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jerry f 06-08-2005 15:23

chartplotter/fish finder
I have a customer who wants a chartplotter gps/ fishfinder installed (and recommendations). I'm probably going to go with the Garmin 172c w/external antenna but my main question is transducer selection. I want water temp so I need a through hull or transom mount. Why would anyone intall a through hull transducer instead of a transom mount which requires less work, no large holes in the bottom of your boat etc. I assume because MAYBE you get smoother water flow and can supply more power with the through hull. Neither of these is a concern for a houseboat on the river. Advice on all type transducers is appreciated..

exposure 06-08-2005 16:09

For a river boat I would go with the transom mount.

For a blue water boat the transom is always coming out of the water. Also, sailboats heel and the unit could come out of the water.

When we delivered our boat down the ICW, the depth sounder was TU. I bought a portable unit that had the transducer mounted with a suction cup. It worked well stuck to one hull of our Catamaran. But, every time a swell passed by it would come out of the water and we would lose data. I am keeping it as a back up.

Alan Wheeler 06-08-2005 21:06

Exposure is correct. But to add, it also depends on hull shape, thus accuracey. All hulls will cause the water to "flow" around it, thus increasing the speed of the water. Depending on hull shape and transducer position, this speed increase can be small or large, but certainly it is occuring. A through hull can be placed in a area where this affect is not so strong, especially on a full keel hull. On a flat hull, it isn't going to be possible to find an area not affected, but the affect isn't as pronounced anyway.

Ryan 11-08-2005 13:58

If you need a fish finder, you want the 178c, not the 172c. Unless the unit will be mounted inside, or under a hard top I'd go with the internal antenna. It's easier to install, and the BNC connector is one of the more common failure points after a few years.

Another disadvantage of transom mount transducers is they often get knocked off by boat lifts, swimmers, etc. A well installed through hull should last forever. That being said, I've seen a few poorly installed through hulls. Drill straight!

If you do install a transom mount, pick the spot carefully. When the bottom doesn't track at speed, most people blame the unit when they should be blaming the transducer installer.

jerry f 12-08-2005 05:03

Thanks Ryan, I agree about the 178c. I see it comes with a transducer plug on the harness where the 172 does not. It will be mounted inside at the lower helm so i will use the external antenna but i will recommend the internal to anyone mounting in clear sight.

Talbot 12-08-2005 10:22

Personally not a great fan of garmin chart systems. Last time they changed chart types they immediately stopped supporting the previous one.
Their hardware is great, and they have a great reputation for maintaining their hardware, too bad that they didnt do the same with their chart support.

I have a Navman 5500 chartplotter and it is a great system, very user friendly. They have a combined plotter and fish finder that certainly deserves a look.

Alan Wheeler 12-08-2005 20:01

YEp, the Navman plotters and Ffinders are fantastic. If you can afford to look at this one, take a look at the Trackfish6600. This is a dual finder/GPS unit, but the real clever part about it is the Deisel Fuel computer. This is not a toy computer, It is a real McCoy that does a very professional job and very very accurate. There are plenty of Petrol ones out there, and petrol is very easy to monitor, but Deisel is not, because of two reasons. It is returned and it changes in Volume rapidly with temperature. So accurate measuring has to be temperature compensated, which is not easy nor cheap. In the past, the only way to do an accurate job, meant that the fuel monitoring equipment was large and expensive. And I mean EXPENSIVE. There are many makers of electronics that add Fuel monitoring packages in either stand alone or combinations, but none have been worth a darn. Navman are the first to actually produce a real deal package in an affordable price range. This was independantly tested by a very well known *(famouse in NZ) Marine Deisel Engineer Len Gilbert. Kiwi boaties reading will instantly know his name. At first he was sceptical, as he has been down this track before and no one has been able to do it for real. But Navman totally blew him away.
Anyway's, the advantages of fuel computing, you can work out the most efficient RPM/speed/fuel usage for the conditions. It calculates the amount of fuel in the tank(without having to use a sender) and it calculates the range your vessel has in the conditions you are in.

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