23
Shoot-Thru-Hull Preparation
Hulls With Floatation Materials
The transducer installation inside a fiberglass hull must be in an area
that does not have air bubbles in the resin or separated fiberglass lay-
ers. The sonar signal must pass through solid fiberglass. A successful
transducer installation can be made on hulls with flotation materials
(such as plywood, balsa wood or foam) between layers of fiberglass if
the material is removed from the chosen area. See the figure below.
WARNING:
Do not remove any material from your inner hull unless
you know the hull's composition. Careless grinding or
cutting on your hull can result in damage that could sink
your boat. Contact your boat dealer or manufacturer to
confirm your hull specifications.
Epoxy the transducer to a solid portion of the hull.
For example, some (but not all) manufacturers use a layer of fiberglass,
then a core of balsa wood, finishing with an outer layer of fiberglass.
Removing the inner layer of fiberglass and the balsa wood core exposes
the outer layer of fiberglass. The transducer can then be epoxied di-
rectly to the outer layer of fiberglass. After the epoxy cures for 24
hours, fill the remaining space with polyester resin. When the job is
finished, the hull is watertight and structurally sound. Remember, the
sonar signal must pass through
solid
fiberglass. Any air bubbles in the
fiberglass or the epoxy will reduce or eliminate the sonar signals.
Fill with polyester resin
Inner hull
Epoxy to hull first
Outer hull
Flotation material
Fill with resin
