During the reign of Peter the Great’s successors, the pace of shipbuilding slowed down. Many design drawings and half-models were neglected. In the mid-1730s, the maritime technical collections began to be amassed. Between 1731 and 1738, the Admiralty house was basically re-built under the supervision of I. K. Korobov. Larger areas for storing the Admiralty collections could be allocated. The collection made at the Chief Surveyor’s office required a separate room. By December 16, 1737, a new inventory of ship drawings, slipways and cranes was compiled. It included 63 models and 92 drawings (total 155 items). In eight years, from 1729, the collection increased in two and a half times. The inventory of 1737 included all the items mentioned in the earlier lists, which proved the consistency in the development of the collection.
The collection of models and drawings at the Chief Surveyor’s office was a kind of a reference bureau for the shipbuilding, and an active storage of design documents. On March 2, 1741 the Admiralty Collegium decided to allot a special room to store the collection of models and drawings. It was still in the Main Admiralty building, on the first floor in the central tower, ‘under the spire’. Special attention was paid to the fact that plans and drawings were often kept in various departments or at the construction site, and it was difficult to spot required materials. With the allocation of the room and clearly expressed intention of the Admiralty Collegium to concentrate all documents and models in the same storage, collecting was stirred up and in a short time the collections increased greatly. Moreover, in 1741 and 1742 beside technical documents, ‘the Room under the Spire’ housed a huge collection of geographical maps and nautical charts brought together by the Navy. The inventory of 1742 enlisted 495 maps, charts, plans and drawings while in 1737 only 92 drawings and no maps were mentioned; thus a five-time increase in the number of the relevant items was observed.
On November 3, 1742 a special storage was made where models, maps, charts, plans and drawings were to be kept, described in detail and restored if necessary - all this under the supervision of an appointed official. New charts were to be drawn there, too, based on the available geographical data and new information. All holders of models, drawings, plans and charts had to make a signed statement of being informed about the consolidation of the maritime collections. ‘The Room under the Spire’ where the collections were brought together, soon was given the name of the Model Chamber. There a model or a drawing could be borrowed to develop a new ship, or a chart to plot a route for a new voyage or naval campaign, or a plan to build a new naval structure. Every item stored in the Model Chamber was registered in the inventory book and could only be lent after a respective entry was made.
So, in the early 1740s the collection of the Chief Surveyor Office entered a new stage of its development to turn from the ship-building document depository into an ‘information center’ with technical and navigational documents, models and visual aids available. In September 1743 the collection of the Model Chamber was divided into two parts, dedicated to shipbuilding (ship models and drawings) and geographical items (maps, charts and plans), with both parts still stored in the same room. In 1748 the room itself was re-built into a chapel and collections were relocated to the eastern wing of the Admiralty, next to the Admiralty Collegium office.
In 1763, more rooms were allotted for the Model Chamber and the ship-building and navigational parts of the collection were stored in separate, although adjacent rooms. The 1760s and 70s were the culmination period in the development of the Saint Petersburg Model Chamber in the 18th century. This was the time when the Regulations of 1722 were observed. But since the 1780s the acquisitions became more random. By the end of the 18th century, rooms cram-full of items, or the lack of funds or foresight brought the Model Chamber to its decline. Another cause for the poor condition was that the Model Chamber was regarded as a narrowly-specialized institution and hence it became unpopular. The development of shipbuilding and the technology in general inevitably brought about obsolescence in the design drawings and models. Once valid documents, they became the historical evidence of design concepts and shipbuilding practice. In the end of the 18th century the Model Chamber was losing its significance as the specialized information center to become the storage of naval rarities instead. By the beginning of the 19th century, the idea to transform the Model Chamber into the museum on the condition that the exhibits could be treated as historical monuments and still used in practice took its shape.