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I am finalizing the installation of a Vexilar SP200 fish finder / depth finder system.

Any tips on the best spot on the transom to mount the transducer?

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I mounted mine just off center, right at the lowest point but not in back of the engine.

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Hey Mike: even though the principles are the same for any Whaler, or any boat, if you tell us what your boat is, or even post a shot of her transom, you'll get some more particular advice.

One thing I recall is that some motors wash sideways more than others (with bubbles, I think?). Thus a mounting on the port or starboard side of the motor mattered. This might be based on hull design, not motor, itself.

I think the principle was near to center (to keep the transducer always wet), but not too near to center (to keep any possible interference from the motor away). Always on the transom. And always on a mounting block.

I made my own with marine board (all plastic). I cut it to the size I wanted, rounded over the trailing edges, flamed it with a torch, and glued that sucker on with 3M 5200. I then misted the area with a spray bottle and kept it warm with a light bulb (both because I was doing the install in the winter in my garage).

So no screws into the hull, just glue. Screws go into the mounting board. There are commercially available, pre-made boards. I'm just a DIY jerk. I probably paid as much for my raw board as one of those pre-made boards would have cost me.

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Bill,

The boat is a 1988 Boston Whaler Montauk. The Sonar System is a Vexilar SP200.

I tested it this past weekend and it worked very spotty. It would lose depth quite often and not work well at speed. The transducer is currently mounted on the starboard side. I was in a rush this past weekend when installing the transducer and drilled right into the hull and sealed the screws with marine sealant. As it appears im going to need to move the placement, I will be taking your advice and putting it on with starboard and adhesive when i take the boat out to remount.

Any help getting this placement pinned down is appreciated.

Mike

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Bill,

The boat is a 1988 Boston Whaler Montauk. The Sonar System is a Vexilar SP200.

I tested it this past weekend and it worked very spotty. It would lose depth quite often and not work well at speed. The transducer is currently mounted on the starboard side. I was in a rush this past weekend when installing the transducer and drilled right into the hull and sealed the screws with marine sealant. As it appears im going to need to move the placement, I will be taking your advice and putting it on with starboard and adhesive when i take the boat out to remount.

Any help getting this placement pinned down is appreciated.

Mike

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I recommend placing it on the down side of the propeller stroke. You try to place it as parallel to the water without submersing the unit. You only want the bottom third or so to be bellow the bottom of the boat. With the angle of the boats bottom you kinda split the difference for submersing and parallel. Also tilt the back of the unit down a little so it reads what is under the entire boat and not just the transom. Eye ball an imaginary line if you are looking at the bottom of the unit it intersects the boat 2/3 up. As far away from the prop as reasonable/possible and still stay submerged.

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Mike: that's a great boat ... the classic Montauk 17. The Montauk hull was redesigned in 2002, which many people felt made for a better ride in chop (the V was extended?), but others still like the original. As far as a light, sprightly, easy to manhandle decent sized boat ... the classic Montauk is really something!

Holes aren't the end of the world ... there's about 1000 different ways to fix them when you relocate the transducer. Here on this website, you're going to hear all 1001 of the right ways to do it!

But seriously, these guys have been there ... and let their mistakes be your guide. That's one of the great advantages of being here.

Finally, gchuba got the port/starboard thing right. The downstroke side is the one which produces less turbulence at the transducer. The splitting the difference advice is also what I used, and mine works great. The owner's manuals all say to do that. What's hard is actually lining it up right. I used a straightedge and was surprised to see where I really needed to be lined up ... my eyes deceived me, but the straightedge never lies ...

Of course after you mount it, you should have a little up/down play on the bracket (slots) and a little tilt control on the transducer unit (adjustment bolt). Fine tuning is often necessary, though sometimes you get lucky.

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Can you explain the splitting the difference part? Also when using the straight edge should the bottom of the transducer be parallel with the striaghtedge? This would make it not parallel with the water? If you have a picture of yours it might help.

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I am picture challenged. ".........splitting the difference........." would be trying not to immerse the entire transducer into the water attempting to make the unit parallel with the water. When the transducer is too low the turbulence affects it signal. That is why you only try to have 1/3 +- of the unit below the bottom of the boat. Let's say the boats bottom is at a 30 degree angle to the water (looking at it from the transom side). Install the unit at 15 degrees.......maybe a little more parallel to the water. If the unit is installed completely parallel with the water on the starboard side of the motor. The port side of the unit would be 1/3 below the bottom of the boat but the starboard side would be completely below creating bubbles that create a disturbance and poor reading. Just tilt up the starboard side of the unit in degrees so maybe 1/2 of the unit +- is below the bottom. I install them with the attachment screws on the upper side of the unit with the top 3/8" open for adjustment.

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Thanks for the feedback everyone. In regards to actual location, ive seen a few pictures and saw a post with someone saying 8 1/2" from the center of the drain plug. Does this seem like a good location? I am going to pull the boat of out the water tomorrow or Thursday to make these adjustments.

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I need to install a transducer on a 2012 150 SS. Do you have any measurements, or picture, or anything that would help me with placement? Thanks in advance.