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Full Version: Airmar R109LH/ LM or LHW with Raymarine CP570
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Am new to this forum, so I take a chance first to say Hello to everyone.
Navigation area: Adriatic/ Croatia
Fishing conditions : offshore. Depth range 15 to 200 m. typically + deep sea fishing down to 1.200 m.
Currently own Botnia Targa 32 equipped with e165 display + CP100 sonar + CPT120 Transducer.
Looking to upgrade to CP 570 Chirp sonar module.
Question : considering the above, what would be the best 2 kw thru-Hull transducer in between R109LH/LM/LHW to optimize detection.
R109LHW seems a good candidate with the advantage of the wide beam, although the High Wide frequency is limited down to 500 feet - not enough to reach the typical +/- 656 feet (200 m.).
Should I therefore rather consider R109LH with narrower beam yet deeper (1.500 feet) signal or the R109LM, which will not give as a good signal in the upper 150 m. ?
Or else, should I rely on the CP100/CPT120 combo to give me the upper water column High frequency signal and therefore combine with the R109LM. I doubt this is the right way to go, since I am not impressed by that configuration.
Not sure I want to use two detectors ( budget issue), although I'd be interested to hear your comment about that option as well.
Thanks in advance. Do I dare saying this is URGENT as my dealer awaits my decision and the boat is on dry berth.
Thanks in advance.
Hello Michel,

For urgent support, I would always recommend calling us or your Raymarine national distributor. You can get a list of contact points at https://www.raymarine.eu/view/index-id=773.html. Croatia is looked after by Raymarine UK technical support and Raymarine Italia in Milan.

The LHW (and also LWM such as R409) transducers are fantastic if you are looking for pelagic fish (e.g. tuna) in the top 150m or so, but are not good for looking for fish close to the bottom or for bottom structure because the wide beam spreads the power over a large area, and blurs the fine details of fish close to structure and the structure itself.
The LH transducers give the very high level of detail from High Chirp into quite deep water, and are very good at showing the details of fish around bottom structure, but are bad at showing fish in the water column because of the narrow search-light beam.
If you want to do a range of fishing then the LM transducers are a good middle-ground: they have better depth performance and structure detail than LHW, but a wider beam for mid-water fishing than LH, and they still give very crisp detail and clarity: far better than 200kHz non-Chirp and very usable in <10m of water. They have another advantage that fish such as tuna can show up very well at that medium frequency around 80kHz.

I don't know exactly what sort of fishing you're doing in those depths, but it sounds to me as if LM might be the best option for you.

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