Raymarine Transducers - Installation in a Cored Fiberglass Hull

Chapter 2: Installation 29
Installation in a Cored Fiberglass Hull
The core (wood or foam) must be cut and sealed carefully. The core
mustbeprotectedfromwaterseepageandthehull mustbereinforced
topreventitfromcrushingunderthehullnut,allowingthehousingto
become loose.
WARNING:
Alwayswear safety goggles and a dustmask whendrilling.
1. Drilla 1/8" (3 mm) pilot hole perpendicular to the waterline from
inside the hull. If there is a rib or strut near the selected mounting
location, drill from the outside (see Figure 2-10 ). If the hole is
drilled in the wrong location, drill a secondhole in a better loca-
tion.Apply masking tape to the outside of thehull over theincor-
rect hole and fill it with epoxy.
2. Usinga 2" (51 mm) hole saw, cut a hole from outside the hull
through the outer skin only.
3. Usingthe23/8"(60mm)holesaw,cutthroughtheinnerskinand
mostof thecore from inside the hull. The core material can be
very soft. Apply only lightpressure to the hole saw aftercutting
through the inner skin to avoid accidentally cutting the outer skin
Note: The optimal interior hole diameter is affected by the hull’s
thickness and deadrise angle. It must be large enough in diameter to
allow the core to be completely sealed.
4. Removethe plug of core material so the inside of theouter skin
and inner core of the hull is fully exposed. Clean and/or sand the
inner skin, core, and the outer skin around the hole.
CAUTION:
Completelyseal the hull to preventwaterseepageinto thecore.
5. Coat a hollow or solid cylinder of the correct diameter with wax
andtapeitinplace.Fillthegapbetweenthecylinderandhullwith
casting epoxy. After the epoxy has set, remove the cylinder (see
Figure 2-11 ).