(The tug Kesarin 10 at sea trials on the Chao Phrya River near the ancient Thai capital of Ayuthya. C.S. Inter Marine’s shipyard manager Khun Patum Sardsiri is a practical man. He works with management to balance costs and benefits through out the company’s sizable fleet of tugs, barges and bulk cargo handling stations. In some cases this can result in relatively large expenditures, such as one made recently to swap engines on a one year old boat. The handy little steel tug had been launched with a 500 HP second hand engine that quickly began accumulating costs in down time and repairs.