FV 342 Replacing Depth finder

davidbrooks

My stock depth finder decided to go this past summer so i bought a new one.  The stock one is the old Lawrence model that is almost impossible to just upgrade.  The newer units aren't compatible with the frequencies of the older transponders.  I went with a Faria and as i already have a hole in the boat i got a new in hull transponder as well.  So this winter i was going to pop out the old one and put in the new one.  I am looking for advice from anyone that has ever swapped out in hull transponders.  Existing one is plastic and just forward of the Starboard engine.  Not easy to get to but doable.  Honestly my first thought was to just cut the wire, and beat it out with a sledge hammer.  Drill the hole clean, clean up the bottom and pop in the new one.  

Anyone have a more elegant or less bull in china shop approach you would recommend?

Thanks.

Ian

I wasn't keen to touch the old one so went a different route. I have an HDS-5 GPS/chart plotter that had been fitted before I got the boat but the stock dash mount finder and transponder were still in and working. But I wanted another knowing how good the Faria gauges were so I ran a new transom mount in and connected to it. Now I have hull depth plus waterline and water temp on the HDS-5.

Lowrance told me all gen 1 HDS units can use all traditional sonar blue connection transducers.  I used the Transducer part# 106-77 HST-DFSBL,Transom-mount, dual frequency skimmer with built in temperature sensor. I also had to get a 12' extension cable, part# XT-12BL to add to the 20' on the transducer.

I also thought there may be interference with the built in puck and after questioning they replied: The 3500 (existing) uses a 192kHz transducer and the HDS-5 uses a 200kHz transducer. With them being 6' apart you should not have any interference. With the existing forward of stbd engine, I fitted the new back corner port side, well away from it and as far possible from outdrive.

davidbrooks

Thanks I also have a backup fish finder that is a transom mount and it works great...up to about 24pmh.  So i was looking for something that would also work full time.  Mine was just blinking a random number and i hate not having working parts on a boat so it was time to replace.

zaverin1

I believe you are talking about the drilled thru the bottom of the hull ducer?
if so make sure you double check the Id of the existing hole to make sure New ducer will fit nice and snug.
if it’s the same size you will have to drill it out from the outside in and then collapse it. Once that’s done you will have to clean the edges and install your replacement.
if they are different sizes then you will have to drill opposite side of the boat for new ducer.
you other option could be in hull ducer that doesn’t require drilling. Base mounts to the glass and gets filled with antifreeze. Then ducer gets mounted to it and bingo.