Help with mounting in-hull transducer

Hello everyone. I'm looking to mount my transom mount transducer in-hull, in the engine compartment. I have a Maxum 1800MX bowrider. My fishfinder/chart plotter is a Lowrance Elite 5 Gold. I've been researching this quite abit but haven't put it all together yet.

I'm thinking of using 3 or 4" plastic pipe, cut on the hull end to match the hull angle so the pipe will sit vertical. I assume I want the transducer to sit vertical? It seems mounting the TD directly to the hull with epoxy or silicone it is recommended to mount it to match the angle of the hull.

The other end will be threaded to be able to screw on a cap to keep the mineral oil or whatever I use inside and prevent leaks. A hole in the lid for the cable to pass through will have to be 3/4" which is the diameter of the display unit end. The cable is permantly mounted on the TD end. Unless I can cut a slot in the pipe to have the cable pass through the side wall rather than the lid. Sealed with silicone?

I plan on taking a buddy to find a good mount location that gives good signal at rest as well as at speed.

How is the TD held in position? It must be anchored somehow? None of the posts I've read discuss this.

Is the TD mounted touching the hull or is it kept suspended in the oil?

I understand some signal loss will occur due to the fiberglass hull. What about the fish finder capabilities? This has not been mentioned in any posts I've read. The unit is rated for 1000' so I'm not concerned about losing the ability to read the bottom. As I'm going to be salmon fishing I am concerned with the ability to pick up fish or not. Anyone shed some light on this area?

Thanks in advance,

Ken

Re: Help with mounting in-hull transducer

I just installed huminbird DF in my stingray. I followed the instructions in came with to a tee and it works great. I used some pretty expensive epoxy from west marine that does not have alot of air bubbles in it and just glued it to the hull. I found a pretty flat spot right near the plug but not blocking the plug. When I get home I will try to post a pic for you.

Re: Help with mounting in-hull transducer

You can epoxy the transducer directly to the floor. Find a nice place where it will be out of the way, scuff the bottom of the transducer with some 600 grit paper, do the same to the floor. I then created a small dike with clay around the area where I wanted to mount it. Mix up some 30 or even better 60 minute epoxy. I poured the mixed epoxy in a small jar with a bolt in the cap and centrifuged it in a drill motor to eliminate any bobbles. Then I poured about 1/4" layer into clay dike, slowly floated the transducer in place as not to create bobbles underneath and poured the rest of the epoxy in place. My fish finder worked great potted in this way. Even at planing speeds I was able to get accurate readings without any glitches.

Re: Help with mounting in-hull transducer

http://72land-n-sea.blogspot.com/2011/08/shoot-through-hull.html

Re: Help with mounting in-hull transducer

3gsdad said:

I found a pretty flat spot right near the plug but not blocking the plug. When I get home I will try to post a pic for you.

Click to expand...

Pictures would be great.

jeffnick said:

http://72land-n-sea.blogspot.com/2011/08/shoot-through-hull.html

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This sounds too easy! I posted some comments/questions on your blog, thanks.

Re: Help with mounting in-hull transducer

chiroken said:

Pictures would be great.


This sounds too easy! I posted some comments/questions on your blog, thanks.

Click to expand...

You'd be surprised how little sloshing takes place. But if you're worried, get a cap and cut a slot in it for the wire - then cover the slot with a piece of duct tape. No need to get fancy.

Re: Help with mounting in-hull transducer

The idea of cutting a groove in the cap is exactly what I was thinking about. There is no risk to the equipment of the pipe running out of water is there? Just means the signal will be lost correct?

Hopefully I can get on the water today and play around with the transducer in a bag of water to see what kind of signal I can get through the hull.

Re: Help with mounting in-hull transducer

This sounds silly but if you just let a few gallons of water into the bilge and have the transducer under the water it will read. No need for the bag of water. I also took the epoxy path. I even epoxied my Skimmer TD in the bilge first and it worked fine. Once I saw that it worked I got the shoot-thru TD and installed that. My finder reads fine all the way to my top speed of 50 mph. No issues. Yes, I'm sure I lost some sensitivity but most of my fishing is in less than 50' of water and I have a high wattage finder so it works fine. Just take the process slow so you don't get bubbles and you'll be fine.

Re: Help with mounting in-hull transducer

OK, abit of an update. The transducer won`t fit into a 4 inch pipe so had to go to 6 inch (of course no 5 inch available) sewer pipe with a cap as well. I`ve cut the bottom edge to match the slope of the engine well (15 degrees) and now I want to make the pipe as short as possible due to tight spaces. Hoping the cap will have enough clearance to fit over and then on. It`s about 3+ inches deep so I may have to cut it down so it only covers abit of the pipe to seal (1 inch).

I will run the side wall of the cap through the table saw and just run the cut into the top part to allow the cable to exit the cap. The pipe will be filled with either water or mineral oil, can't really decide which to use. Water seems a whole lot easier...

Questions:

1) I assume no need to sand down the painted fiberglass as I`m not using epoxy? I will be using sicaflex to adhere the pipe to the engine well. Just give it a good cleaning to get the grease and grime off should be good?

2) How close does the transducer have to be to the actual hull to maximize function? I would like to get it as close as possible (maybe 1/4+ inch) so I can minimize the height of the pipe.