Transducer location and performance
Where is the best position to mount a transom mounted transducer to gain a good picture? The more people I speak to and the more research I do the more this all sounds like black magic. I had lenghty discussions with the manufacturer of the boat I purchased some 4 years ago and went with their recommendation to have the 1kW transducer transom mounted. What seems to work well on some boats doesn't on others. I receive what I believe is aeration disturbance over the transducer at less than 10knots and am looking for other options that may increase picture quality. I'd be interested in comments from others who have transom mounted 1kW transducers and get what they consider to be a good quality picture at 15knots+.
Pics attached of the current set up. In the down position the underside of the transducer is approx. 85mm under the hull.
fishy fingers
Posts: 1719
Date Joined: 28/04/07
too low
the face of the transducer should just be below the surface underway or just below the level of the
underside of the hull by about 5 mm it also looks to be too near the chine so the water passing over it will probbably not be
clean it needs to be further toward the keel but not behind any strakes.
smiley
Posts: 118
Date Joined: 23/11/10
transducer
i would position it on the starboard side, you want the transducer as close to the centre of hull as possible, where it is at the moment, it would be copping all the surface interference, if you are able to being twin motors, fit transducer between them
fishfish
Posts: 307
Date Joined: 01/09/09
Too far out ???
At a quick guess I'd say its mounted to far outboard { acctaually I've never seen one this far out } possibly picking up turbulence off the corner of the hull ???
Height seems to be ok if anything too low but thats safer than being too high ...
Also noticed thats its mounted on the port side which aparantly is not the ideal side due to prop rotation ??? but Ive yet to prove that point myself so I'm still open to proof..And I did notice you have an aux or twin outboards so space maybe limited ...
Something to think about cheers fishfish...
Edit Damn I'm slow see above posts !!!
MattMiller
Posts: 4171
Date Joined: 15/06/09
Looks like
a cat of some sort fella's
till
Posts: 9358
Date Joined: 21/02/08
Yeah, transducer mounting IS
Yeah, transducer mounting IS a black art, and doubly so on cats. Ask noha and scottonofish, they have a cat qand can probably offer some mounting tips!
fisho-ron
Posts: 2539
Date Joined: 26/09/09
matei had all sorts of
mate
i had all sorts of problems with mine, be it only a 600w, i went to a thru hull wetbox setup and it is excellent now.
used to lose reading at 10+knts. know all good up to 30+.
as soon as i get the funds i will be putting in the 1kw wetbox thru hull.
cheers ron
Rick
Posts: 1115
Date Joined: 22/12/06
Agree
I'm no expert, still trying to clear a few issues with mine, but have to agree with what has been posted so far. I think it's far too deep and too far from the keel.
Does it throw a big rooster tail when your travelling quick ?
It should be that the leading edge is just in the water and the transducer is tilted a touch down on the back end.
PGFC Member
grayzeee
Posts: 2283
Date Joined: 09/07/09
http://www.thehulltruth.com/m
http://www.thehulltruth.com/marine-electronics-forum/87299-catamaran-transducer-location.html
maybe some info in there??
If I spent half as long fishing , as I do reading this bloody forum , I'd be twice the fisherman I am.
alfred
Posts: 3097
Date Joined: 12/01/07
It's to far out and set too
It's to far out and set too low.
It only needs to be down about 3mm.
You'd want to keep it as close to the center of the hull as possible, but out of the prop wash. 
the ferret
Posts: 70
Date Joined: 11/12/09
Mate, buy a wet box or make
Mate, buy a wet box or make your own and have it inside the hull.
6 inch sewer pipe, glass it to the hull and fill it with olive oil, or better still, Glycerin.
It'll work near on flat out.
THE FERRET Rapid tyre deflator, watch a demo-- http://www.youtube.com/watch?v=e1NJjaXbgmA EGR "Shims" and rear light brackets www.ferretdeflators.com
glastronomic
Posts: 892
Date Joined: 16/02/11
excelent subject and
excelent subject and hopefully very informative.
I have found an old wetbox inside my hull and wondering how i can test it if it works still and if I could use it with my Navman4500?
This box is connected to nothing.
Who to see or what can I do?
allrounder
Posts: 1853
Date Joined: 10/11/08
Ok i am not an expert in any way
But from the pics i would say it is a markam.If so you will struggle to get a wetbox in without alot of $ and damage.The best setup i have seen on one was a plate that runs flat off the hull and around the tranny.If you go down that road put one the same on the other side as it does throw the balance out a bit.I wouldnt run it that deep either as others have said and it prob needs to be in off the edge a fraction more.It is hard on the dominators with the shape they are but good luck with it.
So tell me have you got your info from years on the water or hours on the internet?
Alan James
Posts: 2227
Date Joined: 30/06/09
Thanks for the comments guys
Yes it is a Markham Dominator. I wanted to go wet box when the boat was being manufactured but this was not the option recommeded by the manufacturer. Now I wish I had of stuck to my guns. At least if the wet box didn't work the option to transom mount would not have been too complicated. To go to a wet box setup now I think is in the too hard category.
Allrounder - In discussions with others I have heard of a plate being run off the hull as you have suggested. Do you have any info as to who I could contact that may have further knowledge with respect to how this is actually achieved and the results?
Rick - yes it does rooster tail if left in the down position as shown in my pics. In the up position it is more level with the hull as people have recommended. The screen picture isn't noticeably different in the up or down position.
I don't actually loose bottom defintion when going over 10 knots. The full water column just clouds up with bluey yellow streaks so you can't see fish.
I think a mate of Paul G's also has a Dominator. I can't recall his name so if someone could tell me I will sent him a pm to see if he has a better solution.
Cheers
iana
Posts: 652
Date Joined: 21/09/09
This may be way off
This may be way off but I just recently fitted a transducer to my transom, the picture was not good, before I did anything more I installed a software up date to the fishfinder, and had a good picture even at cruising speed. Mine is an older Lowrance.
just dhu it
Posts: 1081
Date Joined: 14/05/09
varies
Alan , i have the same unit on my alli rig and yes by all acounts the wet box would solve the problem
i cant install a wet box due to the hull and i would say that your to far out and coping interference from water coming down the side of the hull and the hull leaving the water when rocking causing air under the tranny, i have tried various positions in height and found slightly deeper was better but i was also getting water over the top of the transducer and the rooster tails , i noticed that the front edge of the transducer doesnt touch the transom as does mine so i made a plate out from the rear of the hull to ensure the water travelled around the head and prevented the rooster tails, mine now can give reasonable readings up to 20 knots
glastronomic
Posts: 892
Date Joined: 16/02/11
One of the downfalls could be
One of the downfalls could be inferference (EMF) due to proximity to other current carrying cables that distort the signal being transported and received by your end unit.
Alan James
Posts: 2227
Date Joined: 30/06/09
At slow speeds or stopped
the picture clarity is perfect. The picture deteriorates with speed. From discussions with Taylor Marine they believe the loss of screen clarity is due to aeration / turbulence over the transducer.
scottnofish
Posts: 1621
Date Joined: 28/08/07
you wont get a good reading
no matter what with a transom muont on a cat there is just to much air at speed under the hull beleive me i have been stuffing around with the 600w on the back of our cat for a while and the best i could get was 15 knots before it turns to crap
we put a 3kw wet box in and problem solved ,wasnt that hard only took a day
Alan James
Posts: 2227
Date Joined: 30/06/09
Did you put the wet box
in yourself or have it done? If by a third party, who ? Where did you locate the wet box?
Cheers
scottnofish
Posts: 1621
Date Joined: 28/08/07
we bought the R299 trany
just had to cut a hatch in the deck between the stringers then cut the box to shape and sikaflex to the hull fill with glycol and glass the hatch back in.
we still get air under the hull but no where near as bad as the tranny mount
Alan James
Posts: 2227
Date Joined: 30/06/09
That's a serious bit of gear there
I would prefer not to cut into the deck but if I decide to go wet box I have no option I guess.
Cheers
iana
Posts: 652
Date Joined: 21/09/09
The old plastic bag full of Water trick.
May pay you to do the old plastic bag full of water trick first, if you can get to the bilge easily. Just incase the hull has air bubbles trapped in the fiberglass, or other imperfections that will cause "noise" on the screen. Place a plastic bag containing water in the planned position of the wet box, then placing the transducer on it will simulate the wet box. If you hold the transducer & bag in position while your buddy pushes the throttle, you shold be able to find the potential best spot for the wetbox.
Alan James
Posts: 2227
Date Joined: 30/06/09
And therein lies the problem
Being a self draining deck I don't have a bilge or access to it.
Teflon Coated
Posts: 33
Date Joined: 28/03/11
Im in the process of fitting
Im in the process of fitting my new sounder and transducer, found this info really helpful!!
http://www.lowrance.com/Products/Marine/HDS-High-Definition-System/HDS-10-FishfinderGPS-Chartplotter/Downloads/
The English version of the HDS - 10 install guide
RUSS - Another punter in the Pilbara!