Solution

Let's consider the following figure

The normal force $N$ is what the equipment measures as apparent weight. From Newton Second Law $$N = mg-F_A$$ $$N = \rho~g~V-\rho_w~g~V$$ $$N = (\rho -\rho_w)~g~V$$ and taking $\rho_w = 1000$ kg/m$^3$ $$\boxed{V = \frac{N}{(\rho -\rho_w)~g}=147 \rm{cm}^3}$$