Vertical rising boat lift

For mounting in a boat well having opposed parallel vertical sides spaced above the surface of a body of water, the spacing between the sides of the boat well being dimensioned to receive a boat therein floating on the water, an apparatus to lift a boat within the boat well above the water surface, comprising:

• a forward pair of trunnion members supported to said boat well side wells in horizontal axial alignment and a rearward pair of trunnion members supported to said boat well sidewalls in horizontal axial alignment, the axii of the forward and rearward pairs of trunnion members being parallel and spaced apart from each other;
• a frame adapted to be lowered to receive a boat floating in the water thereon and to be raised with a boat thereon to lift the boat thereon above the water surface, the frame having a forward pair of guide members and a rearward pair of guide members, the four guide members each being in vertical planes and each having an elongated slot therein which slidably receives a said trunnion member, the slots in each of said four guide members being of the same angle relative to vertical of between 15.degree. and 75.degree., the frame having means thereon to engage the bottom of a boat when the frame is lowered to a lowermost position with a portion thereon below the water surface;
• a pontoon secured to the lower portion of said frame;
• means for admitting water into the pontoon to sink the pontoon and a portion of said frame below the water surface;
• and
• means to evacuate water from said pontoon to float the frame upwardly to support a boat thereon above the water.