It is just material settings, not a blueprint. To create this effect you have enable render custom depth\stencil inside your project settings first.
Then you have to enable custom depth rendering for your mesh (inside mesh properties)
And create a material like that
This material compares current stencil buffer value with the given constant (I used 25, it doesn’t matter) and chooses the alpha for water between 0 and other value.
With this material as water and any static mesh you will get something like this
Until you enable custom stencil and specify stencil value greater than used in material.
To get best effect you have to separate your boat mesh to two parts: inner and outer. And enable custom depth stencil on both parts but set stencil value > 25 for inner part and < 25 for outer.