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Random Quote: give a man a fish feed him for a day teach him to fish he will be dead of murcury poisening in 3 years
I am looking at buying the Garmin 238 GPS/Sounder. I noticed they have both plastic and bronze transducers in the thru-hull, in-hull and transom mount varieties. Any feedback on the 238? Which transducer do you think I should go with? Why? How hard is it to mount/install them?
It is not particularly difficult to mount a transducer in any of the three mounting styles. The thru-hull would be the most difficult, the transom-mount would be next, and then the In-hull would be the easiest. That doesn't tell you much about how hard it actuall is. Works about like this, it really helps if you have some experience at it to mount a thru hull, not that you couldn't get it dead right the first time, and in fact you probably will. Anyone with a cordless drill can mount a transom mount and get it to work. You can mount an In-hull without a cordless drill.
In terms of performance the Thru-hull is still king but the In-hull's work about as well. Transom mounts can work real well too, and in fact usually do, but they are more likely than the other two to loose bottom at speed. Oh, when it comes to cost it usually goes Highest to lowest as Thru-hull, In-hull, Transom-mount. Plastic is just fine on the transom or in the hull, but not under the boat.
If you want more information on how each is actually mounted just give a yell. I'd bet there are 100 guys logged on right now who have installed each of the three types more than once.
Thanks Thom. The application is a 23' bay boat. I'll be fishing in smooth water in 10' or less depth, choppy to rough water 10-40' depth, and offshore swells 20-150' depth.
Let's say I've pretty much decided to eliminate the transom-mount. How do you mount a thru-hull versus in-hull? Any reason a thru-hull is better.
Thom...has some great PICs on a thru hull M260 install.* In general, if the transducer you want* www.Airmar.com* comes both thru-hull and shoot through; I would go shoot hull.* I've had lengthly conversations with Raymarine and they insist, that if properly installed, there is NO loss of signal using shoot thru.* The new units (R199) will shoot thru 1" of fiberglass.* Check the site.* Now, if you have foam/core, or air voids in the fiberglass you'll have to use thru-hull.* Some people will just remove the core material/foam and go to solid fiberglass.* Most will agree, when running, the transom mount is not the way to go, it tends to loose bottom at speed.*
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Boston Whaler, "MUMBLER", 24 Outrage, twin 175 HP Evinrude Ocean Pros
Take a look at* www.AIRMAR.com* Most thru-hull transducer require a 2", or so, hole in the bottom of the boat...the transducer is on the outside of the boat then.* The shoot thru has the transducer inside the boat, in a can, with* mineral oil in it.* Then the unit shoots the signal thru the bottom of the boat.* They are also called in-hull transducers.* *
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Boston Whaler, "MUMBLER", 24 Outrage, twin 175 HP Evinrude Ocean Pros
I have a Garmin 235 Sounder which is the same unit as the Garmin 238. I have the in-hull transducer which is just epoxied on the inside of the hull. This was the easiest to install & is very accurate. The only down side of using an in-hull ducer is that you can't get water temp. The reason I chose the in-hull over the thru-hull is because in the future, if I decided to change electronics which required a different type/size of ducer, I may be stuck w/ an unwanted hole in the bottom of my boat! You will be very happy w/ the Garmin 238 no matter what ducer you choose, it's a great unit for the money.
Check out the Airmar Tilted Element through hull transducer. I use a bronze one with my Garmin 320. Works well and eliminates the need for a fairing block.
All,
I want to use a thru-hull setup also. Confused.
Looking at the Garmin 250. Will transom mount transducer that comes with it work mounted as shoot through if I mount it in mineral oil filled container?
I notice Garmin offers a puck style in-hull transducer retails for about $119. PN 010-10327-00
Any info on this?
I will not get any deeper than 100'.
I have a Garmin 240 blue fishfinder. I bought a garmin "transom mount" transducer (part# 010-10272-00), but I never mounted it on the transom. In my haste to get the boat in the water I just laid the transducer in the bilge and ...guess what?...it worked perfectly all year. The small amount of water usually in the bilge made up for the lack of the mineral oil box. The transducer worked better than the transom mount that I had on my previous boat because there was no turbulence to deal with. Moral...go with the "shoot through" mounting. There are no holes to drill through your hull or transom and the thing will work as good if not better than the other two mounting choices. I will mount the transducer a little better this year and maybe add a water box, but I'm sold on the in-the-bilge approach.
Seacat FL,
How well does it work? Gem electronics claims the M260 has 50 times the discrimination of the others but it is a huge ducer with a huge price tag. I'm not a professional fisherman and don't know if I need that kind of power. I would probably be happy if I didn't lose bottom at WOT.
John
I just installed the 320c in November and have only used it in the Indian River Lagoon because the locks to the ocean at Port Canaveral have been closed all winter for maintenance.
Running at 200 khz in the relatively shallow waters of the Lagoon it never loses bottom at speeds up to 40 mph and reads down to <3' in the shallow waters.
I will have a deeper water report when I can get it out in the ocean. They are supposed to reopen the locks 3/17/05.
I saw a question asked that indicated that there was some confusion as to what the different type names really meant. So here goes"
The thru hull mount, as its name implies, has a part that passes through the hull of the boat. This would be the stem of the transducer, It is a section of threaded pipe that protrudes from the actual transducer and carries the data cable from the transducer's element (which is encased in plastic which is held in a casing of either plastic or stainless steel but much more commonly bronze). The transducer element is in the broze part at the bottom and when installed it will be outside of the boat. The pipe part passes through the hull and a large nut holds the transducer in place. In models that also have speed and temperature measuring capability the hole the pipe passes through has to be about 2" in diameter. On models without its more like an inch. These transducers are normally 'streamlined' to some extent with either a fairing block shapped to match the hull and hold the transducer in position. It is important that the transducer point straight down. An alternative method of mounting one is to glass in a pocket for it to ride in.
An In-hull transducer resides in the hull and no holes have to be drilled anywhere. The transducer element is contained in a plastic part and that part is then either bonded to the hull bottom directly or suspended in a tank which is bonded to the hull bottom and then filled with a liquid - thin oil or antifreeze. The result is that the sound waves created pass through the hull and the return echos do the same.
The third type is the transom mount. With these the transducer element is held in a plastic case and that case, in turn, is attached to the boat's transom. Attachment is normally done with screws. The transducer mounting allows for adjustment after attachement, normally in two planes. They can also be knocked up and out of the way if they strike something.
That's about it. Each style has its pros and cons. I do not care much for Transom mounts and never have. I am certain they are the most common sort. In-hulls have always been popular with the fresh water guys. If you boated in places with lots of stumps and logs you'd want your transducer in the boat too. I have to say though, it has long seemed a bit odd to me to use a $25,000 hull to protect an $80 transducer. However there has always been a perception that performance suffered with In-Hulls. The largest manufacturer of transducers now tells us they are comparable to Thru-hulls (which always had the advantage of direct contact with undisturbed water).
Transom mounted transducers have a unique problem, or one you should hope is unique. They operate in disturbed water. They are right there where the rubber meets the road in terms of turbulence created by your boat. On many boats this causes them to simply quit reading at some speed or another. With careful mounting - and the grace of Gods unnamed - you can get one to work up to reasonable speeds though. Its basically a matter of mounting it low enough to stay in the water but high enough that it doesn't create its own turbulence. Its got to be pointing straight down too, not off to the side and not behind the boat - a little forward tilt won't hurt anything and can often be used to allow one to operate at higher speed - but it will cause a more abrupt and consistant failure if you mount it that way, usually right around 30 knots.
So, that should give you something to mull over for a little bit. I'm sure the guys here will be more than willing to pitch in and tell you how much or how little difficulity they had mounting theirs - and it would be particularly interesting to hear from guys who have only done it once or twice. Everyone seems to have their own opnion of what works best but if you pay close attention you'll notice pretty quickly that it depends more on how they use their boat than it does on which Manufacturer made their fish finder. Seems that way to me at least.
If did it again would go with shoot thru and optional temp in transom. Mine loses signal at 13 MPH or so-basically when wake leaves the stern. my problem is a sw pickup,lifting stakes, and trim tabs limit mounting options. Have moved it with minor benefit. Will post a picture for suggestions before launch this year
Which transducer? Mounting? 
