A wireless message received yesterday from the captain states that she is experiencing bad weather on the final stages of her voyage, and will not reach the lower harbour until Monday morning. The Port Dunedin is carrying a large general cargo for discharge at this port, and she also has a fair quantity to land at Lyttelton and New Plymouth.
The Port Dunedin is a unit of the Commonwealth and Dominion Line, and is the first motor vessel to come from London to New Zealand with cargo. To mark the arrival of the first ship in connection with the new cargo service between London and South Island ports, a function will be held under the auspices of the Otago Importers and Shippers’ Association during the Port Dunedin's stay at this port.
Novel engine powers ship
London, June 11: During the week several small luncheon parties have been held on board the new motor ship, Port Dunedin, and an opportunity has been given to certain interested people to inspect the Commonwealth and Dominion’s latest acquisition. This is the first vessel of the Diesel engine type built to trade between New Zealand and Great Britain, and it is one of the first vessels to be fitted with the Doxford type of engine. Engineers will be greatly interested in the engines, where the new principle of two pistons in each cylinder is introduced. The explosion in the cylinder takes place when the two pistons are almost together. The end of each piston is hollowed so that when they are together there is a spherical space wherein the explosion occurs. Oil is injected at such high pressure that it explodes inside this temporary sphere without ignition spark. One piston goes downward, the other upward, and both act on the same screw shaft below the cylinder at the same time. When the two pistons are at the extremities of the cylinder, an air stream at great pressure enters at the bottom and drives the gases out at the top. When the pistons come together again the explosion is repeated — thus there is an explosion for every sweep of the piston, unlike other internal combustion engines where the explosion occurs at every second sweep. The engines are started with compressed air contained in three large cylinders in another part of the engine room. A special engine keeps these air cylinders charged. The main engines then propel an air pump for each set of four cylinders, the air pump being used to clear the cylinders of gases after each stroke of the pistons. Fumes are carried off through insulated shafts to the funnel, which acts as a silencer. Thus the main engines do not create a very great noise. The oil fuel capacity is 1758 tons and the vessel burns 20 tons a day at a speed of 13½ knots when fully loaded. A steamship of the same tonnage would need to carry a staff of 39 for the engine room. The Port Dunedin will carry ten engineers, two refrigerating engineers, three electricians, three cleaners, one donkeyman and one storeman — 20 in all. This reduction in staff and a certain economy if oil remains at a reasonable price, are the main factors which should make for economy in the ship. — by ODT London correspondent — ODT, 31.7.1925
Compiled by Peter Dowden
