MULTIHULLS QUARTERLY INTERVIEW WITH THE BALANCE SOUTH AFRICA TEAM
Multihull Quarterly Publisher George Day discusses the launch of a new Balance 486 and 526 with industry veteran and co-desinger Phillip Berman, co-designer Anton du Toit, and chief builder Jonathan Paarman and Phil Harvey, formerly with Gunboat, who consults with the Balance Catamarans build team.
George Day: Phil, You’ve assembled an impressive build and design team at Balance Catamarans. It’s a pleasure to discuss modern catamaran fabrication techniques with your team. Let me start by asking why you chose to build your new 486 and 526 catamarans in E-glass rather than carbon fiber? Carbon fiber seems to be the rage these days in the performance cat market.
Phil Berman: It’s not that we are not using carbon fiber, or do not think it is a great building material. We use it extensively in the high load areas of our hulls and under bridge. The reasons are mostly economics. We just do not feel we gain enough with an all carbon fiber boat to justify the higher price. Just not enough benefits for the money spent, that’s all. It is to my mind wiser to get your speed from length and hull fineness than from stiffness or marginal but very costly weight savings.
Phillip Harvey: I agree with Phil here entirely. You put two things together, best value and best performance. There is no question the best value is E-glass with carbon, carbon stringers and reinforcements. If you were going for absolute best performance carbon is for sure a winner because it is stiffer than e-glass, and stiffness adds to speed. It is a question of how much more you get for the extra expense. The best value for a new performance cat build is currently e-glass as the general laminate with your structural areas out of carbon and epoxy.
Anton du Toit: Many people wrongly believe speed is all about weight in catamarans, but it has more to do with the hull fineness ratio where a moderate displacement vessel with all the other parameters optimized carefully will perform very easily above par. If you walk up to a 45 foot cat with 6 foot wide hulls I can assure you you’ll not be sailing very fast. So, if you want more performance, and you want it at a lower cost, you simply design longer narrower hulls to carry the interior comfort you wish to achieve with the payloads you plan to carry. Of course, the advantage of building a light catamaran is that you can keep your hulls narrower at any length as you do not need to displace as much build weight. Narrow is faster, always. It is a question of where the line best crosses value with performance. Obviously an all carbon boat can be a tad lighter, we can engineer them to be quite light for non-production racing yachts for sure. If money is no object, sure, why not.
GD: How much do you save by using E-glass over carbon?
PH: Today the gap is certainly narrowing, carbon is becoming cheaper. But the pricing fluctuates a lot.
JP: I think the big misnomer about carbon is that it is so much lighter than E-glass; that you can make the boat so much lighter.
PH: Agreed. The advantage of carbon is less the weight savings than the stiffness it provides. What a lot of people do not understand is that to comply with ABS regulations you still need to add e-glass to carbon structures to thicken them to meet a minimum hull thickness. The reality is that a carbon boat could be thinner, and lighter, as many racing boats are, but production boats have to build it up with e-glass – they have to be bulked up to meet skin thickness regulations.
GD: Is an all carbon boat that meets regulations infinitely lighter than an e-glass/epoxy boat?
Anton: No, not much really. I would say on the order of 15 to 20 percent, but it definitely is stiffer but this comes at a cost, of course. A well-engineered and built E-glass and epoxy boat is a good compromise after looking at all the other factors.
PH: Agreed. Not infinitely lighter because, as I’ve said, you have to bulk it up on a production basis. There are different rule sets for custom producers, mostly builders of high end racing boats. But a production builder has to meet CE certification. If they do not adhere to the rules they would not meet compliance. More than likely you will always have some e-glass in the laminate on a production carbon cat of any kind. So carbon fiber can be a bit of a waste in this respect.
JP: I am always asking myself, as a builder, how can I build the lightest, strongest and stiffest hull for the best value? I have always been a value-oriented person, and I figure if you can lower the price of a build significantly and still have a fantastically strong and light hull, it makes no sense to do everything in carbon. But I do get that there are people who have all the money in the world to spend and value is not driving their decision making. For them, I guess, an all carbon boat has sex appeal. It’s obviously very good for a certain type of marketing. Where one should not compromise is in using closed cell foam coring, carbon stringers, reinforcements, and either vinyl ester or epoxy resins.
GD: What about bulkheads? What do you suggest?
JP: Well, marine plywood bulkheads are not high on my list. I cannot understand why anyone still uses it for a modern catamaran. At Balance, we’ve elected to use foam cored, carbon stringer bulkheads. It is a load area where you get great benefits from the carbon.
PH: Agreed 100 percent. On a cat you have very high torsional loads, so it is ideal to use carbon on the main, primary bulkheads and e-glass on lesser structural bulkheads.
PB: You know, I myself have always loved wooden cats, cold molded cats, or West System builds, because a solid wood core is actually quite stiff and pretty light. The problem is that such boats are so labor intensive to produce. They are better suited to one off production, and for people with a lot of time on their hands. I’ve also learned that they are often hard to sell, that many buyers have an issue with a wood epoxy boat.
GD: Are there negatives of wooden cats? Of carbon cats? Are they stiff? Good and Bad?
ADT: Well built cold molded wood cats can be really strong, stiff and light. The problem with them is that they have to be built just so. They have to be saturated with epoxy and fabrication of structural details needs care and fittings need to be bedded carefully so as to prevent rot. Most home built boats come out sub-standard I am afraid, not to mention resale value and demand, which is not high either. The typical lower cost builds are balsa core, mostly polyester resin, marine plywood bulkheads, and a fiberglass modular interior fit-out.
PH: As for carbon, it makes for a great race boat. More rigid, less forgiving. When it breaks, though, it just shatters. When carbon breaks it is a sudden crack, just a mess of a structural failure. Yo have the same issues with all carbon bulkheads. When it goes, the boat breaks in half, no warning, it just explodes. So when you do a carbon boat for the cruising market you really must engineer it carefully and over engineer it. Race boats are right on the limits.
ADT: Yes, right on the limit and as the margins are so fine every structural detail needs to be thoroughly reviewed as any weak links cannot be tolerated.
GD: Why are you using epoxy on your builds in South Africa, and not on your models from China?
PB: The 421 and 451 we build in China are tooled up for faster production, as they are heavily female tooled boats. We build with vinyl-ester resin and gel-coat finishes. It takes us a lot less time to build such a hull. With the South African builds we are fighting very hard to create a stiffer, even higher performance cat, so we elected to build the boats more or less as Jonathan built racing boats, using a post-cured epoxy structure and spray finish. Our female tools are limited to hulls, coach house, and under-bridge.
JP: Yes, the way we are building these boats is very similar to the way most of the early Gunboats in Cape Town were done. Very labor intensive hull builds that lead to a lighter boat all around. What they are doing in China is the lightest possible hull for a female tooled production hull – e-glass, vinyl ester resin, foam core, foam core bulkheads, and gel coat finish.
PB: Gel coat of course ads more weight. It is just a bit easier to maintain and requires less care over time. The reason you see so many racing cats painted in a range of colors is that we can do that easily when we are spraying out the boats . You want red, or green, or blue, it is not a problem.
GD: What about resins? What are the advantages and disadvantages of the various resins being used today in modern catamaran builds?
JP: Well, the largest advantage of polyester resin is that it is cheaper than the others and a bit easier to work with, more forgiving of mistakes. It is simply not impervious to water incursion over time, so you often do find blisters or osmosis issues on a polyester boat. Vinylester resins are more costly and in my view the ideal resin to use in a production cat because vinyl ester, while not totally impervious to water incursion, is darn good. A lot of water pipes are made in vinylester, so that tells you it is a pretty good material. Epoxy is just, in the end, really a lot more costly, but totally impervious to water incursion and leads to a stiff, light, and bullet proof hull. It is much more costly to build with because we have to post-cure the boat and then spray finish her. But it does reduce a lot of weight.
ADT: Epoxy is stronger, tougher, has a higher elongation before breaking and has far superior adhesive properties than the other resins, although more expensive than polyester or vinylester resin these properties make this the resin of choice for building a modern E-glass performance catamaran.
GD: Thank you all for this every informative discussion.
Biographies of participants:
Jonathan Paarman is the Chief of Production at Nexus Yachts, builders of the Balance Catamarans in South Africa. He has been fabricating yachts in South Africa for over 35 years, most recently managing the shop floor for Voyage Yachts in Cape Town. In the 1970’s he was a professional surfer on the ATP pro tour, ranked 13th in the world.
Anton du Toit is a Cape Town based yacht designer who has designed a wide range of sailing yachts and multihulls. He is the designer, with Phillip Berman and Jonathan Paarman, of the Balance 486, 526, and 640.
Phillip Berman is the founder and owner of Balance Catamarans and the owner of The Multihull Company, a global multihull brokerage firm. Phil was the Hobie Cat World Champion for 1979 to 1981. He is the author of several books on catamaran sailing and racing.