So, first calculate the weight (w=mg), which comes to 823.2N
Then, find the resultant force of which is given by: F(resultant)=F(water)-W => 1900-823.2 = 1076.8N
Use Newton's Second Law (F=ma) to find the acceleration; which equals 12.819... ms^-2
Sub that into your 'suvat' equation with u=0, s=5 and a=12.819..., to find v.
Therefore, v = 11.322... ms^-1 => 11.3 ms^-1