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The Keel That Could Not Be Inspected: Tyger of London and a Hidden Defect Nobody Could Have Caught

🕑 5 min read words Safety • Incident • Vessel-design

Vessel: Tyger of London, Comar Comet 45S sailing yacht, privately operated
Date & location: 7 December 2017, approximately 1nm south of Punta Rasca, Tenerife, Spain
Outcome: Keel failure and capsize — the shallow-draught lead keel separated from the hull; no injuries, all crew wearing lifejackets and rescued by a passing vessel
Human factors: Normalisation · Complacency
Source: MAIB Report 13/2019

0 injuries4 crew rescued, all wearing lifejackets~6 min read + Knowledge Checker

A Keel That Simply Came Away

On 7 December 2017, the Comar Comet 45S yacht Tyger of London was on passage about 1 nautical mile south of Punta Rasca, Tenerife, when the shallow-draught lead cruising keel separated from the hull. The yacht capsized immediately following the keel loss. All crew were wearing lifejackets and were rescued unharmed by the crew of the passing vessel St Barbara V.

A Fabrication Change Nobody Was Told About

MAIB's investigation found the stainless steel keel frame had not been fabricated in accordance with the designer's drawings. A shipyard had made undocumented changes during manufacture that weakened the joint between the keel plate and the internal keel rods. The keel had no valid CE approval under the Recreational Craft Directive — meaning no independent design verification had ever checked this specific configuration.

Why Nobody Could Have Caught It

Once cast, the interior of a lead keel like this cannot be inspected by conventional survey methods. The defect that ultimately separated the keel from the hull was invisible from the day the keel was manufactured to the day it failed — not because nobody looked, but because there was nothing to look at from the outside. A similar MAIB safety bulletin (SB3/2018) had already been issued the previous year, warning owners of Comar keelboats about exactly this risk.

Recommended Actions

MAIB made no new recommendations following this report — the previous recommendation (2018/119, to British Marine) had already been addressed through an amendment to the applicable ISO standard, following the earlier safety bulletin. The value of this fuller report is in documenting exactly how the failure occurred, and why survey alone could never have caught it.

Human Element Analysis

Normalisation

The keel had been on the vessel for years and had survived previous groundings without apparent consequence. A component that has performed without incident for years quietly earns a level of trust that its internal condition may not actually justify.

Complacency

Fabrication shortcuts taken during manufacture were undocumented and unknown to the designer, the owner, and every certification body involved. The absence of CE approval for this specific keel type meant no independent structural check had ever been made at any point in its life.

How This Pattern Repeats

Industry	Incident	The parallel
Aviation	Turkish Airlines Flight 981, Paris, 1974	A known design departure in the DC-10's cargo door — identified after an earlier, non-fatal incident but not corrected fleet-wide — later caused a catastrophic in-flight failure, echoing how an undocumented fabrication change on the Tyger of London keel went uncorrected until it separated at sea.
Automotive	Takata airbag inflator recall crisis, from 2014	A manufacturing defect that only manifested under conditions outside the original design and test envelope took years to detect and led to a global recall — the same kind of hidden, undetectable-until-failure defect that MAIB found in the keel's internal stainless steel frame.
Space	Space Shuttle Challenger disaster, 1986	An internal component failure mode remained invisible right up until the moment of catastrophic failure, because the specific vulnerability had never been part of what was actually tested or verified — the same gap between what the CE approval process should have checked and what it actually did.

See How You'd Handle It

The scenario opens mid-passage, south of Tenerife, as the keel separates without warning. Play the Tyger of London decision scenario and find out where each choice actually leads.

Lessons for Yacht Owners and Surveyors

A safety-critical component whose internal integrity can't be inspected in service depends entirely on the integrity of its original manufacture — if that process isn't controlled and verified, there is no safety net.
All crew wearing lifejackets is what turned this into a survivable incident. In an offshore capsize, that decision is not advisory.
Emergency equipment (liferaft, EPIRB, grab bag) needs to be stowed where it can actually be reached after a capsize, not in a locker that becomes inaccessible when the boat is inverted.
A yacht keel that has grounded should be inspected by a specialist surveyor — internal damage from a grounding may not be visible externally, and CE approval is not a formality to skip when buying second-hand.

Test Your Knowledge

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