Vancouver Island Marine Surveying Blog

  The condition of a vessel’s underwater profile is a primary indicator of its overall maintenance history. A "fouled" bottom is more than an eyesore; it increases hydrodynamic drag, compromises fuel efficiency, and can lead to engine overheating by obstructing raw water intakes. When choosing a bottom coating, owners must navigate the technical trade-offs between Ablative and Non-Ablative (Hard) paints. Selecting the wrong product for your operational profile can lead to premature coating failure or a costly "strip-to-gelcoat" restoration down the road. I. Comparative Analysis: Ablative vs. Non-Ablative Coatings The choice between these two systems depends entirely on how—and where—the vessel is used. 1. Ablative (Self-Polishing) Coatings Ablative paints are designed to wear away over time. As the vessel moves through the water, the outer layer of the coating "erodes," constantly exposing fresh biocides. Best Suited For: Coastal cruisers, seasonal boat...

  A common point of inquiry during marine surveys involves the presence of surface discoloration on bronze components—specifically the transition from a bright metallic finish to a blue-green hue. It is critical for vessel operators to differentiate between stable passivating films and active corrosive processes such as de-zincification. While the "pink" hue of de-zincification indicates structural compromise, the presence of a green patina is often a sign of a healthy, self-protecting alloy. The Role of Cupric Carbonate (Verdigris) In high-quality marine bronzes, exposure to a saline environment initiates a controlled oxidation process. This results in the formation of cupric carbonate , the characteristic green film often seen on thru-hulls and fasteners. Unlike de-zincification, which is a subtractive and destructive process, this patina is additive and protective . Once a uniform layer is established, it acts as a microscopic barrier that stabilizes the metal, significa...

  I was recently doing a sea trial and saw a lonely mast sticking out of the water.  This is a sobering reminder to inspect your underwater fittings as you get ready for the start of the busy cruising season. In marine surveying and naval architecture, the hose clamp is a critical mechanical fastener responsible for maintaining the water-tight integrity of the vessel. Failure of these components—particularly in raw water cooling, exhaust systems, or below-waterline penetrations—represents a primary cause of preventable emergencies. Inspection  An inspection goes beyond a visual check for "tightness" - look for the following:  Crevice Corrosion: Frequently occurring in 300-series stainless steel when deprived of oxygen (common in shielded or submerged areas), this manifests as dark pitting or a dull red oxide. Any sign of "bleeding" or staining requires immediate replacement. Mechanical Deformation: Inspect the "housing-to-band" interface. If the housing ...