Depth sounders/Fish Finders

[surekandoo]

I want to fit a new depth sounder to my Limbo 6.6 to replace the old rotating red LED jobbie, which is difficult to see from the cockpit & has no alarm. Looking at types/prices etc. I could do with some advice. The fish finders seem cheaper than the conventional depth sounders and give a more useable display. There must be a catch! Any advice most welcome.

 

[brianrunyard]

Fishfinders give you the best of both worlds, you can select a digital display just showing the depth in large numbers, or have the more usefull graphical display of the bottom with a digital depth display. The advantage of the graphical display is that you can see at a glance if the bottom is shallowing and also with most fishfinders you can get a very good idea of whether the bottom is hard or soft.
I can certainly recommend the Garmin 240.
Hope this helps,
Brian

Brian
http://homepage.ntlworld.com/brunyard

 

[pvb]

Main differences...

You can get some quite cheap fishfinders, but they usually come with a transom-mounted transducer. And they usually don't have the ability to program in a keel offset, so that you know the actual depth under your keel. Regular depth instruments usually come with a through-hull transducer, have the keel offset function and, crucially, have much bigger easier-to-read numbers.

On-line chandlers, such as <A target="_blank" HREF=http://www.yachtbits.fsnet.co.uk>Yachtbits</A> are offering regular depth instruments such as Raymarine ST40 for around £135, or NASA Target for around £95.

 

[Guest]

Transducers ....

Depending on the transducer - who says a transom one cannot be in-hull ???

Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[pvb]

Probably borderline...

The cheaper fishfinders, such as Garmin's 100 model, have very low power output, so mounting the transducer in-hull would probably result in quite a patchy performance.

 

[spannerman]

Having installed many depth sounders and fishfinders as a marine electrician, I would definitely go for a fishfinder as correctly stated by someone else they can show you the 'trend' of whats happening below. I have one on my boat and it has a transom type transducer but they lose the signal after about 20 knots due to turbulence in the water at the transom. So we always glue them with 2 pack epoxy to the interior of the hull, after sanding it clean and degreasing, and being careful that there are no air bubbles inbetween the transducer and hull. Mine works fine in a cruiser that goes at 36knots. Its a Hummingbird unit and its given no trouble it the 6 yrs I've had it.

Regards Steve

 

[Johnjo]

Good info,
being able to fix stern mounted tranducer inboard!

mike

 

[Nigel_Ward]

I bought a "Garmin Fishfinder 100 Blue" last year and it is a marvellous piece of kit. I followed the instructions about testing the transducer inside the hull of my GRP Manta 19 using a water bath, but decided against glueing it permanently in place with epoxy. The transducer is now fitted in water filled tube with a cover on it and the signal is perfect. You can set up the readout to display battery voltage and put an alarm on it. Mine runs on a car type battery only charged by the outboard engine. Keel offsets can also be specified.

 

[pvb]

But not what you might call cheap...

The Garmin 100 Blue is about £180.

 

[surekandoo]

Thanks everyone. You've answered my question. A fish finder it is! Garmin have a new model coming out, the 80 which look OK. I'm looking for low power consumption and would prefer an in hull transducer.

 

[brianrunyard]

Re: Probably borderline...

Not necessarily, in about 1990 (on a previous boat), I had an "Eagle Fish ID" with a transom mounted transducer that gave intermittent readings above about 14 knots. I refitted the same transducer inside the hull with epoxy and cured the problem, with no apparent loss of sensitivity.

Brian
http://homepage.ntlworld.com/brunyard

 

[brianrunyard]

Should have added

By today's standards, the "Eagle Fish ID" was fairly low power and quite basic.

Brian
http://homepage.ntlworld.com/brunyard

 

[pvb]

That\'s encouraging...

Sounds like it might work. Never had much success myself with in-hull transducers. Does lay-up thickness affect the performance?

 

[hlb]

Re: That\'s encouraging...

I have a Plasmo (or whatever) fish finder with through hull transducer. Works fine through the hull of my P35, cant think theres much thicker than that. Did take a bit of time to get it positioned right.

<font color=blue> Haydn

 

[stamfordian]

Re: That\'s encouraging...

Thanks chaps that,s another question ansered for me project...god another 180quids on the list!!

<A target="_blank" HREF=http://www.arweb.co.uk/argallery/stamfordian>http://www.arweb.co.uk/argallery/stamfordian</A>

 

[brianrunyard]

Re: That\'s encouraging...

Not so much layup thickness, as solid layup, (ie. no voids or wood laminate.
I tried mine in various places inside the hull to determine the best position, just put some water in the bilge and moved the transducer about until I found the best place, then dried it and epoxied it in place.

Brian
http://homepage.ntlworld.com/brunyard

 

[longjohnsilver]

silicone sealant

I have used this to position several transducers, each time successfully and allows me to fairly easily remove it if and when I want to.