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blooztune · 14-11-2018, 11:26

Hi! Long time lurker, first time poster.

I am adding a Garmin GPS to my old boat that currently has a working depth sounder with a thru hull transducer. I bought an in-hull transducer with the new system, but it occurs to me that I could replace the old transducer with a new thru hull for the GPS and reap the benefits of thru-hull vs in-hull without having to put another hole in the hull. (This would obviously disable the Standard Horizon depth sounder I currently have.)

On the other hand, I'm a proponent of redundancy with those sort of things so I'm tempted to go with having both.

Thoughts?

Steve

J.Kitchens · 14-11-2018, 11:54

If the in-hull and thru-hull operate at the same frequency they will affect each others signal. Likely making them both useless if operated at the same time.

It is my opinion that the depth finder should be a dedicated system, independent of other electronics. -Feel free to devise your own opinion.

If you want to use the sounder features of the Garmin and keep the Standard depth finder, install the in-hull transducer and turn off your depth finder while using the sounder.

The Standard Horizon depth finder is a highly reliable tough piece of equipment. I have a feeling it will outlast your Garmin.

Ultimately, depth is depth; do whatever you want.

**Pete7** · 14-11-2018, 12:13

Rather than use a through hull, how about using one of the shoot through Garmin transducers? Test it by putting it in a plastic bag full of water and place inside the hull.

We have a Ray ST60 near the mast and a Garmin transducer towards the stern which operate on different frequencies so both play together without problems. The later Garmin's have dual frequencies which might help if there is a problem.

Pete

J.Kitchens · 14-11-2018, 12:19

Quote:

Originally Posted by Pete7

Rather than use a through hull, how about using one of the shoot through Garmin transducers?

I think that is what he means by in-hull.

It would help if we knew what transducers you have.

blooztune · 14-11-2018, 12:42

Quote:

Originally Posted by J.Kitchens

I think that is what he means by in-hull.

It would help if we knew what transducers you have.

Yes, that's what I meant. And that's an excellent point about possible frequency clash.

The in-hull (new) transducer is an Airmar P79 That shows
Frequency: 50/200kHz-A

I'm not sure about the Standard Horizon. Researching now.

J.Kitchens · 14-11-2018, 12:50

The Standard Horizon is most likely 200kHz. There should be a tag on the display end of the transducer cable.

Dooglas · 15-11-2018, 12:09

I replaced a transducer recently and took the opportunity to upgrade to the current CHIRP technology. It is so far superior to the older 200/50 kHz systems that I am certainly not looking back. If your new Garmin system is CHIRP compatible, be sure you fit a CHIRP transducer. If you want a backup sonar readout, the Garmin Strykers are CHIRP compatible and very cost effective.

stnick · 18-11-2018, 07:08

There are just 2 Frequency of transducers both are airmar who make 99 % of all transducers. If you use a Garmin installer, he has a black box the size of a package of cigarettes and that changes your old transducer to the other frequency !
I have such a device on my boat with the Garman 741 which is nema with that depth sounder . Garmin installers say a black box comes with every unit the order . ! Im not sure you can buy the box separately !

KeelMe · 18-11-2018, 08:11

Quote:

Originally Posted by stnick

There are just 2 Frequency of transducers both are airmar who make 99 % of all transducers. If you use a Garmin installer, he has a black box the size of a package of cigarettes and that changes your old transducer to the other frequency !
I have such a device on my boat with the Garman 741 which is nema with that depth sounder . Garmin installers say a black box comes with every unit the order . ! Im not sure you can buy the box separately !

WRONG!

1. There is no magic frequency changing box.

2. Transducer frequencies I can think of off the top of my head (there are more):
50kHz, 77kHz, 150kHz, 170kHz, 200kHz, 235kHz

3. If the magic box comes with every order why do you have to use a Garmin installer?

4. If Garmin made a magic frequency changing box (which would in fact have to be magic) I think they would sell it instead of giving it away.

Dooglas · 18-11-2018, 12:54

Quote:

Originally Posted by stnick

There are just 2 Frequency of transducers both are airmar who make 99 % of all transducers.

Quote:

Originally Posted by KeelMe

Transducer frequencies I can think of off the top of my head (there are more): 50kHz, 77kHz, 150kHz, 170kHz, 200kHz, 235kHz

KeelMe is coming closer to the truth, but both of you are overlooking CHIRP technology scanning sonar which uses ascending frequency range transmissions. This is a game changer in terms of penetration and resolution which is now becoming readily available for recreational boaters. And, yes, Airmar makes CHIRP transducers.

Here is a good description of the technology by West Marine - https://www.westmarine.com/WestAdvis...Scanning-Sonar

J.Kitchens · 18-11-2018, 13:19

KeelMe is actually in the process of writing a book about transducers. I seriously doubt he overlooked anything.

KeelMe · 18-11-2018, 13:19

I assure you I have not overlooked anything. Other than your comments, CHIRP transducers have had no part in the conversation.

As far as I can tell from the original post the OP is interested in depth sounding not fish finding. 50/200kHz is just about the best depth transducer you can get.

For the record I agree CHIRP is the best for a fishfinder.

KeelMe · 18-11-2018, 13:20

Quote:

Originally Posted by J.Kitchens

KeelMe is actually in the process of writing a book about transducers. I seriously doubt he overlooked anything.

It's not a book. It will be a very detailed interactive guide.

**Pete7** · 18-11-2018, 13:34

Slight thread drift, but let us know when you publish, I for one would be interesting in reading.

Pete

Dooglas · 18-11-2018, 14:25

Quote:

Originally Posted by KeelMe

For the record I agree CHIRP is the best for a fishfinder.

I don't understand why ANY discussion of sonar technology for recreational boats would leave out CHIRP capability. And for the record, I seldom use CHIRP scanning for fishfinding. I use it because it gives me the best returns on soft bottoms and the most detail/resolution of bottom contours. My CHIRP system replaced a 50/200 kHz system and has been a welcome upgrade. My current transducer (and most Airmar CHIRP capable transducers) are also capable of operating in conventional fixed frequency modes so an operator doesn't give up anything by going this direction.