Choose a destination and press [?] to launch yourself.
Anchor's Away is an excellent tool to use when attempting to get to higher ground so Captain Deadbeard can snipe from a safe place. In addition, it's also a decent escape tool since as you can still move while activating the ability. You can launch yourself behind cover, or just to make you harder to hit. If you accidentally trigger this ability, you can cancel it without penalty. As a side note, the anchor actually deals damage to plants (25), but the damage is too miniscule to actually mean anything during combat.