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widebeam chirp transducer

Old 07-18-2013, 08:47 AM
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Default widebeam chirp transducer

Any word on whether Airmar is pursuing a wide beam chirp transducer? There was some discussion on their blog in 2012 (here) while testing a prototype b175w (wide beam, high frequency). I'm gearing up for a boat build and like the advantages that I see in chirp, but fish in 200 feet or less of water. The narrow cone of the b175h isn't very appealing.

Thanks in advance!
Old 07-18-2013, 08:52 AM
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B75M and B75H should be good candidates for your fishing. No reason to have a "1kW" CHIRP transducer at 200'.

I have heard rumors about a CHIRP equivalent to TM270W, but I don't have any details.

The 130-210kHz CHIRP transducers used here is B75H, the fish seen at the bottom is probably bait sized.




Last edited by abbor; 07-18-2013 at 09:13 AM.
Old 07-18-2013, 10:24 AM
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Originally Posted by abbor View Post
B75M and B75H should be good candidates for your fishing. No reason to have a "1kW" CHIRP transducer at 200'.

I have heard rumors about a CHIRP equivalent to TM270W, but I don't have any details.

The 130-210kHz CHIRP transducers used here is B75H, the fish seen at the bottom is probably bait sized.




abbor --

What settings (ping, scroll speed, gain) are you using to get those well-defied arches? I don't see that on my BSM-2/NSE 12 system (with PM265LH transducer).
Old 07-18-2013, 10:50 AM
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One trick is to turn up the gain so that the weaker returns on the side show up. I post a bunch of samples in the CHIRP thread that show arches that way:



The other trick is to optimize the scroll rate for the speed. These are all with TM265 which is the same as your transducer. Transducers with wider beams make this much easier.
Old 07-18-2013, 10:53 AM
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At your 200' the B765C-LH is also an option...effectively 2 B75's in one housing.
So now one is using a dual band unit vs a single band B75.
This has a 13.73 " fairing so not the best for a trailered boat.

It will give 32 to 21 degrees on its low end and 15 to 9 degrees on its high end.

The B765C-LM is 32 to 21 degrees on the Low and 24 to 16 degrees on the Medium.

Last edited by semperfifishing; 07-18-2013 at 11:40 AM.
Old 07-18-2013, 06:51 PM
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Thanks everyone. The system I'm considering is a Simrad NSS12 networked with either a BSM-1 or BSM-2 if we use a chirp transducer. This will be on a Yellowfin 24.

Abbor, those screen shots are impressive. Even in shallow depths the resolution on the BSM-2/B75 combo is something else. At what depths do you find the B75H loses effectiveness?

Semperfifishing, good info. As you point out, the faired through-hull probably isn't a good fit for a trailered boat.

Unfortunately it sounds like there is no additional news from Airmar on the widebeam through-hull model.

Does the B75H have a wider bean than the B175H? I've seen conflicting information on this. The Airmar small boat brochure lists both as 9-15 degrees, but a Garmin brochure shows the B75H as 9-15 degrees and the B175 as 6-10 degrees. The wider beam might be a reason to select the 600W model over the 1kW.

Thanks again!
Old 07-18-2013, 08:36 PM
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Originally Posted by Time_Flies View Post



Does the B75H have a wider bean than the B175H? I've seen conflicting information on this.

The Airmar small boat brochure lists both as 9-15 degrees, but a Garmin brochure shows the B75H as 9-15 degrees and the B175 as 6-10 degrees. The wider beam might be a reason to select the 600W model over the 1kW.

Thanks again!
The B75 H is 15 to 9 degrees.
The B175H is 10 to 6 degrees.
(The 15 to 9 degrees was an error that has now been addressed by Airmar)

Using the B60/B744 as the benchmark:
The B75H has 20 times greater roundtrip sensitivity.
The B175H has 150 times greater roundtrip sensitivity.

If one is fishing in less than 200' to 300' the B75 will give excellent service ...and is cost effective.

I have use both the B75 and B175 with the Garmin GSD-26 and also the new Garmin 547.
I would be happy with any of these variations in water less than 300'....o.k...a wee bit happier with the B175.

The added cost of the B175 (About $270 more than the B75 ) is a factor that is not justified for shallow water use but is for fishing that includes deeper and more challenging conditions.

For fishing under 200' a high quality traditional tone burst system will also be a positive choice.


And lastly...Airmar is barely keeping it head above water with its current production schedule of traditional and CHIRP transducers...don't look for anything new for a good deal of time.
They are firing full throttle on all cylinders.
Old 07-19-2013, 05:51 AM
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Originally Posted by ClassicGuy View Post
abbor --

What settings (ping, scroll speed, gain) are you using to get those well-defied arches? I don't see that on my BSM-2/NSE 12 system (with PM265LH transducer).
The most important factor is transducer cone angle. At the screen shots I posted I had used B75H which have 9-15 degrees cone angle, to get nice arcs at 100' using your transducer you will have to use the Low CHIRP since the High CHIRP has too narrow cone angle for this depth.

I also have TM265LH which is the same transducer as yours but in a transom mount version, I only use the Low part of TM265 when i shallow to moderate depths and when trolling.

I adjust my settings all the time depending on range and depth of the targets so I don't remember the exact settings used.
Old 07-19-2013, 07:04 AM
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Originally Posted by semperfifishing View Post
The B75 H is 15 to 9 degrees.
The B175H is 10 to 6 degrees.
(The 15 to 9 degrees was an error that has now been addressed by Airmar)

Using the B60/B744 as the benchmark:
The B75H has 20 times greater roundtrip sensitivity.
The B175H has 150 times greater roundtrip sensitivity.

If one is fishing in less than 200' to 300' the B75 will give excellent service ...and is cost effective.

I have use both the B75 and B175 with the Garmin GSD-26 and also the new Garmin 547.
I would be happy with any of these variations in water less than 300'....o.k...a wee bit happier with the B175.

The added cost of the B175 (About $270 more than the B75 ) is a factor that is not justified for shallow water use but is for fishing that includes deeper and more challenging conditions.
B260 has 13x the sensitivity of B60 at 200kHz, B75H has 20x the sensitivity of B60. B260 is capable of detecting fish far deeper than 300' using 200kHz, based on this and also my experience with B75H I would not see a problem using B75H at least down to 500-600'.

I have learned a rule of thumb by the professional sonar guys at Kongsberg/Simrad. A 24" (60cm) cod can typically be detected at somewhere between one third to the half of the depth where a sonar can draw a sold bottom. This is supporting the 500-600' fish detection range for B75H.

80m (265') is the deepest fish I've marked with B75H, but the reason for this is the lack of fish in deeper areas where I've fished with CHIRP until now. There is nothing with this screen shot indicating this is close to maximum fish detection range. When increasing the range to the next level, the CHIRP sounder will use a longer pulse transmitting even more energy into the water.


Last edited by abbor; 07-19-2013 at 07:35 AM.
Old 07-19-2013, 08:29 AM
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Abbor...the OP fishes in less than 200'..and that is where my posting is directed.

"If one is fishing in less than 200' to 300' the B75 will give excellent service ...and is cost effective."...that is correct and pertains to the OPs post.

Of course the B75 can go deeper..but the point here is to provide information that is helpful and pertinent for the OP's fishing conditions.
Old 07-19-2013, 08:41 AM
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Originally Posted by semperfifishing View Post
Using the B60/B744 as the benchmark:
The B75H has 20 times greater roundtrip sensitivity.
The B175H has 150 times greater roundtrip sensitivity.

If one is fishing in less than 200' to 300' the B75 will give excellent service ...and is cost effective.

I have use both the B75 and B175 with the Garmin GSD-26 and also the new Garmin 547.
I would be happy with any of these variations in water less than 300'....o.k...a wee bit happier with the B175.
Gil, look carefully at your posting which I responded to once more. Not that much about 200' and less

BTW, I prefer B75H at depths less than 300'. I have a TM265LH where the High part is identical to B175H. I'm not using the High part of TM265LH in 300' or less, I've installed a B75H in addition. I have wired TM265L and B75H to my BSM-2. I'm very happy with this setup for my fishing. When I go to the coast for deep dropping I will rewire to TM265LH. Or actually I hope there will be Simrad baby CHIRP unit available soon such that I will have all the three transducers available from my NSS12.
Old 07-19-2013, 09:08 AM
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Originally Posted by abbor View Post
Gil, look carefully at your posting which I responded to once more. Not that much about 200' and less
Your too funny!.....lol

I see 3 separate references to fishing in 200 or 300' or less in that one post.




1)..If one is fishing in less than 200' to 300' the B75 will give excellent service ...and is cost effective.


2)...I would be happy with any of these variations in water less than 300'....o.k...a wee bit happier with the B175.


3)..For fishing under 200' a high quality traditional tone burst system will also be a positive choice.
Old 07-19-2013, 09:40 AM
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Originally Posted by semperfifishing View Post
2)...I would be happy with any of these variations in water less than 300'....o.k...a wee bit happier with the B175.
If I may ask, what about the B175 would make you a little happier with it vs the B75? Would that still hold true in the <200' range (as opposed to <300' as referenced)?

I should mention, btw, that our current intention is to also have the StructureScan LSS2 to work in conjunction with the sounder. So perhaps beam width is not an issue because StructureScan will help fill that need? Not sure if this changes things or not.

This is very helpful, guys, thank you.
Old 07-19-2013, 09:58 AM
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When answering to someones questions regarding transducers you quite often comes with some general information more for other people reading the thread than the OP. I think this an excellent approach, I quite often do the same, include some information of general interest in addition to answering OP's question.

What I did was commenting the general information you gave, not the specific answer to OP.

Originally Posted by semperfifishing View Post

If one is fishing in less than 200' to 300' the B75 will give excellent service ...and is cost effective.
Since the OP is fishing at 200' or less the way I read it you include some implicit information in the quote above that B75 is maybe not so well suited at larger depths than 300'

Originally Posted by semperfifishing View Post
I have use both the B75 and B175 with the Garmin GSD-26 and also the new Garmin 547.
I would be happy with any of these variations in water less than 300'....o.k...a wee bit happier with the B175.
In my opinion B175H is close to useless in 100' and less due to coverage, it starts to come to it's right between 100' and 200' and from 200' I would also prefer B175H over B75H. When choosing one transducer to be used at all depths less than 300' I would without doubt choose B75H.
Old 07-19-2013, 10:05 AM
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Originally Posted by Time_Flies View Post
If I may ask, what about the B175 would make you a little happier with it vs the B75? Would that still hold true in the <200' range (as opposed to <300' as referenced)?

This is very helpful, guys, thank you.
Everyones fishing conditions around the world of course are far different from one another.

I fish in some very difficult water conditions and one of my favorite targets is halibut...but they are extremely difficult to target with sonar as they lack a swim bladder.
Now... with CHIRP that has changed..and the more sensitive the transducer..even in shallow water like 100' the higher the probability of detecting these fish as they move so I would opt for the B175 over the B75 in this situation.
I also prefer the narrower cone in these conditions as then I can more accurately pinpoint these very elusive fish.
And since a good days catch of halibut more than pays for the extra $300. of the B175 I would think that a positive for these conditions.
CHIRP will not detect them while directly on the bottom but I have had excellent results as they go after bait and move etc.

Those conditions aside.. when fishing for anything in mid water and under better water conditions the B75 would be just fine.

Also ..when I am after salmon many times I fish such areas as the Columbia River mouth the Klamath or similar estuaries where the water is really mixed..lots of sediment and mix.
Sometimes hard on a sonar return.
Again here the extra sensitivity of the B175 does have a marked edge for me over the B75 .

In a nutshell...

Everyone fishing parameters can be very different due to their locations conditions and species sought and much more.
That is why it is always positive taking a step by step evaluation of ones own conditions when considering any system.

What works in in Alaska for halibut is certainly not what I would recommend for fishing for stripers in the Chesapeake.

Last edited by semperfifishing; 07-19-2013 at 01:31 PM.
Old 07-19-2013, 10:25 AM
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Originally Posted by abbor View Post
In my opinion B175H is close to useless in 100' and less due to coverage, it starts to come to it's right between 100' and 200' and from 200' I would also prefer B175H over B75H. When choosing one transducer to be used at all depths less than 300' I would without doubt choose B75H.
Originally Posted by semperfifishing
Those conditions aside.. when fishing for anything in mid water and under better water conditions the B75 would be just fine.

Also ..when I am after salmon many times I fish such areas as the Columbia River mouth the Klamath or similar estuaries where the water is really mixed..lots of sediment and mix.
Sometimes hard on a sonar return.
Again here the extra sensitivity of the B175 does have a marked edge for me over the B75 .
Originally Posted by semperfifishing
What works in in Alaska for halibut is certainly not what I would recommend for fishing for stripers in the Chesapeake.

These are excellent replies, guys. Thank you-- exactly what I'm looking for.

And since I seem to be guilty of not giving the entire picture, my targets in New England water will generally be striped bass, bluefish, and various tuna relatives. Most of the times depths are under 100' (75%), less frequently 100-200' (20%), and rarely to 300' or more (5% or less). This information would have been better given early in the thread-- sorry about that!

It does seem the b75 makes more sense due to the wider beam. I had been concerned the reduced sensitivity was too much of a compromise, but it still looks to be better than than a traditional tone burst system.

Thank you both.
Old 10-28-2013, 12:00 PM
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to follow up on your original request for information:

Airmar has announced the new 275W series CHIRP transducer.

It will be a 25 degree cone and available in:
B275W
Tm275W
PM275W
CM275W
B175W

http://www.airmartechnology.com/uplo...ures/B175W.pdf

Last edited by semperfifishing; 10-28-2013 at 09:41 PM.
Old 10-28-2013, 06:50 PM
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