UNIFUSED™ CONSTRUCTION ...
Seattle Yachts employs Unifused™ fully-stacked resin-infused laminate in both its Northwest and Alaskan lines to optimize strength-to-weight ratios in all major parts. This process involves fully dry-assembling the “stack” of reinforcing fabric, then sealing that reinforcing under a layer of air-tight heavy-duty plastic sheeting and using vacuum (negative pressure) to draw catalyzed resin through all of the assembled reinforcing material for a uniform and complete wet-out.
In our hulls, cores are used only above the waterline to maximize structural rigidity per unit laminate weight . Where cores are used above the waterline in primary structural components, all such cores are of the highest quality, high-density fully engineered PVC foam to optimize the attained mix of mechanical properties such as sheer strength, resistance to heat, and impermeability to moisture.
All cores used are of the “scored” variety to facilitate fitting to curved surfaces and to aid in drawing core bonding material up through the core layer under vacuum, thereby assuring a 100% bond of the core to the substrate laminate, completely filling the bonding passages in the cores, and preparing the top surface of the core layer for the application of the interior laminate layers.
Vinyl Ester Resins
Our Northwest and Alaskan hulls, decks, and superstructures are molded using the highest quality vinyl ester gel coat resin for the unreinforced initial exterior protective layers and vinyl ester laminating resins for the first 3 to 4 exterior back-up layers to improve resistance to moisture permeation and yield the best, most durable exterior laminate available in the industry.
We also employ vinyl ester sealing layers on the interiors of its hulls and other major structural parts because moisture intrusion does not always come just from the outside of the vessel.
Well established in various industrial applications, vinyl ester resins are formulated to perform in a variety of applications where increased strength and durability over polyester resins are required. And in most cases, they offer the best mix of physical and applications-related properties as between polyester and straight epoxies.
Our experience is that vinyl ester resins are superior to unsaturated polyester resins for boatbuilding purposes. Chemically, vinyl esters develop a polymer (a giant-molecule plastic) that is formed molecularly with a polyester backbone and epoxy terminations at the ends of its molecules and are based on either bisphenol-A or novolac-type chemistry with methacrylic acid forming the polymer.
Vinyl esters are used extensively to produce corrosion resistant tanks, pipe and other components because they have a higher resistance to corrosive chemicals and environments than unsaturated polyesters. Similarly, vinyl ester resins have proven themselves in boatbuilding where they greatly enhance moisture-resistance in the outer laminate layers of hulls and other critical structural parts. Which is why Seattle Yachts uses them extensively in our construction processes.
Glass Fiber and Other Reinforcing Fabrics
One of the advantages of FRP (fiber reinforced polymer, aka GRP or glass reinforced plastic) is that unlike steel or aluminum, it is not a homogeneous material. The exact mechanical properties of a given FRP laminate depend heavily on the type, amount, placement, and orientation of the reinforcing fibers and the material from which those fibers are made.
By selecting what type of reinforcing to use, how much of it to use, where to put it, and how to orient the fibers, a laminate engineer can optimize the strength-to-weight and the stiffness-to-weight ratios of an FRP structure. And because yachts are mobile structures which require an input of motive power, the better those ratios can be made, the better the yacht will perform — whether you’re judging performance in terms of speed, range, longevity, or durability.
If you like to discuss the construction details of our Northwest and Alaskan yachts or the details of any of the yachts we sell as dealers, call or email us. We’re always happy to talk shop.
Author: Phil Friedman
Seattle Yachts New Build Manager