Which FishFinder for 1500ft Depths???

[Kamalot]

Soon getting a new Boat, and could use some help from experienced deep water users! The unit on my old boat was only good down to 1000ft and once I went over that depth it was useless!

Thanks Anchorpoint

[Mark Mc]

Quickie reply for ya; others can elaborate -

The 4 main things that affect how well a fishfinder can see things on the bottom in really deep water:

1) frequency - lower freq. is better than higher (i.e. 50 kHz better than 200 kHz). It's a physics thing..the same reason the bass notes come right through your car from the guy in the lane next to you with his boom box...

2) Power - how many watts...use RMS (root-mean-square) figure, NOT peak-to-peak....

3) Cone angle of signal from transducer... given the same amount of total power, a narrower beam angle gets more energy per unit area (i.e. mw/cm^2) onto the target. This becomes progressively more important the deeper you go.

4) Mounting / installation of the transducer in such a way that little or none of the energy is lost. Through - hull allows the signal to hit clean (i.e. bubble-free) water directly. Inside the hull, you may lose some energy, depending on density of the hull material. Transom mount, you are prone to air bubbles interfering, esp. the faster you go.

All of these factors combine, with the sum-total being "how much energy per unit area can you hit the bottom with?" And the higher this answer is, the better you will be able to see halibut or lings on the bottom in 100 fathoms, or maybe even Jimmy Hoffa...

Good luck,

Mark

[Kamalot]

Thanks Mark, but I should've stated another bit of info. Even though I'm fishing in 1400ft of water the fish are usually anywhere between 20-140ft yet my old Fish Finder was still useless in spotting these fish once over 1000ft of water!!

[WP]

for relatively inexpensive purposes, the Garmin 240 blue works for me. If a fathometer can't locate bottom, they usually have a hard time in total. been there done that! I replaced a Bottom line with the Garmin because I had the same problem as you talked about. The Garmin usually performs reasonably for Halibut waters (600') to the tuna grounds (1500 plus) but still occassionally will "get lost". A reset will get it back on the bottom lock. Boat speed also has a big bearing on performance. The deeper the water, and the faster you go, the harder it is for the unit to stay locked on.
Dave

[ 02-14-2004, 02:31 PM: Message edited by: WP ]

[fishwhenican]

I have a Garmin 240. The trick to marking fish is to set it for max depth display of 200-300', then it seems to give up trying to find the bottom and starts marking fish even if it isn't registering the bottom depth.

[DB_Cooper]

After much research I decided on the Lowrance X126DF. Price, resolution, dual frequency and depth range were all met with this unit. Just installed it so I have no report yet on the performance. Here's a link

I have an old Raytheon V700 that is good to 999fa but it was obsolete a long time ago. When you get this deep the return signals aren't that good.

[Sensei-san]

Keta... whadda mean the Raytheon V-700 is junk? It was a great depthfinder in its day. I had one for years.

If you are really serious about using a fishfinder at 250 fathoms it will take a commercial fishfinder with a genuine 1kw of power or more to give you a readable signal. Anything else will be meaningless.

Besides there is practically no rod and reel equipment that can fish that deep and still call it sportfishing. If you are talking about tuna fishing, the surface depths to 500' are all you really need to look at. Most depthfinders can give you a good image just shooting the top layer.

Like everything else in fishing. One size does not fit all.

Not Junk!!!!! I've had it for years and it is still working good. It just fuzzes out at around 700fa and you loose the good resolution at around 350 to 400fa. I was able to spot halibut on the bottom in 40fa by running the split screen at bottom to 10 feet off the bottom and 10 feet off the bottom down. The second screen showed slightly into the sea floor and by comparing the two views of the same thing we were able to spot the butts. I opted for more power and the amber screen rather than color.

The V700 was $1000+ commercial sounder in 1989.

Sensei, are you at home or Windy Bay?

[ 02-14-2004, 06:14 PM: Message edited by: Keta ]

[Sensei-san]

Nope... I'm avoiding nephew... He has been bitten with two foot-itis. From past experience I know what that means. I have to hold the telephone receiver two feet from my ear. He calls everyday about this boat and that boat. I can do a really good imitiation of... "Ehh??? My hearing aid batteries must be going out..."

Keta... You give away too many good fisherman secrets... I doubt that too many guys have figured out what the bottomlock feature is on most depthfinders.

:grin:

[Miss B Haven]

Originally posted by anchorpoint:
Thanks Mark, but I should've stated another bit of info. Even though I'm fishing in 1400ft of water the fish are usually anywhere between 20-140ft yet my old Fish Finder was still useless in spotting these fish once over 1000ft of water!!

<font size="2" face="verdana,arial,helv">If you are trying to see fish at 20-140 and have your unit on full bottom scale in deep water you won't see anything (on just about ANY unit). It's not that the unit isn't "seeing" the return, just that you can't see the return on the display.
You need to set the range to where you want to see the fish. Just like bottom lock, you need to narrow down that window. Set your unit so the top of the screen is at 20 and the bottomn is at 140 (or the closest you can get to that). Most units can split screen, one side with full depth scale and the other either bottom lock or a set range.

[Kamalot]

Thanks Mel,

That's SOUND advice! Using your information I should be able to stay within my budget.

Thanks Cory