build them lighter Ė one other nice thing about this resin is that it weighs 8 pounds per gallon instead of 9 pounds per gallon so not only is it stronger, but itís marginally lighter, so it saves a little weight in the boats too.
We find that there are a lot of things that you can do in boat building that not only saves weight but increase strength. If youíll notice, it goes against the grain what people think. People think heavier is better. Itís kind of like when America used to build big cars, you know, they thought you were safer in big cars but it turns out that you can engineer lighter weight cars as they are these days that have collapsible front-ends Ė theyíre generally better engineered. They can be even safer than the old big heavy cars were. So, seaworthiness and safety have really nothing to do with weight, they have more to do with proper engineering. And, Carlís [Carl Schumacher, N.A., the Express 27ís designer]background is a structural engineer and so is mine so we pay a lot of attention to the construction of the boat. There is not a lack of glass in the boats or quality of resin.
Another nice thing about it is that this number right down here, this is the amount of water that they Ė a polyester laminate retains, 3.2 percent. This is the amount that a modified epoxy resin retains, .2 percent. And thatís about 1/15th the amount of water, and thatís the reason why Expresses donít get hull blisters and why they donít seem to gain weight sitting in the water. Weíve weighed them after theyíve sat in the water for a number of years against ones that have been dry sailed and there seems to be no real weight change. So, thatís another benefit to the longevity of the boat.
Inaudible question from the audience on hull blisters.
Theyíre osmotic and blistering is a result of the resin being a semi-permeable membrane that water vapor can go through. Thereís no mystery and everybody talks about the mysteries of hull blisters. Theyíve been known for a long time to cause this osmotic action and itís caused by a couple reasons. One is because sometimes thereíll be voids in the laminate and Ė I was just up at Ken VanWagnenís service facility where there is a guy that rents slips and shop space and he was repairing another boat. I wonít mention the brand name but he was pointing out that the reason why it blistered wasnít because the kind of resin they used but because there was air left in the laminate all over the inside surface and thatís just bad workmanship.
Then the other reason for blistering is the inferior resins most builders use. Some resins tend to be permeated more by water vapor than others. The cheapest resin, and itís what most boats are built out of, is orthothalic polyester resin. Isothalic polyester resins perform a little better than that and are less prone to blistering. When you get to the modified epoxy resins you go way down in the amount of water that will go through them and you really stack the cards in your favor, so its highly unlikely that youíll get blisters.
On top of that, we use NPG gelcoat which stands for neopenthalglycol. Itís an additive they started adding to the gel coats that were used in the hot tub industry where they have the works Ė if you want to see blistering, check out the hot tub industry. They have the lowest grade lamination, the cheapest resins and the hottest water. This guyís just a real nightmare. They developed this gel coat for. . . anyhow, they developed this gelcoat for them and we started using them and its also a nicer gelcoat because it has better gloss retention and resistance to ozone attack. So between using better materials and better workmanship, youíre reasonably ensured of being free of large amounts of blistering.
About the only osmotic blistering we have had sometimes is a couple of boats have gotten a fine rash right around the keel, the lead to stubby joint because we try to do a really nice job of fairing in that joint, we spray gelcoat on it afterwards and a spray gelcoat that you spray for repair has solvents in it in order for it to be sprayed, sometimes itís a little more porous so we have had I think about four or five Expresses get a fine rash about three inches wide just around the seams by the keel. This is not structural at all and usually goes away with just light wet sanding. I donít know of anybody from this fleet thatís ever had that problem.
Just a little Ė itís probably just a band about 2-3 inches wide, about six inches down from the boat. Right. From the hull, and just usually wet sand it and it goes away and doesnít return. If for some reason it ever should return, we can try and re-spray it. Thereís no guarantees it wonít come back. Itís the problem of what we call gel repair spray gelcoat as opposed to in-the-mold gelcoat because it has to be thinly sprayed.
Do you recommend an epoxy barrier coat below the waterline?
I donít think its necessary because itís Ė I mean, Iíve built now 200 hulls, never had a single hull blister over almost seven years in August. And, weíve had about, like I say, a handfull of boats literally that have had a very minor and fine rash right around a cosmetic joint that we repaired on the keel joint that Ė most people, they wouldnít even repair the seam, theyíd just leave a big caulk seam where the lead joins to the boat. At least we try and fair it in and usually a little bit of light wet sanding will take the blisters away anyhow. But, itís by no means structural. Itís not even in the boat, itís on the lead part of the keel basically where weíve attached it.
This is just like a little slide show about how we built the original 27. Thatís the shop when we first moved in and a lot of people were behind us and if youíve ever seen a boat being built from scratch, thatís a strongback with what we call stations set up on it.
The first boat, by the way, was a real boat. We actually Ė we didnít build a plug, we built a real prototype to test out the concept. We wanted to make sure the keel was in the right place, the rig was in the right place and so forth in case we had to modify the design before we actually molded. Iíll talk a little bit more about how un-needed that concept was. There are the (Inaudible) and sheer clamps, kind of traditional on a wood boat (inaudible portion), itís cold molded, fairly exotic the way itís built. Itís now planked up and weíre getting ready to put the stem on. We just glassed over the third layer of planking and flow coated.
That boatís still sailing isnít it?
Yes. Just heard from the owner the other day and they said everythingís just fine on it. Getting ready to roll it here. We just lifted it off the strong back. Itís always a really nervous time as the boat builder when you roll the boats over.
Here we are feeling kind of proud of ourselves.
Thatís the start of the deck framing. The deckís all planked up now and glassed. They start applying things like the [inaudible] on it. But this deck wasnít plugged, and was not used. We ultimately ended up putting a fiberglass deck on. Thatís the start of the mold. After you get the plug just right, then you spray gel coat on, you build molds just like you build the boats. Basically start with gelcoat and then much later, the fiberglass. Fairly similar to the materials that you build the boats out of. The reason why I changed from black to red is because you spray two layers of gel coat on, one black and then one red for a warning layer when you wet sand on the molds to burn it through when you start seeing red show through. And you put a steel framework on it. Then youíve got a mold. Weíre getting ready to spray it up now. Thatís all gelcoated. Then we stuck it on top of the wooden hull and the mold next to it. Oh, we call this one hull number zero, our normal numbering system, and it looks kind of rough and dull now because we didnít finish it off first because we knew we were going to have to take all the hardware off in order to make a mold off of it. So we just put it together barely enough so we could sail it to see if the keel was in the right place, and the rig was in the right place, and so forth.
There it is in the water. It floated right on its lines. That was Carl Shoemaker in the cockpit; thatís him holding onto the backstay. Sail makers and designers like to hold onto back stays. We had 17 people on board when this picture was taken. Some of them are down below, some on the foredeck. You want to know how many a 27 will carry-- up to 17. We had life jackets for every one of them in case the Coast Guard asked us. And there it is after we took the mold off and painted it white and put a teak transom Ė itís hard to keep bright boats looking bright so we painted it white for easier manageability but then we wanted to make sure everybody knew it was a wood hull, so we vacuum bagged some teak onto the transom and varnished that up really nice. And as it usually goes, when you take out an insurance policy, you donít need it. It turned out the keel was in just the right place, and the rudder was in just the right place and basically it was a nice exercise, and after that we kind of trusted Carlís calculations and never tooled a prototype first and put it in the water. Itís a very expensive way to tool boats. Itís much easier to build Ė just what we call plug which is a non-sailing pattern for a mold.
How many yearís ago was that done?
That was Ė I went sailing first I think in June of 1981. Weíre going on the sixth season of Express 27. Going on the seventh Ė be six years in June then right? Seventh season coming up. Can we turn the lights on. Any questions before I hand out some visual aids here?
Are they still using the same mold?
Gone through 120 boats?
Yeah, they say molds are good for Ė Iíve heard numbers like 500 parts. It all depends on how you take care of them. They get damaged from time to time, and you have to repair them. Thatís what tends to wear them out. If you stick a part and chip a piece of the mold by popping the part and then you have to work on them a little bit.
People have sometimes wondered about, you know, how do you build a strong boat thatís light and everything. And I brought some samples here that are examples of boats Ė Iím going to hand these around in pairs Ė both cored and uncored laminates of approximately equal weight. And all I want you to do is just try and bend these. This is the way most boats used to be built. Thereís not a lot of single skin boats anymore. But you can bend that and then try and bend this. And then notice how wide or heavy this is. This is Ė both of these are from the Express 37 deck. Thatís the uncored portion by the hatch where all that is removed is the core and thatís Ė yes, you can break that. (Much laughter.) You get a feel for how much is added when you start coring boats.
A lot of you people probably havenít seen all the materials that were used in the boats. I get asked these questions. What does a balsa core look like? Hereís some things in envelopes so you wonít get all itchy from it. Thereís some balsa core. Your boats are built out of both balsa core and KlegecelóI mean the hulls are Klegecel, the decks are balsa. Thereís a panel right around the keel for balsa also. Some boats are not cored with balsa. They are cored with this material instead. Itís a cheaper material. We only use it in a couple areas in the boat. We use it along the cabin sides of the 27 where the windows are to thicken it up so we can bolt screws through Ė itís called corermat, and we use it also in parts of the pan of the 37. We just want to add a little bit of stiffness to the short panels. But this whole [Ďbrand xĒ] boat is built both out of that Ė not a particularly good way to build boats. Itís a very heavy way to add core to a boat. Basically, itís like a felt that soaks up resin and adds thickness to the hull. Quite an expensive way . . .
Does the coremat completely soak up the resin?
Yes, it kind of just bulks up, it gets fluffy and gooey with resin.
Yes, Merit 25 are done with the core mat, Olson 25 are done with core mat, thatís all the boats I can think of. And a lot of people Ė itís a cheap and easy way to build a boat but I donít consider it real elegant. This is mat . Mat comes in different thicknesses Ė the thinnest you can buy is ĺ ounce mat and your boat has three layers of that in it Ė not much.
This is what we use on bulkheads. This one comes in long strips-- taping c) material, itís got uni-directional on one side and mat on the other side. And the matís there because that [inaudible--adhesion?] and that is one of the things that mat is good for.
This is what your deck is made out of. This is called cloth, and itís an aircraft cloth. And most boats use cloth or roving for most of their laminate in and alternating layers. We use very little mat. Almost all of these two materials. Two different kinds of uni-directionals. This is called S-glass. If you ever hear about S-glass, thatís what that stuff looks like. And thatís a pure uni-directionalóit runs entirely in one direction.
Right. Very expensive. Itís about ten times the price of regular glass. So we donít use a lot of it. We use it under winches and Ė mostly under winches and some areas of the keel, to add stiffness to the high load areas. Itís real nice stuff to work with.
Yes. This is the stuff that we use primarily to build the boats out of. This is called Cofab and itís a knitted uni-directional which means it has a 9 ounce uni-directional knitted to another 9 ounce uni-directional and allows you to put down 18 ounces of uni-directional in one shot and handles almost like a woven material but itís not a woven material, itís a knitted material. Like some of these more exotic sail cloths you see that have fibers without crimps, just glued to other layers, and thatís what your hulls are made out of. Thatís an E-glass. I donít think you guys could afford to buy boats built with S-glass. That would probably bump the price from $5,000 to $10,000.
From audience--What are the problems with balsa core hulls?
Alsberg--What are the problems with balsa?
From audience--Well, youíre obviously giving up Ė youíre gaining stiffness and you open yourself up for water entry if youíre not sealing properly.
Alsberg--That gets talked about a lot. Itís funny how much that gets talked about and how little of it Iím actually aware of. Lloydís approves balsa core. Theyíre a pretty stringent company. Theyíre a pretty stringent company Ö
Below the waterline?
Oh, absolutely. Yes, itís absolutely approved. And thereís no problem with it below the waterline and Iím not aware of any boats in Santa Cruz that have ever had water-logged core which is not to say that some boats donít have water logged core. The idea is, ďHow does the water get into the core?Ē Well, itís either because thereís some flaw in one of the two skins Ė you can see these sandwiches and how theyíre put together. Thereís virtually no paths through the skins to get into the core.
Or water can enter at a through-hull fitting. If the through-hull was improperly installed you could allow water into the hull, but when you cut a hole in the bottom of your boat, and youíve got a cored boat, youíre supposed to carefully seal the core around the hole. And some boat commissioners may not do that--people doing commissioning work on your boat, installers. But if thatís done right, thereís no place for water to get in there. The skins themselves are water tight and the core is hermetically sealed. Also, balsa Ė youíll notice the way the grain goes in that, itís whatís called end-grain, and water does not tend to migrate across the grain of wood. Thatís why barrels work. And, theyíve done studies where theyíve drilled holes in a panel like that, stuck it into water with a dye in it so they can see how far the dye goes into the grain and left it in water for years, put them in pressure vessels and built the pressure up and drive the water across the grain and usually the water migrates about 1/8 to ľ inch maximum after a few years, across grain. Very little migration across grain.
About the only way that water could get in, and I brought along a cane pole -- this is Ė Iíve only thrown away one hull in my life and this is a piece of it. Itís an expensive thing to throw away a hull. But this one didnít have a perfectly bonded core so we bit the bullet and threw it away. I took a piece of it because I thought I could look at it sometime and gain some lessons from it. But in answer to your question Ė here, Iíll pass this around to the other people Ė you can see that itís got a void there. And if water would get here, it could migrate back a ways in a void like that. But in a laminate like this Ė this is the way hull stretches are built, theyíre essentially close to perfect laminates.
How did the void happen?
Why did this happen? It was a slow vacuum bag is what happened. When we vacuum bag Ė all you people understand what vacuum bagging is? Letís talk about it a little bit. Would you like an explanation? Whoís got the bag thatís got the balsa in it or the Klegecel?
This is how a vacuum bag works. Basically. Iíll explain a little bit further but this is a quick demonstration. You can see how when I suck on it, the bag collapsed and pressed on the wood here. Can you hand me that piece of the boat there? This is the actual piece of the real boat that we actually really threw away. This is the outer skin of the boat. After you get the outer skin laminated, you take a material called vacuum bag tape and you run it along the gunwaleĖ this is the gunwale of the boat, and it goes all the way around the perimeter of the boat and you take a Visqueen bag which is material not unlike what that bag is made out of only Visqueen 4 mils thick, and itís cut so it easily fits over the whole surface of the boat with a little extra material in it so itís nice and loose so it can have wrinkles in it. In fact, you want wrinkles in it. And when you pump the air out of the bag, pressure is exerted evenly over the entire laminate. This ensures a complete and uniform bond between the core and skins of the hull.
TAPE ENDED (Side B)