 The P 6-class torpedo boat ("Project 183 Bolshevik") is a development of the P 4-class TB originally intended to be a successor of P 4, but it instead complemented P 4 when both types served with each other.As with the P 4 class, the P 6-class also comes in two versions, one with radar and the other without, 183T and 183 respectively.The P 6 class TB is larger than the P 4-class TB, with its size increased by 3 times and being more heavily armed, with two 21-in torpedoes replacing the 18-in torpedoes of the P 4-class, and twin 25 mm gun mounts replacing the 14.5 mm gun mounts of P 4-class.