Fiberglass Boat Inspection

Is Your Hull Waterlogged By Osmosis?

What Is Osmosis?

Water seeps into your boat's hull (often through tiny stress fractures associated with the various fittings and fastenings attached to the hull and deck) and travels via capillary-like action along layers of the fiberglass and resin laminated structure (or fiberglass and balsa wood sandwich) to accumulate in trapped pockets.

Prolonged osmosis, if undetected and untreated, can seriously shorten the lifetime of your valuable boat, and reduce its resale value. For racing craft especially, the additional hull weight due to absorbed water could be disastrous.

Gel Coat Blistering

Chemical reactions take place between water absorbed by osmosis, and water soluble molecules in fiberglass-composite hull structures. This causes surface blistering of the gel coat. The blisters are usually below the waterline and will swell and contract due to temperature changes. If unchecked the bubbles will enlarge and hull deterioration will escalate as blisters open and admit even more water.

Osmosis + Blistering = Hull Delamination

Protect Your Investment With An Electrophysics Meter

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The CT33 is our most popular model for fiberglass.
To learn more about this meter in marine use visit the web site of the renowned sailor "R.C."

Our other models designed for fiberglass are shown below.

Model GRP200 Digital Meter
Direct Reading Of Fiberglass (GRP) % Moisture Content


More Information: GRP200 & Optional Remote Sensor
Available from J. R. Overseas Co. or Electrophysics

NEW: The Dolphin
With Audio Moisture Level Indication
And Fiberglass % Conversion Chart


Available from Rayplex

Electrophysics continues to manufacture the popular GRP33 with analog display

The Model GRP33 is available exclusively from:
J. R. Overseas Co.

Electrophysics Moisture Meters Warping Nightmares Building Inspection
Fiberglass Boats Dual-Mode Meter Pinless Remote Pin-Type Meters
Pinless Meters Ordering Information Request Catalog Send email