Furuno 620
 

I have asked Jim at BOE about using a shoot through the hull transducer with a Furuno 620 on my Parker 2120. He said to use the Furuno 520-IHD ADJ in hull transducer. I'm hoping Jim or anyone else will reply with information on installing this unit and hopefully comments on how well this transducer works. Thanks a lot.

Using an in-hull ducer is usually not ideal because you will lose about 30% of your range, but you won't lose any clarity in the 70% you have remaining. A thru-hull is best, transom mount second best and an in-hull third best. If the absolute best performance is not important, but preserving hull integrity is important then an in-hull is a good choice. Installation is easy, simply sand a spot in the bilge to smooth it out, clean the spot with solvent, then glue in the ducer using something like 3M 4200. Then fill the ducer cavity with anti freeze or mineral oil and close it up.