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The split mold next to Hull No. 2 under construction.
by Kate Simpson
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08/01/2005
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After Timur Mohamed bought Palmer Johnson Inc. in Sturgeon Bay,
he sold his Savannah River facility – purchased from Intermarine – to Global
Ship Systems (GSS). On contract, GSS produces the 123-foot series hulls and
superstructures, which are barged to PJ’s Wisconsin yard for fitout. In
fabricating these components, GSS utilizes a vacuum infusion process developed
by Intermarine, a composite specialist with a long history of building
state-of-the-art GRP minesweepers for the U.S. Navy.
The latest thing in fiberglass construction, vacuum infusion
uses vacuum pressure to draw the resin through the laminate. GSS’s process
improves upon this in that there is no need for separate resin distribution equipment. Grooves in the core material provide the resin’s flow path through
the outer skin, core and inner skin, and return through the vacuum manifold.
There is no limit on component length, but the vertical
distance between the inlet and vacuum manifolds can’t exceed 12 feet. So the
123-foot mold is actually two pieces divided on the centerline. The halves are
infused, then joined with fiberglass along the keel. Longitudinal frames and
bulkheads are separately infused in place after the primary resin infusion.
Vacuum infusion takes fewer man-hours and uses less resin than
traditional lay-up. Its higher fiber-to-resin ratio means greater strength
relative to weight. There is a better core-to-skins bond since the media is
drawn through the core, rather than the core being applied to a wet laminate.
Results are more consistent and styrene emissions are greatly reduced.
The 123-foot hulls are the largest vacuum-infused hulls in the
industry. Service consultant Leslie Lallande credits GSS’s success to its
experience working with vacuums, which he says is the most difficult part of the process. The experience comes from a skilled work force that has remained
much the same throughout the facility’s turnover in ownership.
 Big Ego
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