Tranducer Positioning

[caughtafish]

Hi All

I have a 80's Savage Tasman on which i have a Lawrence fishfinder.This has worked fine till it started to loose signal at high speeds. I have just bought a gps/fishfinder combo to replace this unit and was thinking of repositioning the Tranducer whilst installing the new unit.

I have a picture of the existing setup and the propsed new location of the Tranducer any advice would be appriciated.


Thanks

[mydauphin]

You will probably end up damaging unit against roller one day. You don't have much of an area to work with there.

[caughtafish]

I did take the rollers into account and will move the post back so there is more space , the space from the roller to the unit is bit more then it looks ,the trailer is made for a bigger boat thats why it's so close , thanks for the tip

[Landlubber]

...mount the transducer onto one of those alloy mounting plates that can be raised and lowered, that will solve the problem.

[CDK]

The current position is the best one: horizontal and deep in the water, so there is minimal air.
If you need to know the depth at high speed, fix the transducer one notch down instead of lined up with the bottom. Sound needs time to travel to the bottom and back, at high speed most of the returned signal reaches the surface behind the boat.

[Fishton]

Originally Posted by CDK

The current position is the best one: horizontal and deep in the water, so there is minimal air.
If you need to know the depth at high speed, fix the transducer one notch down instead of lined up with the bottom. Sound needs time to travel to the bottom and back, at high speed most of the returned signal reaches the surface behind the boat.

And you get a 'cleaner' flow under the transducer.

[caughtafish]

What i just found after taking a closer look is that the Tranducer of the old unit is identical to the one on my old one , even the part part number is the same.I will angle it down one notch and see how it works with the old tranducer. I have searched the net for boats same as mine and all of the photos i have seen have the tranducer in the same position or close to it.

[caughtafish]

One thing i was warried about, the rib that it's mounted next to at present would that not cause water turbulence?

[J3]

Originally Posted by caughtafish

I did take the rollers into account and will move the post back so there is more space , the space from the roller to the unit is bit more then it looks ,the trailer is made for a bigger boat thats why it's so close , thanks for the tip

I like a trailer which supports the boat as close to the transom as possible or ideally, bunks that extend slightly beyond the transom. After some years, you don't want it to develop any hook from the weight being carried by an unsupported spot some distance in front of the transom.

[J3]

Originally Posted by caughtafish

One thing i was warried about, the rib that it's mounted next to at present would that not cause water turbulence?

Yes I noticed the strake there.

[BTPost]

Just a NOTE, here.... When deciding on where to place a Sounder Transducer, the critical factor in non-commercial type rigs is to get it in "Clear Water", and out of the bubbles and turbulence near the hull. This especially critical with any Planing type hulls. Any Air Bubbles that cross the transducer face will cause a BIG loss in Transmit Power coupled into the water, and an equally BIG loss in Receive Signal coupled from the water back into the transducer crystal. On displacement hulls, this is not so critical, but most Commercial transducer mounts set the face at least 6" off the hull surface, so as to minimize the turbulence that is flowing down next to the hull from crossing the face. Where Sounder Data is a critically important factor, (Like Crab Fishing) most commercial vessels will build the Transducer Trunk as much as 18 inches off the hull.

[pistnbroke]

a the hull is fibreglass you can mount it to the inside of the hull against the outside skin with epoxy...no air bubbles please in the fibreglass or epoxy...works for me ....

[Fishton]

Its on the Wrong side of the boat.

whoever put t on the Port has no idea of what they were doing.

Your Prop Was will cause all kinds of cavitation over the transducer where it is located.

Move it over to the Starboard side roughly about the same distance.

run the wire up higher wher you wont submerge the hole under water. leaks in the hull are not a added feature.

better yet, get rid of that silly transom transducer and install a Bronze Thrull hull aft amidships close to the centerline.

[pistnbroke]

That would be because american boats have the steering on the port side whilst the rest of the world has it on the starboard..hence they run the wire shortest route to the console so it ends up on the "wrong" side