Yachts Resources
Craig Marine's
Building Standards and Structural Design
ABYC, ISO Standard, CE Mark of Certification

The ISO (International Organization for Standardization) small craft standards are the emerging worldwide regulations governing the design and construction of vessels both power and sail, of up to 24 meters (79 feet) in length. In order for boats to be sold or imported into Europe, it is currently mandatory that each model obtain CE mark certification. This certification is based on the ISO standards, which cover the entire vessel and its systems. They include the boat's designated type of use, stability and buoyancy, structures, cockpit drainage, visibility from the helm, and the fuel, electrical, steering, and fire protection systems. Onboard equipment, including engines, electrical equipment, pumps, tanks, hoses, hatches, port lights, navigation lights, etc., must also be CE mark certified.

New structural requirements are now in the process of being incorporated, into the ISO standards. These are based on the vessel dimensions; type of use, speed, and structural arrangement, the new standards will require that calculations be performed in order to determine the required scantlings and laminates for the various parts of the boat. All our boats have passed these requirements.

Structural Design

The structure design of most of our powerboats have been designed to exceed the 2003 draft ISO small craft structural requirements for design category A, "ocean". This is the international standard's toughest design category, and is defined as the "category of boats considered suitable for seas of up to 7 meters (23 feet) significant wave height and winds of Beaufort Force 9 (41-47 knots) or less."

The ISO calculations, category "A" were used at the top design speed of 50 knots on most of our powerboats. Design pressures have been calculated for the hull bottom, hull sides, decks, bulkheads, grid, and superstructure.

ISO has specified material standards of the required laminates. These material standards are based on E-glass fabric with polyester resin, which are by far the most common materials used in the boatbuilding industry today. The standards specify, for the type of glass fabrics used in construction and a glass/resin ratio of 50%.

The laminates we use in our construction exceed the ISO material standards, by a considerable margin:

1. All of our boats are entirely built with epoxy resin, NOT the less expensive, polyester resin. Epoxy resin is a superior laminate to polyester for a number of reasons:

Higher mechanical properties- Epoxy resin is stronger than polyester resin.
Improved fatigue characteristics- Epoxy resin is more durable than polyester resin.
Superior resistance to water degradation.
Superior adhesion properties- Epoxy resin is much better at "binding" than polyester resin. This "binding" of the resin to the E-Glass fabric will hold the entire boat together much better!
All Craig Marines boats use E-Glass and Epoxy resin , some may have Carbon fiber and Kevlar incorporated into the materials used

2. Our boats have a higher glass/resin ratio than that specified by the ISO standard. The high-tech construction methods and process controls employed by Craig Marine result in a higher glass/resin ratio. That will significantly exceed the ISO standard of 50%. Our higher the glass/resin ratio will make you stronger the boat.
3. Craig Marine boats are Vacuumed bagged resin infused and oven controlled cured at 120 degrees

The Highest Strength and Lightest Weight Possible

Our laminates and build process exceed ISO standards' toughest requirements.
However, aren't there Builders saying the more weight, the better? Yes, but that claim does not make much sense. The problem with weight, demands for larger engines to get the boat up on a plane, which demand more fuel.
A stronger, high-tech lighter boat provides its owner with significant advantages:
It is more fun to drive, offering higher speed and increased maneuverability with the same horsepower. A smaller engine with less horsepower is required for equal speed, reducing fuel consumption and operating costs.
Lighter weight makes a narrow beam possible (if needed), which in turn makes trailering possible.
Cored construction with high strength skins enables the boat to be dramatically stiffer.
The principal core material employed in the construction of our boats comes from DOW Chemical. We use the highest density of DOW Core in the hull, topsides and bulkheads.

While most other builders use a lower density foam in the topsides and bulkheads.

Rugged where it Needs to be........... and more

Our boats are just overbuilt where it really matters. The hull bottom includes a reinforced cored grid, which incorporates the engine foundations and the hull stiffeners into one single very strong unit. The grid exceeds the ISO structural requirements for this part of the boat; think about that when driving into a seaway at high speed.

For extra protection against possible grounding or impact, we have solid fiberglass keel and chines running from bow to stern.


The structure and laminates of Craig Marine are significantly stronger and more durable than the new ISO structural requirements because of:

Epoxy instead of polyester resin laminates
Over the 50% glass/resin ratio of the minimum ISO Standard
Thicker, structurally stiffer, cored composite hull, deck, and bulkheads.
Overbuilt grid in hull bottom
Solid epoxy glass on bottom centerline and chines for protection against grounding
Vacuumed bagged resin infused and oven cured

Composite-Cored Construction

Exceptionally strong, light, High-Tech Composite Cored Construction utilizing only the highest grade of Epoxy resins along with knitted Bi-axial / Tri-axial E-glass, Kevlar, Carbon Fabrics and DOW Core, then the materials are precisely cut, fitted laid by hand into the mold. The components are then Vacuum Bagged, Resin Infused, and Oven Controlled Cured, this greatly improves the Fiber-to-Resin ratio, ensuring maximum laminate adhesion, and even penetration of the resin.

Vacuum bagging makes possible a lightweight construction without compromising strength and durability.

Our boats are just overbuilt where it really matters. The hull bottom includes a matrix of longitudinal and transverse composite cored stringers to provide maximum stiffness this reinforced grid incorporates the engine foundations and the hull stiffeners into one single very strong unit. For extra protection against possible grounding or impact, we have solid fiberglass keel and chines running from bow to stern. We glass in the stringers, bulkheads, inner liners, all other structural components, and the fuel tanks while the hull is in the mold. This insures that there is no hull distortion.

The Hull and Deck are assembled using Plexus "Fiberglass Fusion" adhesives, which chemically fuses the deck and hull together at a molecular level. This actually creates a bond that is stronger than the fiberglass/resin itself.

The result is a stronger, lighter, faster boat.

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