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Transducer for Boston Whaler Conquest 325

Guest Contributor

We have a Conquest 325 with two through hull transducers installed (B175HW and B175 - both 20 degrees).  The depth reading drops in an out on occasion (often in shallow water) and I am being advised by the dealer that 1KW transducers are too powerful to read reliably in shallow water. I'm told the signal strength is too high in shallow water and when it bounces back the reading is corrupted and so goes to nil. The dealer solution is to install a transom mounted transducer to read depth and leave the through hull transducers for fishing. This is not ideal as the boat is stored in Seapen and so the transducer has to come up and down each time the boat is used. 

This is the first Boston Whaler I've owned. My previous boat was a 6.2m centre console with one x 1KW through hull transducer and it always read the bottom (shallow or deep - I didn't use it above 100m).  I expected a Boston Whaler would be able to have a reliably reading through hull transducer for general running and reading depth. The electronics are Raymarine AXIOM MFDs, and when using the sounders for fishing the units appear to be working well.  

Does anyone have any similar experience and if so, do you have any tips on how I can get accurate depth readings without having to use a transom mounted transducer?



Guest Contributor

I had a similar experience (Raymarine Axiom Pro). Wasn't a problem, per se. Just noticed that the depth reading would go haywire over certain shallow areas (Depth: 4'). There were a few areas where it occurred constantly. The water was murky but I'm guessing there is something weird on the bottom in those particular areas. 

That was a few years ago. I keep the Axiom software updated and we now boat in a different area.  Currently, we never go shallower than 6th feet. I don't recall seeing anymore weird fluctuations in depth readings. 

For more detailed troubleshooting, you may want to email Raymarine directly. They can be quite technical in their responses but they are extremely knowledgeable and serious about their products.

I don't turn my fish finder on in shallow water, so I believe those transducers remain off (I may be mistaken). However, my Outrage came with a Smartcraft Depth Transducer (the first page of the manual describes offers a dirty water explanation and limitations).

Sidenote: Be sure to register all of your electronics, and keep the software up to date. 

I hope this helps!

Thank you very much for posting the suggestions. Since I uploaded my post, I have been back to Raymarine and they have proposed a new solution - a through hull zero degree transducer that will read depth in shallow water. The transom mounted unit is not reliable and should not have been specified knowing the boat is in a Seapen. I also received a reply to an email I sent to the manufacturer of the high and low chirp transducers and they confirmed those units are not going to read depth when in shallow water. 

We'll see how the new through hull transducer goes when it gets installed. Not sure when that will be, but hopefully in the next couple of weeks. 


Guest Contributor

Great post and glad to hear of progress. I have one 1,000 watt B175 on the current Outrage hull; not sure of the orientation. 

Raymarine's explanation makes perfect sense regarding the B175 1,000 watt performance in shallow water. I'd like to hear how your new transducer performs.

I'll have to check under my hull to get re-famliar with my setup. Now I'm curious to know what reads my depth while the fish finder is off.

Guest Contributor

Morning R_Bluewater.  We had the through hull transducer (RV-200) fitted and picked up the boat on Friday. On the run home it worked well in the shallow water while travelling at 6knots, but we lost the depth at what looked like anything over 24knots. Raymarine  and the dealer say this is normal and to be expected (nobody told me).  Apparently some hulls will hold the bottom at >40knots but this one does not. Has anyone else had this issue on a Conquest 325? Mt previous boat is a Seafarer 6.2m centre console and it held the depth at all speeds (up to 40knots). 

Thanks for following up! Although, I regret to hear of the unique tendencies that you’re experiencing. Just FYI, it remains extremely rare that I lose bottom depth on my 2019 Outrage 230 hull (even at top speed), and the fishfinder provides clear readings up to about 25 mph, depending on water clarity. 

I’m really curious to hear from others who have your hull. If you haven’t posted already, you may want to check for feedback on some additional sites 😉

Thanks for the tip. I actually did register on the other site you suggested on the same day as I updated this post. I'll keep an eye on it, but couldn't find similar issues after searching.  We'll keep using it to see how we go. Maybe I just had higher expectations of the Whaler? 

On the bright side, it sounds like you’ve pinpointed the issue. It’s great that Raymarine was able to weigh in, but it seems your transducer installer may not have fully comprehended the concept of a Seapen (I had to Google it, myself. I’m fascinated by the technology but have yet to see it in in person). Now I’m wondering what Seapen users do for bottom readers. 

I don’t know the physics of why a rear mounted transducer is preferred for depth (rather than a through-hull). However, maybe there’s a different brand throughhull transducer that Seapen users tend to have installed. It’s a longshot, but perhaps Seapen can offer some ideas. If the company has been around for a while, I’m guessing they may have seen this challenge before.

Just a thought.