Thorough keel surveys inspect the condition and integrity of a vessel's keel(s), keel fastenings, and the hull's structural reinforcements by way of the keel (floors, frames, stringers and/or keel matrix).
It is recommended that a keel survey is carried out; prior to offshore and ocean sailing; following offshore and ocean sailing if damage is suspected following an impact with a submerged object (or otherwise) and/or extreme conditions were experienced; and/or as part of routine vessel maintenance.
Typically keel bolts are either constructed of mild steel or stainless steel depending on the age of the vessel. Both materials corrode. Mild steel oxidises (rusts) where oxygen is present, and stainless steel pits where moisture is present but oxygen is not (such as in the through hull keel bolt apertures).
A keel survey will inspect and test the keel and the complete reinforcing and fastening structures and will conclude on the condition of these parts. This is a non-destructive survey. However, as corrosion may be present out of sight, destructive testing will be recommended if considered necessary.
Please call or email to discuss your requirements and discuss any questions you may have.
Structurally, bolt on fins keels are very strong, having a large factor of safety calculated into the design (usually around 17/1). None the less there are several cases of bolt on fin keels failing at sea. There will typically be several influencing factors which lead to full keel failure. Hitting a submerged object is the most likely final cause of failure, however, poor design, cost cutting in the build process, poor seamanship (persistent groundings), poor maintenance, and sub-standard repairs will have likely weakened the structure to varying degrees prior to the incident which causes full failure.
It is considered that there are three typical conditions where fin keeled vessels may be more at risk; high performance race boats with a minimal factor of safety designed / built into the vessel to keep the vessel's weight to a minimum; vessels which have suffered from impacts or groundings previously and have not been inspected or repaired; and vessels with a poor maintenance record/schedule.