FishFinder - Which one?

I need a new depth finder/fish finder.
I really want the dual imaging because I am more concerned about the bottom detail than the fish.
Right now, I am trying to decide between the Garmin Echo 301Dv and the Humminbird 561 DI. They both fit the bill as far as features and price.
I sure the Garmin with color would be much easier to see in all conditions than the Black/greyscale Humminbird would be.
Anyone here familiar with either of these units?

Thanks in Advance

Tony B

Garmin with the Down Vu all day long IMO.

Simrad StructureScan is current state of the art. Though Furuno lovers may argue with that. Lowrance has a budget version but I haven't seen it.

Thanks for the input guys.
It turns out the Humminbird 561 was defective and so it was returned. Problem was with the transducer running intermittent. I liked the screen size but didn't like the grayscale. Hard to see at some angles because of sunlight glare. Anyway, I returned it and ordered the Garmin with a much smaller screen but it is in color.

I'll offer my two bits worth: Simrad probably has the best technology and research of any of the manufacturers. They build high-end systems for fisheries research and commercial fishing applications. However....

You should be aware that the devil is in the details and I suspect that most of the vendors oversell the capabilities of their units. Most units only show "targets". Whether these targets are fish, debris or entrained bubbles is uncertain for the most part and requires "biological sampling" for confirmation. In other words, you need independent knowledge of fish in the area and their likely abundance and target strength. Even in fisheries applications where users should be better informed, there is considerable uncertainty and misinterpretation of results. Where conclusions about target information are important, most researchers are moving towards imaging sonars. The prices of these units have declined to a more modest $80,000 USD. See for example DIDSON. Note however that these units are only capable in 2D, typically distance and width of the horizontal plane: In a side-scan application, you cannot determine the depth of a target. They are also very susceptible to pitch and roll of a boat, the effects of which increase dramatically with range.

"Bottom" or depth is more certain, however a pitching or rolling boat often results in overestimation of depth. In addition, the user should be VERY careful in interpreting side-scan sonar information for identifying near-field obstacles. Note that when one edge of the beam strikes a strong target, such as bottom, objects further away from the source of the beam are uncertain and not interpretable without bias. Beam-width becomes an important consideration for longer-range side-scan sonar applications, particularly in shallow water.

I am VERY suspicious of the claims of the "Simrad StructureScan". As the range of an imaging sonar is increased, the width of the individual beams increase and detail is declines exponentially with range. You WILL NOT get the same resolution at 100 meters as you would at 10 meters. In addition, you should be aware that these sonars ARE NOT 3D! Only very high end units such as CODA OCTOPUS achieve such capabilities and require very sophisticated echo integration technology. Also, in the 3D applications, the results are not real time: i.e., you don't get instant gratification--you achieve the 3rd dimension by moving the transducer platform, something that requires absolute platform stability. My team used DIDSON technology. I have since retired from fisheries work.

Other situations that are problematic for hydroacoustics technology occur when a vessel passes between or over water with different densities such as haloclines, thermoclines, or convergent tidal fronts. Large aggregations of plankton, jellyfish or small particulates can also blank out a sounder.

Jim

I am VERY suspicious of the claims of the "Simrad StructureScan".

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I have seen it in action first hand here in NC, over various bottoms, depths to 300 ft, including wrecks. It is VERY good, especially when also mated to one of the new CHIRP technology transducers, which are amazing if you need to see more and deeper. But then, I am something of a suspicious character myself....

caltexflanc said:

I have seen it in action first hand here in NC, over various bottoms, depths to 300 ft, including wrecks. It is VERY good, especially when also mated to one of the new CHIRP technology transducers, which are amazing if you need to see more and deeper. But then, I am something of a suspicious character myself....

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We have had a Structurescan on board since last year, and it is phenomenal in my opinion down to about 350 feet. The bottom detail is incredible, especially on the 800 kHz setting, which is good to about 150 feet. The 455 kHz gets you to 350 feet with only a slight degradation of detail.

It has two viewing options, downscan, which gives a "standard" perspective of the bottom, and sidescan, which gives a "3D" (not really) bottom view of both sides of the boat. The latter is a bit of a challenge to interpret, so I've been primarily using the downscan view.

It truly is a quantum leap forward in seeing the bottom in detail. (I've also seen Garmin & Humminbird versions on display and they look very good as well.)

But I'm not a fisherman so can't tell you how good it is for finding fish.

I have used the Lowrance Structure scan for 2 years and for detail on bottoms down to about 80 feet (800KHz) it is wonderful picture. I use it when anchoring in unknown areas to check the bottom for stuff that will fowl an anchor. Using the cursor you can mark things on the bottom to avoid and if using sidescan look off to the side to see the bottom profile toward shore. I'm still learning to interpret the return. In fishing, the side scan can tell you which side of the boat the bait ball is on. Seeing it on downscan doesn't mean you can drive back over it again.

Tom

The work that my team did with our agency using dual frequency imaging sonar clearly showed to us that degradation of the beam resolution with extended ranges was severe enough that we usually only operated it on the high frequency setting. We operated a longer range unit for several years and continue to do so, but the image quality makes this unit marginal at best at the 40 m. range setting. Long range units are no longer the preferred choice going forward.

FYI, figure 6 page 12 of the attached link below shows a schematic of the difference between images for split beam and dual frequency imaging sonar. The bullets discuss the range limitations of such units...

http://www.psc.org/pubs/psctr16.pdf

Again, I guess my point is, the devil is in the details.

I'm curious what the Simrad units cost? As I have mentioned Simrad produces some very high end technology but they are new comers to imaging sonars as the technology had been proprietary until the US govt, allowed it to be released to research agencies such as ours. Does Simrad reveal details of the technology? In the past they have been "closed mouth". I'd be curious about technical detail about the number of beams deployed, their geometry and the resolution between two closely spaced targets of known size at range. It's that kind of information that is required in order to assess the claimed capabilities.


Jim
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Surprise, surprise !!!!!!!!

I received my Garmin this evening and as I am studying the installation, I notice there is no instructions for hull mounting. Instructions are only for transom mount or trolling motor mount. I'm sure it can be epoxied in place like all of the others but I'm not going to do it until I get a written confirmation via e-mail from Garmin I will call Garmin in the morning.

I am really enjoying northern Alabama on the Tennessee River but......it is very frustrating to not have any marine supply places around. Everything is mail order and the normal sales people I talk to are usually clueless. The nearest West marine is well over 100 miles away.

I guess my alternative is to figure out what I think I want and get put on hold for an hour with Tech Support for each company I call.

CRAP!!!!!!!!

Bass Pro Shops is pretty close to you in Decatur. They have a pretty good range of marine electronics, and generally one or two people around who know something about it.

JDCAVE said:

I'm curious what the Simrad units cost?

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We paid $895 CDN for the Structurescan module (c/w transducer) in Campbell River BC in June 2013. That does not include a display (it does tie nicely in with our Simrad NSE12) or installation.

tpbrady said:

Bass Pro Shops is pretty close to you in Decatur. They have a pretty good range of marine electronics, and generally one or two people around who know something about it.

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Thanks for the info. I will be going to Decatur in a few weeks. I'll check them out.

Garmin Tech Support told me that they are getting away from inside hull mounted installations. Now they offer a transducer for about $170 which can be hull mounted. However, after a while on the phone the tech Support person conceded that if PROPERLY installed, the unit I have will work inside the hull. I think Garmin and the other companies are all doing this because they have had a lot of returns because of poor installation and so, don't want to recommend this procedure. If you look at the catalogs, most Depth Sounders/Fish Finders state "for transom and trolling motor mount'.

Most people/boaters are not familiar with epoxy and so it would be really easy to screw up.

While it's pretty far back, I have my Structure scan transducer and another transducer transom mounted. That puts it about 18 feet back of the thru hull transducer. The transom mount works as well as the thru hull.

Tom

I have Sikaflexed my transducers inside the hull, as far forward as practical, because I want to know what the depth is under me, not after I have already travelled over it. Also I did not want any more holes in the hull, or the inconvenience of having to pull out the boat to fit thru-hull transducers. I felt epoxy was a bit too final and permanent, whereas Sikaflex works fine, but gives a bail-out option if removal required for any reason.

I have Lowrance units, and they are a subsidiary of Navico, which also owns Simrad, and their performance for price in my view is excellent.

I don't have the structure scan because I want to know depth more than anything, and when it first came out it was pricey. I'm not a mad keen fisherman, and the bottom in our bay does not vary all that much, so bottom detail not a huge issue. However, now those extra features have come down a lot in price, if fitting new now, I'd go for the Lowrance structurescan HD colour for sure.

Greetings,
When I purchased our Garmin 531S (I think) GPS/sonar I had the option of a transom mount, shoot-thru the hull or thru hull (for extra cost) transducer. Like many, not wanting to have the boat hauled for 'ducer installation I opted for the shoot thru unit. It is similar to this:

I caulked the base to the hull and filled it with mineral oil. Works fine for what I want which is simply an estimate of how much water is generally under the keel. I probably lost some sensitivity but I didn't really care. Using the charts and the "trend" of what the bottom is doing is good enough for me.
As a matter of fact I have done this with 2 units. One for pilot house and one for FB. I currently have 2 redundant thru hull units and one old style paddle wheel speed unit which will be removed, probably next haul out.

RT Firefly said:

Greetings,
When I purchased our Garmin 531S (I think) GPS/sonar I had the option of a transom mount, shoot-thru the hull or thru hull (for extra cost) transducer. Like many, not wanting to have the boat hauled for 'ducer installation I opted for the shoot thru unit. It is similar to this:

I caulked the base to the hull and filled it with mineral oil. Works fine for what I want which is simply an estimate of how much water is generally under the keel. I probably lost some sensitivity but I didn't really care. Using the charts and the "trend" of what the bottom is doing is good enough for me.
As a matter of fact I have done this with 2 units. One for pilot house and one for FB. I currently have 2 redundant thru hull units and one old style paddle wheel speed unit which will be removed, probably next haul out.

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Ah yes, the Airmar P79 (Airmar makes virtually all transducers regardless of brand name). Not gonna find fish; I had one hooked to my Furuno courtesy of the PO. You have to move up to something like a M260 to do that, best of all a CHIRP. And the OP wants a fish finder and side scan.

I decided to get the Humminbird 346C Di Color Fish/Depth finder which can be inside-the-hull mounted. The instructions for installation are the same as I have done over the last 20 years or so and I'm good with that.

Lessons learned: Always test the unit BEFORE installation even though you never had a problem installing them in the past. After running the transducer cable from the bilge to the flybridge, you really don't want to take it back out again because the transducer didn't work.

I have 2 tests I used:
Test 1). Rough wire the Control head in its approximate permanent location, plug in the transducer and throw it overboard about a foot or so below the surface and turn on control head. It should read the approximate depth with no flashing lights. Because the transducer is moving around and pointing every which way, don't expect miracles. You just want to see if everything APPEARS to be OK. I left mine overboard for several hours, turning it on and off again.
Test 2). Move your whole operation to the bilge. Mark off the location where you want to permanently mount the transducer. In my case, the hull has exposed roven woven fiberglass and did not give me a flat surface. I used a multi-tool to sand the paint off it and then mixed up some epoxy and spread it over the area trying my best to flatten out the surface by filling it in. Easy enough with a 4" wide putty knife. Only took a few minutes. You must have a good surface to work from.
That evening, the epoxy cured and I sanded lightly to make sure surface was flat.
Temporarily get 12V dc to the control head and plug in the transducer. Now place the transducer inside a sandwich baggie partially filled with water. It only has to keep the bottom under water but to make sure, I added enough water to submerge the entire transducer. Set the transducer in its proposed permanent location and use 2 sandwich baggies half filled with sand to hold it in place and weigh it down.
Now turn on the unit and Voila! This will show you exactly what you will see when unit is permanently epoxied in place. If all goes well, dry up the wet transducer and permanently install.

I know this sounds like a bit of overkill and this is the first time I have ever gone through this much trouble. I really, really did not want to run the cables and then remove them again due to a faulty transducer a second time.

Does your hull have any dead rise angle to it at the area you mounted the transducer in? If you the beam from the transducer is shooting off at an angle instead of straight down.

I note'sd that no one brought up Raymarine. I bought one on recommendation that the monitor would run my autopilot & of course the depth sounder & fish finder....did I make one of those ?

Sine a lot of FL is shallow depth is important. I like the moving scan display of a fish finder because it shows trend, I hate just numbers. The dual frequency types seems better for cutting through stirred up water from boat wakes.

I don't think you can mount a transducer inside on a cored hull.

Capt.Bill11 said:

Does your hull have any dead rise angle to it at the area you mounted the transducer in? If you the beam from the transducer is shooting off at an angle instead of straight down.

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Generally, just about anything other than a jon boat or a barge will have some dead rise. That is why you have to pick and chose the most reasonable position usually based on accessability, prop cavitation, water past the hull while moving or planning cavitation. These are all concessions that have to be made when shooting through the hull. The transducer will be slightly at an angle and will be slightly inaccurate - how much? I don't know I never calculated it. I can tell you thid though, It has never beed a problem on any of my sailboats and so I don't expect it to be a problem on my power boat. keep in mind that these inaccuracies bcome greater at greater depths. My concern was never how deep the water is but rather how shallow it is. The shallower the water, the more accurate the transducer will be in regards to actual depth.
Another real concern is that most transducers will not shoot accurately through a fiberglass boat that is more than an inch thick or a hull that is cored. Even if the hull is not cored and is less than an inch thick, I will still probably lose at least 20% of the definition of the fish or the bottom.
If these are concerns, Then a wedged through hull mounting will be required. I personally don't need that type of accuracy or definition because I don't fish.

If the angle is to great you have to compensate for it.

I have a Garman 300c on a removable mount on my tender. It just drops over the transom on a home made bracket with a sealed lead acid battery. Great for exploring depths around the anchorage.
This is the cheaper non side scaning unit, but I can report the screen is nice and bright and it has been a great unit.

BTW if you want to test an internal transducer placement just use a sealed plastic bag filled with water (no air). If you put the bag on the hull and the transducer on top (there is no need to put it in the bag) it should work well. If not find a different spot.

Or you could just hold the transducer up to your ear and listen to hear if it's ticking.

Greetings,
Mr. 11. "...up to your ear...". I don't know about THAT one. Could be it would detect a void in some cases.

My experience with transducers is that they typically come as 12 degree to 15 degree units, meaning that they can handle that much offset due to dead rise without any adjustments. There may be options beyond that, but I never had the need to investigate.

Some of the things mentioned just need to be verified berfore you toss them out.

Airmar right in their literature discusses shoot through the hull ducers are powered to make up for the glass in your hull...if 1000 feet of water to sound waves isn't an issue a little fiberglass isn't either.

Airmar FAQ - What affect does hull thickness have on the performance of an in-hull transducer?

What affect does hull thickness have on the performance of an in-hull transducer?


[FONT=arial,helvetica,sans-serif]The thicker the fiberglass the more signal is lost passing through the hull. However, our in-hull transducers are designed to more than compensate for this loss.[/FONT]


As far as install angles..remember the ducer transmit cone only sends back info on what it first detects...so the wider the cone the less critical the angle of install is...it may be a bigger deal for a sailboat that stays on a heeled tack...less for a trawler that rolls back ad forth. I have installed flat ducers on deadrise that are say 10-15 degrees in beam angle...so up to 15 degrees deadrise and as long as your boat rolls back through center...no big deal..not perfect but you'll probably never know it. If it is..go to the 50kH which is a much wider cone most of the time I'm pretty sure.

Thanks to N4712's help, I'll be getting 1 (Possibly 2) GARMIN 840XS unit(s) with a CHIRP Tec Transducer. Can't wait to get it/them.


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Hendo78 said:

Thanks to N4712's help, I'll be getting 1 (Possibly 2) GARMIN 840XS unit(s) with a CHIRP Tec Transducer. Can't wait to get it/them.


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Yes that's what's nice about them, unlike other brands they have the built in sounder so you don't have to spend another 1K on a ducer box.