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Old 01-19-2014, 09:06 AM
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Default Downscan/sidescan saltwater application?

In my quest for upgrading my chart plotter, I am seeing all the new sounder technology available. CHIRP is not a option at this point, but I am intrigued by the downscan/sidescan technology. Is anybody utilizing this technology on the west coast for salmon or rockfish? Is it useful in waters up to 200' for these purposes, or is it just a neat toy? If I was a freshwater bass fisherman, this would be like x-ray vision, but I am curious how it functions real life in saltwater in an application like I described. I assume it would have no value offshore for albacore, regardless of the depth the fish are holding at. If it will be useful, this will affect my choice of chart plotter brand.
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Old 01-19-2014, 04:26 PM
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That's a big question that will have answered in a couple weeks once Garmin releases their unit for sale. The website says downscan uo to 700' which I have my doubts but I am hoping for 200' and will be very happy with 300'.
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Old 01-19-2014, 08:20 PM
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With my HDS 9 the structurescan is the real deal. I have found the sidescan feature more useful than the downscan. If finding structure, reefs, rock piles, bottom compositions, dropoffs and bait balls hundreds of feet out to the sides of your vessel and being able to mark a waypoint on structure off to the sides then I would say get it, you will not be dissapointed. Being able to track back on the screen and put a waypoint on some good spot you just found is a very neat feature.
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Old 01-19-2014, 08:25 PM
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As for albacore I could see where the sidescan would come in very handy in locating baitballs and albi schools, put you finger over the object and it gives you the depth, distance and heading to the baitballs or albi schools. I think that could be usefull and help put a couple extra in the box.
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Old 01-20-2014, 01:46 PM
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As for albacore I could see where the sidescan would come in very handy in locating baitballs and albi schools, put you finger over the object and it gives you the depth, distance and heading to the baitballs or albi schools. I think that could be usefull and help put a couple extra in the box.
I have been wanting to get sidescan for just such an application. The only hesitation I have is how useful it will be on days that the pond is not relatively flat (like 90% of the days out on the pacific off of the Oregon coast). If it has to be really flat water to work then the system may not be that useful offshore.

I almost pulled the trigger on a HDS12 a few months ago but decided to wait to see what others come out with. I'm starting to look into it again and may upgrade the electronics before the spring season.
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Old 01-20-2014, 04:01 PM
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Exactly my thinking on the conditions. It seems that is what is causing the CHIRP to be less than stellar in saltwater. Blurred return because the detail is so fine. Maybe less is actually more here.
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Old 01-20-2014, 07:43 PM
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I think the 60 degree fan Downvision from Raymarine is the best if both worlds. You may not have extreme side views but with 60 degrees it's like 5x the area. Even if you spot a bait ball it's not like you can turn around. that would be some serious boat driving with a spread behind you. Frankly if it's not a surface bait ball it's likely deep enough for the Raymarine wide beam. Also, it also will go down 650' vs Lowrance Simrad of maybe 150 or so.
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Old 01-21-2014, 01:37 AM
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CME, you are still welcome to post screen shots to prove your statements regarding DownVision performance at larger depths. And just not a weak bottom, but something showing value over a 2D sounder.

I've several times posted StructureScan screen shots from 90m (300'). This is the wreck of German WW2 war ship Blucher.

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Old 01-21-2014, 05:52 AM
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When I am trolling with baits on the surface of course I am looking for bait balls at or near the surface. Why would I want to find deep baits when my baits aren't anywhere near them? If I see a bait ball off to my port 50', I veer my boat to the port side and by the time my trolled baits get there, I hope for it to run by the side of the bait ball and attract the predator fish nearby. I don't want to crash the center of the bait fish and cause them to disperse. Is it better I don't know the bait fish are there and keep going straight because it's hard to turn with trolled baits? I can also mark the bait fish on my side scan screen, go up and turn wide and come right back through the center if you prefer. I know you find the lack of a Raymarine sticker troublesome, but some of us have figured out how to use technologies that don't have the Raymarine sticker technologies embedded on our bezels.
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Old 01-21-2014, 07:30 AM
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Ive seen bait balls and fish down 240' with mine (Dragonfly).

Second, I said "turn around", not turn--keep your comment in context.... If you had a super flat day and side scan actually worked and you could see bait balls 20' to the side of the boat. What are you going to do? By the time you turn around, how are you so sure the bait hasn't moved into your wake? Sidescan is great for a river, lake or a FLAT OCEAN.....But I believe the 60 degree beam is where it's at. -- I've fished it and it works damn good..... and all I had to do is turn it on. ZERO setup!!

Lowrance and simrad are just upset that their structure scan can't do the depths that Raymarine's CP100 and DragonFly CAN do. While trolling 7 knots!

I have seen many postings on the CP100 and and DragonFly. The only reason I haven't posted more is that the season isn't underway yet and the CP100 wasn't introduced till the end of the season. (2013)
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Old 01-21-2014, 07:54 AM
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And how is the sideways beam width supposed to influence the results in rough seas?

BTW, do you know the Lowrance DownScan horizontal coverage?
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Old 01-21-2014, 07:59 AM
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If you want 60 degree Lowrance has that too. Humminbird has it. Garmin will have it. It's amazing that because Raymarine doesn't have the capability to do something, it's automatically useless. Guess what, I use mine in the ocean all the time. Rarely do I get a flat day. You said seeing a bait ball on the side was useless because you can't turn the boat fast enough. I do it all the time. I have no concern with how deep Raymarine can do down vision because if you want to talk about a useless capability you just hit on one. I can see that there is bottom much deeper with my sonar than down vision. You can't see accurate structure below a certain depth unless the ocean is 100% flat, which like you pointed out is almost never. A 5 degree shift in boat from wave action(a clam day) causes over a 50' shift in your down scan beam at 300'. At 650' you will get a shift of over 110'. What does this mean? It means the bottom painted on screen is wildly different than what is below your boat in the real world. There is a saying that it is better to have no data than bad data.
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Old 01-21-2014, 08:18 AM
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Question for you Abbor,

This is a small section of the screen shot you posted. I assume that this was a boat wake on an otherwise very flat surface. Is that what happened in the very first part of your capture there? The area you were in looks to be a very protected inlet south of Oslo which would be very different than what we see in the open ocean.

Now, as far as bait balls, and finding albacore (my main target when fishing the ocean) all I really need to know is if something is there. I don't need minute detail. If it is choppy out I assume sidescan will have more "white" at the top of the water column, say maybe the top 10ft versus the top 3 ft on a perfectly flat day. But if it will still show a "cloud" for a bait ball or some type of cluttered return for a school of tuna then it is still giving me crucial info. I may not be able to turn on a dime but it is telling me there is life in the area. If I am seeing returns on the sidescan no matter how cluttered I would keep fishing the area a bit more before pulling in the spread, burning fuel to move and re-deploying. If sidescan can tell me if there is life to the left or right of my boat for up to 200 feet that is 66% more info than just old fashioned sonar and will be well worth the cost to add structure scan.

When I am fishing for Albacore I only concentrate on the top 200' of water so going deep is not a concern. Halibut Hill is another story.

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Old 01-21-2014, 08:29 AM
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Crnook, you understand it properly.

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Old 01-21-2014, 08:57 AM
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In 2' to 4' swells with any wind chop, side scan is non functional. It's been posted on the bass boat forums many times. There is way too much motion for any real imagery. So, other than a less powerful downscan beam of small angle, the Raymarine unit is STILL functional. I'll admit that it doesn't have side scan, but with 60 degrees and the ability to punch through water better, it's a better choice in rougher water. There is no setup required except range and it's spot on.

Halibut, what would you rather have, a unit WITH CHIRP and DOWNVISION capable of reaching 650+ feet or a 250 watt depth finder with a useless downscan after a hundred and a half feet or so? Also, try all that in the more turbulent ocean on the West coast.

East coast vs West coast is a huge difference.
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Old 01-21-2014, 09:20 AM
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Quote:
Originally Posted by CME View Post
In 2' to 4' swells with any wind chop, side scan is non functional. It's been posted on the bass boat forums many times.
So in 2-4' chop your saying I would not get any type of a return from a bait ball or school of tuna that is 75' to the side and say 30ft down? No grey cloud, no white-red-blue clutter on the screen? It will look just like the rest of the water column? I am not being facetious. It's a serious question. Can you provide a link to the source of your data?


Quote:
Originally Posted by CME View Post
Halibut, what would you rather have, a unit WITH CHIRP and DOWNVISION capable of reaching 650+ feet or a 250 watt depth finder with a useless downscan after a hundred and a half feet or so? Also, try all that in the more turbulent ocean on the West coast.
Halibut is a very minor concern. I can catch 6 Halibut per year, one per day. I know exactly where they will be and I burn very little fuel looking for them. If I were up north or our halibut quota was larger and I spent more time targeting them then deep water returns would concern me more. I should never have mentioned Halibut in my post above.
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Old 01-21-2014, 09:39 AM
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Quote:
Originally Posted by CME View Post
In 2' to 4' swells with any wind chop, side scan is non functional. It's been posted on the bass boat forums many times. There is way too much motion for any real imagery. So, other than a less powerful downscan beam of small angle, the Raymarine unit is STILL functional. I'll admit that it doesn't have side scan, but with 60 degrees and the ability to punch through water better, it's a better choice in rougher water. There is no setup required except range and it's spot on.

Halibut, what would you rather have, a unit WITH CHIRP and DOWNVISION capable of reaching 650+ feet or a 250 watt depth finder with a useless downscan after a hundred and a half feet or so? Also, try all that in the more turbulent ocean on the West coast.

East coast vs West coast is a huge difference.
Bass forum has a much different use case. They are looking for structure details and not bait balls. The OP is not bass fishing. The fan angle of the Lowrance down scan is the same as Raymarine, but it doesn't surprise me you don't know that. It seems we also have a quite useful down scan SCREEN SHOT at 300', so calling it useless below 150' in a thread with a SCREEN SHOT showing otherwise just shows how blindly you argue for Raymarine. You should really stop trying to insult other manufacturers products and technologies as a means to promote Raymarine. It is obvious and you don't have the technical background of the people you are arguing with. Post screen shots showing the Raymarine is as good as you claim it is and you will silence the critics. You are not dealing with anti-Raymarine people here, but I can sure tell you that you are creating them.
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Old 01-21-2014, 04:07 PM
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crnook, you and I have the same or very similar needs. Is there a cone angle horizontally as well with side scan? Meaning, you see 30' of water 100' to the side of the boat but only 10' of water at 20' to the side? I am seeing a potential high value for downscan/sidescan with regards to tuna and salmon fishing, if in fact it works in somewhat rough conditions. I fish mostly out of Bodega bay, and is isn't nicknamed BLOWdega for nothing. Also, with regards to depth, I also don't care much for what happens below 250' or so, even when I am fishing albacore way off the shelf in thousands of feet of water. Will these units still work well when they can not find bottom?
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Old 01-21-2014, 04:38 PM
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You can manually set the depth and it will work fine with no bottom. The angle you are referring to is below 6 degrees, very small. It creates it's image by adding these slivers together as the boat moves.
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Old 01-21-2014, 04:47 PM
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So at 100' I'd see about 20' of water to the side? I assume that because my cone on my b260 is 6 degrees and that is about what I see at 200 kHz at 100'. Essentially side scan only will show the very top of the water?
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