Workers roll epoxy on the hull while others staple pre-coated laminate strips. The application of epoxy both to the hull and to the laminate strips ensures an adequate glue line. The Sheepscot meter/mix equipment is also used to replenish adhesive trays being used by the workers. Note the overlapping diagonal pattern of the laminate strips, which provides an extremely strong matrix and hull rigidity.
The benefits of epoxy have long been known throughout the boat-building industry, particularly with regard to medium- and large-sized hulls. A company that has incorporated and embraced these benefits is Hodgdon Yachts, located in East Boothbay, Maine. It is one of the oldest yards in the country (1816) and a world-class builder of large luxury yachts. Tim Hodgdon, owner of the company and the fifth generation of his family to carry on the name, is currently engaged in the construction of the Bruce King-designed 154’7” ketch Scheherazade.

Having taken over the business from his father “Sonny,” where the time-honored method of fastening planks on frames was still being practiced, Hodgdon knew that to compete in an increasingly high-tech market, it would be critical to research and implement the latest technologies and processes into the design and construction of his yachts. That research led to the use of cold molding, a process that uses epoxy to bond a successive series of thin wood laminates to a wood frame, providing an extremely strong and stable hull.

Workers prepare the hull for vacuum bagging after completion of a large laminate section.
After the first layer of planking has been fastened to the frames using traditional methods, which also serves as the finished interior, wood laminate strips are coated with epoxy and stapled in place over the planks. Successive layers of laminates ultimately yield a hull thickness that can approach 3-1⁄2" or more depending on the size of the hull.

Following the application of each laminate series, the strips are further held in place to achieve full bond strength by using a unique but simple method known as vacuum bagging in which large sheets of plastic bubble wrap are laid over the wood and sealed around the perimeter. A vacuum pump is connected to the plastic “tent” and the resident air removed, yielding an even clamping force over the entire surface.

Hull sitting upright in a custom-built steel carriage, upon which it will sit until launching. Note that the lead keel has been attached to the hull, bringing the combined weight up to 265,000 lb.
Having already built two large yachts using this process, Hodgdon was aware of the importance not only of being able to mix large quantities of epoxy in a timely fashion, but also being able to maintain the mix ratio during the entire planking process to ensure optimal bonding. On previous boats, the standard practice was to hand-mix about five gallons of epoxy at a time, then pour it into paint trays so that workers could roll the adhesive onto the wood strips. The drawbacks included difficulty maintaining proper mix ratio, loss of working time from mix to application, as well as excessive handling, waste and mess. The primary concerns were that improper mix ratio could cause loss of critical bonding properties and potential delamination issues, which, although fixable, would necessitate extensive additional man-hours and cost.

For these reasons, Hodgdon turned to Sheepscot Machine Works, a manufacturer of meter/mix and dispense systems, to provide a solution to these issues. Todd Williams, sales manager for Sheepscot and also a neighbor and friend, consulted with Hodgdon on the best type and size of equipment, as well as the optimal configuration for use in a boatyard environment. They chose the Model 9450 Double Acting System, which would provide continuous fluid output, a critical feature for satisfying the large-output demand. With pneumatic supply pumps and using a low-viscosity epoxy supplied by Gougeon Brothers of Bay City, Mich., Sheepscot determined that the Model 9450 could deliver upwards of one gallon per minute of mixed material, more than adequate to keep up with production demands. A cart-mounted configuration with casters was chosen to provide maximum mobility, allowing the meter/mix and its associated drum feed to be moved throughout the building, depending on where the planking was taking place, or to be moved between the two buildings that were being used for various gluing tasks.

Cart-mounted Model 9450 Double Acting Meter/Mix System.
Although the 9450 meter/mix system was chosen primarily for its ability to optimize the cold-molding process, the staff at Hodgdon’s began looking for other uses for the equipment once it understood the advantages and usability provided by the system. So far, this has included miscellaneous gluing projects on interior components.

Now that the hull has been molded and turned upright, work will start on a multitude of other projects, including epoxy saturation of carbon fiber sheets used in the fabrication of deck tops and interior partitions. Wherever medium to large quantities of adhesive are called for, the 9450 system will be put to use.

Launch date for the Scheherazade is 2003.

For more information on Hodgdon Yachts and Scheherazade, visit the Web site

For more information on Sheepscot Machine Works, call Todd Williams at 207-563-2299 or visit the Web site Or Circle No. 202.

Additional information on the ProSet series of low-viscosity epoxies is available from Gougeon Brothers, PO Box 908, Bay City, MI 48707-0908; call 989-684-7286; fax 989-684-1287; e-mail; or visit the Web site Or Circle No. 203