Longshore and Harbor Workers' Compensation Clarification Act of 2017 This bill amends the Longshore and Harbor Workers' Compensation Act to define "recreational vessel" as a vessel: being manufactured or operated primarily for pleasure; or leased, rented, or chartered to another for the latter's pleasure. In applying such definition under such Act, the following rules apply: a vessel being manufactured or built, or being repaired under warranty by its manufacturer or builder, is a recreational vessel if the vessel appears intended, based on its design and construction, to be for ultimate recreational uses (the manufacturer or builder must bear the burden of establishing that a vessel is recreational under this standard); a vessel being repaired, dismantled for repair, or dismantled at the end of its life will be treated as recreational at the time of repair or dismantling, provided that such vessel shares elements of design and construction of traditional recreational vessels and is not normally engaged in a military, commercial, or traditionally commercial undertaking; and a vessel will be treated as a recreational vessel if it is a public vessel (such as a vessel owned or chartered and operated by the United States or a state or local government) at the time of repair, or dismantling, provided that such vessel shares elements of design and construction with traditional recreational vessels and is not normally engaged in a military, commercial, or traditionally commercial undertaking. The Department of Labor must revise a specified federal regulation defining a "recreational vessel" to conform with the definition set forth in this bill.