Question. I have a humminbird 858 on bow and a 998 SI at consol. Both with independent transducers and are both linked up together to share waypoints. I'm wanting to add a Helix 12 to consol, sharing the 998 SI transducer. Is this possible to have all 3 units sharing waypoints, but with the 2 units at consol sharing transducer and what special equipment will be needed?

Yes it's possible,you would need a 5 port ethernet switch. You would need Ethernet cables from each unit to the switch and the Helix 12 would need Ethernet cable adapter to connect to the back of the unit. Then all you would have to do is go into the network menu and choose waypoint sharing and choose choose to share the transducers with the Helix 12 and 998