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Depth finder v Fishfinder/depthfinder

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britinusa
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Initially Posted - 06/07/2008 : 09:32:13

Reading the C25 thread on fish-finder wiring route, it dawned on me (not a fisherman!) that the fish-finder is a really nice device and probably better than the simple depth finder.

We have the Raymarine ST40 BiData system (Wind, Depth, Speed, Water temp) however the depth unit just tells us what the depth is right now (the transducer is in the sump under the v-berth).

Looking at fish-finders for the first time, I see that you get a lot more info.

Do they show the bottom directly beneath the boat or do they point ahead/astern slightly? I know the admiral would like more info on the bottom (gets very annoyed at herself if we bump anything!)

Paul

Update: AhHa! 100w!!!! That would suck the battery pretty quick! The ST40 uses just 0.84watts.

Ok, scrub that idea!

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

Edited by - britinusa on 06/07/2008 09:44:30

John Russell
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Response Posted - 06/07/2008 : 09:57:29

I asked a similar question recently. The answer I came away with was that the fishfinder would provide a good picture of what I just hit since they're not forward looking.

Edited by - on

Dave Bristle
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Djibouti
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Response Posted - 06/07/2008 : 10:10:17

A fishfinder gives a scrolling chart of the readings of the bottom essentially under the boat--not truly a picture of the bottom. Regardless of your speed, the scroll continues at a constant rate--even if you're standing still. There are some variations in color that supposedly tell you something about the composition of the bottom--I've never figured them out. For a fisherman, it recognizes the interruptions that fish make and displays them on the scroll--for sailors, the fishfinder is basically a depth sounder with a short graphic historic record. Scanning sonar, which can show the bottom ahead, is a whole nuther thing. (Think ten grand or so, to start.)

Edited by - Dave Bristle on 06/07/2008 10:14:24

JimB517
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Response Posted - 06/07/2008 : 11:03:36

I have a cheap Hummingbird fishfinder that cost less than $100. Much cheaper than a depth finder, and much more interesting. It is on 100% of the time I am sailing. You can easily see trends in the bottom like rocks, kelp, it is sloping up, or you are going over a drop off.

Power consumption is not an issue. I run fishfinder, GPS, autopilot, stereo for days without worrying about a charge.

Edited by - on

britinusa
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Response Posted - 06/07/2008 : 12:39:11

Thanks Jim, I guess that the power consumption may be 100w but it must not be a continuous rate. (or the hummingbird info is wrong.)

Paul

Edited by - on

OLarryR
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Response Posted - 06/07/2008 : 13:01:36

Paul,

Some of the fishfinders have a slightly enhanced dual beam signal that would still be a stretch to indicate it is really going to give you "advance" warning of impending doom. However, the reality is and I find this extremely beneficial for my Potomac River sailing is that as Dave pointed out, the scroll of the depth continues at a constant rate and while this does not give you a true sense of the actual bottom contour it is pretty close to that indicating at a glance if the riverbed is coming up and t how fast a rate and if it then levels off and continues to come up at a different ascent rate or starts to drift down. This is a real benefit.

That is not to say that if you were to come to an abrupt shallow depth, for example come upon an underground log, chances are you are going to get bumped. The fishfinder will not give you the advnaced warning you need for that type of instance. But it is better than a depthfinder in that it has a road map of where you have been and gives a sense of the road immediately ahead based on the rising and falling of the contour line. I find it a great benefit for river sailing short of having a sonar dome !

Edited by - on

britinusa
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Response Posted - 06/07/2008 : 14:44:56

Good points Larry.

Our most used ramp is blackpoint marina and the channel is pretty slim, put a boat coming the other way and some side winds you know that it's a little tense onboard. The channel is well marked, but our biggest problem is keeping in the grove when other (power) boats force us to the edges and that's where it's really skinny water, with rocks!

I often remind Peggy to look behind, because sometimes you get a better idea of where you are in the channel when you look at the poles behind you.

$89 for the fishfinder is pretty reasonable, and the admiral loves electronic gadgets (so far we have GPS, wind, depth, speed, water temp, handheld gps, SPOT, vhf but no remote yet!)

She's tough to live with

Paul

Edited by - on

bear
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Response Posted - 06/07/2008 : 15:03:16

Paul, I have had a Garmin 140 fishfinder installed for the last two
years, price at WM was about $140.00 It does show me the bottom
directly down, water temp,depth and fish. I do have an aural
alarm which is set at 10 feet so it does give you somewhat
of a warning. Transducer installed under V berth in the
recessed area with toilet bowl putty.

Edited by - on

piseas
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Response Posted - 06/07/2008 : 18:20:05

Paul, I too was wondering about this issue. I had been looking at a
Humminbird 383c Combo Fishfinder, around $350 but it does not show bouys or other navigational aids. I also like the Garmin 440x, under $400 which includes navigational aids but not a fishfinder. Lets get more input people.

Steve A

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britinusa
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Response Posted - 06/07/2008 : 18:32:44

Wayne, do you get the water temp with the transducer waxed in?

Paul

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SCnewbie
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Response Posted - 06/07/2008 : 18:33:05

If anyone is getting a fishfinder and has a control head for their old bidata 30, I'll buy it from ya. :)

My last sailboat ( a san juan 21) had no depth indicator other than the swing keel. My C250 has the bidatea but it doesn't work at the moment. Fortunately I am pretty familiar with the local area. It is when I plan on heading elsewhere that I would like to have it working. I had a garmin fishfinder on my old power boat that worked like a champ.

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bear
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Response Posted - 06/07/2008 : 20:15:56

Paul, The air temperature was 92 on the lake today, I suspect that once the boat moves through the water the temp reading is fairly close to actual water temp. I was getting readings in the mid 60s today once I started moving. I like the depth alarm, it can be set to any depth you want, has worked the nuts for me.

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OLarryR
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Response Posted - 06/07/2008 : 23:10:05

My fishfinder (Humminbird Matrix 217) has transducer mounted in-hull and reads both depth and temperature. The temperature is not accurate to the water since the transducer is mounted in-hull. It would appear that sometimes the temperature is reading closer to the water temperature but best to just consider it inaccurate....otherwise too much guess work.

The fishfinder also display the current battery voltage but this is generally displayed in the mode with the smaller character format displaying the depth and I like to keep the display in the mode that yields the largest numbers for the depth. In that display mode the voltage is not seen...but I also have a solar controller and that displays the battery voltage whether the solar panel is charging or not.

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stampeder
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Response Posted - 06/08/2008 : 00:25:11

I have a hummingbird fish finder/depth finder. It is either very unreliable or suffers from consistent operator error.
Don't like it, can't get it to stay on, when it does display data, it has been incorrect.
I ran aground in 27 feet of water last summer.

Edited by - on

OLarryR
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Response Posted - 06/08/2008 : 15:42:22

There is obviously something wrong with your fishfinder. I have a Humminbird and I rely on it constantly as I tack up a channel on the river. During high tide, I can go further outside the channel before tacking. I consistently continue on my tack toward the center of the river outside the channel until depth goes to about 4 feet and the 3 foot depth sometimes shows on the fishfinder. If the contour is still coming up, thenI tack. Sometimes toward the center of the river, if the we are progressed sufficiently toward high tide, the fishfinder contour levels off and then depth increases. If that happens, then I can continue on across the river amd make much longer tacks...a big time saver and away from some of the traffic in the channel. On the river side hugging the channel, there are rocks built up on that side of the river. I normally will tack much sooner but the depth can change rapidly as that side is approached and so I will normally tack once depth gets below 6-10 feet. In the channel, depths range from about 15-40 feet.

I find my fishfinder is pretty much dead-on and it has been that way ever since I installed it in the VBerth area next to the original transducer. I have never tweaked the settings/calibration. I know that where the transducer is mounted, the hull is underwater at that point and so the draft on my boat is 2' 11" (wing keel). SO...when the fishfinder is reading say....exactly 4'...the hull at that point to the bottom of the keel is probably not more than about 2' 6". So...I am cutting it a bit close sometimes and who knows what is lurking down at the bottom ? (Sometimes a log)

One time I was eating lunch at the Washington Sailing Marina (across the river from my marina) and I was sitting outside at a table. I was viewing their narrow channel which opens up to the Potomac River...it was low tide....and saw 2-3 shopping carts sticking out from the water just past the piers south of Natl Reagan Airport. I knew it was not a wise idea to cut that channel at high tide to enter their marina and much better to wait to much further downstream and then it is safe to cut into the channel.....now I see another reason why not to cut across too soon even if at high tide!

Edited by - OLarryR on 06/08/2008 15:47:28

Sloop Smitten
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Response Posted - 06/09/2008 : 09:41:02

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I have a hummingbird fish finder/depth finder. It is either very unreliable or suffers from consistent operator error.
Don't like it, can't get it to stay on, when it does display data, it has been incorrect.
I ran aground in 27 feet of water last summer.<hr height="1" noshade id="quote"></blockquote id="quote">

Sounds like your source voltage is weak. You might check the voltage and ground at the fishfinder to make sure you are not experiencing a voltage drop from corroded connections or old wire. They will lose their display and give you faulty readings if there is insufficient voltage.

Edited by - on

Stardog
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Response Posted - 06/09/2008 : 10:29:41

I have a Standard Horizon depth sounder, I called their tech support line to find out the best mounting scenario and they recommended setting the transducer in a pool of epoxy resin directly agains the hull, ahead of the keel. I did this by cutting a short section of cardboard tube to fit against the hull, setting the transducer level at the bottom and pouring the resin over it until it was just covered. It has been there for more than ten years and has never given me any trouble. Not sure if you can do this kind of mounting with a fish finder? I saw Paul mentioned waxing in a transducer. I take it this is the same sort of mounting, but with a softer material which is easier to remove for maintenance? I know I'll be down there with a saw and grinder the day I have to replace it.

I have to say I really like having a depth sounder, it has saved my butt any number of times, when navigating in shallow water.

Edited by - on

JimB517
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Response Posted - 06/09/2008 : 12:29:42

My transducer is epoxied to the hull forward of the keel and works great. I see the full 600 foot depth.

When they way "100 watts" that is the power of the audio pulse sent down. That is not continuious current draw. There is one short pulse per second and even slower in deeper water (pulse repetition frequency goes up when the water is shallower).

My autopilot draws far more current.

Edited by - on

piseas
Former Treasurer

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Response Posted - 06/09/2008 : 12:37:04

Jim, what unit do you have?
Steve A

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dmpilc
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Response Posted - 06/09/2008 : 14:33:50

Since mine is waxed in, I turned off the temp reading and enlarged the depth readout. Also, I set the alarm for 8 ft. since my transducer is set behind the keel cable, at least temporarily, the 8 ft setting gives me a bit of reaction time to tack before I hit bottom.

Edited by - dmpilc on 06/09/2008 14:36:31

JimB517
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Response Posted - 06/09/2008 : 16:30:09

Humminbird 100 FX purchased on sale at West marine for $75. No temperature. Has digital readout of system voltage which is very nice for monitoring batteries/solar panels. Sees down to 600 feet (and works good for all of that). Shows fish, kelp, structure.

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piseas
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Response Posted - 06/09/2008 : 17:22:40

Jim, I believe you do a lot a solo so taking up cockpit space not a bid deal and its all there for you. Its that a Garmin(for navigation) next to Humminbird.
Steve A

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Deric
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Response Posted - 06/09/2008 : 20:04:31

I recently purchased the Garmin 440s and am in the the midst of installing it, perhaps next weekend.
The unit has many more options than I can ever figure on using, but I wanted to have a unit that appealed to me visually, and had chartplotting, fishfinder, and GPS.

The unit will be installed on a RAM swing arm that allows me to position it from inside the cabin so it points outward.

I sail on Oneida Lake, which is more akin to a very large puddle - - it is about 40 feet deep, but very wide.
Fishfinders appear to be advanced depth finders to me.

A matter of interest: I heard there are cards you can get for the units that have a 3d contour of the bottom of lakes etc...does this feature add to this email thread?

Deric

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Dave Bristle
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Djibouti
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Response Posted - 06/09/2008 : 21:33:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Deric
 A matter of interest: I heard there are cards you can get for the units that have a 3d contour of the bottom of lakes etc...does this feature add to this email thread?<hr height="1" noshade id="quote"></blockquote id="quote">Those are computer-generated pictures based on depth readings from charts--not actual "pictures". Graphically interesting, but based on a lot of interpolation (guesswork), with dubious added-value.

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piseas
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Response Posted - 06/10/2008 : 01:08:03

Deric, I would be interested in your review of 440s. I am also looking at the 440x. Where did you get the swing arm and what transducer are you using? Pics would be great.
Steve A

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JimB517
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Response Posted - 06/10/2008 : 15:09:07

You see my nav center with fishfinder, Garmin GPS II+, and autopilot. This is wired to a bus/power distrubution point in the starboard settee behind the water tank (marine grade wires) which also powers the VHF and stereo. That connects to a 15 amp fuse in the main power panel that now reads "Instruments". There is a little push-pull switch to turn off the autopilot.

I usually sit on the opposite side (where the outboard is).

The nav center is covered by a snap on marine vinyl cover I made when not in use. If it is raining at sea I can also snap on the cover.

I single hand alot and so don't miss the cockpit seating.

I unplug the autopilot and plug in the anchor light to that socket, which I then hoist up on the spinnaker halyard. Almost never do you need the autopilot and anchor light at the same time!

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