Is a forward looking sonar / fishfinder worth adding?

[FionaJC]

I have a Victor 34' Ketch fitted with all sorts of gizmos. I have a Garmin GPSMAP 4010 with Radar which I love. I have a NASA Clipper Depth gauge and repeater. I am tempted to buy and fit a GSD22 forward looking Sonar.

I sail on the east cost of the UK and I travel to France and back each year so I do have to watch the sandbanks. (typing that line I think I have answered my own question) Passage plan attached my route is red.

Is it worth the hassle of fitting one? They come up on ebay at around $200. Our son says why? the depth gauge works but I fancy a bit more info having gone aground twice thinking I know best (Who said women drivers?)

My question is "Is it worth getting one" bearing in mind that I have seen dry land above our position while crossing to France?

[skipmac]

Haven't seen discussion on the GSD22 but from owners of other brands/models of forward looking sonars the experience is generally good but one must understand the limitations.

The transducer can't see a long distance directly ahead of your boat, especially in rough or choppy seas. So don't expect to go flying along at hull speed in 1-2 meter seas and see sand banks far enough ahead to avoid grounding. But in calmer waters and slower speeds one can work into a shallow harbor or narrow channel and avoid the hazards.

[Stumble]

My impression is much the same (never used one, but have researched them). For motoring into unfamilure harbors, or rivers, at low speed they can be very helpful, but they are close to useless when underway at speed.

[jeremiason]

When I outfitted my Catalina 470 for cruising, I installed Interphase Forwarding Looking Sonar.

That was one of the best gadgets I had on the boat.

It worked great moving around shallow rivers and it was invaluable in unfamiliar anchorages.

If I was outfitting for cruising again, I would definitely put one on this list.

In 2012, Interphase was purchased by Garmin and shut down.

Garmin now uses similar forward looking sonar technology.

Here is a test on five different units
Forward-looking sonar: 5 units tested - Practical Boat Owner

[zboss]

We recently bought a Dragonfly and installed it on our dinghy! We use it to scout out anchorages accurately using the Navionics link. I'll take the dinghy and drive around all the local anchorages for a few hours recording the bottom. I have been able to find many places to anchor that are not shown on the charts or locations within a known anchorage but off to the side where we can drop a stern anchor in a crowded anchorage and stay in place.

If we could fit a Panoptix sonar on our boat we would!

[44'cruisingcat]

I have an Echopilot FLS, and it's very useful when anchoring amongst coral heads.


It's less useful in shallow sand/mud , because it only "sees" forward about 4 times the depth. Given that we're fairly often in < 1 metre of water...

[Jim Cate]

FWIW:

I read the 5 unit comparison article and found it pretty Anglocentric, especially where it reported the Echopilot to have been the best of the lot historically. IMO, and as a long term user, the Interphase units were a step up in range and interpretability from the Echopilot. A moot point now, due to the dissolution of Interphase's product line after purchase by Garmin.

For the OP, if you do a bit of searching, you will find several previous threads where these units have been discussed at lenght. I've posted our long term experience with the Interphase Probe, and don't feel like typing it all again. Suffice it to say that in our cruising, which often takes us to poorly charted areas, we find it to be very useful indeed. Some hands on experience is needed to learn how to interpret the screens, but that is easier than getting towed off of a reef...

Jim

[rosatte]

goodday we have the B&G forward sonar scan one of the best gadgets we have on board it reads out 8ft ahead for every 1ft of depth ..10 ft water it scans 80 ft ahead ...a little more money around 850 dollars canadian..

[S/V Alchemy]

I will follow this with interest as I am debating the same questions. We are heading into poorly/not currently charted areas, however, and much as I admire the hydrography of Captain Cook, I feel I need more recent information. So I will get one for tidal waters, river or harbour entrances with known issues, and (I hope) coral heads recently grown. There's plenty of places that would make excellent anchorages save for the shifting bottoms/oddly placed ledges. Forward scanning sonar can mitigate that.

[S/V Alchemy]

Originally Posted by rosatte

goodday we have the B&G forward sonar scan one of the best gadgets we have on board it reads out 8ft ahead for every 1ft of depth ..10 ft water it scans 80 ft ahead ...a little more money around 850 dollars canadian..

Having sailed to Belleville in October after the lake's started to drain, I can see exactly why you bought it. Some of those areas out by Trenton are skinny and hard and if you aren't in the channel, you'll know right away. I've never been so interested in a fish finder display in my life, but there was 10 feet of boat ahead of that transducer.

[Dockhead]

I have the Echopilot FLS, installed by the PO of my boat.

I never found it to be useful. As others have said, these devices will only read some multiple of the depth, which means the range is really limited in shallow water -- such that even if you could interpret the data easily (which you can't), it would only be useful if you were picking your way dead slow around an anchorage, with your eye on it. Certainly no good for avoiding uncharted hazards while you are underway at speed.

Mine, when it was working, was mostly useful as a redundant depth gauge.

I somehow disabled it when I was installing the new boat network a few years ago. I might try to get it working again this year.

[toddster8]

Excellent question. If the price were reasonable, I'd consider one specifically for picking my way into anchorages and narrow entrances. Secondarily for picking out dive sites. I asked about these from every dealer at the boat show last month and was told that there are only two available (Garmin, Simrad). Or maybe only one? The salesmen that I talked to seemed to be limited to the concept of "turn on switch, see fish!" They couldn't really comprehend my question.

[Dougtiff]

I installed a Interphase on myboat a number of year's ago and found it almost useless, very difficult to interpert, i have been on commercial boats with indestrial grade if you will and they really do the job, the problem with the recreational units, is lack of power, i.e. 12 volts D.C., the stacked array [tranducer] just doesn't have the power, having been around alot of survey equipment, i.e., side scan, sub-bottom boomer, look ahead sonar, bottom coring,while running surveys for insurance for jack-up drilling rigs in S.E. asia and the Middle East.

[Andy on Destiny]

We have an Echo Pilot and also on our previous Yacht. I guess it depends on the type of cruising you do.
We spend 6 weeks Sailing around the NE side of Svalbard which last summer which to all intense purposes is uncharted. We set or regular depth sounder to alarm at 25m and once that sounds we reduce speed and pay attention to the forward looking one. They are not great in very shallow water but it sure beats an echo sounder that is just in front of your keel. We have used it numerous times to avoid obstructions, and always do a 360 look around before dropping anchor. We would not be without one.

[ramblinrod]

Originally Posted by rosatte

goodday we have the B&G forward sonar scan one of the best gadgets we have on board it reads out 8ft ahead for every 1ft of depth ..10 ft water it scans 80 ft ahead ...a little more money around 850 dollars canadian..

This is something I don't quite get.

I'm not doubting anyone's claims; just looking for a point of reference and trying to solve the apparent logistical issues.

With my prior boat, I used to practice navigating by chart contour and regular sonar quite frequently. (My current boat doesn't have sonar...yet.)

(I understand this may not work so well in some locations where the depth is constant for 10s of miles in every direction.)

My experience with sonar alarms, is that the alarm has to be disabled, or it will drive everyone crazy.

Here is my dilemma.

If the furthest one can see ahead is 80 ft (in 10 ft of water) at 6 knots, they are travelling 10 ft / sec; that 80 feet will be covered in 8 seconds.

Assuming one is not staring constantly at the display, and it takes say 10 seconds to see an approaching obstruction on the display, and another second to start to react, one will begin to respond 3 seconds after running hard aground at full speed.

My boat thrown in hard reverse from 6 knots, probably takes another 15 seconds (at least) to stop, if the coupler wasn't sheered.

So at 6 knots the sounder would have to see about 200 ft ahead to prevent the grounding.

So for those who are now using forward looking sonar and believe it worthy, before purchasing, did you attempt with the same enthusiasm to navigate shallows in a similar manner with regular sonar, or is the difference experienced based on a forward looking sonar vs no sonar at all, perhaps just a depthsounder? (Which is still a valuable tool for navigation, but not even close to regular sonar IMHO.)