Saber Marine Construction - For the Ride of Your Life
A fiberglass laminate is a combination of fiberglass strands which provide most of the strength, and a resin which bonds the glass strands together and transfers the load between the strands. A fiberglass laminate is similar to a reinforced concrete section where the resin is the cement and the fiberglass strands are like the steel reinforcing rods. One hundred percent hand layup is used. Hand layup gives a uniform thickness of glass and allows stronger reinforcing layers to be used. It also maximizes the percentage of glass verses resin in the laminate. The more glass, the stronger the laminate. The optimum is 50% fiberglass and 50% resin. Chopper gun boats are similar to all mat construction which is only 25% fiberglass and 75% resin. It must be thicker and heavier to be as strong, performance suffers as a result.
Saber Marine uses bi-axial knitted cloth instead of woven roving reinforcement, this lays flat without weave crimps so it is structurally stronger. This also allows fewer spaces for "pools" of resin so higher fiberglass (and therefore strength) content per pound of laminate. When laying up, glass fiber strands are oriented in various directions to provide strength in all directions.
Vinylester resin is used instead of Polyester resin or a blend. The resin is the weakest link in the laminate with only one tenth or less the strength of the glass strands. Once the resin fails it can no longer support the glass fibers which then also fail.
Glass fibers can stretch four to five percent in developing their full strength before they fail. Standard Polyester marine resin stretches only about two percent before it fails. Only a portion of the potential strength of the glass fiber is used before the resin fails and the laminate along with it. A Vinylester resin will elongate or stretch four to five percent before it fails, which more closely matches the fiberglass properties. The vinylester resin can flex more before it fails allowing the fiberglass strands to do the work. As a result, the vinylester resin is tougher, more impact resistant, and has more fatigue strength than standard resins.
Why don't all boat builders use Vinylester? The main reason is cost. It is twice as expensive as Polyester resin. It is also harder to work with than standard resins. It is questionable whether a standard cruising boat is stressed enough to warrant Vinylester. In an offshore hull, the properties of Vinylester resin, its toughness and impact strength, make it a better choice than the more brittle Polyester resin. Saber Marine feels that the expense is justified by the superior hull that is the result. Our five year pleasure hull warranty backs this up. Another benefit of Vinylester is that it is more resistant to blistering than standard marine resins.
Balsa core is used throughout the boat, in the hull bottom, sides and deck. End grain balsa core with a fiberglass skin on each side gives a stiff, strong, yet light weight laminate, this I-beam principle gives it strength. Balsa core will not rot because water cannot travel across the end grain. Balsa core is superior to foams in impact strength, compression strength and shear strength.
Top grade plywood stringers run full length providing continuous longitudinal strength. Bulkheads segment large panels into small stiff ones, this prevents hull flex, change in running shape and resulting failure.
The hull-deck joint on all Saber Marine powerboats are securely fastened together. First the hull and deck are fiberglassed together, including the bulkheads to the deck unitizing the complete structure. A waterproof marine adhesive compound is then used to seal and glue the joint. The hull and deck is then through bolted every six inches with a stainless steel bolt and a nyloc nut when the rubrail is installed. (The Saber 24 hull and deck is joined with bolts and sealed with adhesive.) This bond is waterproof and ultra strong.