Structure Scan: Fwd Looking Sonar ?

[mikefossl]

Now that Lowrance has added a couple of thru-hull transducers what do people think of using that technology as a forward looking sonar? Is a 250ft side scan (or forward scan in this case) range enough ? This would be about 6 boat lengths for us. I imagine myself feeling my way into a coral head infested lagoon with this might be pretty cool. The sample screen shots show enough resolution that I could see how well the anchor is set without risking swimming with the crocs.

Thoughts?

[SeaKing]

link?

[mikefossl]

Specifications for StructureScan

[broach]

hi Mike, I have been search some time a go and i found this
Interphase: V90 se
I think the price is resonable. But have no experience. Maybe some one else has some?
Broach

[Don1500]

Originally Posted by mikefossl

Now that Lowrance has added a couple of thru-hull transducers what do people think of using that technology as a forward looking sonar? Is a 250ft side scan (or forward scan in this case) range enough ? This would be about 6 boat lengths for us. I imagine myself feeling my way into a coral head infested lagoon with this might be pretty cool. The sample screen shots show enough resolution that I could see how well the anchor is set without risking swimming with the crocs.

Thoughts?

I am looking into this right now. Would you mean to mount the transducer sideways?

[prof_mariner]

There are a couple fellows who have experimented with this over on the Humminbird side imaging forums. There's some info and sample scans on this page under "rotational scanning": DrDepth - Xtools

If your goal is to survey the bottom and build custom charts, it's a pretty nifty tool, but if your intention is to use this for navigational purposes I don't think the updates would be fast enough to give you sufficient warning of danger ahead.

[Don1500]

It looks like Structure Scan flows pretty good at <7knts but is iffy at higher speeds. My boat does 6 in calm water. If the current gives me a higher speed it is usually in deeper water. I am trying to find something that shows me the limits of the channel. I would not be expecting danger to be immediate, just a warning that I should adjust a little. The way it is now I don't know I'm off the channel until I'm in trouble. Then I need to find it again. The old saw "Stay in the middle of the channel" doesn't work if the markers are 35' off the center of a 20' channel, and spaced 3 miles apart.

[Dockhead]

Some day we will all have high resolution forward looking sonar which allows us to see cleary what the bottom looks like ahead. And it will be as hard to imagine how we lived without it before, as it is hard to imagine now living without a chart plotter.

We ain't there yet, as far as I know. I have an Echo Pilot forward looking sonar set on my boat which was installed by the PO. It's great as a redundant independent source of depth data, but I'll be damned if I can glean any useful information out the display concerning depths ahead.

[prof_mariner]

@Don - The "updates" I was referring to was not regarding the side imaging scanning rate, but rather the "rotational" scanning rate. If you watch the video on the page I linked to you'll see how they rotate the sonar's transducer to simulate a forward looking "sweep". Looks like they're "sweeping" the sonar ahead once every 10-20 seconds. If you consider that "sweep" frequency and then the sideways range of the sonar (in 30 foot dept it scans roughly 50 feet to either side) that would mean you'd only be able to look ahead 50 feet every 20 seconds. Unless you're going very slow you could very easily miss an obstruction.

Bottom line is, as I posted earlier, a side imaging sonar makes a very poor obstruction sensing tool. Great for building mosaics of bottom relief and looking for ship wrecks, but not suitable for navigating in unknown waters.

If your budget can afford it ($30K+) there are some very good forward imaging sonars out there, give some of the videos on BlueView Technologies website a look.

[Don1500]

Originally Posted by prof_mariner

@Don - The "updates" I was referring to was not regarding the side imaging scanning rate, but rather the "rotational" scanning rate.

I figured that out as soon as I posted, then I went back and added the "Structured Scan" which is what I meant. I would just like to know how far ahead does the Side scan (Structured scan) look. even 20-30 yards would let me know that my course would intersect the side of the channel. I am not looking to map unknown harbors or anchorages, just making sure I don't stray out of the channel.

[prof_mariner]

Take a look at the Interphase line of forward looking sonars. They have some discontinued models that are very reasonable and would be much better suited to what you want to do: Refurbished Sonar Units and Accesories

[mikefossl]

Originally Posted by prof_mariner

Bottom line is, as I posted earlier, a side imaging sonar makes a very poor obstruction sensing tool. Great for building mosaics of bottom relief and looking for ship wrecks, but not suitable for navigating in unknown waters.

If your budget can afford it ($30K+) there are some very good forward imaging sonars out there, give some of the videos on BlueView Technologies website a look.

I would mount the transducer sideways, well forward. I'm thinking more along the lines of a low cost tool to help feel my way through a poorly surveyed channel in lower visibility. It might also help choose a good spot to drop anchor. Since I already have an HDS chartplotter, the incremental cost is less then a boat unit.

[speciald@ocens.]

At least you will know why you ran aground <)

[downunder]

Originally Posted by speciald@ocens.

At least you will know why you ran aground <)

+2

[Don1500]

Originally Posted by mikefossl

I would mount the transducer sideways, well forward. I'm thinking more along the lines of a low cost tool to help feel my way through a poorly surveyed channel in lower visibility. It might also help choose a good spot to drop anchor. Since I already have an HDS chartplotter, the incremental cost is less then a boat unit.

I am thinking along the same lines. I, too, have an HDS8 that would only need the Structure Scan module and a transducer (~$600 total with std transducer, $750 with thru-hull). But I am thinking that it would work fine set up normally. Knowing you are centered in the channel NOW will help keep you there. This is not meant to be something that is your be all and end all of navigating in tight places, just a reference. And it finds fish.