When dealing with Particular Average the normal criterion is the reasonable cost of repairs to the ship, assuming that the shipowner had acted as a “prudent uninsured”. Reasonable cost of repairs could include the cost of removing a ship to a repair yard including bunkers consumed and relevant port charges, drydocking and repair accounts, spare parts supplied and transport thereof, superintendence, surveyors’ fees and wages and maintenance of the crew during the removal. In certain circumstances, and in particular when liner vessels are concerned, temporary repairs can also be recovered, although it needs to be demonstrated that by carrying out temporary repairs the owners were able to save the underwriters’ money. Unrepaired damage (Clause 20) can also form part of a PA claim on the grounds that there would have been a depreciation of the ship’s value by virtue of the damage not being dealt with. In such cases the underwriters’ surveyor must agree the estimated cost of unrepaired damage and an allowance is then negotiated in full and final settlement with the insurers, perhaps 60% or 70% of the estimated cost. The Hull and Machinery insurance policy will also cover expenses and liabilities incurred by an owner if his ship comes into collision with another vessel. Whereas normal American and Scandinavian conditions permit full recovery of such cost and liabilities, the London Market has for historical reasons taken a somewhat different attitude. It must be assumed that before the days of steamships, collisions between two sailing vessels competently handled and subject to the same natural influences of wind, tide and current were comparatively rare. However during the first half of the nineteenth century the London Market underwriters became increasingly concerned regarding the number of occasions when steamships “ran down” or collided with sailing ships. They therefore introduced what was called a “running down clause” into their policies issued to steamship owners by which the underwriters would only pay three quarters of the liability arising out of such collisions. This three fourths collision liability provision carries through to the present day under London conditions (Clause 6). It was a direct result of the imposition of the running down clause which led to British shipping companies during the mid 1800s banding together to form mutual Protection and Indemnity Associations. These were originally specifically set up to provide mutual insurance cover for the remaining one fourth collision liability. How these Associations developed will be covered in greater depth later.