Forward Looking Sonar

[captain58sailin]

Sonars for fish finding are a pretty good tool. Using them for solid object collision avoidance is a waste of time and money. The current sonars available to the retail consumer are not good enough to keep you from bumping into a rock except at the slowest of speeds and if you are doing that you are monkeying around where you shouldn't be with your boat.

[StuM]

Originally Posted by captain58sailin

Sonars for fish finding are a pretty good tool. Using them for solid object collision avoidance is a waste of time and money. The current sonars available to the retail consumer are not good enough to keep you from bumping into a rock except at the slowest of speeds and if you are doing that you are monkeying around where you shouldn't be with your boat.

Why shouldn't I be there. Those are the waters I monkey around in all the time looking for shallow anchorages for snorkelling amongst coral heads. My old Interphase does a pretty good job at that.

[Jim Cate]

Originally Posted by StuM

Why shouldn't I be there. Those are the waters I monkey around in all the time looking for shallow anchorages for snorkelling amongst coral heads. My old Interphase does a pretty good job at that.

My experience too! The Interphase Probe, now over 20 years old, isn't as good as one might wish, but it is way better than no FLS at all. If the new generation devices get better, and at a price we can afford, we'll be interested. Until then, the Probe keeps on helping us avoid disaster

Jim

[captain58sailin]

You are absolutely right, if you wish to put your vessel and lifeline unnecessarily at risk, that is entirely your prerogative. Not for me thanks, that is what the skiff is for, I do not risk my vessel in the shallows were it doesn't need to be, there are enough dangers out there without inviting disaster like that; your vessel, your party, go right ahead.

[Schooner Chandlery]

The Interphase (sorry don't recall our model...180, II something???) works great at what we use it for-when motoring along we see sandbars or other shifting bottom conditions. Sorry to hear the replacement is so much more costly now that Interphase's tech is inside Garmin. The 2 transducer color model we got was about $2500 list/$1900 street in 2008 when we got it.

There are always an endless supploy unknown objects that seem to pop up in or near anchorages when you're traveling. I see Cabin58... is up there in AK and figure he'd be happy to have every resource available. Some of the anchorages up that way in SE AK, at least, are discussed in just enough guide books for one to think that they've been scouted out--hah! They have not. The fellow, um, Don Douglass, with all the cruising guides? I really began to think he just randomly wrote about places that he had never been to. We found so very MANY conditions completely contrary to his writing--some quite unsafe. Other places up that way--the charts look good but when you get in to where you're going, there are ISLANDS (forget about lowly rocks...) where they aren't on the chart. You see enough of the uncharted stuff and you're keen to take any help you can get. The most alarming sight I ever saw was rocks awash with the wave action where the BC charts showed clearly a cliff with depth of at least 30 meters deep (search for "sidecar" in this lengthy post to read about it). I saw the cliff above water, but thank goodness for the wave action showing that the bottom was not as it was shown on the new government charts of BC. If it had been just a bit darker, we'd have missed seeing the rocks from a distance and only the Interphase would have (hopefully) kept us off them.

Point being--we take every resource we can and use it. After seeing those rocks in what was supposed to be very DEEP water, we made sure we had the FLS on anytime we entered or left an anchorage. We did have it on then, too, but we saw the rocks from quite a distance as they were awash.

Prices drop with new tech very quickly these days so we can hope that the new Garmin will very quickly come down into real-people buying land. It was a pretty big investment for us at $2K when we got the FLS we did get. I imagine it will be many years before we replace it, as long as the two transducers keep working. (cross the fingers, knock on wood, whistle, and pray)

--Brenda

PS--skiff? Sometimes its not safe or completely unrealistic for a person to get out in the skiff and look about for the perfect way into a spot. If one has the luxury of time and it's in their own backyard they're sailing it's really different than traveling and finding your way into numerous unknown anchorages.

When doing things like traveling around the sloughs of the CA Delta, there are miles and miles of winding waterways--you just watch the FLS and pay attention to the terrain and expected depths.

[Jim Cate]

Originally Posted by captain58sailin

You are absolutely right, if you wish to put your vessel and lifeline unnecessarily at risk, that is entirely your prerogative. Not for me thanks, that is what the skiff is for, I do not risk my vessel in the shallows were it doesn't need to be, there are enough dangers out there without inviting disaster like that; your vessel, your party, go right ahead.

Hmmm...

Do you ever cruise in waters unknown to yourself, with poor or no detailed charts for potential anchorages? Do you really, should you encounter such conditions, launch your "skiff" and go exploring prior to entering the shelter? I sure as hell wouldn't want to have to resort to that technique.

We've arrived in poor visibility, been tired and really in need of anchoring and in a cove with no charts at all. That's what some cruisers face... we're not talking about "shallows", just an unknown anchorage. It sounds like you must never get into such situations... but they have lead to some of our finest cruising experiences. And the point is that with some care, the Probe reduces (a lot) the chances of the disaster that y ou seem to fear. Perfect? Hell no. A big help? Hell yes.

Is this "putting your vessel and lifeline (?) unnecessarily at risk"? Not by my definition... cruising in general is putting oneself at risk to some degree, our practice isn't a big increment IMO. As you say, it is a decision each skipper must make. Your implied criticism of our decision seems unwarranted to me.

Jim

[Pelagic]

The best "NAVIGATIONAL" forward looking sonar I have ever used was called "American Pioneer Dual Scan" manufactured in Seattle.
The inventor Nathan Roundy, had a simple solution of 2 fixed transducers positioned well forward that needed to only scan about 20° on one side each to give you a clear picture much further ahead than the normal commercial sonar which had severe range limitations based on depth and side lobe interference.

Used it confidently for years in poor light conditions to enter/leave coral pass entrances or uncharted lagoons with coral outcrops all over the place.

You simply set the tilt on each transducer to skip over any depth (say deeper than 5 meters at a distance of 100m and you would see either a shallow obstruction (Red) or clear water ahead as you moved forward.

No idea if they still have something like that, but it was idiot proof for what I needed.

[Neptune's Gear]

As usual it seems, I agree with Jim. The probe is/was a great tool when you got used to what its telling you, and find the right settings. Takes practice. It did not like the automatic settings, but in coral or poor charted areas, it was a great tool.
I'm looking fwd (no pun intended) to trying the B&G fwd sonar...

[Schooner Chandlery]

Originally Posted by Jim Cate

We've arrived in poor visibility, been tired and really in need of anchoring and in a cove with no charts at all. That's what some cruisers face... we're not talking about "shallows", just an unknown anchorage. It sounds like you must never get into such situations... but they have lead to some of our finest cruising experiences. And the point is that with some care, the Probe reduces (a lot) the chances of the disaster that y ou seem to fear. Perfect? Hell no. A big help? Hell yes.
Jim

Glad to know that it isn't just us who ends up in these situations. I do now believe that (poor or no charts) may pretty much be the norm if one is traveling in out of the way places. We do get a heads-up from other seafarers that the charts in a local area are not correct. The local fishermen on the VHF have been very useful. Not as useful as the FLS though.

When we're exhausted, the last thing I can imagine doing is wasting time/energy pulling out the dink, inflating it and going looking into the unknown anchorage. At what point to decide it is unknown enough to pull out the dingy? We were about 2 miles from our destination when we encountered/saw the uncharted rocks in the blog post I linked to. I would never have dingy'd in the entire 8 miles that it was from the open ocean to the theoretically protected anchorage we were going for. At the time, our dingy didn't even have an outboard.

The FLS we have has a 180 degree forward scan and a depth view--so you can look at two different 2D views. Overall, useful. Especially when we have no idea if the charts are correct.

[Schooner Chandlery]

Originally Posted by Pelagic

The best "NAVIGATIONAL" forward looking sonar I have ever used was called "American Pioneer Dual Scan" manufactured in Seattle.
The inventor Nathan Roundy, had a simple solution of 2 fixed transducers positioned well forward that needed to only scan about 20° on one side each to give you a clear picture much further ahead than the normal commercial sonar which had severe range limitations based on depth and side lobe interference.

Used it confidently for years in poor light conditions to enter/leave coral pass entrances or uncharted lagoons with coral outcrops all over the place.

You simply set the tilt on each transducer to skip over any depth (say deeper than 5 meters at a distance of 100m and you would see either a shallow obstruction (Red) or clear water ahead as you moved forward.

No idea if they still have something like that, but it was idiot proof for what I needed.

That one sounds sort of like ours. We can choose what distance forward we want it to look for the depth info for one of the views and we can select to skew our desired depth info point info to even come from one side rather than in front of us. The other aspect of the 180 degree scan also relies on a distance you put in -- do you want 20 ft away from the two sensors or 500 ft or some other distance?

[meshugah]

The feedback has all been very interesting to read. The Garmin Panoptix appears to be a reasonable option as the 3D view looks as though it could be very useful. Has anyone had any experience at using the Garmin Panoptix for navigating in areas of coral reefs or other submerged obstructions? I note that Garmin essentially markets this product as a fish-finder and not as a navigation aid.

[captain58sailin]

I work on the sea all over the world with poorly marked charts and no charts, I exercise a great deal of caution, especially in Alaska where some of the areas have not been charted since the 1964 Earthquake which changed a great deal of the bottom of the Alaskan waters and no corrections have been performed in some of those areas, the Prince William Sound area only got resounded by NOAA during the oil spill clean up in 1989, other more remote areas still haven't been upgraded. I don't make land fall in an unknown area at night if at all possible, and will stand off out to sea until daylight. I use "sonar" as a fish finding tool, and of course to help determine bottom contours etc... My unit cost in the neighborhood of 5k including transducers. Spending 20k for this tech. is not where I would spend my money, as I said, it is your boat, your party, run it as you will, that is why we are not all sailing on the same , kind of vessel in the same areas. I spent a great deal of time sailing around the South Pacific with nothing more than a 60'/60 fathom depth finder, but we sent a man up the mast to spot for coral heads etc... and managed to not bang into anything. Each to their own. By the by, I am not Cabin58.

[Jim Cate]

C-58, the Probe unit that several of us are talking about has been available since th early 90's. I bought my first one in 1996, the second in 2003 when we bought this boat. They didn't cost 20 K$, but somewhere south of 2K$ (don't remember for sure).

We don't make landfall in unknown places in the dark either, but have used the probe to find suitable anchoring spots in familiar spots in the dark. We've hove to at sea to wait for dawn more than once, but being an aging couple, don't have a man to send up the mast very often. Did do that on our previous boat where I had steps to the first spreaders... very useful in coral waters as you say, but I was a couple of decades younger then!

But all this rhetoric is really in response to your statement that buying any FLS was a waste of time and money. I don't agree, nor do many of the other folks who have actually used one in anger. You are right in "each to his own"... but that does not really give you the right to disparage our practices which have proven useful to us.

Jim

[captain58sailin]

I was not intending to disparage you or anyone else. Nothing I posted here was pointed at anyone in particular, just general opinion. And since everyone knows that opinions are like noses, everyone has one and they all smell to varying degrees. Sorry that you took it to be a personal attack, that was not my intent.

[Pelagic]

You're forgiven captain58 as yours seemed to be the only nose out of joint!