Will a inside the hull high speed transducer for a SI unit work inside a tin hull?

[Lundexp]

I have tried messing with my 997 SI transducer placement many times trying to get it to read at high speed but it just won't over 30mph. I believe because of the turbulence from the rivets that are along the back bottom of my 1800 Explorer. Would a inside the hull glued to the inside work even with the double plated hull? I really don't want to drill a hole for a thru the hull transducer.

[Shellback]

The standard transducer wouldn't work, but there is an aftermarket one for aluminum hulls. Not sure if it would work on a double bottom though. Are you sure your boat is double bottom bow to stern? My G3 and some other manufacturers usually have the double bottom just in the bow.

[geareng]

I also have an Explorer and the Alumaducer transducer (which is designed to shoot through Aluminum hulls) will not work because it is designed to shoot through a single layer of aluminum. There is a slight layer of oxygen between the two layers and that is what prevents it from working. On the Explorer the flat area by the transom is double layered. There are some areas that are single, but they are on angle and I didn't want to add that variable to the equation.

Is your transducer currently mounted on the port or starboard side, because that can also make a difference.

[Lundexp]

The transducer is on the starboard (driver's) side. I've went as far as to stick it further down in the water, about half inch below the bottom and rear angled down a bit but it will pop up when I hit 35 to 40mph and this boat is capable of 50mph. Been working my way back up little at a time every time I go out without any luck yet.

[Lundexp]

Well, I feel like a real big idiot right now. I think I got it figured out finally. . . too close to the prop. Obviously I didn't read my installation instructions closely enough and thought it said at least 15 inches from the center of the engine when actually it said from the edge of the prop so it actually was 10 inches to the side of the edge of the prop. Wish I caught that before I mounted my transducer board. Looks like I get to mount a second board to move it away from the prop and see if that solves it.

[geareng]

Please let me know what happens after you try that. I guess I will now have to go measure mine as well.

[REW]

Lund,
You mention:
"It pops up" when I get going too fast.

So, I have to ask, Is the problem with your transducer, that it stops reading, or is the problem that the transducer, when it is mounted 1/2 inch below the bottom of the boat, not mounted solidly enough to stay in the water?

I assume that your transom board is staying in place.
If your transducer bracket is staying stationary, but your transducer is simply rotating back and up out of the water, continue to tighten the bracket until it doesn't rotate back up out of the water.

There is a lot of pressure on the transducer from the transducer going through the water, The bracket and transducer is designed to be strong enough to hold it down.

With an aluminum boat and with rivets, it sounds about right to have the surface of the transducer about 1/2 inch below the bottom of the boat for a good bottom reading.
This will continue to be the case, even if you move the transducer over 5 inches.

Tighten the bracket, and see how it works.

In most cases, the bracket has to be tightened enough to stop it from rotating up at high speed, and this pretty well eliminates the pop up feature in case you hit something in the water. So, if you have the transducer tight enough to stay in the water, it is quite likely that you will snap the transducer if you hit something solid. But, that is generally the case with most transducers and most systems, so tighten it down and enjoy your rig. Just don't hit anything.

Good luck
REW

[Lundexp]

REW, previously the transducer wouldn't read over 30 or so mph. It didn't always pop up out the bracket, just every once in a while when I got going pretty fast and i could tell when it popped up when the depth would jump to like 400 or so so I would be going back to reset it down. Yes the board is holding sturdy. Just put on a second board tonight and moved the transducer over to 17 inches away in the center of the next row of rivets. Set it about half inch below the bottom but will tighen the screws this time to make sure it holds. I don't really care if I hit anything and break off the ducer, I just want to know my depth so I don't hit a shallow spot without knowing and hit my lower unit. A new transducer is cheaper than new lower unit parts for a F150 combined with a ss prop. I know, i've had to replace the shaft and some extras.

Geareng, are you having the same problem? I hope to get it out this weekend weather permitting and I'll let you know how it does.

[geareng]

Lundexp,

I have had similiar issues but I guess I have just gotten used to it at this point. I originally had the transducer on the port side, just switched it to starboard side over the winter. At the same time I installed a side scan transducer and have left it alone at this point. I would say that the transducer face is just below the bottom of the boat and I can read up to just below 30 mph. My boat will not go 50 mph, it is a tiller and I have a 75 Yamaha 4-stroke so my top speed is only in the high 30's. I guess because it is better than it was prior to the transducer relocation, I haven't worried much about it this year. But your conversation caught my ear because maybe I can learn something from what you are going through. I have heard that some people with Lunds have had great success at achieving what you are trying to do, while others have had not very much luck. The other thing that I have seen come up is that some people havs actually installed a type of shield/baffle in the front of the transducer that has worked.

[TomP.]

Originally Posted by Lundexp

I have tried messing with my 997 SI transducer placement many times trying to get it to read at high speed but it just won't over 30mph. I believe because of the turbulence from the rivets that are along the back bottom of my 1800 Explorer. Would a inside the hull glued to the inside work even with the double plated hull? I really don't want to drill a hole for a thru the hull transducer.

Why not go to a Y cable and high speed transducer, there by keeping your high priced SI transducer out of harms way?