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Random Quote: Sometimes I sit and think but, mostly I just sit
Buying this unit, Should I go thru hull or not.
I have a 24 wac Baha, Use it on the great lakes.
Fish Lake Erie, 10-80ft of water.
What do you think?
thanks
Matt
No way. I am personally against thru hulls unless you need them b/c of largeness of boat or engine distubance. They are likely to be damaged if you trailer your boat, they provide water a way to get into the boat and if they are not installed properly they will collect air bubbles and will not work. Bottom line, your boat isn't that big, you don't need it, save you money.
Go with the thru-hull. There is very little additional danger of leakage beyond any other fitting, and in fact considerably less chance of having a problem than with a fitting for a scupper or bilge pump exhaust.
They are a little more trouble to install, and you have to put at least as much effort into making sure the mount results in a transducer face parallel to the bottom but the results are worth the effort. The reason is simple. A transducer, any transducer, will work best when it is in contant contact with the water. That is not the case with an in-hull mount, and it is not the case with a transom mount (which suffer from disturbance more than the other two mounting methods).
So I would suggest that if you are willing to use a thru-hull that you go ahead. A lot f guys won't because they can't bring themselves to drill that big hole, and that's fine. A lot of guys don't mind drilling and they get to improved performance. You can take your pick. If you do decide to go with a thru-hull shoot me an E-Mail a couple of days before you go to drill. I'll give you the process and what hints I can.
Thom hit the nail on the head. I have the 600L and replaced my transom mount with the thru-hull with the Airmar High speed flaring block. Best thing I ever did. I fish out of Port Canaveral and can image the bottom perfectly on a plane in 180-200' of water. It was alot of work, but well worth it. I used the ducer that did not have speed (have a gps for that) only temp.
Here is some else.
The 600L has a feature that is not in the manual, it will detect fish better. When bottom fishing set the range scale to match the relief size, 5' relief 10' scale, 10' relief 20 scale, etc. Got my first three scales set to 10, 20 ,30. Now use your shift key to shift down until you see the bottom. Now the machine is looking at only the bottom on the whole screen, not a split screen. What a difference this makes. Hope this helps.
One more thing:
The key to getting the most information from any depthfinder is in learning how to peak the transducer. Too much power will fill the screen with clutter and overpower the machine. Too little power will not show such important underwater features as thermoclines, schools of baitfish and even game fish. The gain or sensitivity knob controls the signal power output of the unit. The first step in peaking the transducer is turn off any automatic gain controls the unit might have and go to manual control of the power output. Now, select a deeper depth range setting than the actual bottom depth. If you're in 80 feet of water, set the depth range for 200feet. If you're working shallower, say in 20 feet, set the range for 50 feet. Doubling the actual depth is necessary for this operation.
Start to turn up the power gain. First, you'll see the bottom, which only makes sense since the harder and larger the object, the stronger the return signal. The ocean floor provides a solid return. Continue to increase the gain until you get a "second echo."
The second echo is nothing more than the return signal bouncing off the bottom once and then having enough energy to make the trip back to the bottom and up again to the transducer. The second echo shows up on the screen as a second bottom reading at double the depth of the real bottom. The screen will now be showing a bottom reading at say 80 feet and another bottom reading at 160 feet. Now you can understand why you need to have the depth range set at more than double the actual depth to accomplish this procedure.
Once you have a strong second echo reading, you can return the unit back to the normal depth setting for actual fishing conditions. You have maximized the power being sent through the transducer so you will be able to acquire the most information from the depthfinder screen. You will begin to notice things on the screen that you were missing on lower power settings or on an automatic sensitivity mode. You'll mark fish, bait, temperature changes in the water column and more.
Do realize that once you peak the transducer for a specific depth range, you have only about a 20 percent window in actual depth before you have to repeat the procedure. In other words, if you peak the unit while fishing in 20 feet of water and you begin moving into deeper water, say into 80 feet, you will have to repeat the procedure for the deeper water.
This came out of an article in Big Game Fishing, the author is deceased.
I have to disagree strongly with Bill Kratz and concur in Thom's advice. Anyone with direct experience will tell you that for 95% of users, a properly installed through hull transducer always provides the best performance.
In 35 years of boating, I have never heard of a transducer sinking a boat. As for interference with a trailer, that is simply a question of ensuring that you take some care in locating the transducer so it isn't near a bunk.
In your situation, you might also want to consider getting an in-hull. It will give you most of the advantages of a through hull. The slight signal loss should not be an issue in the shallow water. It is a very simple installation, easier even than a transom mount. The drawback is that you would need a seperate sensor for temperature if you need that function.
If you go with a through hull, get the depth/temp only version. It is much smaller and also cheaper than the depth/temp/speed "triducer" and uses a much smaller fairing block. The speed paddlewheel is a total waste of time as far as I am concerned. They are always getting fouled and seldom give an accurate speed reading. Your GPS gives you totall accurate speed over the ground in any case, which is usually what you want to know.
quote: The 600L has a feature that is not in the manual, it will detect fish better. When bottom fishing set the range scale to match the relief size, 5' relief 10' scale, 10' relief 20 scale, etc. Got my first three scales set to 10, 20 ,30. Now use your shift key to shift down until you see the bottom.
Actually that is in the manual.
thinking out loud....
If the thru hull element is made from the same xducer material that the transom mount is, I dont see how it will be any better in performance.
Sea Dad, you're right in theory. The difference is that because of its location aft of the running surface, the water flow over the face of a transom mount is almost always aerated and disturbed at speeds over a couple of knots. This turbulence is what lowers the performance compared to a through hull that is a foot or two forward of the trasom in "clean" water.
"The basic range and range shifting functions used together give you the means to select the depth you can see on the screen. The basic range can be thought of as providing a window into the water column and range shifting as moving the window to the desired depth."
This came straight from the manual. How in the world anybody could interput this into what I said is nonsense.
That is a great question. After all, a transom mount is in the water, and thru hull is in the water, they both are using that 1.7" single element if its the standard transducer that came with 90% of the fish finders sold. So why would a thru-hull be better?
The answer varies with the mounting bracket of the transducer and the deadrise angle of the hull. Generally the answer is 1/2 inch. Huh?
A thru hull should be positioned so that it is in as clean a flow of water as can be found under the boat. In trying to find that point the installer has to look around and make sure that he/she is not going to mount the transducer aft of anyting that disturbs the flow. That would be behind an existing fitting, aft of a strake or any other featrue of the hull that distrubs the flow. Most everyone knows that and takes it into account when doing the mounting.
Then you move to the transom mount. The first thing you have to decide with a transom mount is how far down you please to mount it. If you don't get it deep enough the transducer quits working as the boat comes up on plane (something that guys who cant read bottom even at very low speed need to look at). The alternative, putting it deeper, can present problems too because if you get it too deep the bracket itself produce turbulence, which kills the effectiveness of the transducer. The next problem is the deasrise. Simply put even if you get a good depth on one side of the transucer its not the same on the other side. The side of he transducer that is closest to the centerline will always ride shallower in the water than the side to the ouside, while the side to the outside is farther way from the hull, reintroducing the potential of the tracket/turbulance problem. Finally there is that half inch. The half inch or so I talk about is the space between the termination of the hull and the actuall transdcuer element. This spacing problem, in conjunction with the problem of having to put a level transducer on an angled hull are what cause transom mounted transducers to cease working at speed in my opnion.
None of that is to say that thru-hulls don't have their problems too. Greatest among them, in my opnion at least, is that far too few installers, be they professional or Do-It-Yourselfers, take the time to go to the effort to level the transducer in the fore/aft direction when installing while considering the actualy attitude of the transducer when underway. This problem seems to me to be most prevelent with trailered boats.
Here is what happens. The installer climbs under the boat and looks around for a good mounting spot, one that clears any trailer obstructons. Then you look at the hull and see if there is anything forward that is going to cause problems. If none is seen you typically measure the distance forward from the transom and the distance to the edge of the hull. Then you go inside and start measureing to see if you can gain access in the inside to the spot you chose on the outside. Sometimes you have to do some surgery to get the access you need, and many guys do that - adding hatches or access ports as needed in some cases. So if you hit it lucky and find you have access what comes next?
Well, most guys will measure the outside and the inside two or three more times before they break out the drill. Once you're sure of the spot the best next step is to get in the boat and drill a small hole right through the hull, usually a quarter inch will do nicely. Then you go outside the hull and see where the hole came out. With any sort of luck at all it will be very close to the spot you chose for it. Now you look long and hard at the hole to see if there was any visable coreing. When you see there isn't any (one of the greatest myths of small boats is that coreing of the hull will make it inadvisable to use either a thru-hull or in-hull, almost no small boats have coreing in their bottom).
So, our would-be installer now has a pilot hole, access inside the hull, and a good clean spot under the hull. Time to break out the hole saw. You knock the two inch hole in the bottom and its time to install the transducer. You measrue the hull angle and take the fairing block to the saw and make an exact cut. some guys (me) then take the transducer half back under the boat and fine tune it for an exact fit. Installers break out the level and see that the cut was made properly in the fairing block and virtually everyone makes sure that the transducer face is leveled up in the Port-Starboard direction, maybe even in the fore-aft direction. Great. It all looks good so out comes the 5200, or whatever, and the final mounting takes place. This happens every day and it forgets one thing. It ignores the actual riding angle of that particular spot of the hull relative to the bottom when under way. Here's what I mean. You will always be mounting somewhere in the aft third or so of the hull. Most planing hulls are shaped so that when the boat is in the water sitting dead still that part of the hull actually faces aft but when under way that part of the hull faces forward by a considerable degree. So, when the transducer was being installed and the level in use, what was the angle of the hull? Who knows? Most guys never look. Its usually at whatever antle the trailer jack happened to be at at that moment, might have been up, might have been down, might have even been attached to the truck. What needs to be done is that you have to ride in the boat at its normal speed and see what the angle of the deck is and then match that angle before you get under the boat to start measureing and cutting - - and almost no one ever bothers to do it. What is the result of that? Well, as the boat goes faster and the bow rises the bottom machine looses bottom in an awful lot of boats and I just gave you one of the main reasons why.
So you see its easy to screw up a thru-hull too, but with the thru hull there are fewer things to get wrong and it has the added attribute of being completely submerged in an area where water distrubance should be at a minimum. The thru hull has the added advantage of staying where you put it. With a transom mount every fork lift, every rope, every boarding water skier, every hard bump and loosening bolt offers the opportunity for the transducer to be moved from its carefully adjust optimum position.
So that's how I see the differences and its why I think the thru-hull is generally the better choice. I understand why guys avoid them, the work and the fear of leaks, and all that is fine. Its just that if you want the best you really need to consider going to the effort to attain it, because that's what works most often. Of course at the same time we all know that there are a lot of transome mounted units that work just fine. Of course they do, they were designed to do just that and they do a good job. Ny only point is that the chances of getting all that its possible to get out of that same standard transducer element your best option is to use thru-hull mounting, not that the others don't work.
quote:Originally posted by Mr. T:
"The basic range and range shifting functions used together give you the means to select the depth you can see on the screen. The basic range can be thought of as providing a window into the water column and range shifting as moving the window to the desired depth."
I didnt have any trouble understanding it.
I agree that they have a serious lack of FF 101 lessons in the manual, but they did document it, and thats all I was pointing out.
Wow man, thats thats a lot of info to chew on, Thom.
quote: What needs to be done is that you have to ride in the boat at its normal speed and see what the angle of the deck is and then match that angle before you get under the boat to start measureing and cutting
This should be tattooed on most installers foreheads. That is just short of brilliant, no it is brilliant.
One more note to add...a transom transducer has a plastic acoustic window and a layer of either epoxy or urethane between the ceramic and that plastic surface. A thru-hull has a urethane window, and only urethane between the ceramic and the water. The sound speed through the urethane is extremely close to that of sound through water, where the sound speed of urethane/plastic is slightly lower. Along with the facts of flow and turbulence as mentioned in previous postings, a thru-hull will have a little better sensitivity in most cases due to a solid urethane window (no plastic layer).
Peter Braffitt
Business Development Manager
AIRMAR Technology Corp.
Milford, NH USA
Furuno 600L-Thru Hull 
