The first Boat Designed Specifically as a Lifeboat was Tested on the River Tyne in 1790

The Original, a 30 ft long shore based lifeboat was tested in England in 1790.  Although boats had previously been pressed in to service as rescue vehicles, the Original was the original boat built specifically for rescue.

In 1789 a ship ran aground in a storm at the mouth of the River Tyne. There were stranded men in sight of shore, but no one was willing to risk what was deemed a suicidal attempt to rescue them. A reward was offered on the heel of the tragedy to anyone that could design a reliable rescue boat.  William Wouldhave won the challenge.  Wouldhave's design was used to build the Original, which carried nearly 800 pounds of cork for buoyancy.

Note: Lifeboats as known today - boats carried on large ships attached with davits were not part of sea travel before the late 19th century.

Something else I learned: There is a Wouldhave lifeboat Monument and Memorial at Pierhead in South Shields.