Transducers

[fmaster360]

I want to order a new GPS today or tomorrow, and I was hoping someone could explain how the transducers work. I had some difficulty yesterday with the transom mounted transducer for the fish finder that's on the boat. It seemed that when I was going faster in the wake, it would only show my dept as .9', as it was hitting the water and not going below it. I don't want to put any holes on the bottom hull of my boat. Can a transducer shoot through my hull, or do I need to cut a hole for it to go through? I'm thinking of the Garmin 541s or 441s unless anyone has something else that I really need to look at.

[fmaster360]

Looks like the in hull is the one I want, but it's not looking like it's as accurate as the transom mount. Guess I'll just end up with the transom one. Gives me an excuse to clean up the shotty job of the last one's install.

I'm probably going to pick up the 541s on tuesday price matched at $575 from wm, a transom mount, and if they still have the blue maps on sale, those too.

[Capt. Bill]

I'm a tad perplexed.....A GPS doesn't have a transducer so I have to assume your talking about a fish/depth finder or a combo unit.  A transom mounted transducer should be mounted as far below the water line as possible and away from the propeller.  Set it parallel with the bottom  of the boat and just below it.  The only holes in the bost are for the mounting screws. It you coat them with 4200 they will seal the hole on the way in.  

You can mount one inside the boat and have it shoot thru the hull.  I wouldn't recommend it because they tend the signal when your running hard.  If you still want to go that route,  then you must ensure the transducer is completely submerged in water and secured to the hull.  There are several ways to accomplish this so if you need some help let me know.

[GoneFission]

On an Aquasport boat, the best transom location seems to be 18" up from the center of the V in the transom.  Your transducer will come with directions, but you want a clean flow of water over the transducer when underway.  The good news - a transom transducer usually gets you temp with depth.  

[fmaster360]

Another question. I've decided on getting the 546s. I found one online wicked cheap. I can get two transducers, a dual frequency and a regular I guess. The dual one is for speed, and I assume that means it has a wheel. Is this more accurate as well? I can just switch the gps to use the gps speed and not water speed right?

[fmaster360]

Dual beam is freaking expensive. I got the regular dual frequency. Hopefully will be here soon. I can't wait to install it.

[RickK]

Another question. I've decided on getting the 546s. I found one online wicked cheap. I can get two transducers, a dual frequency and a regular I guess. The dual one is for speed, and I assume that means it has a wheel. Is this more accurate as well? I can just switch the gps to use the gps speed and not water speed right?

Never seen a transducer that has a "wheel" on it - the speed is from the GPS.  Maybe the design allows less drag?
Who are you purchasing from?

[John Jones]

Plenty of them out there.  Thru-hull or transom mount.  Here is one.  I had an Airmar thru-hull with depth/speed/temp for the Furuno bottom machine on my CCP.  The Garmin 240Blue I had before that had a separate speed wheel that could be mounted on the transom mount transducer bracket or un-clipped and mounted separately.

Depth - speed - temperature transducer for boat (thru-hull)
20620011



http://www.nauticexpo.com/prod/comnav/d ... 18322.html

Mine was similar to this one.

[Capt Matt]

Garmin makes a transducer that mounts inside the hull, a base is mounted then filled with oil then the transducer. It works awesome way better than any transom mount transducer I have ever had, even works on reverse and never looses the bottom signal no matter how fast you are going
Capt matt

[John Jones]

[John Jones]

I posted this quite a while back.  My CCP had this fiberglass well when I got it.  I don't know if it was factory or added later.  Fill it with mineral oil (or water but it evaporates over time) and ANY transducer dropped in there worked great at all speeds and attitudes.  So did the giant Airmar (with built-in speed wheel) on the left.

Remember that "shoot-thru" does not work with a cored hull.

[RickK]

Plenty of them out there.  Thru-hull or transom mount.  Here is one.  I had an Airmar thru-hull with depth/speed/temp for the Furuno bottom machine on my CCP.  The Garmin 240Blue I had before that had a separate speed wheel that could be mounted on the transom mount transducer bracket or un-clipped and mounted separately.

Depth - speed - temperature transducer for boat (thru-hull)
20620011



http://www.nauticexpo.com/prod/comnav/d ... 18322.html

Mine was similar to this one.

Still not sure that I "get" why you would want one with a wheel.  Could see if you don't have GPS/Chartplotter or the pitot in the lower unit like on my Yammy. Seems so "old", like the paddle wheel you mentioned that hangs off the transom.  Maybe it's me, no - didn't mean I am "old" - well maybe ....  

[seabob4]

Rick has a good point.  Paddle wheel speed is notorious poor at low speeds, better at high...but both inaccurate.  Pitot tubes are great at low speed, notoriously poor at high speeds...but both inaccurate.

Since we have GPS in our shorts these days, why not just go with that and ditch the old-fashioned...AND INACCURATE...stuff!

$.02 contributed...

[fmaster360]

I wonder if you can disable the wheel, and use the gps for speed.

[John Jones]

People that do a lot of trolling demand water speed indication.  GPS is speed over ground.  If you want to troll at six knots and you are trolling into a 2 knot current the bait will not act the same as if no current.  Going with the current you have to speed up to get the bait to act the same.  With a paddle wheel just troll at an indicated 6 knots and you are good.  People that never took the current into consideration think that a paddle wheel is inaccurate.  I checked mine vs. gps several times when there was no appreciable current and found them to be dead on.  They can be a PITA in the spring when there is all the floating grass getting tangled in the wheel.