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Transom-mount Transducer Location: Single Engine, V-hull

Posted: Wed Jul 10, 2019 4:58 pm
by tdog3
Hi. I have a 2007 240 Outrage which I am getting re-powered, from twins to a single. After problems [with the SONAR depth sounder] holding bottom [at boat speeds] over 10-nautical-miles-per-hour when I first got the used boat, Brunswick helped me by providing a diagram of where to mount the transducer on the transom between the two engines. Now the SONAR holds the bottom.

I will need to have the dealer move the transducer when the new single engine is installed, and am looking for a diagram or other advice on where the dealer should put [the transducer] so [the SONAR] can hold bottom. Brunswick was unable to produce such a diagram. so I hope someone can help me determine optimal location on transom so I can hand-off that location to the dealer. Thanks.

Re: Transom-mount Transducer Location: Single Engine, V-hull

Posted: Wed Jul 10, 2019 5:11 pm
by jimh
I don't have any particular knowledge of the recommended SONAR transducer transom mounting location for a 240 OUTRAGE, but the general scheme for mounting a transom-mount SONAR transducer is given in an article in the REFERENCE section at:

SONAR Transducers ... ducer.html

For single engine boats with a right-hand propeller the usually recommended location is on the Port side of the transom. See the section of the article under the sub-headings TRANSOM MOUNTING LOCATION and SINGLE ENGINE for more details.

The usual problems causing loss of bottom echo when the boat is underway at speed are:

--turbulent water coming off the hull due to a running strake being upstream of the transducer, or

--improper depth of immersion of the operating surface of the transducer into the water; this usually is insufficient immersion, but problems can be created by too much immersion in which the transducer body creates the turbulence itself.

Most SONAR transducers designed for transom mounting will have a mechanism in the mount that will permit some up-down adjustment of the depth of immersion of the transducer.

The real knack for installing the transducer is getting the holes in the transom in the right vertical position, which will permit a range of adjustment of the immersion that will produce the proper location of the transducer working face in the water stream. Usually the manufacturer of the SONAR transducer will provide details about the mounting height.

With a V-hull boat such as an OUTRAGE, the distance off keel centerline is another factor. When the boat transitions to plane the hull will lift. If the transducer is too far off keel centerline, when the boat is on plane the transducer will be running in airy water. Checking the transom while the boat is on plane and observing where the waterline is located can be helpful in knowing how far off centerline the transducer can be mounted. Generally you want it far enough off-center so there is no possible mechanical interference with the engine gear case when the wheel is hard over in the direction of the side of the transom the transducer is located.

If the Port-side mounting is not particularly convenient due to concern about cable path or other interferences, then a Starboard-side mounting will work, too. The SONAR transducer on my boat is mounted on Starboard and works very well.

Keeping the SONAR transducer cable away from other electrical and electronic cables is important. Take care in routing the cable to minimize the chances for other cables to leak interference into the SONAR cable.

Re: Transom-mount Transducer Location: Single Engine, V-hull

Posted: Sun Jul 14, 2019 11:33 am
by tdog3
Jim, thank you very much for pointing me to that information!