An anchor booster is designed to increase the final penetration depth of the gravity installed plate anchor. Moreover, the booster can also improve the directional stability of the gravity installed plate anchor during its free fall in water. After installation, the booster is retrieved by pulling its retrieval line up and can be used for the subsequent installation. The booster is comprised of a cylindrical shaft with three rear fins. The shaft is designed with an ellipsoidal tip and a contracted rear. The shaft rear is set with three slots thus the rear fins can be inserted into the slots to improve the directional stability of the hybrid anchor (i.e. the gravity installed plate anchor with a booster). The booster tip is fabricated with a cylindrical slot and the anchor tail has a compatible bar, such that the booster can be connected to the anchor tail by a shear pin.