Transducer Questions

[toplsvette]

Hello All,
I just bought a new Northstar M84 Setup (@ turtle marine for 1199.00) and am wondering which transducer would best suit my fishing. The unit will do both 600w and 1kw. I fish alot offshore in the gulf but only in 200' or less waters. I also fish in shallow waters behind the house. The 1kw transducers go for $700+ and would rather not spend alot more $$$ if a 600w would be sufficent. I would appreceiate any feedback..

Thanx,
Eddie

 

[Boatist]

Re: Transducer Questions

I do not know your unit at all but 600 watts RMS is plenty of power for 200 feet of salt water.
600 watts RMS is the same as 4800 watts PEP.
Cone angle of the transducer also makes a difference. A narrower cone angle will work deeper.
An Example is my Lowrance depth finder has 375 Watts RMS or 3000 Watts PEP.
Off shore in the Pacific ocean we can see fish down to 150 to 175 feet with my 20 degree 200KHZ transducer.
Deeper than that all we see is the bottom.
When I switch to my 8 degree 200 KHZ transducer with the same power can see fish to more than 400 feet deep.
This is because to signal is more concentrated. It like useing a spot light instead of a standard light.
So with 600 watts of RMS power even with a 200 Khz 20 degree you should be able to see fish to at least 300 feet of salt water.
If your useing a 50 khz transducer then would be able to see fish much deeper still.

 

[toplsvette]

Re: Transducer Questions

Thanks for the reply.. I should have mentioned the unit does transmit in 50kz and 200kz. Your answer was just what I was looking for. I picked up a airmar p66 transducer that is a 600w 50-200kz. The m84 will allow you to use a split screen that shows both the 50kz and 200kz at the same time so i think i will be in good shape come fishing season. Thanks again for the good info..

Eddie

 

[Boatist]

Re: Transducer Questions

The 50 khz frequency will likely have a wider cone angle, about 45 degrees is standard and 37 degrees is narrow.
Still the 50 khz will penatrate salt water much better than the 200 khz.
200 khz transducer will give more details like seeing individial fish in a school or seeing a fish on the bottom.
The 50 khz the fish on the bottom will usually look like part of the bottom and a school of bait fish will look like a big blob.
Fishing rocky or uneven bottom or even a sloped bottom then the transducer with a narrow cone angle
will show the most fish right on the bottom because of the dead zone.
Airmar makes great transducers so it should work great.
As with all depth finders make sure to turn the sensitivity up so you have many false return at the depth you are fishing.
So if your fishing bottom in 200 feet of water turn up the sensitivy until you see some false returns near the bottom.
This may mean the top of the screen near the surface nearly solid black from surface clutter.
Most of the good fish finders will have a control for surface clutter that will allow you to turn up the sensitivy for fishing deep
and then adjust surface clutter control to reduce the return near the surface.
Some even automaticly adjust sensitivity on each ping so the sensitivy is low right after the ping and
increases as the signal get deeper and weaker until it see's the bottom echo.
Then the process starts all over with the next ping.
Have fun and catch lots of fish.

 

[Mark_VTfisherman]

Re: Transducer Questions

I learned stuff. thanks!

 

[dingbat]

Re: Transducer Questions

The M84 is a digital sounder so depth is no longer the determining factor. It's the resolution of the transducer that makes the difference.

In the 600W transducer they use a single element then excite it using both frequencies which is not optimal for performance. The 1 kW transducers use multi or arrays of elements. They use 50kHz elements for 50kHz and they use a 200kHz elements for 200kHz. The results is a (B164 - mid-price 1kW) transducer that is 2 X times as sensitive @ 200khz and 6 times more sensitive @ 50kHz. If you jump up to say the 264N transducer your looking at a transducer that is 13X times as sensitive @ 200kHZ and 50 times more sensitive @ 50kHz than a 600W transducer. You now have the depth and wide vision capabilities of the 50kHZ transducer with a resolution far superior to that of a 200kHz transducer.

I?m running a B614 on a Furuno 585 sounder. The B164 provides as good if not better picture in 30? of water @ 50kHz than any 200kHZ picture I?ve ever seen on a 600w transducer with an old school power head. The difference is like going from regular braodcast television to HD. If you can afford the 1KW transducer that?s the way to go.

http://airmartechnology.com/uploads/brochures/High Performance Comparison.pdf