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Old 15-03-2020, 05:22   #1
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where is the forward looking sonar at?

Hi everyone,

I've been doing a little bit of research on forward looking sonars / depth sounders. I was surprised to find few post debating the technology here on the forum and mostly 5 or 10 year old reviews elsewhere. Hence this post, to do a bit of probing (pun intended) as to your experience if you have one.

Has the technology gone through a fad but revealed to be disappointing?

Do you have one?

What sort of range do you think is useful, at what speed and how far from the coast?

And anything else you'd have to say

Fair winds!
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Old 15-03-2020, 06:06   #2
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Re: where is the forward looking sonar at?

I've been considering buying a setup, but I keep deciding the money is better spent on other things. Even if the published ideal conditions range is exactly what you'll get in the real world, most of the systems don't have enough range to be useful in my book. I'd love it for getting into places that are a bit questionable depth-wise or have a usable, but un-marked channel.

However, Simrad claims the forward looking range of their unit is only 8 times the current depth. So if I'm in 6 feet of water (about the least I'll willingly go into), it can only see 48 feet ahead. Subtract distance from transducer to the bow and now I've probably got 25 feet of useful range.

25 feet isn't much better than feeling your way in by braille (although for me, that would be bad, as I'd be feeling with the props as much as the keel). In places with fairly clear water, a person on the bow will likely be able to see more. And for 25 feet to tell you much, you'd have to be going so slowly that wind / current influence would make keeping the boat in the deep spot a real challenge.
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Old 15-03-2020, 07:27   #3
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Re: where is the forward looking sonar at?

Saw a video recently by a cruising couple using one to find spots to anchor in. They suggest maintaining 4 knot speed to enable system to work and helmsman to respond in time. As lufkin suggests, the range is not enough to be really useful in avoiding Random Floating Objects while under way. The topic came up with the Brest-Atlantiques foilers, each trying, and mostly failing, to avoid hitting things at 30 knots while crossing the north and south atlantic on their 30,000 mile race.
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Old 15-03-2020, 08:21   #4
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Re: where is the forward looking sonar at?

I have one by interphase. Came with the boat. Claims to be able to see 300 feet ahead. To be honest where I sail I havenít really looked at it so canít vouch for it either way. I did see that companies are now making ones which give you a 3D view of the bottom. Requires two sonar senders. Looks very cool. Mine is just a 2d LED screen and no way near the fancy end of things which money can buy you now.
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Old 15-03-2020, 08:33   #5
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Re: where is the forward looking sonar at?

This is the 3D one I saw previously:


https://echopilot.com/products/fls-3d/

No idea how much it costs. I suspect a lot.
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Old 15-03-2020, 08:43   #6
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Re: where is the forward looking sonar at?

Quote:
Originally Posted by robinmay View Post
Has the technology gone through a fad but revealed to be disappointing?

It is useful in certain circumstances but is not the game changer it was hoped to be.


Quote:
Do you have one?
No, but I think I will on my next boat.


Quote:

What sort of range do you think is useful, at what speed and how far from the coast?
They are useful when you are motoring along just making steerageway. You'll get just enough warning to turn or stop. Useful if singlehanded, or if the light or turbidity make it difficult to see into the water.



Quote:
Originally Posted by rslifkin View Post

However, Simrad claims the forward looking range of their unit is only 8 times the current depth. So if I'm in 6 feet of water (about the least I'll willingly go into), it can only see 48 feet ahead. Subtract distance from transducer to the bow and now I've probably got 25 feet of useful range.

The forward-scan transducer is ordinarily placed farther forward on the hull.


The idea is that you use it in a channel that does offer some clearance and use it to identify shoaling or obstructions.


Quote:

25 feet isn't much better than feeling your way in by braille (although for me, that would be bad, as I'd be feeling with the props as much as the keel). In places with fairly clear water, a person on the bow will likely be able to see more. And for 25 feet to tell you much, you'd have to be going so slowly that wind / current influence would make keeping the boat in the deep spot a real challenge.
Here are some videos that show it in use.









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Old 15-03-2020, 09:25   #7
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Re: where is the forward looking sonar at?

We've had B&G Forward Sonar for 2 years, which was the only manufacturer to have a long enough transducer to fit the curved hull angle of our sailboat (the transducer must install vertically).

I've found it to be a bit of a learning curve and am still playing with it. Here's a few things I can pass along-

- Similar to using radar, during use you can easily set and adjust the depth and how far forward you want to see.

- You have to be going slow enough for the data to be meaningful and have enough time to react. You won't get useful data faster than 3-4 knots, and slower is better.

- It's a bit mind bending (to me) because the sonar looks forward but the readout is from left to right, so I have to remind myself when using it that the boat direction on the sonar screen is different from the boat direction on the chart screen. I'm sure this gets easier with practice.

- It does have a cool feature to overlay on the chart and show a cone in front of the boat. The cone extends how far you set the forward looking, is green when your depth is safe, and turns yellow when the depth shallows within your parameters, at which point you can view the sonar screen for specifics (sharp spike showing an obstacle or angled line indicating the bottom shallowing.

I hope this helps!
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Old 15-03-2020, 09:33   #8
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Re: where is the forward looking sonar at?

Using them since 20 years, had none for 4 months bcs late delivery and broke my daggerboards twice in dirty water. They are only useful below 5kn, visibility in water 0. But then they are worth every Penny!
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Old 15-03-2020, 09:41   #9
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Re: where is the forward looking sonar at?

I installed an echopilot unit some years ago. I have not needed to use it much so I can't give much info on it other than to say that it does what it is advertised to do very well. I haven't seen anything else that matches its specs as yet.
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Old 15-03-2020, 10:04   #10
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Re: where is the forward looking sonar at?

I have the B&G unit. Like radar, this is not a turn it on and it's useful. There is a learning curve. Do not try to learn in a storm and try to navigate out of the channel. I tried that with 2.5' of draft and still ran aground lol. Of course 35-40 know winds and driving rain didn't help.

You have to go slow as stated above. I bought because I singlehand and when I get to the tropics next year, it will be one more tool to help avoid ugly accidents.

Is it worth it? Kinda like a liferaft. If you never need then no but if you did need it, even only once then it was worth every penny you spent.
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Old 15-03-2020, 12:00   #11
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Re: where is the forward looking sonar at?

It is always necessary to sail slow in shallow waters certainly with a classical one but FLS will add safety. Keep still paying the assurance invoice.

I have an Echopilot, it broke down quit fast in an remote country. They gave bad service because I was not allowed to let it open by a qualified technician if I wanted to keep the guarantee. Because we needed it, it was repaired temporarly by my technician but it was very, very , very hard to get the spare part for final repair for which I had to pay a lot.. My contact was with the factory. It was the reseller who convinced them to send it.
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Old 15-03-2020, 12:26   #12
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Re: where is the forward looking sonar at?

I had the old -2 sender Interphase on previous boat, now I have the Simrad forward scan as shown by Jammer. Both units came with each used boat. Agree with others - it’s useful for slow navigation in dodgy waters. Not for routine faster cruising. I find both work well, the Interphase gives options for horizontal (my preference) or vertical scan. The Simrad is a narrower, predominantly vertical cone in shallow water. The Simrad projects the green, yellow or red cone on the chart plotter based on your alarm limits which is a handy visual for quick reference. I didn’t think they were worthwhile initially but with each boat, I deployed them with increasing frequency as I advanced along the learning curve.
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Old 15-03-2020, 12:51   #13
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Re: where is the forward looking sonar at?

I installed a Interphase year's ago, based on my experience using a commercial one on a survey vessel [along with sub bottom boomer,side scan sonar.], the interphase was a big disappointment, the problem with the design of pleasure look ahead system's is POWER, they use 12 volt's, so only so much power is available, unlike the commercial units' using AC voltage, i.e. 220 volt's, allowing the system to punch forward much further.
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Old 15-03-2020, 13:07   #14
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Re: where is the forward looking sonar at?

I had the Garmin Panoptix forward looking sonar on my boat for a couple of years but took it out and sold it on Ebay.

The problem is that the range depends on the water depth. Garmin says right in the manual (but not in the ads)

"The transducer has an effective forward range of between five and eight times the depth of the water. For example, in 3 m (10 ft.) of water, the effective forward range is between 15 and 24 m (between 50 and 80 ft.). Water conditions and bottom conditions affect the actual range"

So in 7 feet of water - where I'm worried about running aground - the range is 35-56ft forward from the transducer. Since the transducer is about 8ft back from the bow, I have less than a boat length to turn or stop.

If I needed a forward looking fish finder, it would be a much better idea
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Old 15-03-2020, 13:16   #15
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Re: where is the forward looking sonar at?

We have been using the Probe for years. Had one on our first Insatiable, and on this one, too, both bought by us.

What they are most useful at, ime, is in water so muddy you can't see into. It kept us off a reef we couldn't see. It has been useful anchoring, countless times. You really get a better sense of what's down there, after you've learned to interpret the display.

I agree that it is best used at speeds of about 1.5-2 knots, to allow time/ space. to reverse out of a trap.

I think regular depth sounders tell you enough most of the time. But if you're investigating a new-to-you anchorage where there are coral heads, and it's too late in the day to have good visibility into the water, they can be a boat saver.

They may be less useful to longer boats than shorter ones. If you're a 50 footer, and you can only see 100 ft. ahead, that's 2 boat lengths to extract yourself in. You probably don't like to go at only one knot. That patient speed can do your boat a world of good, but it is a skill to make yourself do it.

Something else the Probe is good at is when you do your circle, looking for bommies (coral heads or other rocks), it picks them out, you can see them on the display, and you can move off so that eventually you have a whole, clear, swinging circle. We have done this with only a depth sounder, but with the probe you get a swept view, not just learning about the shallower depth right under the sounder. It shows clearly the edges of sand banks, when it is aimed at them.

When we first got ours, we'd "look" at stuff in the marina: other boats' keels, pilings, the banks and correlate with the display. Eventually you figure out what a rocky bottom looks like on the display, vs. a nice, smooth mud bottom, etc.

In the old days, when we had no insurance (as none was available for twosomes), we'd buy something for safety with the $$ set aside for ins. Bought a radar, a Probe, etc., bigger anchors, etc.

Ann
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