Finding the weak link in a highly stressed chain is like picking winning lottery numbers. Rig defects are invariably invisible. Electronic rig testing has been around for more than 15 years, pioneered by Dennis Maidment, of Maidsure Services, Southampton.

Just as a bad connection in an electrical circuit increases resistance, so a bad joint in a rig connection, like an under swaged terminal or internal corrosion, can be detected. Higher resistance is also a sign of broken strands of wire, cracked terminals or defective swaging.

Electronic testing can be done with the mast stepped or unstepped. It took just an hour to test 17 terminals. The proof of Dennis’s method comes from the Wolfson Unit for Marine Technology which tested terminals he condemned and confirmed the defects.

Seventy per cent of rig failures are found at the top end of the lower shrouds. Common causes are fatigue, due to vibration of the wire and salt water entering terminals.

An insurance brokers confirmed: ‘Electronic rig testing can reveal a lot of problems. If it catches 50 or 75 per cent it’s better than nothing. Tangs are more reliable than T-bar terminals.’

Dennis charges around £120 for a 30ft yacht if the rig is down and within 25 miles of Southampton.

Enquiries: 9 Southern Road, West End, Southampton SO30 3ES

(Tel/Fax: 02380 472 422; mobile: 07860 346373).