The F-22 Raptor Stealth Fighter has over 350 carbon parts.
When the McLaren Company decided to create the most exotic sports car in history they built the first production car to use a carbon-fiber monocoque chassis. The 627hp – F1 LM6.1
Goetz Composites – the early days of carbon fiber
Carbon fiber has its earliest history in the aerospace and military industries. Only recently have we begun to see its more widespread use and application in high performance consumer products and the automotive industries. One of the few exceptions is Yacht Racing at its highest levels where results matter at any cost and Carbon Fiber has been in use for many years.
Goetz built their first boat in 1975, started working with carbon fiber two years later, and built their first full carbon fiber boat in 1984. Jubilation was a 54’ German Frers design built in Kevlar, Carbon Fiber & Plascore honeycomb. Goetz went on to pioneer the business. The process has evolved into a highly engineered and exacting science. Simply put: Goetz delivers the absolute structure possible at a required strength.
In addition to construction and integration, Goetz typically manages a team of engineers, material suppliers and other experts for each project. Throughout the process, Goetz works closely with the client to ensure proper reporting and documentation is submitted.
Prepreg Carbon Advantages
- The ability to design and align the fiber orientation with the direction of principal stress.
- Carbon has excellent fatigue life and is extremely strong and rigid.
- When combined with a core material Carbon Fiber will deliver substantial weight reduction.
- Consistent (minimal) resin content – about 33% for carbon unitapes.
- Greater interlaminar shear strength due to better fiber-to-fiber contact.
- Curing at 100 C [212 F] delivers a very stable part with a very low coefficient of expansion.
- Ability to mold complex shapes and easy to repair.
Prepreg material is the correct (minimum) amount of epoxy resin applied to reinforcing material (ie carbon fiber) via a machine. The resulting fiber/resin medium is then frozen to prevent the epoxy from curing. Pre-preg carbon is precisely applied to the mold surface, with the orientation of the fibers closely managed. The entire structure is then vacuum bagged and brought to an elevated temperature to cure the resin. The whole process is completed in a clean and controlled environment.
The major benefit from the use of prepregs in boat construction are lighter weight and greater strength. Weight is controlled by regulating the amount of resin in the laminate. Each boat is designed with a fixed laminate schedule for the cloth, but the actual resin content in a wetpreg boat is a variable depending on application technique, temperature, and humidity. Using prepreg materials results in a consistent laminate with the correct (minimum) amount of resin already applied. More resin, which is inevitable in a wetpreg or infused boat, simply gives you more weight, not a stronger boat. The strength is in the fibers, resin is simply in the matrix to hold the fiber bundles in alignment. More resin than is necessary to hold the fibers is wasted weight.
At 330 square meters for the hull shell of a 106 foot sailing yacht, and 260 square meters for the deck, this translates into a weight savings of over 840 kilos compared to wetpreg, and 958 kilos compared to infused. The projected weights for the boat ‘off the mold’ are:
Prepreg: 4,277.5 kg (9,410 lbs.)
Wetpreg: 5,118.25 kg (11,260 lbs.)
Infused: 5,236.25kg (11,519 lbs.)
Reducing the resin content of the laminate also actually increases the interlaminar shear properties due to better fiber-to-fiber contact. This shear strength advantage results in greater stiffness of the laminate as well as the total structure of the boat. The shear strength increase is also a safety factor as it rates heavily in impact situations.
Prepreg laminates are less porous than those of wetpreg laminates. This factor results in less moisture pick-up, which can be significant over the life of the boat. Boats that don’t accumulate moisture over their lifetime will weigh less and be faster than their wetpreg counterparts.
An additional benefit to using prepreg is cosmetic; a boat that has been baked at 100 degrees C (212 degrees F) will remain stable in the hot summer sun, where dark painted topsides can reach 150 degrees F. This means that the topsides of a prepreg boat will be smoother and fairer, and require less maintenance than a boat cured at a lower temperature. Prepreg’s only disadvantage is a slightly higher material and labor application cost, resulting in a price premium of about 15% compared to wetpreg.
Weight control is critical to the success of every Goetz structure. As a result, everything is weighed and recorded. No exceptions.
Racing yachts are often constructed with composite skins of carbon fiber, glass or Kevlar laminated around a honeycomb, foam or balsa core. Cruising yachts can be built with similar materials, or less exotic materials can be selected to achieve appreciable cost savings. Regardless of the materials chosen, Goetz always makes use of its high tech building techniques to maximize strength, speed and overall quality.
Carbon Cruising Yachts
If you want to get there quickly, the same advantages prepreg carbon bring to racing yachts apply to cruising yachts.
- Light boats are easier to handle because of reduced loads, and therefore safer.
- A Prepreg carbon boat is strong and safe in the event of a collision.
- Light yachts are environmentally friendly, reducing fuel consumption and increasing range.