[jfish]

Ok guys, it's too windy to fish and too cold to work on the boat. Figured I would use this time to try and get some education. I'm interested in trying to perfect my Bottom Machine skills. I realize ever machine if different and depending on what you are targeting will determine how to set the dials. But generally speaking educate me on what you do while targeting tunas. ( the things you do that work :thumbup

Equipment: Raymarine C*80 1000 watt thru hull transducer. (everything hooked up and working well)

Conditions: Average water conditions, area of "Point" 100fa +-

General questions: Feel free to answer and say why or pros and cons
1. Frequency?
2. "A" Scope?
3. Zoom, what range or what portion of water are you looking at?
4. Gain, Auto and Manual? If manual what are you looking for in setting?
4. Scroll speed
5. Any other setting that helps or need adjusting?

Thanks

 

[kapoc]

Their was a great thread about this last year but i will chime in my .02 to get you started. Go to man setting and adjust your gain till you can mark the thermocline, as far as the speed as fast as she will go, no zoom thought as your looking for the tunas not looking for bottom fish

 

[ultangler]

IMHO:

1. Frequency - stay on high until you lose the bottom, usually between 600' and 800' depending on the unit & transducer. Go to 50khz only when you have to, to get a bottom reading, and don't expect to see a whole heck of a lot more with it.
2. "A" Scope - irrelevent for this type of fishing, unless you can stare at the FF screen non-stop, you'll miss the A-scope return 99% of the time anyway.
3. Zoom, what range or what portion of water are you looking at - in water that deep, you'd only want to zoom if you were looking for tilefish or orhter groundfish. Otherwise, keep your eyes on the top portion of the water column. One exception: a strong thermocline with fish holding just above/below it, you may want to zoom to keep a sharp eye on it.
4. Gain, Auto and Manual? If manual what are you looking for in setting - Auto on modern units is great; you shouldn't need to go to manual unless conditions are causing a cluttered screen. Lots of guys will disagree with this, but it's what I've found over the past few years of using a lot of different units.
4. Scroll speed - as fast as possible; even then you'll have plenty of history.
5. Any other setting that helps or need adjusting - I know you mentioned the deep, but when looking for bluefin on the inshore lumps bottom lock is a good move. Many of those fish will be spotted 5' to 10' over the bottom. If you're trolling I suppose it doesn't make a huge difference, but jiggers will want to spot these fish, stop ontop of them, and drop.
Now, for the other winter acivity: start rigging!!!

 

[jfish]

Here's a follow-up question?

I have heard folks say that when trolling for tuna no need to worry about whats 400+ feet down? Zoom in on the top several hundred feet of water as that is where you target fish will be coming from. Any word on this??

 

[lmontagnaj]

Here's a follow-up question?

I have heard folks say that when trolling for tuna no need to worry about whats 400+ feet down? Zoom in on the top several hundred feet of water as that is where you target fish will be coming from. Any word on this??

If the fish are too deep, they will never see your baits. I troll a little on the fast side when trolling for tuna and have spreads that produce quite a bit of splash to get the fish interested in coming up for a look. It works for me.

Also, if I mark fish that are deep and I am not getting bites, I'll often try dropping the planer down with a nice long wind on leader. It has saved the day on occasion.

I keep my sonar on duel frequency and am constantly comparing both low and high freq., it's amazing the difference you'll see between the two sometimes and I'll drill a hole on a mark until I can squeeze some bites out of it.

Good Luck

 

[Chumlord]

Ok guys, it's too windy to fish and too cold to work on the boat. Figured I would use this time to try and get some education. I'm interested in trying to perfect my Bottom Machine skills. I realize ever machine if different and depending on what you are targeting will determine how to set the dials. But generally speaking educate me on what you do while targeting tunas. ( the things you do that work :thumbup

Equipment: Raymarine C*80 1000 watt thru hull transducer. (everything hooked up and working well)

Conditions: Average water conditions, area of "Point" 100fa +-

General questions: Feel free to answer and say why or pros and cons
1. Frequency?
2. "A" Scope?
3. Zoom, what range or what portion of water are you looking at?
4. Gain, Auto and Manual? If manual what are you looking for in setting?
4. Scroll speed
5. Any other setting that helps or need adjusting?

Thanks

I have a Sitex 832, 600 watts w/a transom mount transducer.

Freq at 100 fathoms I use 50 kHz 200 kHz won't punch through that deep. A scope no. Zoom when bottom fishing I use bottom lock (like zoom but it zooms on the bottom) my zoom feature can be set to look at a specific section of the water column. I look at the top 10 or 20 fathoms when trolling for tuna in 200 kHz mode. My unit won't read well in 50 kHz while trolling at seven knots too much "noise". Gain manual and adjust till the "noise" just goes away kinda like when you set your radar's gain. Scroll speed as fast as possible. I also reject certain colors to get an accurate representation of what I am looking at Basically eliminating all but the most solid returns.

 

[jfish]

I'm really starting to think only zooming in on the top 3rd of the water column may be the ticket.. I have no question the equipment I'm using should get the job done. Just want to make sure I'm using it most advantageously..

 

[twobyfour]

Post this on the "Hull Truth".

 

[Persistence2]

Question...why the fast scroll speed? Is this also standard for say Rockfish trolling?

I have not used my new Furuno 620 offshore much (only a handful of trips) but inshore, I'm just curious as to the fast scroll speed and why.

Thanks guys.

Glenn

 

[Chumlord]

The reason I always understood is that your machine is giving you more data that way in other words it's showing you what's under you boat faster and more often. Hard to explain typing. But if your screen scrolls as slow as possible you will need to wait longer for updated info.

 

[usual suspects]

Depthfinder

this has a lot of info...A-scope works well locating structure.

Reason for fast scroll is scanning bottom for "real time" relative to a-scope. however, some garmin machines scroll a little too fast

 

[Tuna Hound]

Fast scroll stretches the signal out so you can see it. What may be one pixel on slow would be several on fast (a dot vs. a streak). The disadvantage is your screen rolls faster and if you aren't watching could miss it. I have a furuno 1850 and it has an interesting feature where a deep object is made to appear larger on some logrithmic scale.

 

[Persistence2]

Thanks guys...I'll try pumping up the scroll speed on my Furuno

 

[jfish]

After reading post on other sites and info here, I'm thinking I need to peak the transducer power, watch top 1/2 or 3rd of the column and significantly reduce the filters if not completely off. Still thinkin on this one?

 

[Reel Draggin Tackle]

For many, the auto functions on the newer units will fit most needs. To get the most out of your unit you need to put it in manual and tweak gain and filters for the different conditions you are fishing in. Most of the sonar return from a fish comes from air bladders. When fishing offshore for tuna, you have several things working against you, small air bladders, high frequency attenuation (loss due to rand/depth). You have to work the gain and filters to make sure you are not filtering out target. We use split screen, 200 Khz to watch down to 200 feet and 50Khz to watch the deep. We only use a-scan/scope when looking for structure, like when setting up on a wreck.