Bottom breaking up over 10kn - transducer placement advice
Hi guys,
I'm sure this is a frequent question, so apologies in advance for covering a common topic. I've just installed and tested a Furuno 628 on my boat. I'm stoked with the unit and reading under about 10knts, however once I get above 10knt the image starts to break up and loose bottom.
I tried playing with the settings and increasing the scroll speed etc but nothing seemed to help. This makes me think that the transducer placement might be an issue - even tho I followed the instructions to the letter and was super careful.
I've attached some pictures of the placement.
Please ignore the apparent swiss cheese appearance of the hull. The previous owner seemed to have a million holes drilled so I had to drill them all out larger, fill and resin over. Doesn't look pretty but I'm alot more confident that it is water tight now.
My guess is that it might be too close to the engine ? I did that because the are strakes running down the hull and I wanted to avoid the previous holes that I repaired. I did have a look over the back when my boat is underway is there is nothing the even resembles clean water behind my boat
Interested to hear any opinions.
Cheers !
Darren253
Posts: 570
Date Joined: 23/07/16
There is lots of talk about
There is lots of talk about this on the Simrad/Lowrance page on Facebook and The Hull Truth.
It's all trail and error, i.m cuirrently going through it myself.
kirky79
Posts: 1351
Date Joined: 13/01/12
It looks pretty good, as
It looks pretty good, as Darren has said maybe try the wedge to get the back edge down a little more
bleicester
Posts: 219
Date Joined: 10/09/14
Before moving the transducer
One way to tell if you need to raise or lower your transducer is to monitor the display as you make a steady turn left or right while maintaining a constant speed.
Assuming transducer is mounted on starboard side:
- If the image improves while turning to port you need to raise the transducer.
- If the image improves while turning to starboard you need to lower the transducer.
Error 404
Fish not found
nathan hume
Posts: 42
Date Joined: 03/11/12
My moneys on it needing to
My moneys on it needing to go lower going from the photo . A side on photo would be better to tell that plus angle
Faulkner Family
Posts: 17971
Date Joined: 11/03/08
looking at the pic i would
looking at the pic i would say go a bit lower. i think the right hand side should be level with the hull. placement looks ok tho
RUSS and SANDY. A family that fishes together stays together
Francis
Posts: 326
Date Joined: 17/06/08
Aimar P66 - added side photos
Interesting responses - really appreciate it. After doing more searching and research there are alot of forums that suggest running the Airmar P66 about 10mm lower than recommendations.
I've taken and added some side on shots with a straight edge placed along the hull line. It does look like it's a little bit high. Will try to drop it 10mm. The wedge that comes with the P66 seems to create a large angle so I am reluctant to put that in yet. So maybe I will lower it and try again, then I'll add the wedge if still no luck.
I think I know the answer to this one, but keen to hear what others would do - obviously I squirted marina sika in the holes and on the screw threads when I installed this. Would it be better to completely remove each screw, remove as much of the dry sika as possible and re-apply sika ? Or if I only wind them back enough to lower the height, then tighten them back up will the sika still form a seal ?
Tim
Posts: 2497
Date Joined: 26/09/06
Lower
10mm lower should improve it. Try it first before adding any more wedge.
Best bet is to just change one thing at a time so you are sure what improved or didnt
nathan hume
Posts: 42
Date Joined: 03/11/12
Drop it 15mm mate going off
Drop it 15mm mate going off your photo angle looks good . I have a p66 on the opposite side of a tm260 and it sounds really well up to 20 knots or more
sea-kem
Posts: 14918
Date Joined: 30/11/09
Yep I agree with dropping
Yep I agree with dropping but try 3-4mm or so at a time. I found my sweet spot that way.
Love the West!
Ant1derooster
Posts: 32
Date Joined: 13/09/16
Just installed one myself
Hey mate, like you I've recently installed one myself (FCV 628 and a P66) and I’m getting solid bottom in over 20 knots (very fair conditions)
My P66 is definitely installed a lot lower than yours, try moving it as low as possible without drilling new holes. You may be lucky and this will do the trick.
The only time I have lost bottom is when I smash through/over solid wind chop but I am putting that down to air moving under the hull. (or when i lift the prop
)
Francis
Posts: 326
Date Joined: 17/06/08
Excellent - I will start
Excellent - I will start dropping it and give it a good test tomorrow ! Will post an updated photo of the eventual location that improves the reading (if it does indeed improve the reading).
thanks![](http://www.fishwrecked.com/sites/all/libraries/fckeditor/editor/images/smiley/msn/thumbs_up.gif)
Bluedog
Posts: 251
Date Joined: 28/07/11
Put that bracket as low as
Put that bracket as low as it will go and you will be laughing.
just dhu it
Posts: 1081
Date Joined: 14/05/09
Drop unit
as the other said drop another 10 mm. If you have on going issues I would also make up plate from rear of transom out to transducer so to eliminate any gaps where water and air especially can form between to two surfaces.
ranmar850
Posts: 2702
Date Joined: 12/08/12
One aspect not mentioned here.
I have seen it discussed at length on other forums, and that is the actual placement relvant to prop rotation. For example the OP has it mounted on the downsweep side of the ( assuming RH rotation) prop. Conventional wisdom in other places states it should be on the upsweep ( ie, in this case ,left) side of the prop. Let me stress i have no opinion on this subject, just throwing it out there for comment.
Ktreloar
Posts: 115
Date Joined: 05/08/16
When it come to the perfect
When it come to the perfect set up with p66 they need to be buried passed disturbed water. Usually on the side closed to the keel needs to be 10-15mm lower then the Hull. The next thing is angle, working off your Hull isn’t a true indicator. You need get on the plane with a level and work out how your boat sits then level your tranny from there. Most smaller boats quinnys, savages etc ride nose down on the plane. I had to give mine some angle and looking at it looks wrong but mine reads 29knots flat out even in crap conditions. One way to work out if the angle is wrong is if your loosing bottom while going into the plane as the nose drops if so more angle. Just play around with it mate once it’s set mark around it with a permanent marker and you will always have the spot to mount it
Ktreloar
Posts: 115
Date Joined: 05/08/16
When it come to the perfect
When it come to the perfect set up with p66 they need to be buried passed disturbed water. Usually on the side closed to the keel needs to be 10-15mm lower then the Hull. The next thing is angle, working off your Hull isn’t a true indicator. You need get on the plane with a level and work out how your boat sits then level your tranny from there. Most smaller boats quinnys, savages etc ride nose down on the plane. I had to give mine some angle and looking at it looks wrong but mine reads 29knots flat out even in crap conditions. One way to work out if the angle is wrong is if your loosing bottom while going into the plane as the nose drops if so more angle. Just play around with it mate once it’s set mark around it with a permanent marker and you will always have the spot to mount it
Francis
Posts: 326
Date Joined: 17/06/08
Just in this, does the
Just in this, does the additional angle cause problems when you are drifting or going slow searching for reef?
I just wonder if the angle might make the beam shoot a fair way in front of the boat when drifting in 30-40m of water ?
Ive added the wedge and will take it for a test tomorrow I hope, but like you said it does look a bit too much.
Francis
Posts: 326
Date Joined: 17/06/08
Cheers guys, I dropped it
Cheers guys, I dropped it today and tested, then dropped more (as low as I could go with the screw locations) and tested again. I think I got marginal improvement but not much. Otherwise I was super happy with the reading I was getting (even if the fish I appeared to be seeing didn’t seem to want to bite!)
Will try to insert the wedge and see if that makes any difference, otherwise I might need to patch up the holes and try again.
Interesting point re: being installed on the downsweep side. I’ll have to revisit this and read into it as I thought I put it on the correct side.
Darren253
Posts: 570
Date Joined: 23/07/16
I believe it is on the
I believe it is on the correct side too. I’m testing mine with the 4.5deg wedge tomorrow after various different height tests.
Francis
Posts: 326
Date Joined: 17/06/08
Good luck - will be
Good luck - will be interested to hear how you go!
Francis
Posts: 326
Date Joined: 17/06/08
Just a follow up to close
Just a follow up to close this out and help anyone else out - I ended up having no luck with the original mount location OR using the shim/wedge when over 10knt, so I moved the transducer over a bit closer to the keel and removed the shim. I added a new photo and you can see the 3 previous holes (need to finish the patch job). I didn't have to move it over too far and I can still go lower if needed but I am getting a solid reading at 20knts now ! Very happy.
It does start to break up over 20kn, but if I turn to starboard, the transducer goes deeper and the image clears up. I don't think I will be bother lowering it further tho because I can't be bothered playing around with silicone again and I rarely exceed 20knt unless im done for the day.
I also changed the Transducer setting from "600W" to "525STID-PWD". Apparently this is the part number for the P66. Not sure if that actually helped or not but I'm super happy with the result now.
Hope this helps someone else.
Cheers