Transom Mounted Transducer

[Jabez]

Hi All

Have just purchased a merry fisher 805 and i am looking to buy a raymarine elements 9 hv fish finder originally i was told that as it has a inboard engine and i would not be able to fit a transom mounted
Transducer due to the cavitation from the prop
however when i went out on the river test the guy who was with me from the marina he said it would work fine as long as it was fitted to the side of the boat
Has anyone done this heard of this and if so did it work

Cheers up front

 

[Silvercloud]

I had a transom mounted transducer on my 6m rib for many years and it worked just fine.
Just fit it as far to one side as low down as possible.

 

[Jabez]

I had a transom mounted transducer on my 6m rib for many years and it worked just fine.
Just fit it as far to one side as low down as possible.

Did your rib have outboards this is a mid engine shaft driven boat

 

[Silvercloud]

My engine was outboard but with a shaft drive like you have there is much less cavitation that could effect your transducer

 

[DavidJ]

I guess one side of the transom will have less cavitation than the other. Worth some experimentation before you start to drill holes.

 

[Davy_S]

Fasten the transducer to a length of wood, then G clamp it to different areas of the transom, find out where it works best before you fix it permanently.

 

[Jamie Dundee]

Antares 760, very similar to the 805. I wanted to fit the Totalscan transom transducer from my previous boat, the preferable side would have been to starboard of the right handed prop except that there are three raw water intakes in a line (stern gland, engine and deck wash) on that side. I fitted the td to port of the prop, more in hope than expectation, and it works perfectly. Standard 200mhz, high and low chirp and down/side scan. Wonders never cease

Old photo, pre antifoul, anodes etc but you get the drift.

 

[Jabez]

Antares 760, very similar to the 805. I wanted to fit the Totalscan transom transducer from my previous boat, the preferable side would have been to starboard of the right handed prop except that there are three raw water intakes in a line (stern gland, engine and deck wash) on that side. I fitted the td to port of the prop, more in hope than expectation, and it works perfectly. Standard 200mhz, high and low chirp and down/side scan. Wonders never cease

Old photo, pre antifoul, anodes etc but you get the drift.
View attachment 95304

Would it be possible to fit one to the underside of the swim platform do you think save having to drill holes in the hull ??

 

[Jamie Dundee]

Would it be possible to fit one to the underside of the swim platform do you think save having to drill holes in the hull ??

No, as a) the swim platform (at least on mine) is rarely in the water and b) the transducer would be in all the disturbed aerated water coming off the hull. No problem with a couple of well sealed holes in the hull. Or Sikaflex a piece of wood to the hull and screw the td to that.

 

[Pleinmont]

Interesting post this - i have an Antares 760 and was keen to fit a 3-1 Chirp/Structure stern transducer that came with my Simrad Go9 but was equally put off by most people saying the signal would be trashed by the propeller wash. My boat still has it's orginal Raymarine DS500 and it's a good clear image from the thru-hull transducer but it's getting a bit long in the tooth now.

For minimal disturbance I was assuming the starboard side would be best for the TD but you have made me rethink this (and good point about the other hull fittings further to the bow).
Do you have any screen shots from your totalscan sonar that you could post?
Be really interested to see what they look like.

Thanks for the inspiration

 

[Pleinmont]

Sorry Jamie I meant to quote you on the reply above.

Also, how far in from the edge of the hull did you fit the transducer?

Thanks

 

[Jabez]

Sorry Jamie I meant to quote you on the reply above.

Also, how far in from the edge of the hull did you fit the transducer?

Thanks

Hi have just had twin transducers fitted to my merry fisher 805
Went down yesterday to have a look at there placement I will attach a couple of pics
She gets relaunched today so fingers crossed there are no issues

 

[Jamie Dundee]

Sorry Jamie I meant to quote you on the reply above.

Also, how far in from the edge of the hull did you fit the transducer?

Thanks

First rather fuzzy pic at around 17kn, not much detail but clear bottom and depth. The second pic was at around 6-7kn which shows much more bottom detail, sidescan is also ok at these lower speeds.

Didn’t really understand the question, the transducer is between the trim tab and rudder mounted as low as I could get it.

 

[Pleinmont]

First rather fuzzy pic at around 17kn, not much detail but clear bottom and depth. The second pic was at around 6-7kn which shows much more bottom detail, sidescan is also ok at these lower speeds.

Didn’t really understand the question, the transducer is between the trim tab and rudder mounted as low as I could get it.

Nice one, thanks - those images look way better than I had hoped might be possible given all the advice not to put that type of TD on the back of an inboard boat.
Very impressed. Once I get this week's leak sorted that will be next on the list!

Sorry re the question, I just wondered how far along (laterally) the TD is mounted - you've obviously hit a sweet spot to copy
Say how far left of the centreline?
It looks like you've attached it about 2ft left of the rudder (when centred)?

 

[Jamie Dundee]

Sorry re the question, I just wondered how far along (laterally) the TD is mounted - you've obviously hit a sweet spot to copy
Say how far left of the centreline?

I’d have to check to be exact. I’d have preferred it further outboard but didn’t want it too close to the trim tab. Stuck between the devil and the deep blue sea so to speak but it works surprisingly well.

 

[Pleinmont]

I’d have to check to be exact. I’d have preferred it further outboard but didn’t want it too close to the trim tab. Stuck between the devil and the deep blue sea so to speak but it works surprisingly well.

Thanks, nice one - yes does look like it works perfectly well.
I've tried loads of times to find screen pics or evidence online of whether this type of install worked out ok on inboard boats but always drew a blank.
Thanks for posting the pics and info

 

[tillergirl]

V. interesting Jabez. The manufacturers have recommended I don't use a transom 'ducer (shaft). I think they cannot guarantee a transom 'ducer so they recommend a pair of thru-hulls with a splitter cable. But I think your people have adapted the transom 'ducer as a thru-hull and I assume just a standard second ducer was fitted in the same way. That would save £1K for two thru-hulls. Am I right it is an adapted transom 'ducer? And how is the side scan performance please?

 

[Irish Rover]

My previous boat was a Jeanneau Leader 805 with a VP D4 and outdrive. Against all advice, I fitted a transom mounted transducer and it worked perfectly well for 7 years at speeds up to around 8/9 Kn. It became a fuzz at speeds above 10 Kn but resumed normal service once back down around 7.
I now have a power catamaran with twin props and again, contrary to advice, I fitted a transom transducer on the starboard hull. As the hull is relatively narrow the transducer is effectively directly aft of the prop but it works perfectly well, at least at my normal speed of 7/8 Kns. I rarely go above 8 Kn so I can't honestly say how it works at higher speeds.

 

[Jamie Dundee]

Just found a better pic on a different iPad, this one’s a bit clearer. The increase in ‘noise’ in the water column corresponds to an increase in speed. Still not too bad for 16kn though.

 

[Pleinmont]

Thanks for the extra pics. Looks good.

By the way, does your propeller turn clockwise or anti clockwise (when looking ahead)?
Just wondered for prop wash being worse one side than the other when going along.

Mine looks to bite clockwise and the stern moves slightly to starboard when you put it in FWD.