CHIRP B265LH vs B275LHW

[Anonymous]

While refitting my boat, I will soon purchase a new sounder/transducer.
My primary use is salmon and halibut fishing in Alaska in 300' or less.
I am considering the DFF1-UHD paired with either the CHIRP B265LH or the CHIRP B275LHW.
The 265 has "bottom discrimination" but a 10 degree beam near 200 kHz, 15-25 near 50 kHz.
The 275 does not have "bottom discrimination" but has 25 degree beam across all kHz.

For finding halibut grounds, the 265 bottom discrimination could be useful if in fact it results in a more robust bottom signal signature.

For example, my old school Furuno sounder doesn't have "bottom discrimination" but still does a great job at showing mud bottom (thin red line) vs. rock bottom (thick green/yellow mass).

So my questions:

Is the difference between the two just that the 265 is programmed to sort out the type of bottom return into the 4 bins (rock, gravel, sand, silt) and the displays on the two would actually be the nearly the same, or does the 265 provide a more definitive bottom signal signature?

If the bottom signatures were close to the same, I might be inclined to go with the 275, as the wider beam near 50 kHz would be good for upper water column salmon, and I can still manually track the bottom type when hunting halibut.

Interested in your experience/perspective.

 

[Snips]

SwanSong,
I think I would lean towards using the 275 mainly because of the wider HF beam angle. The LF side of both transducers is the same. The gentlemen that are using the 275's in Alaska like the wider beam angle to track what depth their weights and baits are at. Sometimes turbulence will hinder the performance of the LF side of the sounder. As far as bottom classification goes, you still will be able to use the LH side to look at the tail of the bottom. However with the newer low "Q" transducers, sometimes the bottom hardness doesn't show up as well in the tail of the first echo as it does looking at the strength of the second/third returns.

Snips

 

[Anonymous]

Snips:
Is it the LF or HF band that is more important for bottom discrimination?
Also, the specs say the B265LH is 25 to 16 degrees for LF, 10 to 6 degrees for the HF, while the B275LHW says both LF and HF is always 25 degrees. Would the wider cone of the B275LHW result in less concentrated power on the bottom and less ability to discern gravel or mud etc? Just trying to understand how much different the bottom returns are likely to be in 300' or less.
Thanks

 

[Snips]

SwanSong,
The beam width specs (10-6 degrees) for the 265 HL side is from 130-210Khz. The HF side of the UHD transmits from 175-225Khz. The HF side of the 275 has a range of 150-250Khz it is a better match for the UHD frequency wise. The bottom discrimination mode on any of our sounders uses both frequencies to classify the bottom. Even though you may only be looking at one, it is using both in the back ground. You are correct in that the wider a transducers beam width the less energy you will have coming back to work with.

Hope this helps.

Snips

 

[Anonymous]

Thanks Snips,

I have zero experience with either. You at least have some. So do you think the difference between the B265 and the B275 would result in a meaningful difference at being able to distinguish the bottom at 300 feet or less?

Thanks

 

[Snips]

SwanSong,
Another option would be install two transducers. One would be a 265 and the other a single wide beam for the 200khz side. You could run the two high frequency transducers into a toggle switch, that way you could both features. Just a thought.

Snips