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Discussion Starter · #1 ·
I have pretty much settled on getting a Garmin 498c, which is a color sounder (GPS/depth combo). With the detailed coastal blue chart data built in, it seems like a great price/performance package at about $600.

My question has to do with a speed sensor. Garmin sells a transducer with a built in speed sensor (as well as a temp sensor), or you can buy a TD (with temp) and a separate speed sensor.

Not surprisingly, it is cheaper to buy the combo TD/temp/speed unit rather than the 2 separately.

MY QUESTION: Does anyone have any experience or advice concerning Garmin TDs with the speed sensor built in?

While I have your attention :D my boat has a canvas top (over an aluminum structure). In this setup is there any real advantage to an external antenna GPS. I already have an external antenna for the old/lousy GPS I am replacing, so I may be able to avoid any drilling any new holes.
 

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The unit I bought last year had the TD with separate speed sensor that I could have opted to mount, more holes in the boat is not a good thing. Plus your GPS is going to show you your speed so it's a waste of time/money/holes in the boat/etc. As for the external antenna, that is up to you. If you already have the holes from your old one then I would suggest getting a new external since you are not going to be putting new holes in the boat. Plus if you get an internal antenna you will have to plug the holes from the old one if they are through something like your cabin top.
 

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I do know Garmin. The 3way (speed, temp, depth) is the way to fly. When trolling you want speed through the water and not speed over the ground. The transducer with speed is the only way to get that. The transom mount is adequate even though it limits your sounder to 600 watts. That's more than adequate for the bay. Try the built in GPS antenna. If it takes a long time to catch a half dozen or more SAT stations or you keep losing position, go for the remote antenna. It should fit the standard mount that you currently use eliminating any new holes in your T-top.

Bill
 

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I'm looking at adding a 2nd unit to my boat and am thinking about the 498c also. I've got about a 9" x 12" space. Will it fit?

BTW, go with the combo speed/temp transducer.

Thanks,

- Dae
 

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I would only go with a combo unit if the speed and temp sensor was replaceable. TMP/SPD sensors are notorious for going bad and I'm not replacing the transducer every time to resolve the problem.

You may want to look into installing one of those starboard sensor mounts on the transom. No more worries about mounting sensors on your transom every again
 

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Discussion Starter · #6 ·
Dae; It depends on what kind of mount your are going to do. If you are going to do a surface mount (where a permanent stand gets mounted, so the entire stand + unit is above the mounting area), and if 9" x 12" is your available footprint size, you should be fine as long as there is enough overhead space. The entire unit's measurements are 6.3" wide by 3.3"deep, so you should have plenty of space. The internal unit's height is 7.1" tall (internal antenna version...external is smaller), plus the height added by the surface mount.

If you are going for a flush mount that size is fine also. The mounting holes for the flush mount are 5.58" by 4.33" (the actual unit is larger than that by less than 1" in each dimension).
 

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Discussion Starter · #7 ·
Seahunter;
I'm not sure what you mean by "You may want to look into installing one of those starboard sensor mounts on the transom. No more worries about mounting sensors on your transom every again"

Could you tell me a little more about this alternative?
 

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ABTER1, I have a 3206 with the speed,temp, depth and it works great. I have had similar Garmin equipment on previous boats as well with never a breakdown. Of course we all know that the speed part is the one always to get scumed up so you need to keep it free or simply use a GPS reading to get speed. I also like the above post of the sensor mount, sounds like a good idea. When I flush mounted my unit, I layed out the space and used a Dremel tool with a tile cutting bit (drilled holes in the corners first) that made the job a breeze!! No splintering whatsoever but I did masking tape the area first. I would prefer the external antenna. I wasn't sure how to drill a hole through the canvas so I went with a rail mount (allows you to swing down when covering for the winter) and it works terriffic and allows you to put anywhere around the outside of the top. Hope this helps, good luck. Paul
http://www.consumersmarine.com/modperl/product/browse.cgi?r=aisle&aID=32C

2206 Robalo R220/F250
Locust Point Marina
www.liquidfun.com
 

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I have a garmin thru hull transducer with speed & temp. No problems with the temp, and the speed sensor is mounted through a hole in the center of the unit. It is removable so the paddle wheel can be cleaned. Plus it was awful nice of Garmin to include a blank to fill the hole when removing the speed sensor.
 

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I recently installed a 498c (transom transducer) and I really like it so far. I like the size, easy enough to read, but you don't feel like your driving a "virtual" boat. Haven't seen enough fishing action to comment on the fishfinder's accuracy, but seems good. I also used a rail mount for the external GPS antenna with my canvas ttop, and matched it with a rail mount VHF antenna for the other side.

I chose the external gps antenna after extensive forum searching, even though I had to do a new install through the ttop. Might be overkill in some ways, but why not get the best signal possible from the beginning? There was some concern that the WAAS signal is the most prone to fail with a lower mount- I don't know, just figured I'd eliminate one possible issue.
 
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