The time [tex]t[/tex] it takes for the key to fall 44 m is
[tex]44\,\mathrm m=\dfrac12\left(9.8\,\dfrac{\mathrm m}{\mathrm s^2}\right)t^2\implies t=3.0\,\mathrm s[/tex]
(notice I'm taking the downward direction to be positive)
The boat, moving at a presumably constant speed, then has 3.0 s to travel 19 m to the point of impact, which means its speed must be
[tex]v=\dfrac{19\,\mathrm m}{3.0\,\mathrm s}=6.3\,\dfrac{\mathrm m}{\mathrm s}[/tex]
