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mertzer

Sonar Transducer mount location

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Likely an oldie but a goodie.

So I want to put an sonar / bottom imager on my boat. Mostly just for fun but may use it for light fishing. So the age old question of “A transom mounted transducer” It seems to me that drilling holes in the transom of a boat below the water line is a generally unwise idea. Probably better than a hole in the bottom of a boat for an in-hull unit.

It seems everyone says the CHIRP / DSI technology does not work if you try and shoot through the hull. Plus all units now seem to have water temp sensors as well, would be nice to know I guess. So I am leaning to a transom mount over an in-hull unit

AM I a nut for worrying about this on a two year old boat? Does it violate the hull warranty? Any thoughts / experiences?

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thru hulls are the best, transom mounts work, I doubt it voids the warrantee, make sure u seal it with 5200, others like 4200.

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This came from the Garmin Site. I personally went with the Transom mount Chirp transducer.

Hope it helps...

Choose the Right Mounting Style

Transducers are typically mounted in one of 3 ways: through the hull, inside the hull or on the transom.

In-Hull

An in-hull transducer is installed inside a boat hull against the bottom and sends its signal through the hull.

mount-insidehull.jpg
Pros
  • No need to drill through the boat; no drag
  • Boat can be trailered without damaging the transducer
  • No exposure to marine growth
  • Can be installed and serviced with the boat in still in the water
  • Give great high-speed performance as long as water flow below the transducer is “clean” (no turbulence)
  • Work with any engine type: inboard, outboard, and I/O when installed over solid fiberglass
  • Perform well on both power and sailboats
Cons
  • Not recommended for metal, wood and cored fiberglass hulls
  • Lose signal by transmitting through hull
Transom

These are attached to the back (transom) of a boat hull.

mount-ontransom.jpg
Pros
  • Good for trailered boats, out of the way of the rollers
  • Easy-to-install and remove —especially if a kick-up bracket is used
  • Good performance at boat speeds below 30 knots (34 mph)
  • Can be used with any hull material
Cons
  • Will not work on a boat with an inboard engine due to the turbulence forward of the sensor
  • Not recommended for sailboats because of excessive heeling
  • Will not work on stepped hull
Thru-Hull

Thru-hull transducers, as their name implies, are installed in a hole drilled thru the hull.

mount-throughhull.jpg
Pros
  • Work with any engine type: inboard, outboard or I/O
  • Work for power and sailboats
  • There are thru-hull transducers for every hull material
Cons
  • Do not use plastic thru-hull housings in a wooden boat. Wood swells as it absorbs water, so it may crack the housing.
  • Do not use bronze thru-hull housings in aluminum and stainless steel boats. The interaction between the metal hull and the bronze transducer, especially in the presence of salt water, will corrode the metal hull and/or the bronze housing.
Thru-hull transducers come in two styles: Flush and External

Flush mounts sit flush or nearly flush with the boat hull and are recommended for smaller boats with a minimum deadrise angle.

External mounts extend beyond the hull surface and usually require a fairing to aim the sound beam vertically and are for larger un-trailered boats.

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Transom mount is fine. Just put 5200 or 4200 in the holes before putting screws in, and then apply between the transducer and transom to insure no water in between and you'll be fine. Also you only need to drill a 3/4" to 1" deep hole, so it won't penetrate completely through the transom. You just don't want to allow the water in and be absorb by your transom.

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Transom mount is fine. Just put 5200 or 4200 in the holes before putting screws in, and then apply between the transducer and transom to insure no water in between and you'll be fine. Also you only need to drill a 3/4" to 1" deep hole, so it won't penetrate completely through the transom. You just don't want to allow the water in and be absorb by your transom.

all of the extended plane hulls like chaps that I have mounted transducers on are not very thick 1/2 inch or so and coring is in there also, not the thick fibreglass one would think, all the strength is by the outdrive and below the motor. If u use a transom mount make sure you get it below the water line but not in the way of the boat hull strake to avoid turbulence. I have always felt on alum. fishing boats or deep V hulls transom mounts are good, anything with a modified V with a hull pad it can get iffy.

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Can someone post a picture of where they put their transom mount for sonar on an H2O?

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I also have a 244 xtreme and putting in a Lowrance hybrid dual imaging (downscan and sounder). As an aside my boat has a factory installed thru hull transducer, and I think yours should also. There are two thru hull sensors one for depth and the other speed. Look in your engine area right behind the gas tank.

I was thinking of replacing that with a full HD thru hull sounder for my lowrance. Talking to Lowrance they make one that would work for ~400 deer. You may be able to directly replace the OE with a better one for use via your fish finder.

Others have reported better performance with transom mounted than thru-hull, but for me I suspect it's personal preference. An IN-hull will not allow downscan imaging or water temp.

When the boat is in the water there is nobody to see this sensor, and it seems easy enough to install, so going to just go with transom mounted. There is some pics of what others have done in the thread I started last week:

http://forum.chaparralboats.com/index.php?showtopic=25684

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I also have a 244 xtreme and putting in a Lowrance hybrid dual imaging (downscan and sounder). As an aside my boat has a factory installed thru hull transducer, and I think yours should also. There are two thru hull sensors one for depth and the other speed. Look in your engine area right behind the gas tank.

I was thinking of replacing that with a full HD thru hull sounder for my lowrance. Talking to Lowrance they make one that would work for ~400 deer. You may be able to directly replace the OE with a better one for use via your fish finder.

Others have reported better performance with transom mounted than thru-hull, but for me I suspect it's personal preference. An IN-hull will not allow downscan imaging or water temp.

When the boat is in the water there is nobody to see this sensor, and it seems easy enough to install, so going to just go with transom mounted. There is some pics of what others have done in the thread I started last week:

http://forum.chaparralboats.com/index.php?showtopic=25684

A in the hull will allow down scan but not temp. a thru hull will allow both, the thru hull on your boat is a transducer for depth, the speed is measured either by merc thru the outdrive or volvo thru either a hole in the outdrive or a pitot tube ( think thats what it is called) mounted to the back of the transon, don't know when volvo switched to the outdrive like merc. over.

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A in the hull will allow down scan but not temp. a thru hull will allow both, the thru hull on your boat is a transducer for depth, the speed is measured either by merc thru the outdrive or volvo thru either a hole in the outdrive or a pitot tube ( think thats what it is called) mounted to the back of the transon, don't know when volvo switched to the outdrive like merc. over.

Lowarance told me downscan is impaired and generally does not work with shoot-thru hull method, for their transducers. My 244 xtreame came with two thru hull sensors, one is a transducer for depth and the 2nd is a paddle-wheel for speed. I was going to perhaps replace the depth for a HDI transducer, but did not finish the research on if this possible.

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will have 2 look into the speed x-ducer, must be a smart gauge think that I have been trying to avoid, but I learned somthing, thank you for that.

shoot thru the hulls work if the bottom has no coring and probably would not work on a chap?

I left my faria depth x-ducer ( thru hull hooked up and us it as a back up,) I have lowarance on the big boat with hd and love it, have a thru hull just can't use both at the same time, never know when seaweed etc will wrap around and ruin picture. transom mounts work good, easier to clean and mount, make sure there not mounted in any turbulance, sometimes u can go 2 fast and get eratic readings but when you slow down it comes back.

here is an add a x-ducer tool that mighthelp in the decision.

http://www.lowrance.com/transducerguide/

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mertzer

Hey Mertzer,

I ended up going with the Lowrance Elite 4 HDI - For under 300 deer, it has both downscan and sounder, GPS, maps, water temp and is a small color screen. These 244 do not have a lot of room to mount, so small screen. I went ahead and just used the factory included 83/200 transducer. Drilled a 1" hole right where the transom connects to the swim platform on the starboard side. On the port side there is a drain hole, so I just went opposite of that hole.

To refill the 1" hole I saved the fiberglass plug, and after running the wire, chipped it out to make room for the cord, then stuck the plug back in. Coated everything up with some 4200 quick bond.

I was going to put a claim shell cover over the hole, but all of this is in a location nobody can see so not going to worry about it.

After doing this, I'm still not happy about drilling a 1" hole in my boat, but it's not so bad. I'm short deer right now or perhaps I would have seen about replacing the thru hull OE transducer with the one from Lowarance. If that one would fit in the same mount as the OE one, then that would be a better way to go.

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