Furuno Fairing Block for 165T-B54 & 165T-SS54 Transducer

If you're running the Furuno DFF3D multibeam sounder with a 165T-B54 bronze or 165T-SS54 stainless thru-hull transducer, this is the fairing block that gets the transducer sitting right against your hull. It's the factory Furuno part, MPN AIR-033-719-01, and it ships with the anti-rotational bolt kit you need to lock the transducer down so it can't twist out of alignment.

Here's why a fairing block matters, and why you don't want to skip it on a DFF3D install. The 165T transducer sees 120 degrees port to starboard. That wide multibeam picture is the whole point of the DFF3D, and it only looks right when the transducer face is pointed true. Most hulls have deadrise, meaning the bottom is angled, not flat. Bolt a thru-hull transducer straight through an angled hull and the beam ends up cocked off to one side. The fairing block is the wedge that sits between the hull and the transducer, taking up that angle so the face aims where it should.

The other job it does is flow. A bare thru-hull sticking down into the water trips up everything passing over it, and that turbulence shows up as noise and dropouts on the screen once you're up on plane. This block is shaped to fair the transducer into the hull so water slides past clean. That's the difference between a picture that holds together at cruise and one that hashes out the moment you push the throttle up.

One thing to know going in: this is an uncut fairing block. Furuno ships it oversized on purpose so it can be trimmed and faired to your specific hull deadrise during the install. You cut it to your hull's angle, bed it in a good marine sealant, and fair the trailing edge smooth so there's no step for water to catch on. It's a real install, not a bolt-on, and it's the kind of job that rewards taking your time. Get the block faired properly and the DFF3D pays you back with clean, stable returns.

The included anti-rotational bolt kit is not an afterthought. On a thru-hull, the nut wants to let the transducer spin as it's tightened, and a multibeam transducer that's rotated even a few degrees throws the whole port-starboard picture off. The kit keys the transducer so it stays put. Use it.

This block fits both the bronze 165T-B54 and the stainless 165T-SS54. Pick the transducer that matches your hull material and running conditions, the fairing block is the same part either way. It's a DFF3D-specific accessory, so if you're running the multibeam sounder this is the mount you want. If you're not sure whether your transducer is a pocket mount or a straight thru-hull on your boat, give us a call before you drill anything and we'll help you sort it out.

We sell a lot of DFF3D systems to sportfishers and center consoles that want the side-to-side coverage for structure and bait, and the fairing block is the part people forget to order until the transducer is in hand and they realize it won't sit flat. Order it with the transducer and save yourself the wait. At 3.25 pounds and about 15 inches long, it's a compact part, but it's the piece that makes the whole multibeam install come together right.

For the install itself, plan on the usual thru-hull toolkit. You'll want a hole saw sized to the transducer stem, a way to fair the block flush, quality marine bedding compound, and a helper to hold the transducer from inside while you snug the nut from below, or the other way around depending on how your boat is laid out. Dry-fit everything first. Check the beam is aimed straight down at rest and that the faired trailing edge is smooth before you commit any sealant. A little patience here saves a haul-out later.

And because this is the genuine Furuno part, it carries the full Furuno warranty and it's dimensioned to match the 165T transducer body exactly. Shop-fabricated fairings can leave gaps that let water track along the transducer and kill your returns. This one seats the way the engineers intended. If you've already got the 165T-B54 or 165T-SS54 on the bench and you're staging a DFF3D install, add this to the box and you'll have everything you need to mount it right the first time.