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7-13-2013

SUBJECT: # 35479: thru hull vs. transom mount transducers

Submitted by jim bob from ALABAMA on 7/15/01 12:39:00 PM

Getting a new Furuno 582l bottom machine. Most of my bottom fishing for grouper is done in less than 100 feet. I'm wondering if there is anything inherently better about a thru hull over a transom mount transducer. I know all about the advantages of a thru hull as far as less noise while running, etc., but what I need to know is whether a metal thru hull is better at discerning fish and bottom over a plastic transom mount. Are they more powerful than the transom mounts or what? Also, would it make sense to get as powerful of a transducer that Furuno makes (maybe one of its commercial ones or something), rather than the stock tranducer they recommend thru the retail stores. Any thoughts? Thanks. jimbob


  1. 7/15/01 2:08:00 PM Submitted by Thom (208.1.148.87) from WEST VIRGINIA says Power In Your Hands
    The power of the bottom box doesn't come from the transducer, it comes from the display unit. Take a good look at the various sales outlet for the bottom box you've picked and you may notice that the same suite of transducers is recommended for the LS6000 (300 watts) the 600L (350 watts) the 667 (whatever its rated at these days) and the 582L (600 watts). There are other transducers available of course but they have characteristincs specific to special dutys and they don't have any effect on power. Actually in your case, with the sort of depth you're talking about, the power is basically meaningless anyway. You could get away with 100 watts and still have plenty to spare. I guess that brings up another point, power has absolutly nothing to do with picture clairity as long as the power you have is adequate, so if 100 watts is enough you don't get a better picture with 300 or 500 or 1,000 watts, about all you get is greater battery drain.

    As to the choice, well, if you're bottom fishing from a still boat in still water it really doesn't make any difference at all which one you pick. If, on the other hand, you expect that you will ever use that bottom box when the boat is moving then in every single case you will be better off with a true thru-hull (not the shoot-thru the hull that more properly should be called in-hull-mounted) than a transom mounted unit. The reasonis simply enough that the water will always be cleaner under the boat than it is after it exits the transom. Granted the differce may not be much but its still there. If you want to get the best out of that $1,500 you're getting ready to spend then you should buy the bronze thru hull and leave the transom mount on the shelf. On the other hand if you simply want easy of installation go with the transom mount but understand that you gave up the best available picture. Its sort of like using a so so antenna on your radio in a way, use the best and you get the best, use somehting else, and you get what you were willing to accept. Oh, this opnion is mine (though not mine alone) and you will certainly get other opnions from folks who believe their transom mounted transducers are just fine. Good for them.

    Thom


  2. 7/15/01 3:18:00 PM Submitted by tarpon (24.129.25.160) from ALABAMA says Transducer matches the unit
    Furuno recommends a transducer with their unit. Go with their recomendations.

    To determine bottom type, important when grouper digging, get a high power unit.

    The transducer is not as important as the display. The metal transucer is mostly to protect the boat in the event of grounding. You don't want a plastic unit failing and a hole in your boat when it does.

    I have had several units from different manufacturers on different hulls, and most work 'sort of' at high speed. All work acceptable at troll speeds.

    The Furuno 582L is my current favorite, it does a good job of registering bottom type and small depression/humps. It has a thru-hull on it and will work on plane. The boat has a special transducer pocket built in the bottom which allows the transducer to be properly mounted.

    However, something to consider ... a unit that you know how to use and understand the readout of will be far more valuable than any one which has the capabilities but you don't know how to use the controls or what the screen means. It is not easy to learn how your unit reads the bottom, but it is very worthwhile to take the time to learn. It takes a lot of time and practice to get the hang of using any capable bottom machine.

    tarpon


  3. 7/15/01 3:19:00 PM Submitted by jim bob (64.45.216.246) from ALABAMA says More ducer questions
    Thom, Maybe you've hit my question/concern square on the head, when you said "There are other transducers available of course but they have characteristincs specific to special dutys..." Well I don't give a darn about power and all the other stuff. I guess I want to know what the absolute best transducer is for the particular kind of fishing I do. In other words,is the retail thru hull transducer the best transducer I can get for my fishing pattern or is it a kind of middle of the road transducer that will be adequate for a broad range of activities. BTW, I just got back from the store with the new 582L but I still don't have a transducer. Thanks jimbob


  4. 7/15/01 5:36:00 PM Submitted by Constantine (216.254.80.194) from NEW JERSEY says transducer location
    From my experience and what I've read the only real difference between the transom and bronze thru-hull will be on what kind of boat your mounting it on. Mounted properly they will both give 100% since they both have direct contact with the water. The original reason for both of them is whether you are using a inboard or outboard powered boat. With twin inboards it is very difficult to find a location on the transom that isn't affected by the prop wash, thus you usually must go to a thru-hull so you can mount it in clean water. Transom mounted x-ducers on the other hand work fine with single outboard powered boats where it is relatively easy to find a spot on the transom where you get clean undisturbed water. I use a thru-hull simply because I hate wires and unsightly crap hangin off my transom, and I feel my boats more directly over the entire cone of the ducer whereas with a transom mounted x-ducer at most my boat is covering half the area, proably to little of a difference to matter but it's something. Hope it helps.


  5. 7/15/01 6:46:00 PM Submitted by Hawkeye (24.15.188.191) from VIRGINIA says Sounds like you don't need the 50khz.
    For under 200' a 200khz ducer is what you need. See if they have a 200khz with like a 10/45 deg dual beam. On my Sitex the wide beam is 50 khz and the norrow is 200. My old Rayethon had a 9/27 deg 200 on it and it worked good to 600' at trolling speed and up to 200 to 300' at 30mph.

    Hawkeye


  6. 7/15/01 8:05:00 PM Submitted by Thom (208.1.148.87) from WEST VIRGINIA says Jim Bob
    I suspect that your local boat emporium is going to try to sell you either the 524ST-MSD or the 520-5MSD. Given a choice between the two I'd opt for the 524 myself but that's just me. I think you might want to go over to the AllCoast board and ask for transducer suggestions. As I recall there are a couple of guys that are regulars over there ( http://www.sport-fish-info.com/dcforum/cgibin/dcboard.cgi?az=list&forum=private&conf=mainconf ) who are using a new transducer that seems to be well suited to the kelp paddy sort of fishing those guys do, which has very similar requirements to yours. I'm afraid I don't know the designation of the one they are using though. Beyone that you next bet is to contace Furuno directly through their webpage. Their technical support folks are extremely helpful in my experience and I'm sure they will do everything in their ability to make sure that you get the best match to your requirements .... besides that, they know one hell of a lot more than I do.

    Thom


  7. 7/15/01 10:44:00 PM Submitted by Capt. Ken Roy, Whopper Stopper Sport Fishing from FLORIDA says Shoot it throught the hull
    Get the narrowest beam angle transducer available for the unit. At your target depth, 200kHz is best. I have an 8 degree on a Lowrance X-85 and shoot thru the hull. I can read bottom in 400' plus. I also have a cheap Apelco mounted the same way with a 20 (200kHz)and 45(50kHz) degree transducer. Lots of my clients have boats and lots of them have switched over to my installation for clarity when running.

    Benefits are cheaper transducer, super easy to install, no danger to transducer at sea or on trailer,i f you screw up on a transducer location, you can move it easily, perfect picture with no hash. Best of all, NO HOLES IN HULL OR TRANSOM. My Dusky has a super thick hull and both depth finders work great.

    I strongly disagree with epoxying a transducer to the hull. If you screw up on location, you can't get it loose without possibly damaging the transducer.

    I make my living running Grouper charters. The way I described works. You may loose some power shooting it thru the hull but I haven't had a problem. I guess if I were seeking max depth penetration, I might go to a thru hull.

    If you decide to try this type installation, shoot me an e-mail and I will send complete installation instructions.


  8. 7/15/01 11:32:00 PM Submitted by Longfisher (66.25.63.68) from TEXAS says Shoot Through Hull Without Epoxy
    Ken, can you post your information on how to do this to the Board vice just to individuals via private e-mail. I'm sure many others would like to know how you do this (myself included). Plus it becomes part of the archives for future queries.

    Oh, didn't you used to maintain a web site. I can't find one for you now. Or, maybe you didn't and I'm confused.

    Thanks,

    LongFisher


  9. 7/16/01 8:03:00 AM Submitted by bonefish from TENNESSEE says To glue or not to glue, that is the question...
    You can simply drop your transducer in the bilge, run with some water covering it, and it will shoot thru the hull. Or you can stick it to the hull with epoxy, then run with a dry bilge. Or, some folks like to use silicone adhesive because it can be removed.

    I prefer to use the epoxy, never had a problem.

    As for thru-hull transducers, they are for large inboards and boaters who like to drill big holes in the hull (Yikes!)


  10. 7/16/01 9:52:00 AM Submitted by Capt. Ken Roy, Whopper Stopper Sport Fishing from FLORIDA says Installing Transducer well in your bilge
    Here is the blurb on installing a transducer well. I used cut and paste directly from my "Tips and Tricks" column.

    Tip #76

    I use Marine-Tex or the rubber windshield mounting compound to "glue" a PVC pipe coupling into the bilge. The hull must be squeaky clean or the stuff won't adhere. I first use degreaser, then wash it down with water, and dry thoroughly and follow up with a rag soaked in Acetone.

    Take your transducer to the plumbing store with you and get the smallest coupling that it will fit in. I epoxy glue a small length of plastic to one side of the transducer and then cut it to length so that it rests on the bottom of the hull when the transducer is perfectly horizontal.(takes care of the vee in the hull problem)

    Put the transducer in the PVC pipe well, chock it in place with 4oz sinkers Pyramids work great but I think I have eggs in mine right now. Fill the well with water and she is ready to go.

    This beats epoxy because if you choose a bad site the first time, you can move the transducer. If you epoxy the transducer in, you can seldom get it loose without damaging the transducer. +++++++++++++++++++++++++++++++++++++++++++++++

    In the Lowrance manual, they caution against using silicone rubber for mounting. I do not know what their rationale is. Another caution if you choose to use the epoxy method---Makes dang sure you have no bubble in the epoxy.

    If you have further questions, e-mail me or post 'em here.


  11. 7/16/01 10:03:00 AM Submitted by Capt. Ken Roy, Whopper Stopper Sport Fishing from FLORIDA says Installing a Transducer well in your bilge
    Here is how I do it. I have installed several dozen this way. I used "cut and paste" from my site.

    Tip#76

    I use Marine-Tex or the rubber windshield mounting compound to "glue" a PVC pipe coupling into the bilge. The hull must be squeaky clean or the stuff won't adhere. I first use degreaser, then wash it down with water, and dry thoroughly and follow up with a rag soaked in Acetone.

    Take your transducer to the plumbing store with you and get the smallest coupling that it will fit in. I epoxy glue a small length of plastic to one side of the transducer and then cut it to length so that it rests on the bottom of the hull when the transducer is perfectly horizontal.(takes care of the vee in the hull problem)

    Put the transducer in the PVC pipe well, chock it in place with 4oz sinkers Pyramids work great but I think I have eggs in mine right now. Fill the well with water and she is ready to go.

    This beats epoxy because if you choose a bad site the first time, you can move the transducer. If you epoxy the transducer in, you can seldom get it loose without damaging the transducer.

    Sanding the area where the coupling is to go plus sanding the mateing surface of the coupling might not be a bad idea either

    Lowrance suggests not using Silicone rubber. I do not know what their rationale is. If you decide to use the epoxy method, make darn sure the area is squeaky clean and there are no bubbles in the epoxy.

    If I can help further, e-mail me or post the question here.


  12. 7/16/01 10:16:00 AM Submitted by tarpon (24.129.25.69) from FLORIDA says An easy way to test
    To try out your transducer, any kind will do, make a round depression with dux seal or silly putty in a clear area in the bilge on the boat bottom. Needs to be solid fiberglas to effectivly 'shoot thru'. Foam or double bottom will give misleading results and add lots of noise to the signal. Make sure the transducer is near vertical otherwise it will not point straight down in the water column. Fill the depression with water and test. Pull it off, place it in another location fill with water test again. You can even attach the transducer this way and go fish.

    If you can swing it, get cozy with your dealer, he may allow you to test several transducers before deciding which you want. I find the dual frequency transducers are the best.

    A simple way to mount your transducer is to call the boat manufacturer and ask them where to put it for best results.

    I have two boats with thru hulls and they work just fine. Just find a proper location fisrt. I don't see a thru-hull as a big boat only use. It is to allow best use of the bottom machine, ask Furuno what they think. You paid for the performance, why screw it up with a poor install.

    If you do make a mistake, any boatyard can fill the fiberglas hole. I have done this myself on older boats when I wanted to move something ... it is no big deal. Just messy. West Epoxy has all the info you need if it ever comes to that.

    tarpon


  13. 7/16/01 12:11:00 PM Submitted by Thom (208.1.148.132) from WEST VIRGINIA says Why?
    Why would a person go out and pay very good money for the best small boat fish finder made and then couple it up to the very least efficienct transducer mounting method known, a glued in shoot thru? We're talking about a fellow who spent somewhere around $1,300 for the display unit alone, this isn't some guy with a bass boat and a three hundred buck piece of junk Humminbird or Lowrance bolted on the dash. Having bought the best there is for his application he now needs to finish up the job by coupling it to the most efficienct end piece he can put on the boat (or in this case through the boat). His order of perference for transducer type is clear; first, thru hull; second, transom mount; and then if nothing else will do he might consider a shoot-thru.

    Thom


  14. 7/16/01 1:27:00 PM Submitted by Palmetto Bug (128.23.108.8) from SOUTH CAROLINA says I'll tell you why Thom.
    Sometimes shoot-thru-the-hull works best, even better than transom or drill-thru-the-hull mounts. I tested the different mounting options on one of my boats. It's a single engine outboard C/C. First I tried transom mount. That gave me a great picture but was skippy when running fast no matter how I positioned the transducer. It was located in the cleanest water available at the transom, which coincidentally was the position recommended by the depth finder manufacturer. I then tried mounting in a PVC well inside the hull. The picture was equal to the transom mount except it then even worked at wide open throttle. Indeed, the picture looks as good running as it does sitting still. The only way I can make it get a bad picture is by backing up. I didn't bother to try the drill-thru-the-hull method because I could see no advantage to making a hole in the hull if shooting through the fiberglass made no apparent difference in the reception. With the shoot-thru-hull, I get as good a picture as the unit will provide, no visible ugly wires, nothing to get ripped off the transom, and no holes in the hull to worry about. Add to that the fact that the installation needs no permanent alterations to the boat or transducer and it's a no brainer.

    Tommy


  15. 7/16/01 1:53:00 PM Submitted by willg (216.116.184.130) from ALABAMA says Temp/Speed
    One other thing to consider is if you will use either the temperature or speed option of your finder. With "in the hull" transducers, these options are lost.

    As for speed, I prefer my GPS for speed, since I am more concerned with how fast/slow I am getting there, not how fast my boat is going up and down over the waves. However, if I was slow trolling livies, and needed to see how hard my baits were going against the current (ex. if going against a 3 knot current, your gps might say you were going 3k, but your boat and depth finder speed, and thus your bait, would actually be pushing six knots, which could wash out your live bait), I would want the speed option.

    So, "in the hull" is may or may not be a problem, depending on if you want the speed gauge.

    For grouper fishing, temperature shouldn't matter (some may disagree, I'm admittedly not sure, so don't hound me). However, for trolling, temperature definitely matters, as you should be looking for rips with temperature changes.

    If you are spending as much as you are talking, I would get a cheap lcd for full time running, and mount it in "in the hull." Therefore, when going full speed in the bays, you will always have a clean picture of the bottom, with alarms, etc. to help make sure you don't run up on a bar. A cheap LCD will also use a heck of alot less battery power than your Furuno/Ray CRT.

    Once you get to your grouper "spot", and you slow down, your transom mount transducer (even if it has some interference) should do just fine, assuming it's properly mounted.

    One more consideration, I would be very careful if I chose to do a through the hull if you have a Whaler or other foam filled boat (Scout & Edgewater are other examples), because even a pinhold leak can result in water-logged foam over time.

    Hope this helps.

    -Will


  16. 7/16/01 2:30:00 PM Submitted by bonefish from TENNESSEE says I can "ditto" the words of Palmetto Bug.
    I have a 240 BayScout with 200HPDI (23'6"X8'6") with a Garmin 168 Map/Sounder (sonar is the same as Garmin 240). I epoxied the transducer in the bilge and get a clear picture all the time, up to maximum speed (47MPH). The only time it loses bottom is sometimes when backing up.

    The last 4 boats I have owned had the transducers epoxied in the hull. I have never had problems with this method and consistently get clear LCD pictures.


  17. 7/16/01 4:50:00 PM Submitted by Bill (209.240.220.226) from NORTH CAROLINA says Dang, Capt. Ken, it sure takes you a long time to look at a horseshoe....
    You say you have installed dozens using your method. Maybe you should look at another method and then maybe you'll only have to install it once. (Just screwing with you, Capt. Ken)


  18. 7/16/01 5:26:00 PM Submitted by Jim Bob (199.44.53.3) from ALABAMA says Here's what Furuno Says
    Talked to the transducer xpert at furuno. his name is Jack Levers I think. He says that down here in the gulf fishing for grouper in less than 100 feet of water you need a special transducer to get the best look at FISH. The specific transducer he recommends is the 520T-HPD, which is actually a 1000 watt dual frequency (50/200) ducer,(the 582L is a 600 watt machine) but its most important attribute is the 5 degree beam at 200khz and 25 degree beam at 50khz. He says most of the "over-the-counter" retail ducers have beams of 12-15 degrees at 200khz and 45 degrees at 50khz. He says this thing will "burn a hole in the bottom" in the water we fish in and will show you the grouper when nothing else will.

    The recommended ducer is only offered in a thru hull mount and requires a special fairing block to operate at high speed.

    I think some people in this discussion may be more concerned about picking up the bottom at a given speed, and certainly an in-bilge mount may be the best way to go if you are primarily looking for bottom characteristics. I know where the bottom is, what I want to know is are there groupers on that bottom. I think Jack Levers understood completely where I was coming from and I trust his recommendation of this specialized transducer for identifying groupers in shallow water. I have ordered one.

    Thx for all yall's input. jimbob


  19. 7/16/01 10:07:00 PM Submitted by Capt. Ken Roy, Whopper Stopper Sport Fishing from FLORIDA says I'll buy Jack Levers a beer on that.
    The narrow beam angle is the key to finding the tiny spots I fish. As far as a dual beam w/50kHz goes, I see no need for 50kHz in 100'.(at least for my kind of fishing) The wide beam angle may show you that you came close to something by showing fish that were missed by the narrow beam, however.

    Regardless of Transducer type and size, a box for mounting INSIDE the bilge can be built if a pipe coupling cannot be used. I built a rectangular fiberglass well in the bilge of my old 23' Formula for a huge Si-tex transducer.

    Re: the speed wheel and the temperature probe.

    Mount them as per normal on the transom. Lots of them are stand alone units anyway.


  20. 7/16/01 11:27:00 PM Submitted by bonefish from TENNESSEE says Garmin's transducer selection
    010-10105-00 200KHz, 20deg, plastic, transom mount transducer $44.00

    010-10106-00 200KHz, 20deg, plastic, transom mount transducer $106.00

    010-10107-00 200KHz, 12deg, bronze, thru-hull mount transducer $142.00

    010-10118-00 200KHz, 20deg, plastic, transom mount transducer $71.00

    010-10119-00 200KHz, 12deg, plastic, thru-hull mount, depth $71.00

    010-10177-00 200KHz, 9deg, bronze, thru-hull mount transducer $337.00

    010-10200-00 200KHz, 14deg, plastic, trolling motor transducer $74.55

    010-10217-00 200KHz, 12deg, bronze, thru-hull mount transducer $194.98

    010-10218-00 200KHz, 12deg, plastic, thru-hull mount transducer $112.24

    010-10228-00 200KHz, 8deg, plastic, transom mount transducer $142.67

    010-10229-00 200KHz, 8deg, plastic, transom mount transducer


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