Mr. Gilmore:

Mr. Smith has stated that the maximum possible increase in length for a canaltype vessel is about 50 ft because of the limit of length/depth ratio of 13.5 imposed by the loadline regulations. While this is true for ships which have a standard longitudinal strength as laid down in the rules, a vessel can be lengthened to have a length/depth ratio of up to 16 if the inertia and modulus of section are suitably increased. In the standard canallers, with a depth of 21 to 22 ft, the possible increase in length is then about 80 to 100 ft. As the length is increased, however, the strength requirements become progressively more difficult to achieve, with more and more reinforcement to the existing structure being required. The problem then becomes largely one of economics, with the rapidly increasing cost of conversion being balanced against potential earnings. As suggested by Mr. Smith, the simplest method of lengthening, in many cases, is to increase the depth either by continuing the level of the raised quarterdeck or by building a trunk in way of the hatches.

The problem of minimum shell thickness is probably the most difficult with regard to lengthening, and a ship which has been built with the shell and its stiffening reduced to the absolute minimum allowable is not too good a prospect for lengthening. However, owing to the fact that most of these vessels rarely operate continuously in salt water, their shell plating generally is in exceptionally good condition and, as the minima include an allowance for corrosion, the slightly lower shell thicknesses are sometimes acceptable, provided the vessels are to continue to operate in fresh water after conversion.

The author recalls with pleasure his association with Professor Baier during the tank testing of the canaller model and is interested to learn that a water pipe arrangement, similar to that proposed by Professor Baier for the canaller, was later fitted, with success, in a river towboat.

The canaller installation was not carried out, owing to various practical difficulties, and the vessel eventually was modified by making two troughs or gouges in the shell. These troughs proved very satisfactory in service, with appreciable gains in both speed and maneuverability.

Mr. Lowery points out the space savings in Diesel installations and it is notable that, as in the case of the Iroquois, the Franquelin of 1936, a hold 22 ft longer than steam vessels of otherwise similar type was realized. It might have been expected that this obvious advantage, coupled with savings in operating expenses, would have led canaller operators to change to Diesel power much earlier than they did.

The all-welded vessel Peter G. Campbell referred to by Mr. Lowery was not a canaller but a barge, 179 ft long and unpowered. She was later converted for propulsion and fitted with twin Sulzer Diesels of 400 bhp each. The Franquelin was the first all-welded canaller to enter service and was actually the second of two identical vessels. The first, the Joseph Medill, was lost with all hands on her delivery voyage in 1935.

The low average cargo figure of 1300 tons, given in Table 4, was noted during the preparation of the paper. Unfortunately, however, the official canal statistics from which the table was derived are so framed that the number of canallers in the total cannot be determined. The average for true canaller cargo is probably about 2300 tons. As suggested by Mr. Lowery, the deadweight figures given in Table 5 have been revised in the light of additional information obtained from the owners.

Mr. Benson has added to the information in the paper, but has assumed a use of the word "obsolete" not contemplated by the author, who intended to convey the passing of a class or type, not the wholesale disappearance of the vessels themselves. The author has in fact expressed the opinion in the paper that many of the present canallers will continue in service after the Seaway is opened.

Mr. Benson refers to 27 ft as being the allowable draft when the Seaway is opened. The author would respectfully point out that 27 ft will be the actual depth of the Seaway and that the maximum permissible draft will be in the neighborhood of 25 ft 6 in.

The author is indebted to Dr. Corlett and Mr. Venus for the information on some of the latest developments in canaller design, particularly with reference to the form and performance of the Lachinedoc, which, indeed, may be one of the last canallers to be built. For the record, however, it should be noted that the Lachinedoc has been followed by the Sarniadoc and Calgadoc for the same owners, N. M. Paterson & Sons, Ltd., theMetis for Canada Steamship Lines and the Westcliffe Hall for the Hall Corporation of Canada, Ltd.; in addition, four further vessels are presently on order, viz., three for the Hall Corporation of Canada, Ltd., and one for Canada Steamship Lines, Ltd.

Dr. Mathews' observations regarding the importance of the hydrodynamical aspects of canaller design are extremely pertinent and the author heartily endorses Dr. Mathews' plea for the extension of the Taylor Series 60 lines to include Seaway types.

The author deeply appreciates the opportunity thus afforded by the Society of placing on permanent record the story of the canaller and would like to thank the discussers for their valuable contributions to the paper.

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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.