Transducer location

[jdbb01]

Why does a transducer have to be mounted on the starboard side of the motor ???

[dnej]

I believe this is due to prop wash direction.
David

[jdbb01]

That's what I thought it might be. Just wondering if prop wash is an issue on my boat (signature 520C). The motor is mounted on a pod that is sticks out about 8" behind where I can mount the transducer. This puts the prop 600mm behind, 500mm to the side, and 300mm below the transducer. Is prop wash still an issue when the transducer is that far away from the prop?

The other thing I thought of is that the battery and all electic cables go down the starboard side pretty close to where the transducer cable would go through the stern. What effect does this stuff have on the transducer signals?

[Big_Kev]

RAFLMAO your joking aren't you. I have not heard that one before.

[jdbb01]

Not sure what was so funny Reel Hard but I'm presuming it was the bit about being near other electical sources.

It was supposed to be a serious question as the instruction manual says "To reduce electrical interference, separate the sensor cable from other electrical wiring and "noise" sources." Seems to me that bringing the transducer cables out right beside the battery and other wiring running to the motor might be contrary to this instruction.

Maybe it was stupid - anyway thanks for your valuable input.

[peterbo3]

hello jdbbo1,
Stbd side of boat is where the cleanest ( less turbulent ) water is.
Prop wash will make a big difference as water is aerated & transducer signal may be distorted or totally lost.
As for the electrical cable separation you will be pretty safe with a passive circuit i.e. one drawing power from a battery such as a radio, nav lights, etc. No real need to keep the transducer cable too far from those wires.
However with an active circuit such as the main cables coming from your engine to your battery which are pumping out up to 40+ amps depending on your motor, then separation is a good idea. 300mm should see you right. Flor lights mounted under your gunnels will also impact on your sounder if the transducer cable runs next to them. You may also pick up interference from live bait tank pumps, etc if they are on the same power circuit as your sounder. It is a good idea to run a dual busbar system with sounder, GPS & radio coming off one with a surge protector wired in & everything else off the other.

[jdbb01]

Thanks for the reply Peter. I will do a search for dual busbar sytems to see what's involved in setting it up.

John

[Big_Kev]

Sorry for my humor.( I have a strang sense for it)
It was the about the prop wash. I have never heard about only mounting to the starboard side. Not saying I am not wrong.
I have had the transducer set up on both sides of boats I have had and did not seem to worry (including #Signature). I can't see the prop affecting the water at the transome as said, unless you mount the transducer to close to the leg of the outboard. This would have effect on either side. #
Good clean water is what you need and it helps to tilt the face of the transducer down slightly.
Cheers Kev. #

[NQCairns]

I have had one boat with the trans on the wrong side and noticed no problems.

Thinking around it, prop wash on an O/B if it was to be an issue could happen at very slow speeds only or in reverse.

I dont really know but suspect it all relates to the broad application of best practice, which to the average boater means little in this instance. But if he owned an inboard shaft drive craft it might be relevent.

[Mantaray]

RAFLMAO your joking aren't you. I have not heard that one before.

Then today you have learnt something new.

[Big_Kev]

Then today you have learnt something new.

So is this actualy written in an installation manual or is it just hear say?
Cheers Kev.

[Mantaray]

So is this actualy written in an installation manual or is it just hear say?
Cheers Kev.


The principle is covered in many manuals and I'm a little surprised you are doubting what is basically a well known principle? Propellers on single outboards generally all spin clockwise, which simply makes for more turbulent conditions on the port side of the outboard. Less turbulent water then has to be the starboard side. Turbulence is that reason why transom mounted transducers don't work at all well on shaft drive boats, way too much turbulence, which is why transom mounted transducers are only basically suitable for outboards and stern-drives. #

But yes there are some manuals get this simple principle very wrong! Perhaps you might have read too many Lowrance manuals?

[Big_Kev]

The principle is covered in many manuals and I'm a little surprised you are doubting what is basically a well known principle? Propellers on single outboards generally all spin clockwise, which simply makes for more turbulent conditions on the port side of the outboard. Less turbulent water then has to be the starboard side. Turbulence is that reason why transom mounted transducers don't work at all well on shaft drive boats, way too much turbulence, which is why transom mounted transducers are only basically suitable for outboards and stern-drives. #

But yes there are some manuals get this simple principle very wrong! Perhaps you might have read too many Lowrance manuals?

I see the principle in the theory.
As said I have not heard of it before, for a supposed well known principle. I did not say I doubted it.
When the writer fits his sounder to the Signature with the outboard he will have some good info from here.

I am in the market for a new sounder myself so I will have to read the instalation manual when I get it.
Cheers Kev.

[Mantaray]

Just remember some manuals get it wrong!

[Big_Kev]

Yeah I am looking at a Furuno 4100. Looks like good value for money for what I do.
I had a Humminbird 100 mounted to the port on this boat and it worked well at all speeds, the best I have had yet. The wiring did run along without any electrical as well, so I think I would stick to the same set up. .

[Wyoming]

The NavMan sounder manual clearly instructs you on the mounting position and describes the correct side for mounting the transducer. It is not an urban myth.

[basserman]

well nether the lowrance or garmin manules say anything about what side to mount them on however they both say now closer than a foot from the motor

i have two boats also and have the transducers on oppisite sides and nether of them have ever had problems with readings
southwind is on the starbord side while the quinny has the transucer mounting bracket on the port side

[Mantaray]

Isn't it a bugga when boat manufacturers even put things in the wrong place and people then think that's where it should be. Just crazy man.

Well bugga me guess where Furuno says to put it? Maybe it's time to read the manual unless of course you've also got one of those boats that's been fitted wrong from scratch?.

[basserman]

would like to hear from other quinny owners where your transducer mount is on the boat and also from other makes of boat ;)


but do need to say nill effect from being on the wrong side
would be a intresting one for the myth busters but ;D

[Dehydrated]

I have a port side mounted transducer on my Sea Jay. It has always worked perfectly for the 2 sounders I have had in this boat. (Have had the boat for 6 years.)

[laiborcimitna]

well nether the lowrance or garmin manules say anything about what side to mount them on however they both say now closer than a foot from the motor

My Garmin came with a template to assist in locating the holes for the screws that hold the transducer in place. This template is clearly designed for the starboard side of the hull.

Sam

[Mr__Bean]

Copy below of the installation instructions for my Raymarine transducer.

- Darren

[Pual]

Hi, I have attached about 4-5 tranducers in my boating life.
I have always run the wiring down the opposite side to the motor wiring loom to avoid electrical interference, which worked, but had trouble with airation. Till last time.
Each previous time the manual had said to position the transducer behind a strake, but this time I have put it much closer to the keel about 6 inchs to the drivers side.
This has resulted in excellent high speed bottom contact and none to very little airation, which is great because I am interested in what I travel over to and from the fishing grounds.
Pual

[gogecko]

Ive been reading up on this a lot, as I am about to install anew transducer. Theres a lot of info on it in another forum that has a marine electronics section. (Can I say that here?)
Yes, theres a lot of manuals that say Starboard side.

Now can someone please explain to me why theres less aeration on that side? It seems simple physics to me, that the prop must exert equal thrust in all directions, or the boat wouldnt go forward, it would tend sideways. I dont care whether the prop spins clockwise or counterclockwise, it MUST thrust evenly on both sides.

Wheres that physics teacher I saw on towbar thread?Can someone enlighten me? Shall we all have a look at our wash next time were out?

[Fishin_Dan]

gogecko - I think it has to do with the direction the water/air is travelling across the transducer. You are correct in that there is equal thrust on both sides of the prop (Actually equal the full 360 degrees) but, by looking at the direction of the prop and the tangents from it, you see the direction the force is going (See pic). If the transducer is mounted to the right in this picture, the turbulence (force generated from the prop) runs over the top of the transducer in a "down and to the right" angle. This doesn't affect the "face" of the transducer too much... If it was mounted on the left in the picture however, the force/turbulence would run "up and left" across the face of the transducer.

In practice of course, you wouldn't mount the transducer too close to the prop anyway, so any turbulence is not going to be an issue.... But this is the physics (I think) of it all... I did physics for many years, but I could be rusty as it wasn't called HIGH school for nothing!!!! :o [smiley=beatnik.gif] [smiley=freak.gif]

[gogecko]

Thanks Dan. Sounds like your high school days were a lot like mine.Some of still think were in high school, for that matter.

I see your explantaion makes some sense. I was thinking that the manufacturers of sounders are giving this advice needlessly, because it only matters when the transducer is BEHIND the prop. Yet most are mounted beside the prop or slightly in front. Id expect there is some suction effect from prop wash, not blowout efect.

In hindsight, your explanation would be correct, so thanks. Thrust may be equal, but air bubbles travel sideways.I'll stick my head over the back and have a look tomorrow. As Dr Karl says, 'do the experiment!'.

[Mantaray]

The up swing side of the propellor creates turbulence on the hull, bubbles and transducers don't go together. Mount it on the down side whatever side that might be, usually the RHS.

[dnej]

WOW, and my answer was only a one liner.

I didnt think I was being a commedian, just passing on information.
OH THIT
David

[Roo]

Hey basserman,
my quinnie explorer has mounting plate (alloy) on the port side and i've found suffers from aeration quite a bit. I sort of fixed last trip by angling the face of transducer slightly forward but soon returned to old ways when some weed tangled up and dragged it back again. I 've almost given up on meaningful sounder readings when underway.

cheers, Roo.

[Mantaray]

WOW, and my answer was only a one liner.

I didnt think I was being a commedian, just passing on information.
OH THIT
David

Interesting the responses sometimes David, for some it doesn't appear to matter how much info or how little or what, there's always the distractors ready to knock, must get annoying. Maybe the doubters can understand the following

3. Mount the transducer on the side of the hull where the propeller is moving downward. The upward motion of the propeller generates pressure waves and pushes bubbles up against the hull. By mounting on the downward side, the hull shades the transducer from this effect.
http://www.oceandata.com/support/install/images/177f2.gif

[Fishin_Dan]

Geez Mantaray.... Here I was thinking my piccie was pretty schmick after spending 2 minutes with Microshaft Paint, when you go and post this work of art!!! ;D ;D ;D

It explains it so much better than my pic though...!

Dnej - Don't worry mate, it's usually me making smart @$$ comments... ;)

[magicpudding]

Umm excuse me if i'm wrong, but the prop wash isn't going to be affected by the hull at speed, as the turbulance will be out the back of the boat by the time it rises to the surface. Most badly posintioned transducers drop out at HIGHER SPEEDS, thus the hull interference of the turbulance can have no affect!
Also, regarding the positioning for in reverse. I am yet to go on a boat, big or small, that has a transducer which works effectively in reverse. I think this is caused by turbulance from the hull not the prop.
Just to throw a spanner in the works, what side do you mount the transducer on a boat with 2 counter rotating engines [smiley=jester.gif]

CJ

[Fishin_Dan]

Umm excuse me if i'm wrong, but the prop wash isn't going to be affected by the hull at speed, as the turbulance will be out the back of the boat by the time it rises to the surface. Most badly posintioned transducers drop out at HIGHER SPEEDS, thus the hull interference of the turbulance can have no affect!
Also, regarding the positioning for in reverse. I am yet to go on a boat, big or small, that has a transducer which works effectively in reverse. I think this is caused by turbulance from the hull not the prop.
Just to throw a spanner in the works, what side do you mount the transducer on a boat with 2 counter rotating engines [smiley=jester.gif]

CJ


Hmmm.... Good Point!

However, we all know the answer is IN THE MIDDLE!!!! ;D

[Mantaray]

Fishin_Dan, got to be honest can't lay claim to that piccie, had to borrow it from people who know these things, can't be questioned that way.

[Mantaray]

Somebody mentioned that it doesn't matter if the prop spins clockwise or counterclockwise, it MUST thrust evenly on both sides.

A couple of questions then

1) All things being straight put the engine in reverse does the boil emerge out the left side, the right side or smack bang down the middle?

2) All thing being straight if an engine is put into gear no power on but prop turning over, which way does the stern have more of a tendancy to go, left, right or doesn't move either way.

3) All things being straight if the trim tab was removed from the motor which way would the bow tend when put into forward gear, left, right, won't tend either way?

[DR]

where would it be mounted on a cat?? would the tunnel make any diff to turbulance ??

[Mantaray]

Twins are easy, either side but not in the middle, starboard side of the starboard and port side of the port motor, starboard prop on most twins spin clockwise, port is the counter clockwise motor. If you don't have counter rotating motors then the principle is the same as 1 engine.

[DR]

thank you..will refine my question a bit.
what about a single engined cat ie a WEBSTER would the sponson break the water flow sufficently so that it doesn't matter which side.
reason for q. is i have a webster ,the manufactures bracket is on the port & seems to work fine, will performance improve by mounting on starboard..

[Mantaray]

thank you..will refine my question a bit.
what about a single engined cat ie a WEBSTER would the sponson break the water flow sufficently so that it doesn't matter which side.
reason for q. is i have a webster ,the manufactures bracket is on the port & seems to work fine, will performance improve by mounting on starboard..

The centre sponson might increase the turbulence further as even a conventional/normal keel is a place to keep a transducer away from due to air bubbles and such things.

[basserman]

would distance from the motor be more important???
reason is that on both my boat the tranducers are more to the outside edge of the transom and maybe that is why i get good reading
mainly in the quinny where the mounting plate is on the port side as it has a fairly flat bottom and the mounting plate is almost on the outside edge of the transom

mind you a mianly use the sounder at slow speeds or while lure casting under the elcetric
always wondered about useing the sounder at speed as i would think by the time you have your reading you would already be well past that point

[DR]

thank you, good excuse to go fishing, i need to conduct some tests. ;)

[Big_Kev]

After reading the input I would be of the opinion that the transducer should be fitted where it works the best for you and that various positions may be required to get the best.
But I would now tend to install the tranducer firstly on the starboard side of a mono hull and lay the cable away from other electrical cable's??

[empty]

had 2 tranducers on 2 different boats ,both on port side and both havent work very well at speed ,might think about changing the 1 on this boat to starboard and se if it makes any difference

[FNQCairns]

Empty dont worry about moving it to the starboard side, you might try locating it deeper on the hull or anywhere on the same side that you could assume would introduce less bubbles captured by the hull and compressed along to exit at the rear.
How a prop can thrust forward half a foot and sideways as much as 2 or more feet as well as behind at any planing speed has me stuffed ???

[blaze]

my transducer is mounted about 10mm below the hull, people may say thie is too low but it is clean water and works, if the water is calm it works at 4okmh ok, not so if its choppy. I have had to fabricate a cover to stop the spray hitting the trim tab and sucking into the boat but it all seems to work ok
cheers
blaze