Newer Hobie--Pro Angler Question... - Kayak Fishing Adventures on Big Water’s Edge

bolocop · 02-26-2014, 11:05 AM

Have a question for you newer Hobie and Pro Angler owners. So the newer models come with a Lowrance-ready transducer mount.

My question to everyone is how is this really different than a thru-the-hull application by using grease or glue? OK, I know, it sits in water so that you can get temp, BUT...

My point is that the Lowrance-ready fitting still has to shoot through black plastic. Wouldn't it be better to just dremel out the black plastic plate except for the mount and the three mounting screws so there is an unobstructed view?

ful-rac · 02-26-2014, 11:25 AM

The plastic plate is very thin compared to the hull of the kayak, so you will get a better reading than a shoot thru hull transducer set up.

02-26-2014, 12:17 PM

The theory is there is no risk of an air gap. The reason we use goop isn't to keep it in place, rather to ensure there is a constant medium for the waves to travel. If waves travel over a gap they will encounter "defraction". The severity of the defraction is dependent upon the size of the gap vs the wave length.

Waves also travel differently through Air, Water and Solid. Going Air->Solid->Water is more distorting than Water->Solid->Water. That is why some of us actually use water in our hulls instead of goop. A "wet mount" we call it. The speed of sound through sea water is approx 1500m/s and through silicone 1480m/s. They are nearly identical. That is why silicon goop is preferred as an adhesive. However, you run the risk of air bubbles with using silicone.

Sound travels through air at only 332m/s. Reduced by a factor of around 4.5? So these air bubbles might seem insignificant, but the affect on the behavior of a wave is actually quite dramatic.

The wave length of 200khz through water is aprox 8mm and through air 1.7mm. So you can see a significant change.

The distortion between solid and water is minimal because the velocity of the wave isnt that different depending on the solid, So their wavelength is closer in value

Hope this makes sense

ful-rac · 02-26-2014, 12:26 PM

Drake you just gave JimDay a run for his money....!

In simple terms:

Lowrance ready gooood...
Shoot thru hull not as gooood...

bolocop · 02-26-2014, 01:27 PM

Drake, that makes sense! I enjoy a good dose of scientific reasoning!

tacmik · 02-26-2014, 08:04 PM

Where is
dgax65

when you need him.

Old Man in the Sea · 02-27-2014, 08:47 AM

yes drill though the plastic until you hit water...
then your fish finder will work properly

TJones · 02-27-2014, 04:18 PM

I did what he suggested . I bought an extra cover and cut it away with a jig saw. The unit has down imaging so I gave the transducer a direct shot. . Needless to say , the picture is great . If the the unit does not have down imaging , and is traditional sonar only , is cutting the plate a bad idea ? Does the thin plastic even hinder the signal on say a hds 5 ?

02-26-2014, 11:05 AM	#1
bolocop Senior Member Join Date: Aug 2012 Posts: 332	Newer Hobie--Pro Angler Question... Have a question for you newer Hobie and Pro Angler owners. So the newer models come with a Lowrance-ready transducer mount. My question to everyone is how is this really different than a thru-the-hull application by using grease or glue? OK, I know, it sits in water so that you can get temp, BUT... My point is that the Lowrance-ready fitting still has to shoot through black plastic. Wouldn't it be better to just dremel out the black plastic plate except for the mount and the three mounting screws so there is an unobstructed view?

02-26-2014, 11:25 AM	#2
ful-rac Emperor Join Date: May 2009 Location: Buena Park Posts: 3,649	The plastic plate is very thin compared to the hull of the kayak, so you will get a better reading than a shoot thru hull transducer set up. __________________ There's nothing colder than yesterday's hotdog.

02-26-2014, 12:17 PM	#3
Drake Guest Posts: n/a	The theory is there is no risk of an air gap. The reason we use goop isn't to keep it in place, rather to ensure there is a constant medium for the waves to travel. If waves travel over a gap they will encounter "defraction". The severity of the defraction is dependent upon the size of the gap vs the wave length. Waves also travel differently through Air, Water and Solid. Going Air->Solid->Water is more distorting than Water->Solid->Water. That is why some of us actually use water in our hulls instead of goop. A "wet mount" we call it. The speed of sound through sea water is approx 1500m/s and through silicone 1480m/s. They are nearly identical. That is why silicon goop is preferred as an adhesive. However, you run the risk of air bubbles with using silicone. Sound travels through air at only 332m/s. Reduced by a factor of around 4.5? So these air bubbles might seem insignificant, but the affect on the behavior of a wave is actually quite dramatic. The wave length of 200khz through water is aprox 8mm and through air 1.7mm. So you can see a significant change. The distortion between solid and water is minimal because the velocity of the wave isnt that different depending on the solid, So their wavelength is closer in value Hope this makes sense Last edited by Drake; 02-26-2014 at 07:12 PM.

02-26-2014, 12:26 PM	#4
ful-rac Emperor Join Date: May 2009 Location: Buena Park Posts: 3,649	Drake you just gave JimDay a run for his money....! In simple terms: Lowrance ready gooood... Shoot thru hull not as gooood... __________________ There's nothing colder than yesterday's hotdog.

02-26-2014, 01:27 PM	#5
bolocop Senior Member Join Date: Aug 2012 Posts: 332	Thanks... Drake, that makes sense! I enjoy a good dose of scientific reasoning!

02-26-2014, 08:04 PM	#6
tacmik Senior Member Join Date: Jun 2007 Location: East County Posts: 914	Where is dgax65 when you need him. __________________

02-27-2014, 08:47 AM	#7
Old Man in the Sea Senior Member Join Date: Feb 2012 Location: Bay Park Posts: 569	yes drill though the plastic until you hit water... then your fish finder will work properly

02-27-2014, 04:18 PM	#8
TJones Senior Member Join Date: Jan 2012 Posts: 2,526	Drake I did what he suggested . I bought an extra cover and cut it away with a jig saw. The unit has down imaging so I gave the transducer a direct shot. . Needless to say , the picture is great . If the the unit does not have down imaging , and is traditional sonar only , is cutting the plate a bad idea ? Does the thin plastic even hinder the signal on say a hds 5 ?