Bad Boy- The open hose should open an area but it may not be large enough to encompass your entire dock.
If you find that to be true, you may want to pull that hose up and add a diffuser to it even if it is a single stone diffuser. This will spread the smaller bubbles out to entrain more water for circulation.
This summer you may want to look into a circulator attached to your dock to prevent any future worries. Here are some pics of circulators attached to a dock doing a great job of deicing.
