The contemporary descriptions of the Fulton _Steam Battery_ do not agree. This was in part due to differences between the dimensions given out by Fulton during the negotiations with the Federal Government, and after the ship's construction was authorized. From the context of various statements concerning the projected vessel, such as that of the naval officers, the changes in the intended dimensions of the ship can be seen. For example, the officers state the model and plan shown them would produce a battery carrying 24 guns (24- and 32-pdrs.), and a letter from Fulton to Jones,[9] shows she was to be 138 feet on deck and 55-foot beam. The final reported dimensions, given by the Supervisory Committee,[10] are 156 feet length, 56 feet beam, and 20 feet depth.
In addition there are a few foreign accounts which give dimensions and descriptions. The most complete was probably that of Jean Baptiste Marestier, a French naval constructor who visited the United States soon after the end of the War of 1812 and published a report on American steamboats in 1824.[11] The _Steam Battery_ is barely mentioned though a drawing of one of her boilers is given. Marestier made another report on the American Navy, however. Extensive searches have been made for this in Paris over the last 14 years, but this paper has not been found in any of the French archives. References to the original text indicate that the naval report dealt very extensively with the _Steam Battery_. Some of his comments on the battery appeared in _Procès-verbaux des Séances de l'Académie des Sciences_.[12] Marestier considered the powers of the battery to have been overrated due to fanciful accounts of some laymen writers. He was aware of the shortcomings of the double hull in a steam vessel at the then-possible speeds, but he apparently thought two engines, one in each hull and each with its boilers would be better than Fulton's arrangement of boilers in one hull and engine in the other. He noted that the paddle wheel turned 16-18 rpm and that steam pressure sustained a column of mercury 25 to 35 centimeters. The safety valve was set at 50 centimeters. Fuel consumption was 3-5/8 cords of pine wood per hour.
In view of the access Marestier is known to have had to American naval constructors, shipbuilders, and engineers, it is highly probable that he not only obtained the building plan of the ship but also some of the earlier project plans from the builders and from Fulton's superintendent, Stoudinger. It is, therefore, a great misfortune that his lengthy report on the _Battery_ cannot be produced.