Volvo Penta D2-50

[Just Farr Love]

I’m in the process of installing a new Volvo Penta D2-50 with S130 saildrive.
The hoses supplied with it does not allow for raw water filter or anti siphon/ vented loop.
The dealer suggested I install both filter and vented loop which I am in the process of doing but I am wondering if anyone knows why Volvo has done this?
Is there some new technology that I am not aware of?

[Sailmonkey]

They’ve got to supply the engine with a functional cooling system, but it doesn’t need to be correct for the final purpose.

[Just Farr Love]

Thanks