How to Reinforce a Boat for Flybridge Installation

\While most boats can bear an intermittent visitor on the cabin's overhead, a flybridge invites company. The extra stress means you need to "sister" the overhead's supports. This means you will double the support for the overhead by bolting stringers -- the sisters -- to the existing stringers, to double their mass and supporting capability. One you've sistered the supporting stringers to reinforce the boat's overhead for the new installation, visitors to the flybridge won't be a problem.

Things You'll Need

  • Measuring tape
  • Circular saw
  • Screws
  • Screwdriver
  • 1/4-inch marine plywood
  • Drill
  • Stove bolts and nuts
  • Washers
  • 2 adjustable wrenches
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Instructions

    • 1

      Measure the length, width and depth of each horizontal support that holds the overhead of the area upon which you wish to locate the flybridge, using a measuring tape.

    • 2

      Transfer these measurements to lumber of the appropriate dimensions. Cut the lumber, using a circular saw.

    • 3

      Cut two pieces of 1/4-inch thick marine plywood to serve as gussets for each stringer, each 1/4 as long as each of the new stringers, and as wide as the stringers.

    • 4

      Hold a new stringer immediately adjacent to an old stringer. Hold one gusset alongside the new stringer. Drive screws through the gusset and new stringer, and into the old stringer, using a screwdriver. Drive screws through a gusset and into the old stringer, to secure the gusset in place, opposite the gusset on the new stringer.

    • 5

      Drill a hole through the gusset, the old stringer, the new stringer and the gusset on the other side. Slide a stove bolt through a washer, then push it through one of the holes through the gussets and stringers. Add a second washer on the threaded, protruding end of the bolt and spin a nut onto the bolt. Tighten the nut and bolt with two opposing adjustable wrenches, until you hear the first creak from the wood. Repeat the process until all stringers in the cabin overhead have been sistered.