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68 and under hand-firing conditions as - commonly existing these variations are very wide. It follows that the higher the designed or expected superheat the greater the influence of this variation. In the light of such information as is available at this time there is little to indicate that such in- stalations as have been made have produced any improvement in fuel economy. On the contrary a reference to Table II will show that ships 14 and J and P are among the claimants for front rank in high fuel consump- tion and all are fitted with super- heaters, while none of the best per- formers are so fitted. This may not be conclusive either, for reasons before stated, but must be accepted in the absence of evidence to the contrary, leaving the honors with heated draft and saturated steam. It might be added here that all of the scotch boiler ships, with one exception are fitted with heated draft, and that exception as might be expected is the highest in the list also with one exception and that is the ship already referred to as carrying superheaters. Why Use a Surface Condenser The surface condenser is next mentioned by Dr. Sadler as a feature of questionable value. For our pur- pose it may be grouped together and considered with the auxiliaries. This form of condenser owes its recent introduction to lake practice to an effort to improve feed water conditions, desirable with all forms of boilers but imperative with water- tube, and also to obtain a_ better vacuum than with the jet condenser. We are not confronted here with the feed water conditions which make the surface condenser indis- pensable, as at sea, and the question therefore narrows down to one of comparative improvement and whether the improvement, if any, is worth the cost. The costs are definite and are made up of weight, first cost and maintenance, cost of cir- culating water and loss of heat at hot well. They also include the circulating pump which is an entirely additional auxiliary required only in connection with the surface condenser. The weight cost amounts, including water, to around 15 tons, which is a reduction in deadweight to that extent. _ The difference in first cost is quite substantial and for the ship of to- day is around $7500 to $8000. Main- tenance involves not only repairs, such as renewals of tubes and pack- ings, but constant careful attention in guarding against air and water leakages. Working with fresh cir- MARINE REVIEW culating water these leakages will not be so immediately apparent as at sea, but their development will proceed just the same and therefore all the more easily defeat the entire object of the installation so far as improvement of feed water is concerned. It is entirely probable that a little more experience with this type will abate any interest the engineers of lake ships may now feel. The over- hauling of some thousands of tube ends and packings is not a job to arouse and hold enthusiasm if con- densers are properly maintained. In seagoing ships where leakage makes itself apparent in short order the condenser is the principal battlefield and so serious is this question that in some instances duplicate con- densers have been fitted and the prac- tice is making headway. If owners and engineers imagine that the surface condenser holds its place at sea because anybody is fond of it they are badly mistaken; there is no one thing that would be jettisoned with heartier good will if water con- ditions were no worse than on the lakes, provided of course that turbines are not involved. Those who know it the best and have lived with it the longest hate it the most cordially and pray the most fervently for escape. The circulating pump adds_ its quota to maintenance also. By cost of circulating water is meant the cost of the steam required to handle it and which is a variable depending upon temperature of water, vacuum desired, and the elevation, or difference between the draft of the ship and point of discharge, plus friction losses in condenser and piping. All these can be averaged however and the result will appear for the ship under consideration as of the order of 1200 pounds of steam per hour plus line loss. This will however be treated later with other auxiliaries. The loss of heat at hot well with equal vacuum is safely 15 degrees and is more likely to be 20 degrees and is dependent directly upon the integrity of the condenser. Using the minimum figure however we find that the two items, circulating water and hot well loss, are costing us the equivalent of 160 pounds of fuel per hour or over 3% per cent of the total actually used. There will be some salvage in the way of heat recovery from the exhaust steam but under no possible circumstances can the net loss fall below 2 per cent. So much for the costs, which, as in- dicated, can not all be exhibited in terms of money. The benefits in this case lie entirely February, 1927 in anticipated improvement in feed water as compared with alternative systems ordinarily employed. Claims are made for collateral advantages such as established vacuum facilitat- ing maneuvering. This however is merely a state of mind; in other words auto-hypnotism. Any engine with a good jet condenser and at- tached air-pump can be handled by anyone who understands his subject even superficially just as rapidly and effectively as with any other form of condensing apparatus whatsoever. To assert the contrary is merely to deny the plain facts and experience of the entire history of marine engineering and admit either lack of information or inability to assimilate it. (To be Continued) Shipbuilders Co-operate (Continued from Page 56) Johnson, president and general man- ager, Johnson Iron works; Paul F. Jahncke, vice president, Jahncke Dry Docks Inc; I. H. Aiken, president, and general manager, Aiken Tow Boat & Barge Co.; J. H. Langben, president, Galveston Dry Dock & Con- struction Co.; David R. Dunlap, presi- dent, Alabama Drydock & Shipbuild- ing Co.; John F. Prigge, vice presi- dent, Todd Shipbuilding & Drydock Co., and Thomas A. Johnson, presi- dent and general manager, Bruce Dry Dock Co. Pacific Coast Section—George A, Armes, president, General Engineering & Dry Dock Co.; C. W. Wiley, chair- man of the board, Todd Dry Docks Inc.; J. A. Moore, president, Moore Dry Dock Co.; William Cornfoot, pro- prietor, Albina Engine & Machine works; James C. Craig, president, Craig Shipbuilding Co.; L. E. Caverly, vice president and general manager, Los Angeles Shipbuilding & Drydock Corp.; J. K. Collins, president, Han- lon Dry Dock & Shipbuilding Co.; J. J. Tynan, vice president, Union plant, Bethlehem Shipbuilding Corp., and A. F. Marion, vice president, Pa- cific Coast Engineering Co. Great Lakes Section—A. G. Cuth- bert, president, A. G. Cuthbert Co.; A. G. Smith, - president, American Ship Building Co.; Benjamin L. Cowles, president, | Cowles-Matton Barge Canal Dry Dock Inc.; H. J. Defoe, president, Defoe Boat & Mo- tor works; E. M. Gregory, general manager, Belle Island Boat & Engine Co.; Carl Hartman, president, Green Bay Dry Dock Co.; G. A. Tomlinson, president, Buffalo Dry Dock Co., and Arthur Lanzell, president, Arthur Lanzell Co.