Sharing (splitting) the signal coming from the GPS antennna

My GPS antenna currently feeds directly to my RDP148 (Navnet VX2 vintage), and then there is a cable with GPS data leaving the RDP and going to the DSC equipped VHF so the radio gets location info.

When anchored, I'd like to turn off the RDP as it draws so much power but I don't want to turn of the VHF. But if I do this, the VHF will complain about not knowing a position.

My son suggests we split the signal coming from the GPS antenna before it gets to the RDP148 and send one signal to the RDP and the other to the VHF. (We'd simply splice a "Y" into the GPS antenna cable.) I'm guessing we'd need to look at how to ensure the antenna gets powered if the RDP is off. But the bigger question is can a Furuno GPS antenna send a signal (sentences?) to two different devices at the same time. (I don't know if the signal requires a certain amount of power, and if it is being split to go in two directions at the same time if I'm somehow diminishing the strength of the system.)

Or... if there are other approaches to solve the problem I'm trying to fix, please feel free to suggest.

Splitting the signal of the BBWGPS (aka GP-320B) antenna would not be the best way to do what you are trying to do. When that antenna is connected to a NAVnet, it goes into NAVnet mode and won't transmit correctly to the radio. Your best bet is to get a separate GPS unit, such as a GP32 and wire it to the radio (and NAVnet if you want to replace your BBWGPS). That way, with the NAVnet on or off, position would still be coming from the GP32 that only uses 0.25 Amps on a 12Vdc system.