Sportfishing and Recreational Boating Safety Act of 2005

Sport Fishing and Recreational Boating Safety Act of 2005 - Amends the Dingell-Johnson Sport Fish Restoration Act to provide for distribution of FY 2006 through 2020 appropriations for certain fish restoration and management projects, including for the multistate conservation grant program.

Amends the Internal Revenue Code to require transfer to the land and water conservation fund of the equivalent of certain motorboat fuel taxes received into the Highway Trust Fund.

Establishes the Sport Fish Restoration and Boating Trust Fund (effectively merging the Sport Fish Restoration Account and the Boat Safety Account of the Aquatic Resources Trust Fund). Transfers any excess motorboat fuel taxes not transferred to the land and water conservation fund into such Fund.

Authorizes for FY 2006 through 2010 certain expenditures from the Sport Fish Restoration and Boating Trust Fund, including for aid to States for fish restoration and management projects.

Amends the Clean Vessel Act of 1992, with respect to grants for State marine sanitation device pumpout station programs, to repeal the mandatory priority consideration given to grant applications that, in coastal States, propose constructing and renovating pumpout stations and waste reception facilities in accordance with a coastal State's approved plan.

Amends Federal shipping law to increase from one-half to 75 percent the maximum percentage of a State's total cost for its recreational boating safety program represented by the Federal allocation the State receives. Extends the availability of such allocation from two years to three years. Requires a reduction of such allocation if the State's expenditures for the program for the previous fiscal year is below the average expenditures for the three preceding fiscal years (failure of maintenance of effort).