CHIRP Sonar for Better Anchoring

[Jlp0217]

Probably five, six or maybe more years ago, I added a Raymarine Dragonfly fishfinder/plotter to my dingy. I was really impressed, I could see individual weeds growing on the bottom in the relative shallow waters I used my dingy in.

So 3 years ago, when I replaced my electronics on my sailboat with mostly B&G , and hauled for new bottom paint, I removed my old depth transponder (originally from a Garmin fishfinder but also worked with my raymarine chart plotter) and added Forward Scan, Chirp, and Structure Scan transponders from Navico/B&G.
From what I can tell, the chirp transducer performance is not much different from my old 50/200k transcuducer. The Forward Scan I like, but seldom use because I seldom head for anything that would show up on it, and if I do, I am lookinag forward with my eyes, not looking at the MFD. The Structure scan I am very disappointed in, as it just shows a series of vertical lines that I am not at all sure how to interpret. Their spacing seams to vary with the channel width and depth, but I have no idea of measurements.

[StoneCrab]

Sharing this type of experience is useful. I am sorry it was so disappointing.

[StoneCrab]

Compass790 you got me looking on line at scanning sonars. West marine has a nice write-up comparing all the different types. Apparently my beer goggle dreams are a possibility.

Steerable 3D Scanning Sonar
Forward scan transducer showing shallow water areas
ForwardScan transducer shows shallow water ahead! It aims forward of your boat. The yellow line is the warning line while red indicates dangerous shoaling.

No survey of sonar technology is complete without a discussion of steerable transducers like the Simrad ForwardScan® and Garmin Panoptix™ PS31 Forward Transducer. You can aim these in any direction as if you had a periscope looking down in the water.

https://www.westmarine.com/WestAdvisor/3D-Sonar

To quote one paragraph:
"Some of these steerable models mount on your trolling motor, and you turn the motor to point the beam where you want to look. Others, like the ForwardScan, are thru-hull transducers that are mounted near your bow. The aiming function happens inside the multi-element transducer. Besides finding fish, these units are invaluable for navigation in a narrow or winding channel. You can see rocks and shallows, and avoid running aground. ForwardScan shows you color-coded depth indicators; green for deep water, yellow for medium depths, and red for dangerous shoals. It’s also good for finding a secure anchorage. Not just for fishermen, ForwardScan is popular with owners of cruising sailboats and cabin cruisers, and connects via NMEA 2000 with compatible Simrad and B&G displays."

Sound like a servo steering the transducer instead of a trolling motor would make it doable if you didn't want to spend the money on a ForwardScan.

Fun stuff

[AKA-None]

So I installed a chirp system but only a year in limited service
Airmar transducer, note not at dual frequency transfers are chirp capable.
You have to make certain your system supports chirp and which transducer.
For my particular situation I went with a 7” lowrance.
As a reminder I have a small boat and it’s on a river with lots of variable bottom that changes. Mostly mud and sand with whatever gets pushed down.
Is it perfect no but I do get a pretty good image of what’s there and what the bottom structure looks like.
Also note I’m mostly in less than 50 ft of depth so can’t comment on how well it works in deeper water.
And since it’s a muddy river you can’t see more that a couple of feet even on a bright day.
And since my particular situation doesn’t call for high end product this combo works for me.
Iirc the transducer cost about 500 and the plotter was about 600 so all in a bit over 1200 usd.
The transducer is hull mounted as I already had a hole from the previous bad depth sounder.
Sorry no pix of the screen to share but I’ve been happy with the results so far.

[PineyWoodsPete]

Originally Posted by PineyWoodsPete

I'm looking at this 9" Garmin unit w/ transom-mount transducer for haulout this summer, as the '14 Raymarine 12" MFD has no fishfinder/CHIRP capability:
https://www.westmarine.com/buy/garmi...14?recordNum=1

I'm answering myself here, as I just installed my much discounted Garmin Echomap Plus g3 94sv MFD unit linked above (9" HD touch display) w/ Garmin GTS51M-TM CHIRP 'ducer. West clearance-discounted from $1100 to $700 for both. The TD alone retails for $600.

Depth specs: Traditional CHIRP 1,800'; ClearVü 1,000'; SideVü 750'

The twist here is that - since the transom-mount TD unit couldn't be easily installed in-water - I did a temp. in-hull KY jelly & duct tape job, thinking there was a good chance of it's working pretty well with the hull's dense vacuum-bagged vinylester resin and gelcoat layup, and there was a nice flat area in the gelcoated thru-hull fittings sump where I put it fwd of the fittings.

With temp power supply per cig. lighter socket, Louise and I motored out to the first reaches of Monterey Canyon and saw several Humpbacks spouting in the usual 200-300' - a propitious sign for sure! Going deeper under ClearVu CHIRP, depth tapped out at 810' - a little deeper than my conventional flush in-hull transducer for the 12" Raymar. MFD could read. No SideVu possible of course. I was so amazed at this 80% performance that I didn't switch to the deeper reading Traditional CHIRP until after turning back to about 500' where it was solid.

So tomorrow will do a more permanent but still removable clear silicone sealant sealant job and complete the wiring...

[Dockhead]

Some interesting reading on the subject:


https://www.boats.com/on-the-water/s...ager-vs-chirp/

[toddster8]

I added one on the last haul-out, nominally for scouting out dive sites. Partly for anchoring and "feeling" my way in shallow channels. And also - couldn't stand to see main functions of the MFD left inoperable.

A couple of points to consider:

These things are not really made with sailboat hulls in mind. They need to point straight down, near the centerline of the boat, and well clear of the keel. Mine came with a plastic adapter block that could be sawn to match the hull angle, but IIRC, the maximum angle was something like 15°. Download the installation manual and study before purchasing!

I wanted it near the bow for functionality but this sure wouldn't be any help for light-wind performance of the boat. (The transducer is streamlined, but...) When sailing, the transducer often comes out of the water and causes all sorts of alarms. Need to turn it off when not needed. (In Raymarine-speak, IIRC, it's "ping off" in the MFD menu.)

[Dockhead]

Originally Posted by toddster8

I added one on the last haul-out, nominally for scouting out dive sites. Partly for anchoring and "feeling" my way in shallow channels. And also - couldn't stand to see main functions of the MFD left inoperable.

A couple of points to consider:

These things are not really made with sailboat hulls in mind. They need to point straight down, near the centerline of the boat, and well clear of the keel. Mine came with a plastic adapter block that could be sawn to match the hull angle, but IIRC, the maximum angle was something like 15°. Download the installation manual and study before purchasing!

I wanted it near the bow for functionality but this sure wouldn't be any help for light-wind performance of the boat. (The transducer is streamlined, but...) When sailing, the transducer often comes out of the water and causes all sorts of alarms. Need to turn it off when not needed. (In Raymarine-speak, IIRC, it's "ping off" in the MFD menu.)

Yeah, I have an Echopilot FLS and I can see my own keel with it


Can you give details of your installation?

[Emmalina]

Last time my mfd died I got a Raymarine Dragonfly (think raymarine just badge it cos it works so well) I made a little tank in the hull and tried the transducer with water on it . All good so I epoxied it into the hull. Been working fine for 3 years and I can tell the difference between sandy muddy rocky bottoms and can quickly remove it for thunder storms !

[Barbaria]

We have used a cheap Raymarine CHIRP down scan for a couple of years now. Very handy to scan unknown anchorages for any obstacles, avoiding sea grass, rocks etc. And for fishing of course.

The CPT-100 transducer was included with the A68 MFD, but it was supposed to be transom mounted. However we mounted it inside the hull on a flat surface embedded in “play slime” that my son had to play with. It works like a charm and I am pretty impressed what the little plastic transducer can do.

Here is some screenshots of actual use:

The Slime

[Simi 60]

Originally Posted by PirateGuy

.
The CHIRP sonar easily sees chunks of coral or rock:

After last year twice getting badly hooked up around coral bombies I am following this thread with interest.

We have a Koden fishfinder on board but it didn't save us.

[toddster8]

Originally Posted by Dockhead

Yeah, I have an Echopilot FLS and I can see my own keel with it


Can you give details of your installation?

I thought I had taken photos but none are to be found. I have a Raymarine A78 with the CPT110 through-hull transducer. Now I wish I had played around a bit with inside-the-hull mounting, as above, but the boat was hauled and it was the last chance to drill holes for several years.

I put it in the forward locker, under the V-berth and forward of the crash bulkhead. If it were to leak or somehow get sheared off, it would be contained.


There is a thick block of solid ABS plastic that threads over the through-hull and sits on top of the transducer. You measure the transverse and fore/aft angles of your hull. (Two or three times) Set your bandsaw for compound angle weirdness, test it on a few sacrificial pieces of wood, figure out if you’ve oriented the block correctly (two or three times) and slice through it. No second chances. At the maximum hull angle, the block has zero thickness at the forward inner edge and full thickness at the aft outer edge. I tried to site it so that the zero-thickness spot was on the center line. And seated it in plenty of sikaflex. The top half of the block doesn’t get discarded - it threads onto the through-hull on the inside of the hull, with more sikaflex, so the nut has a flat square surface to tighten onto, and the hull is sandwiched where you made the cut.