Dönitz came to recognise the need for more of these vessels. Only 26 were in commission or under construction that summer. In the time before his command of submarines, he perfected the group tactics that first appealed to him in 1917. At this time Dönitz first expressed his procurement policies. His preference for the submarine fleet was in the production of large numbers of small craft. In contrast to other warships, the fighting power of the U-boat in his opinion did not fluctuate in relation to its size for the torpedo, not the gun, was the machine's main weapon. Dönitz had a tendency to be critical of larger submarines and listed a number of disadvantages in their production, operation and tactical use. Dönitz recommended the Type VII submarine as the ideal submarine. The boat was reliable and had a range of 6,200 miles. Modifications lengthened this to 8,700 miles.