The Submarine Torpedo Boat
Its Characteristics And Modern Development

TYPES OF SUBMARINES 53 submerge larger vessels of this type without the use of forward diving rudders; the increased value of the upward moment of the reserve buoyancy to be overcome necessi- tated a greater angle of inclination accompanied by greater speed, and the larger surface of the hulls when presented Figures. “Even Keel” Boat at this angle and speed brought about such materially increased downward thrusts that, when once started on her plunge, there was small chance of being able to catch the vessel again by the diving rudders aft. Witli increased speeds the thrusts would be still greater and the angle of inclination must be made proportionately less, therefore affecting the tactical value of the boat. In the “even keel” boat the forces at work are practi- cally the same as shown by Figure 3. The better control in this type is brought about by being able to submerge by adjusting the hydroplanes. Theoretically, as the planes are of the same area and symmetrically disposed around the center of buoyancy, the moments of the planes being therefore equal, the “even keel” boat should be able to submerge with the axis of the boat parallel with the