Concrete Hull Repairs
The reinforced concrete hull is the most common flotation system in use by most houseboats in the San Francisco Bay Area. Concrete hulls offer numerous advantages over the other options, such as Styrofoam, fiberglass over plywood, and steel. Concrete is strong and generally cost-effective, and yet some problems are generally inherent with concrete flotation systems. Minor cracks are normal in any concrete structure. Also, concrete is slightly porous. When the concrete structure happens to be in near constant contact with corrosive seawater, some deterioration can begin to occur.
Embedded within the concrete are steel reinforcing bars. When exposed to seawater, the iron in steel is converted into iron oxide or rust. The problem with this chemical conversion is size. Iron oxide takes up more space than iron. This can lead to a widening of the initial crack or fault which caused the rusting to begin in the first place. These larger cracks can then expose additional lengths of steel to the corrosive seawater. Eventually, this damage can manifest itself as large cracks, cracks with rust stains, damp areas, or leaks. Curiously, damp areas and leaks can often dry out and then later reappear in a cycle which is not related to rainstorms.
There are two ways to address the problem of concrete cracks and leaks. One repair protocol is appropriate only for the interior surfaces, and the other is best for exterior surfaces. These two treatments are both very different. The interior treatment of choice for concrete is Xypex™. The best choice for exterior repairs is Marine Grade underwater epoxy. Utilization of both protocols is frequently required, but either can be helpful. What is important is choosing the appropriate repair protocol for damage encountered.