Thru-Hull Locations for transducers

I am a proud new BCC owner in search of answers. Any advice on locations for depth and speed transducers? I am planning to install a ST60 tridata and looking for the optimal spots.


The optimal spot would be at the end of the bowsprit but we all know that is not very practical.

Our knot/log is located just forward of the mast on the port side and our depth sounder is located under the chart table area on the starboard side. The boat was setup this way and is not the best arrangement. For practical purposes, the setup should be reverse - sounder forward and knot/log aft.

Try to locate the depth sounder as far forward as is possible. This may require a fairing block to position the depth transducer so it “fires” straight down.

If you have a good GPS, the knot/log meter is, in some ways, a mute point.

Fair Winds,


I think far better options than a Raymarine Tridata are available in the market place today.

Zygote, for example, has an Interphase Forward Looking Sonar transducer mounted through the keel, about 60 cm forward of the mast. The distance the FLS looks forward is directly associated with the water depth, but any FLS is better than a traditional sonar, which only tells you what you have just sailed over.

GPS-derived SOG is not a substitute for waterspeed, especially if you sail in tidal waters. GPS data can be combined with waterspeed data to give you such data as leeway, tidal current, and tidal offset.

Zygote, for example, has a Raymarine ST60 waterspeed paddlewheel tranducer mounting about 60 cm to port of the mast base. Better options than a paddlewheel transducer are now available in the marketplace - including waterspeed transducers that are tolerant of mild fouling and so can be left in place (instead of having to be withdrawn when not sailing).



I put our paddle wheel thu-hull under the sole in the area of the galley stove. It works well there and is over the deep bilge at that point so water coming in while changing out the paddle wheel for the dead-plug is no problem.

The original transducer was glassed in on the centerline about three feet ahead of the maststep. This failed after 20 years and was temporarily replaced by a hocky-puck cheap-o transducer epoxied in the deep part of the keel…again in the area of the galley stove (about three feet forward of the main companionway opening).

Our interior is not the standard factory one since we did our own…so I’m not sure if the positioning of these items is going to work in the same areas on your boat.

I did notice some complaints about water coming in forward being a problem with the mast step. On Waxwing, the mast step is mounted on a solid oak block glassed into the hull with limber holes passing under it. The butt of the mast is about eight inches above the inner hull, sitting on the oak block which sometimes gets dusty but never wet.

Thanks all for the replies to my post. Update: transducers have been successfully installed, depth located aft under port settee, and speed forward under sink. The depth took a 1 ? inch fairing block to get plumb, speed transducer might get some air when beating super hard on port tack. A good reef reminder system. :wink: