Dr. E. C. B. Corlett, Foreign Affiliate Associate Member, AND Mr. James Venus, Managing Director, Seawork Limited, Dashwood House, London, England. Visitor:

This very interesting paper is in some ways an obituary of the type of vessel it describes. The canal vessel is one of the most interesting special types in service and all who have had anything to do with it must regret the imminence of their passing.

The author has given a comprehensive account of the developments that led up to the present-day ship as we know her and we would like to add one or two comments which may be of interest and which may add to the considerable information already contained in the paper.

The writers were responsible for the basic design of the two ships Baie Comeau and Manicouagan which are similar in hull form to the Franquelin. It may be interesting to note that both of these ships embody a considerable quantity of aluminum. All the deckhouses, pilothouse, and funnel are of aluminum as are the poop sides and deck and forecastle sides and deck. By the use of this material and by careful attention to structural weight elsewhere, a remarkably good deadweight figure has been achieved.

An additional ship, the Lachinedoc is now on her way to Canada. This ship is of particular interest with regard to two features; namely, that she is built with a developable form, having no double curvature anywhere in the hull, and, in association with this, a remarkably good propulsive efficiency has been achieved.

This ship, which is, of course, of standard canaller dimensions, has been designed with simplicity as the prime criterion. She is longitudinally framed on the decks and on the tank top, while the bottom framing is longitudinal in the flat, becoming diagonal along the generating lines of the curved portion of the bow; this being formed by the envelope of a number of irregular cones.

Reference to Fig. 10 of the paper shows a curious feature of the twin-screw canaller forms as originally produced in the Franquelin and perpetuated in subsequent ships such as the Manicouagan and Baie Comeau. Flow in the forebody must be substantially of waterline type and this is underlined if the 14-ft waterline is drawn on Fig. 10. Flow at the stern is essentially of buttock type and the inference therefore is that the flow must traverse the bilge at some portion between bow and stern, leading to form drag and also, of course, to an extended frictional path. In the Lachinedoc, the flow has been retained as buttock flow at the stern; indeed little else can be done with twin screws on these proportions. However, the flow at the bow has been given a much stronger downward impetus and this has resulted in it being far more along bow lines than is the case in the Franquelin type form. The net result is very interesting as the ship has considerably less resistance per ton of displacement than the Manicouagan or Baie Comeau, while careful attention to the stern details has enabled 7 ft propellers to be fitted in place of those of approximately 4 ft in diameter in the ships mentioned.

Fig. 38 The Lachinedoc Which May Be One of the Last of Her Type to Be Built

The Lachinedoc achieved a trial speed of 11.6 statute miles per hour on 915 shp on a displacement of 2350 tons in ballast. The shp per ton of the ship at 10 mph loaded is 0.194 --; a very good figure for this type of canaller -- while extensive remote-control model steering trials were carried out with a particular view to obtaining steering astern on the rudders only in level trim. This, in fact, was achieved satisfactorily.

As the Lachinedoc may be one of the last canallers built, Fig. 38, for the records, shows a picture of the ship which may be of general interest.

In conclusion, we like to thank Mr. Gilmore for his paper which must have entailed a considerable amount of historical and other research.

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This paper was presented at a meeting of the Society of Naval Architects and Marine Engineers and is reproduced with permission.