Hi Sarah,
As far as I know, bathymetric surveys are usually carried out by echosounder equipment. But I’m not really into this field, so I can hardly recommend a particular device.
Using any kind of them, let’s check how it can accept the streamed position from a GNSS receiver. With Reach RS3, you can stream the position via Bluetooth, TCP, or the receiver’s serial port.
What kind of base station is it? Is it your own receiver? Or do you have access to an NTRIP service?
I’d also like to share this post with you. It covers some examples of performing bathymetric surveys with Reach receivers that may help you choose a setup. Of course, I can also help you with the configuration if you decide on a particular workflow.