When to Test Visually

• After any grounding (even soft sand or mud can cause damage)
• Every 24 months for Category 1–3 racing yachts (per Special Regulation 3.02.4)
• During annual lift-outs or haul-outs.
• If you notice unusual movement, creaking, or water ingress near the keel
• as dictated by the production maintenance schedule or the insurance industry requirements.

The main areas of a keel we need to visually test include;

Keel to Hull interface

• Check for: Cracks, movement, sealant failure, moisture ingress
• Why it matters: This joint is the most common failure point. Even minor flexing can indicate compromised integrity.
• Test: Tip swing or deflection test—observe for any opening/closing of cracks while applying sideways force

Keel Bolts

• Check for: Corrosion, torque loss, ovalled bolt holes, crevice corrosion (especially in stainless steel)
• Why it matters: Bolts secure the keel to the hull; failure here can be catastrophic.
• Test: Torque bolts to manufacturer specs; inspect nuts and backing plates for rust or deformation

Internal Hull re (Keel Floor & Sump Area)

1. Check for: Cracking, delamination, tabbing separation, stress marks
2. Why it matters: Internal damage may not be visible externally but can compromise load-bearing capacity.
3. Visual and tactile inspection, especially around the keel floors and sump.

External Hull around the Keel

• Check for: Stress cracks, deformation, signs of grounding impact
• Why it matters: External signs often precede internal failures.
• Test: Visual inspection during lift-out; look closely at leading/trailing edges of the keel

Backing plates and Laminates

• Check for: Rust, swelling, separation from hull
• Why it matters: These distribute keel loads; failure here weakens the entire structure.
• Test: Internal inspection, especially in bilge areas prone to moisture

When to consider NDT

If you own a boat or a considering purchasing a boat, NDT testing would be highly advisable for boats that have done a lot of sea miles and have a hollow fabricated keel. see Further Reading

The main areas of a keel we need to test include;

Weld Integrity, Fatigue and Stress Cracking

Techniques like ultrasonic testing (UT) can detect cracks or voids in welds that hold the keel structure together.

Bolt and Fastener Condition

Eddy current testing or radiography (X-ray) can assess corrosion or fatigue in bolts securing the keel to the hull.

Composite Material Delamination

Thermography and acoustic emission testing can reveal delamination or voids in composite keels or hull interfaces.

Corrosion Detection

Magnetic particle inspection (MPI) and dye penetrant testing (DPT) are effective for surface and near-surface crack detection in ferrous materials.

Further Information – Checks for Fatigue

Further Reading

Checks to Stay Upright – Australian Sailing

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