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Old 01-07-2011, 08:34 AM
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Default Help - What Transducer - Garmin 740S

Need some help on what is the correct transducer for a Garmin 740S. I have spoken to numerous people and the amount of conflicting information is staggering (if not scary).

Here are the facts:
1. 2011 270 Chaparral
2. Current transducer is an Airmar through hull; digital readout only in a Faria gauge from the
factory

I wanted to take advantage of the existing hole in the hull but Airmar (Gemeco) said I could not. Current hole is 2", requires a different transducer with a 2.5" hole required (of course it does...it's a boat). Not really interested in drilling more holes in the hull so Gemeco said the P79 in hull would work as long as the hull is not cored (it is not; all fiberglass). I start checking websites for pricing and some said the P79 is for "digital readout only" not for fish finders. This is in direct opposition to what the guy at Gemeco told me. We had an extensive discussion on digital readout versus pictures/fishfinders. I also called Chaparral who said, yeah, it's all fiberglass but it may/may not read through the hull.

So, what I thought was a very simple question is apparently a rocket science.

What transducer will work with the a Garmin 740S and display depth and pictures (I know I will lose temp with an in hull installation)

Thx
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Old 01-07-2011, 08:42 AM
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These are all your choices .... I have mine connected to a P66 TM works great. If you want to take advantage of the 1000 kW feature you'll have to spend more money.

Select your type of mounting style, engine type, and manufacturer.then select start search it will display all appropriate transducers for the garmin 740s

http://www.airmartechnology.com/2009...ch.asp?Type=FF


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Old 01-10-2011, 07:20 PM
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Quote:
Originally Posted by bluewaterpirate View Post
These are all your choices .... I have mine connected to a P66 TM works great. If you want to take advantage of the 1000 kW feature you'll have to spend more money.

Select your type of mounting style, engine type, and manufacturer.then select start search it will display all appropriate transducers for the garmin 740s

http://www.airmartechnology.com/2009...ch.asp?Type=FF


Thanks. Looks like I will also go with a transom mount for my 740s. Is "P66" the correct model number or is there something more specific (model #) to ensure you get the right connector for a Garmin 740s? Also, where do you recommend I purchase the Airmar? Thanks.
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Old 01-10-2011, 07:36 PM
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This article I wrote may help you - http://www.boemarine.com/support/art...6-2ceff829449f

The ducer you are looking for is called a P79, here is a link to the specific ducer you need which will give you full FF capability - http://www.boemarine.com/products/01...unt-transducer

Why not enlarge the 2" hole from your existing ducer and mount the B60 that Gemeco recommends? - http://www.boemarine.com/products/01...ent-transducer
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Old 01-11-2011, 04:26 AM
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Quote:
Originally Posted by yachtjim View Post
This article I wrote may help you - http://www.boemarine.com/support/art...6-2ceff829449f

The ducer you are looking for is called a P79, here is a link to the specific ducer you need which will give you full FF capability - http://www.boemarine.com/products/01...unt-transducer

Why not enlarge the 2" hole from your existing ducer and mount the B60 that Gemeco recommends? - http://www.boemarine.com/products/01...ent-transducer
Thanks for the information. As clarification, are you saying the P79 will work with a 740"s" and provide the pictures for the bottom reader? That is what Gemeco told me but on several websites, and I beleive Airmar was one of them, for this model it said "digital readout only". I interpereted this to mean I would not be able to get the bottom contour pictures/fishfinding capabilties I want.

Regarding why am I not enlarging the exisitng hole, I am taking a pessimitic aprpoach, unfortunately. I have had too many bad experiences with mechanics/installers and I am envisioning torn up figerglass, a repait that looks like crap, and a huge bill just to remove and install the new. I would much prefer this installation but like I said, my ability to date to find competent work in this field is low. I have moderate mechanical skills but drilling out and installing the new ducer under the waterline is not one I am willing to tackle myself. If anyone knows of a qualified installer in the Tampa area, I would appreciate a recommendation.

Thanks.
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Old 01-11-2011, 05:58 AM
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P79 will work with the 740s and give you a bottom picture. I've been in a couple of fiberglass ribs with GPSMAP5012, GSD-22 and the P79.
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Old 01-11-2011, 08:45 AM
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Quote:
Originally Posted by fun ticket View Post
Thanks for the information. As clarification, are you saying the P79 will work with a 740"s" and provide the pictures for the bottom reader? That is what Gemeco told me but on several websites, and I beleive Airmar was one of them, for this model it said "digital readout only". I interpereted this to mean I would not be able to get the bottom contour pictures/fishfinding capabilties I want.

Regarding why am I not enlarging the exisitng hole, I am taking a pessimitic aprpoach, unfortunately. I have had too many bad experiences with mechanics/installers and I am envisioning torn up figerglass, a repait that looks like crap, and a huge bill just to remove and install the new. I would much prefer this installation but like I said, my ability to date to find competent work in this field is low. I have moderate mechanical skills but drilling out and installing the new ducer under the waterline is not one I am willing to tackle myself. If anyone knows of a qualified installer in the Tampa area, I would appreciate a recommendation.

Thanks.
The P79 come in three variants.

P79 NMEA 0183 Smart sensor
P79 NMEA 2000 Smart sensor
P79 Analog 50/200 Khz transducer

And what you want is the P79 Analog if you chose to use a shoot thru the hull.

This unit has the same crystal element as the the P66 transom mount and the SS60,B60,B117,P319 thru the hull units.
All have a 45/12 degree cone, 600 watt .

The B60 ,SS60 have the additional advantage of being a tilted element transducer.
12 degree for 8 to 15 degree deadrise.
20 degree for 16 to 24 degree deadrise.

Using the P79 is the least sensitive due to the loss of signal this unit will have by shooting thru the hull.

The transom mount is better and the thru the hull will give the best reading if placed in a clean water area.(Plus you are already half way there)

If you go the thru the hull route it is a very simple procedure.
PM me and I can provide detailed photos of what you need to do and will can guide you along.
It will be fun.
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Last edited by semperfifishing; 01-11-2011 at 09:01 AM.
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Old 01-11-2011, 09:07 AM
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Here is a video we did on the B60 Installation:

- Part 1 - http://www.youtube.com/watch?v=QcBdkjCtifA
- Part 2 - http://www.youtube.com/watch?v=nd-RPx34nUE

Its not rocket science. Any boatyard can do it for $200 to $400 depending on local rates. This is what I recommend and is simple to do for any halfway competent boat yard.
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Old 01-11-2011, 09:43 AM
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Thanks guys, Very helpful information. What has me freaked out is removing the exisiting thru-hull and enlarging that hole. It is currently a 2.0" hole and Airmar told me I needed a 2.5" hole unless the B60 fits in a 2" hole. I am not even sure how to enlarge an exisitng hole like that since you can't really use a hole saw given the exisiting hole. Also, I am sure it is bedded with 5200 and I would probably do damage getting it out.

Unless, your guidance is don't even deal with the existing transducer, leave it, move to the port side and just install a new transducer following the video instructions. I do believe the factory Airmar is operating at a different frequency than the one needed for the 740s so interference should not be an issue?

Your thoughts, just leave the original or remove it and I am making it a bigger deal tha it is? I do agree a thru-hull is hands down the best solution performance wise. Semper, I will shoot you a PM.
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Old 01-11-2011, 10:41 AM
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If you are using the existing ducer then leave it. If you are not using it then swap it out with the B60. To make the hole bigger you simply put a piece of wood on the inside of the hull covering the existing hole. You can then put your pilot hole in it and keep the hole saw steady while cutting a new hole around the old one.
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Old 01-12-2011, 10:53 AM
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While its harder to make a smaller hole, its pretty easy to make a bigger hole. Here's how.

Push out the old transducer tube. If it was put in with 5200, soften it with some stuff West Marine carries, and go explain the facts of life to whoever put it in.

Get two hole cutter bits, a 2 1/4" and a 2 1/2" inch. cut a 2 1/4" plug out of soft pine, and sand it down slightly to fit the hole in the hull very snugly. glue it in with anything that will stick, then use the 2 1/2" hole saw to cut around the plug. The 1/4" pilot bit will fit right in the hole in the plug. If you want to make is really pretty you can start from the inside to just barely cut a groove where the saw will come thru from the outside to avoid splinters. Mix up a tiny batch of resin and paint the raw edge of the new hole, then mount the new transducer, this time with 4200.

This will not work if the old dransducer barrel had a flush lip, but that just requires a bit of glass work to do the job right. This will let you use what the factory thought was the best place for a transducer, and give you water temperature.

I used this technique to move a three inch hole to one side, by marking a new center after gluing the plug in.
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Last edited by sandyda; 01-12-2011 at 10:58 AM. Reason: OCE: obsessive compulsive editing
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Old 01-12-2011, 01:33 PM
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If you want to use the full capabilities of the 740s, you will probably want a 1kw transducer. Six months ago I had a 740s installed in a new Bluewater. I went with a tilt-element, 1 kw, Airmar B164, which mounts flush with the hull and requires no fairing block. The B164 requires a 3 3/4" hole in the hull. If you were to enlarge the existing hole as sandyda suggested, which is exactly the way I would do it, it would probably be easier to cut a new 3 3/4" hole than one 2 1/2" only slightly larger than the existing hole. With the sizable investment you have in the 740s, it makes little sense to pinch pennies on a transducer.
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