Depth while in motion

diungerich

Seaman Apprentice
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Sep 26, 2015
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33
Hi All. I have a 2007 Glastron GT205. It has the stock Lowrance combo digital depth finder and temp gauge. Temp constantly reads -4 degrees. Would be nice if that worked, but I really care more about the depth. Depth works fine while stopped and sometimes while underway. Most of the time, it gets confused while cruising along at 30, 35 or faster. I'm wondering if there's anything I can do to get it accurate when cruising. I believe the transducer is one of the ones flushed into the hull that you can't see from the outside. So, I'm not sure if a different transducer would fix it or if I'm just out of luck unless I upgrade to a higher end unit. Thanks in advance for the thoughts.
 

lmuss53

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Sep 9, 2008
Messages
1,227
The temp can be calibrated in the settings section of the menus.

If it's a built in transducer and it's clean on the bottom where it shoots through, there isn't much you can do. If the boat stays in the water and there is crud over the hull where it shoots through you might help the situation by cleaning the bottom around there.

If it's an external transducer make sure it's installed according to the directions, in a flatter place, to the port side, with about 50 - 60% of the body under water at planing speed.

If an internal transducer is failing, a new one properly installed either internally or externally would probably fix the issue.

Ebay is a great place to buy stray fish finder, sonar, parts.
 
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gm280

Supreme Mariner
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Jun 26, 2011
Messages
14,585
Kind of sounds like you're out driving the return signal. And that can happen if the transducer is not pointed straight down but at a rearward facing angle. So as you go faster, the signal arrives back after your gone pass it. And that creates the problem. You have to remember that sound travels a lot slower in the water then in the air and that accounts for being able to out drive a return signal. Even a perfectly positioned transducer can't keep up when the speed exceeds the return ping. And that is also the reason most factories state the maximum MPH speed they will work too. So either reposition your transducer, or live with it... JMHO!
 

diungerich

Seaman Apprentice
Joined
Sep 26, 2015
Messages
33
Good food for thought. Thanks.

FYI, transducer is the built in kind. Boat is trailered and kept clean, so no crud on the hull. I'll have to look at it's position, but it sounds like that's just life. Would be great to know when I'm running along if I'm quickly losing depth unexpectedly, though.
 

lmuss53

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Sep 9, 2008
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Glastron has been around for a long time and should have the transducer in the right spot. It could be that it came loose or wasn't glued in right in the first place. If it is loose but still laying on the hull it will work like you are describing. I would try to see if you can find it and if it's loose reglue it with some epoxy. Clean everything as good as you can and reglue it with some JB weld or similar product in the same spot.
 

GA_Boater

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May 24, 2011
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Glastron has been around for a long time and should have the transducer in the right spot. It could be that it came loose or wasn't glued in right in the first place. If it is loose but still laying on the hull it will work like you are describing. I would try to see if you can find it and if it's loose reglue it with some epoxy. Clean everything as good as you can and reglue it with some JB weld or similar product in the same spot.

While we use JBWeld for a lot of things, it's the wrong product for a transducer. If it's loose, use epoxy as Glastron did originally.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Sound travels much faster in water.

A product like JB Weld isn't a good choice for installing a transducer, you want to use a low viscosity clear product so air can escape more easily and you can see into it to ensure it has.

Transducers wear out over time, or can become damaged, so needing to replace one isn't that uncommon.

Have you owned this boat since it was new, or did it ever work correctly?
 

gm280

Supreme Mariner
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Jun 26, 2011
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Sound travels much faster in water.

A product like JB Weld isn't a good choice for installing a transducer, you want to use a low viscosity clear product so air can escape more easily and you can see into it to ensure it has.

Transducers wear out over time, or can become damaged, so needing to replace one isn't that uncommon.

Have you owned this boat since it was new, or did it ever work correctly?

I do stand corrected ondarvr. Sound does travel much faster in water then in air. But it takes a lot more energy to make a sound in water... Thanks for pointing out my error...
 

Fed

Commander
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Apr 1, 2010
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If you do some quick sums GM you will find a boat has to do a couple of thousand KPH to drive out of a transducer cone.
 

lmuss53

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Sep 9, 2008
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What is the difference between jb weld and any other 2 part epoxy? As far as I know jb is just a well marketed brand of epoxy glue.

From Wikipedia

J-B WELD epoxyEdit

The product J-B WELD is a two-part epoxy adhesive (or filler) that can withstand high-temperature environments. J-B WELD can be used to bond surfaces made from metal, porcelain, wood, ceramic, or glass,[7] plus marble,PVC, ABS, concrete, fiberglass, wood, fabric, or paper.[8] Avoid using alcohol to clean surfaces.[9] J-B WELD is waterproof, petroleum/chemical-resistant (when hardened), acid-resistant, plus resists shock, vibration, and extreme temperature fluctuations.[8] J-B WELD can withstand a constant temperature of 500 ?F (260 ?C), and the maximum temperature threshold is approximately 600 ?F (316 ?C) for 10 minutes.[9] J-B WELD can also be used inside a microwave oven, exposed to microwave radiation instead of infrared radiation (heat).[7
 
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GA_Boater

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Typically JB has metal fillers. The only JB to use is JB Clear Weld, which is ordinary epoxy. The problem is most use JB with metal fillers and that's not good for securing transducers.

Also the Clear Weld is 5 minute epoxy and most in-hull mounting call for slow cure epoxy.
 

NYBo

Admiral
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Oct 23, 2008
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7,107
A temp sensor isn't very useful if it's part of a shoot-through transducer. it won't read accurately.
 

gm280

Supreme Mariner
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Jun 26, 2011
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I do know the JB Weld is a very strong epoxy. The usual 5 minute epoxies could never stand up to JB Weld original. I use to build model RC airplanes and I used Devcon 5 and 30 minute epoxies. But then never got as hard as KB Weld does...
 
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