Hi, new 2021 Compass owner here, and first time poster
Experienced the same issue whereby the paper instructions that come with the boat do not match the fitting hardware supplied. Luckily I noticed before I started drilling holes and came here. There is a quick fix available without the need to purchase any extra fittings:
Drill the 1 3/8” hole as indicated on the vertical firewall behind the transducer scupper. The 3 way (screw in) fitting is required here as the reverse of the fitting cannot be accessed by hand. Simply choose a single hole grommet to fit and seal the single transducer cable.
Drill the second hole, this time a 1” hole, (ignore instructions) on either the left or right of the inner rail in the location of fish finder screen. This 1” hole will fit the incorrectly supplied 1 way plug, and there are no issues getting your hand behind here to attach the rear bracket to the reverse. For this fitting, choose the appropriate 2 hole grommet to fit your twin fish finder cable.
Also for any other Aussies here, a 25mm and 35mm hole saw gets the job done. Hope this helps you get on the water quicker