Bottom Lock - Sounders

Bottom Lock - Sounders

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Bottom Lock - Sounders - 4 May 2005 16:56:51

David Jones

Posts: 150
Joined: 29 September 2004
From: Dongara west australia
Status: offline

There have been many comments on recent posts about the advantages and the functions of 'Bottom Lock' on sounders. Some of the opinions and explanations of the benefits of this facility have been outside my belief of the overall capabilities/design of this feature. With a basic understanding of the facilities that are available to users of 'most' of the sounders that are available on todays market, and most of the brands that reach towards the top end of the scale incorporate this feature - it stands to reason therefor, that some distinct adgantage is to be gained. However, some of the posts on previous threads give cause for me to believe that perhaps misguided information is being handed down to some of the forum members. I therefor request that [as a forum member - and for the benefit of others] that this situation be clarified by manufacturers/distributors, and NOT "those" "who think" they know all that there is to know.

Questions:

What is the explanation of the B/L feature?
What can be expected from the use of this facility?
Can the same benefits be derived by utilising associated controls without using the b/l.? [i.e. viewing area above the bottom to determine fish by utilising the scope of the vrm] [provided that the depth of the viewing area is within the scope of the screen]
[can't explain the 'line thru' - you may be able to help me there too.

Jonesey

< Message edited by David Jones -- 4 May 2005 17:18:54 >

_____________________________

APATHY is the curse of the world -
But who gives a ****?

Post #: 1

RE: Bottom Lock - Sounders - 4 May 2005 19:58:43

Rod Lohoar

Posts: 246
Joined: 5 June 2003
From: Mandurah, WA
Status: offline

Very simply:
"If Bottom lock is selected, the zoom section moves so the bottom is always displayed in
the zoom section, regardless of changes in depth.
If Bottom lock is not selected, the bottom will not be displayed in the zoom section when it is outside the range covered by the zoom bar.
Using the Bottom Lock and the A-Scope features together on a split screen can be a powerful aid in recognising the type of bottom you are fishing on"
Now if you want more detail any of the major manufactur's sites will cover the subject.
If you are chasing bottom fish, it is a requirement. If your not, thats what the "zoom" is used for.
If you use "auto" bottom lock wont work. As with all fish finders a manual setting will enhance the chances for better and more precise reading
Cheers

(in reply to David Jones)

Post #: 2

RE: Bottom Lock - Sounders - 4 May 2005 20:42:19

Garry Frayne

Posts: 404
Joined: 11 August 2003
From: Was Karratha, now Perth Western Australia
Status: offline

Ok I'll bite.

I been reading the bottom lock issue for a while now and to give all of those out there who don't have the function I can honestly say after using units with and without bottom lock that you can do with out it

. However my experience is limited to water under 60-70m and swells under 4m.

Rod your explanation is ok

, but I think you'll find in the higher end Furno and JRC units the bottom lock also gets rid of the undulations caused by the boat moving up and down in swell or chop by holding the bottom at a constant level and then showing whats just above the bottom. This is why the guys describe a spike type of effect as they go over good ground. Easy to see when moving quicky.

I currently run high end colour Lowrance units and have no problems finding fish and fishy ground with my sounder. With intellegient use of the range and sensitivity functions in conjunction with colour line etc it is easy to pick coral and discriminate fish from the bottom. Higher resolution only aids this. The combination of split screens showing a section of the water column as well as the overall sounding is also an advantage in my experience.

We regually fish out wide for reds and never have a problem without bottom lock. We locate fish and likely bottom even in reasonably rough conditions and have the runs on the board to support this. You also have the option of the flasher graphics which can also be a powerful tool in distinguishing fish separate from the bottom. The added bonus of some units is you can also record the days sonar logs and play them back at night on your computer. This allows you to tweak colour settings and sensitivity levels, zooms, ranges etc to better understand the raw data. This will go a long way in getting the most out of your unit. I'm now able to distinguish different fish species as a result.

I'm not saying that bottom lock is not a useful tool, its just that some people reading these latest threads may get the impression that you can't get away without it. In my experience bottom lock is useful when conditions are very rough or the bottom depth constantly changing at a fast rate, necessitating constant range adjustments. But you can make good without it and some units that don't have such a feature may have other features that can be desirable.

My next unit? Probably a JRC unit, but not because of bottom lock.

My two cents worth.

Cheers

Garry

Ps I have no affiliation with any manufactuer or reseller. Just based on my own personal experience.

(in reply to Rod Lohoar)

Post #: 3

RE: Bottom Lock - Sounders - 5 May 2005 7:28:07

Daniel Mance

Posts: 6789
Joined: 5 June 2003
From: TLC Basement
Status: offline

Garry I find the bottom lock probably more useful on flat featureless country, (plenty of that in Bunbury and Coral Bay, where I mostly fish). Any sounder can find rough country, so bottom lock is really a moot point in that case. I find the B/L really shines when the bottom may look flat, but holds fish due to its pourosity (spelling?), this is especially prevalent with coral. Not sure what causes the spikes (flare) on the B/L readout. My theory, which a few others I have spoke with agree on, is that the low density of the porous bottom fools the algorithim of this function, making it constantly change where it thinks the true bottom is, thus the series of spikes. The deeper the pourosity, the longer the spike. I may be totally wrong tho

and something else causes it, but it makes locating this sort of fishy bottom really easy. I would just go over a lot of this ground thinking it dead without the bottom lock feature.

David, this site is essentially a tool where guys can ask questions and have them answered by other guys based on there opinions and experience.
I have used B/L for ages and caught a lot of fish because of it. That said, mate, you don't have to buy a sounder with it if you don't want it.
Anything I have said in regards to B/L is no secret really, I'm sure hundreds of blokes do the same thing.
I think the proof is in the puddin. just about everyone who has posted with B/L sounders, who know how to utilise it correctly, love em and wouldn't go back to not having it. If you ever hop on a pro or charter boat have a look at the sounder(if they let you). Of the (granted small amount, 4or5) ones I have been on, whether down south, metro or tropics, I have noticed, with a nod of satisfaction, they all have used this feature. I reckon there might be a good reason for that.
If you find some other way to increase your catch rates using your sounder, great, let us all know.
Sheesh. You can believe what you want to believe about whats been said mate. Just trying to help out a few blokes.

quote:

I therefor request that [as a forum member - and for the benefit of others] that this situation be clarified by manufacturers/distributors, and NOT "those" "who think" they know all that there is to know.

Mate, what I don't know about sounders would fill a set of encyclopeadias. I've done hundreds of hours of sounding tho, and in that time you tend to pick up a few tricks.

< Message edited by Daniel Mance -- 5 May 2005 8:31:08 >

_____________________________

Mancey

On the v5 revision...

quote:

ORIGINAL: David Adams
I reckon it is a wishy washy decision. Talk about Nero fiddling while Rome burned.

(in reply to Garry Frayne)

Post #: 4

RE: Bottom Lock - Sounders - 5 May 2005 9:39:52

Denis Bechard

Posts: 170
Joined: 17 October 2003
Status: offline

Well put Daniel

At the end of the day anyone can take a boat out and catch fish, even without a sounder - the issue here is utilising available features on sounders available to us as rec fishers to improve our chances of coming home with a feed.

As pointed out by Garry, Rod's reply seems to provide a different definition to 'Bottom Lock', unless we are interpreting this in a different manner.

quote:

"If Bottom lock is selected, the zoom section moves so the bottom is always displayed in
the zoom section, regardless of changes in depth.
If Bottom lock is not selected, the bottom will not be displayed in the zoom section when it is outside the range covered by the zoom bar.

Many manufacturers would use the term 'automatic shift' to describe this feature.

Here-in lies a dilema - 'Bottom Lock' may be a quite different feature depending on which manufacturer you are dealing with.

Having used units with and without Bottom Lock, I can say that I would not be without this feature - BUT THIS IS JUST MY OPINION, and is just 1 consideration when looking at a new sounder purchase. As Daniel has mentioned, it is invaluable on flat Coral - I use it to great advantage on the 'flat coral' out from Jurien and Exmouth - where the bottom may not appear to rise, but could be changing from sand to coral/rubble - being able to find and fish this ground innevitably results in improved catch rates - especially when everyone else is driving straight over it.

Just my 2c worth.....

(in reply to Daniel Mance)

Post #: 5

RE: Bottom Lock - Sounders - 5 May 2005 9:58:51

Daniel Mance

Posts: 6789
Joined: 5 June 2003
From: TLC Basement
Status: offline

What do you think about my understanding of what causes the flare or spiking Denis? I've spoken to a lot of blokes about this, as being a tech head I like to know how and why things work. The unit being fooled as to where the true bottom is tends to be the best explaination for the spikes I've heard which was told to me by a charter boat operator. It's amazing what some top fishermen will tell you if ya ply em with a bit of booze.

I always like to hear what other people think but, as this still puzzles me a bit. I just know it means fish, and man, it works. Bottom fish are usually down in and often underneath the coral and invisible to the sounder, if you can find that pourus plate coral, you find fish.
If you have no problem reliably finding coral without bottom lock guys, don't worry about it.

Bottom lock rules.

I can only say I know about the b/l on JRC and furuno sounders, which are essentially identical, any other brands might call different features the same name. Rod's explaination, while probably spot on for navman sounders, doesn't seem to hold true for what my unit does. My furuno basically shows up bottom lock as a split screen underneath the basic readout. It shows the 5 meters of the water column just above the bottom, keeping the seabed as a flat line, regardless of swell or bottom contours.

_____________________________

Mancey

On the v5 revision...

quote:

ORIGINAL: David Adams
I reckon it is a wishy washy decision. Talk about Nero fiddling while Rome burned.

(in reply to Denis Bechard)

Post #: 6

RE: Bottom Lock - Sounders - 5 May 2005 10:24:20

Denis Bechard

Posts: 170
Joined: 17 October 2003
Status: offline

My understanding is basically the same as yours Mancey. A flat (or slowly rising) sand bottom is easy enough for the sounder to 'process' and show as a 'flat line' on the bottom lock split. Broken coral will result in rapid changes to depth and reflected signal strength - my understanding is that the changes occur too quickly for the sounder to process, hence the flare until the sounder can ' catch up' and show a flat bottom again - same thing happens when you drive over a ledge - a single spike would show on the screen due to the sudden change in depth. This was explained to me by a sounder technician, obviously in simplified, layman's terms.

More often than not I stop and fish the ground that I find - even if I can not see fish on the sounder. Brian Stewart will vouch for the effectiveness of bottom lock - it's amazing some of the spots on 'flat bottom' that produce snapper, dhuies, reds, jobfish etc

Like yourself I take note whenever I go out on charter boats or professional boats - and they all seem to use bottom lock - funny that....

At the end of the day Mancey, the less people using bottom lock, the better for you and I...

(in reply to Daniel Mance)

Post #: 7

RE: Bottom Lock - Sounders - 5 May 2005 10:29:05

Daniel Mance

Posts: 6789
Joined: 5 June 2003
From: TLC Basement
Status: offline

Yay, finally found a pic of a furuno sounder to sort of explain what I am talking about. The unit shown is the Furuno FCV291, a mega power unit (1-3kw) which has a feature known as bottom discrimination described as such:

quote:

The Bottom Discrimination mode enhances the bottom echo tails to easily discriminate between soft, rocky or sandy bottom. This is done by noting the different colors and lengths of bottom tails.

This seems to be essentially bottom lock on steroids(correct me if I'm wrong anyone in the know, this is the best i could find). Pouros bottom shows up as long spikes as shown on the screen on the left. This is basically a flattened version of the actual display (on the right) which is the standard on every sounder.
My sounder is essentially the same but the bottom lock is underneath the main display. Notice how there are spikes coming from the bottom where fish are NOT showing up on the normal display.
Thats true bottom lock, does that help to explain it? Believe me, on the sounders mere mortals use, it isn't as obvious as this pic shows, which is of a high end sounder, but it's great example to help people get the idea.
Man I wish I had one of these babys, raw power

forget bottom lock, get this!! Forget Dual frequency, this bad boy has 5 frequencys.
Only $4200.

quote:

At the end of the day Mancey, the less people using bottom lock, the better for you and I...

Yeah i think i shoud shuddup before i get lynched by the bottom lock mob. Hope my misguided advice has been helpful.

(Click Image for full size)

Attachment (1)

< Message edited by Daniel Mance -- 5 May 2005 11:19:51 >

_____________________________

Mancey

On the v5 revision...

quote:

ORIGINAL: David Adams
I reckon it is a wishy washy decision. Talk about Nero fiddling while Rome burned.

(in reply to Daniel Mance)

Post #: 8

RE: Bottom Lock - Sounders - 5 May 2005 12:13:06

Garry Frayne

Posts: 404
Joined: 11 August 2003
From: Was Karratha, now Perth Western Australia
Status: offline

Some good info guys re bottom lock. It definetly has its uses and can be a great tool.

Our ground where we chase reds is also very flat, but probably of harder composition than down south?. We look for widening and density changes in the bottom composition to detect fishy areas. As this indicates a change from the sandy silt/rubble to a limestone or coral bottom. This shows up by a thicker colour line or alternatively a different colour and/or colours. Very easy to pick once you tune in. Also used in conjunction with an Ascope type function or signal intensity meter it can be very effective.

Also notice when over red schools (when stationary at anchor or slow drift) the signal return tends to be lots of individual vertical arches (almost squiggles) as the fish seem to hover up and down as they move along. NW snapper etc tend to form large dense clusters. Trout, cod etc tend to show as horizontal arches just off the bottom.

I'm still trying to come to terms with the flasher graph on my unit, but apparently it is very good once mastered and probably would equal bottom lock in handiness.

Cheers

Garry

(in reply to Daniel Mance)

Post #: 9

RE: Bottom Lock - Sounders - 5 May 2005 12:52:47

Dennis BryanSmith

Posts: 923
Joined: 5 June 2003
From: Karratha, Western Australia
Status: offline

Bottom lock certainly is a very handy tool .. but dso is zoom if i was purchasing a sounder and the budget didnt allow to have both id certainly want at least zoom my new high density sounder has all the features attached are pics with just 4x zoom

(Click Image for full size)

(Click Image for full size)

Attachment (3)

_____________________________

cheers ..Bushy...Billfish...N...Baitfish ...N... circle hooks

(in reply to Garry Frayne)

Post #: 10

RE: Bottom Lock - Sounders - 5 May 2005 13:17:18

Daniel Mance

Posts: 6789
Joined: 5 June 2003
From: TLC Basement
Status: offline

quote:

Also notice when over red schools (when stationary at anchor or slow drift) the signal return tends to be lots of individual vertical arches (almost squiggles) as the fish seem to hover up and down as they move along. NW snapper etc tend to form large dense clusters. Trout, cod etc tend to show as horizontal arches just off the bottom.

Right on Garry. Must say I notice much the same, especially with the reds and cod. Why, dunno, different body shape maybe, cod is more cylindrical while reds are deep in shape. Air bladder size, who knows. Jewys are simalar to cod, big individual arches or blobs close to the bottom.
Obviously if you can find schools you fish em first before worrying about what the bottom is made of. When the going gets tough and nothing is showing up, thats when the bottom lock can be handy to find the coral, but there are other ways of finding coral as you say.
They are some mad schools of fish there bushy. Any hints on what they are. What power
is your sounder putting out (RMS). Looks like a pretty nice bit of gear.

_____________________________

Mancey

On the v5 revision...

quote:

ORIGINAL: David Adams
I reckon it is a wishy washy decision. Talk about Nero fiddling while Rome burned.

(in reply to Dennis BryanSmith)

Post #: 11

RE: Bottom Lock - Sounders - 5 May 2005 16:32:21

Dennis BryanSmith

Posts: 923
Joined: 5 June 2003
From: Karratha, Western Australia
Status: offline

Hiya Mansey . yeah i agree with u yuh do ask a lot of technical questions .. ..lol ...RMS is 1000 WATTS .. yep is a nice unit and very user friendly as well as with most of the new units . i believe is a must to have soft key prompts usually at the bottom of the screen to show u the options available ..... Frayney and i could see the bait balls being herded up and then the larger arc of the sailfish as they moved in for the kill .. if u look close at the pics on the screen u will see it gives a depth readout of any targets ../echos is great to know how deep the bait schools or the depth the fish are feeding so u know what depth u need to have ur baits ... ill post some pics from the weekend with bottom lock ...

_____________________________

cheers ..Bushy...Billfish...N...Baitfish ...N... circle hooks

(in reply to Daniel Mance)

Post #: 12

RE: Bottom Lock - Sounders - 5 May 2005 23:42:08

Dave Griffin

Posts: 110
Joined: 7 November 2003
From: Falcon
Status: offline

Ok Guys I'll chime in here..

Attached is a photie of a school of NW snapper in exmouth..

Another benefit is that as the fish are shown staying very still (they aren't moving up and down with the swell). I could watch my baits (paternoster with 2 droppers) go down into the school, and watch a snapper peel off the school to nail it.

Very cool to be able to say 4 , 3, 2 ,1 to the young bloke !

Dave

(Click Image for full size)

Attachment (1)

(in reply to Dennis BryanSmith)

Post #: 13

RE: Bottom Lock - Sounders - 6 May 2005 5:36:42

David Jones

Posts: 150
Joined: 29 September 2004
From: Dongara west australia
Status: offline

GREAT STUFF GUYS - Just what I was hoping for! LOTS TO BE LEARNED HERE FOR SOME ISN'T THERE!!

quote:

Here-in lies a dilema - 'Bottom Lock' may be a quite different feature depending on which manufacturer you are dealing with.

Quite right Denis, on the Navman, they have two 'Bottom' features - one being the display of the bottom structure DISPLAYED AS A STRAIGHT LINE - clearly the bottom lock to which Daniel refers
The other - is classified as 'bottom lock' and displays the contour of the bottom but EXAGERATED. BOTH FEATURES ARE ONLY AVAILABLE IN THE ZOOM MODE.

At the risk of repeating myself, ALL of the features to which you refer - [i.e. reading columns of water above the bottom structure] ARE STILL AVAILABLE without the bottom lock feature - simply by resetting your zoom bar [or variable range marker if you wish].
The Bottom lock feature is EXACTLY what it says it is - i.e. Locks the bottom on the screen so that it is permanantly displayed.

Got your pm Mancey - no mate I'm not upset, what would I have to be upset about? I am certainly not a know all either, [your encyclopaedia would pale into insignificance.] Keep up the good work - many of our members [myself included] have lots to learn. Note also that you should keep an open mind -

this comment from another thread -

quote:

And david, bottom lock doesn't exaggerate the bottom, it actually does the complete opposite, basically discounting the bottom and giving you a view of the fish above it.

-is simply not so - if you were itilising the feature where the bottom undulations are ironed out, yes I would agree - but there are obviously conflicting definitions to 'Bottom Lock', and to all our readers, this fact should be clear!

- and again -

quote:

Sorta understand where you are coming from david, but I repeat B/L is not a zoom feature, it merely shows actvity above the bottom structure (hard bottom), which is essentially what we are all concerned about.

- On the Navman units the Bottom Lock is only available in the zoom feature - to the best of my knowledge, my mates Furuno unit is the same [ I may be wrong and he's away on hols so I can't check with him ]

I re-iterate - I seldom, if ever use bottom lock - I have found little added benefit - when the occassion arises where the bottom drops off to such an extent that I have difficulty maintaining the zoomed section on my screen, then I may consider it.

Keep this stuff coming guys - we ALL stand to benefit.

Jonesey

_____________________________

APATHY is the curse of the world -
But who gives a ****?

(in reply to Dave Griffin)

Post #: 14

RE: Bottom Lock - Sounders - 6 May 2005 7:15:57

Daniel Mance

Posts: 6789
Joined: 5 June 2003
From: TLC Basement
Status: offline

Think I've shown I have a pretty open mind David. How else did you think I found this information? By Having an open mind and asking heaps of questions. Think I'll call time on this one.

1000w is some serious power Dennis

May have a few more questions sometime. Wanna Bourbon

< Message edited by Daniel Mance -- 6 May 2005 7:45:21 >

_____________________________

Mancey

On the v5 revision...

quote:

ORIGINAL: David Adams
I reckon it is a wishy washy decision. Talk about Nero fiddling while Rome burned.

(in reply to David Jones)

Post #: 15

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