Sounding help

[Back In Black]

Guys,
On my Sailfish cat, I run a Furuno 585 with a 1 kw transducer, but as soon as I go above 18 knots, the screen goes scratchy & we lose ground definition.
Its really frustrating, as we usually go wide, so I am sure we are running over ground we could pull fish off, but we just can't see it.
Dean, my maintenance man, had a look & was surprised it is built into a rigid bracket that cannot be adjusted at all??
He suggested cutting the bracket off & making a bracket with more of a hinge type arrangement where we could apply some adjustment, saying the rear of the transducer should be pointing down more, shooting slightly ahead of the boat??
Another thing he suggested we try is trimming the port motor slightly whilst watching the screen, seeing if this had any effect??
He thought the transducer & bracket stuck a fair way out, & wondered if the prop being close was hindering a true reading.
Any thoughts??

Thanks,
Tony

[chocolatemoose]

i propose that that lip rise/weld from the plate is causing an effect at speed. and whilst a great transducer. just needs a bit cleaner water perhaps.

[Back In Black]

You may be right Moose, as when I took the tub back to Sailfish a couple of years ago for some maintenance, they did shave down the weld a bit which did help.
I really need a MUCH bigger improvement though.
Thanks,
Tony

[Moejoes]

What transducer is that Tony.
I need a 1KW on mine & that looks way smaller than the TM260.

[Back In Black]

Wouldn't have a clue Rob. Just dug through all my paperwork & there are no specifications??

Hate those damn TM260 jobs, WAY too damn big!! LOL

[scottar]

Most likely a CA50/200 1T combined with a matching box to allow for the 585 requirement for a dual resonant transducer. Noise can come from either water flow issues or props due to proximity. Not all props will cause it and usually if it is props the sounder screen will fill with noise at not to much over idle. Just looking at the photo, the transducer face looks like it does not protrude through the plate - almost like it is ever so slightly recessed with a small gap around the edges. Any gap or edge has the potential to create dirty water flow with a recessed edge creating more turbulence the faster you go. With a transom mount installation it is normal to try and get a bit of angle so the transducer is facing slightly forward. This is done purely for the hydro dynamic aspects and is not as such a requirement for the sounder to work properly provided you can get good clean water flow. As suggested it could be a weld as well

[Moejoes]

Wouldn't have a clue Rob. Just dug through all my paperwork & there are no specifications??

Hate those damn TM260 jobs, WAY too damn big!! LOL

That's why I asked.

Thanks Scottar I think that's it.
I think they are only about $250 for the 1KW

[Aussie123]

That's why I asked.

Thanks Scottar I think that's it.
I think they are only about $250 for the 1KW

They are probably around $800 plus here in Australia.

[Moejoes]

They are probably around $800 plus here in Australia.

Hmmmm, Still cheaper & smaller than the TM260
I'll google them.

[Back In Black]

That's why I asked.

Thanks Scottar I think that's it.
I think they are only about $250 for the 1KW

Ya tight mongrel. Listen to Aussie!!!

[Back In Black]

Most likely a CA50/200 1T combined with a matching box to allow for the 585 requirement for a dual resonant transducer. Noise can come from either water flow issues or props due to proximity. Not all props will cause it and usually if it is props the sounder screen will fill with noise at not to much over idle. Just looking at the photo, the transducer face looks like it does not protrude through the plate - almost like it is ever so slightly recessed with a small gap around the edges. Any gap or edge has the potential to create dirty water flow with a recessed edge creating more turbulence the faster you go. With a transom mount installation it is normal to try and get a bit of angle so the transducer is facing slightly forward. This is done purely for the hydro dynamic aspects and is not as such a requirement for the sounder to work properly provided you can get good clean water flow. As suggested it could be a weld as well

Scottar, what sort of speed should I be able to sound at clearly with this combo??

Tony

[scottar]

Assuming good clean water and no prop noise you will never outrun any sounder. Compared to the speed of sound we might as well be sitting still. The limiting factor with most boats is the clean water flow. Without seeing the picture I suspect you are getting a bit of dirty water. It may be caused by one thing or it could be a cumulative effect from several. You have quite a bit going on with the welds, the possible lip and gap in the bracket and the little "keel" that runs down the sponson just to one side. Cats can be notoriously difficult to get a good reading depending on the hull shape. The downside to your style of transducer is that there is no easy way to try adjustment with an alloy hull without fairly major "surgery". It may be worth trying to smooth/fill the gap between the transducer and the bracket with some silicone but if the face of the transducer is recessed it will always be making it's own bit of turbulence.

[Bremic]

I reckon it needs to be a few mm lower, so it protrudes just below the hull, with the option of having the back end slightly lower, as suggested by your mate.

Have you asked Sailfish, yours can't have been the only one that had issues with the setup?

[tunaticer]

The images don't show it clearly enough but can the transducer slide through the bottom face of the mount? Or is there a ridge above the bottom face that will not go through?
First look at the images I thought you might be able to drill new holes in the brackets to set the transducer deeper below the hull surface if the hole will allow the trasducer to slide through.

To be honest I would remove the entire bottom plate and remake the top bracket to be able to push that transducer a good 20mm lower than the hull and tilted 5 degrees forward i.e tail down nose up.

[scottar]

Rubber block transducers have a lip that they sit on. The transducer face is smaller than the main body of the unit leaving about 5 to 8mm of the rubber block around the edge with the face of the transducer protruding 4-5mm. The brackets simply apply pressure to the top of the block to stop it going upwards and coming out of the mount plate. They are typically used in larger steel or aluminium hulls where a box is constructed either internally if the vessel is high speed and the angles of the hull don't cause an issue or externally protruding from the hull in a low speed application. The cable is brought into the hull through either a watertight gland or a pipe that extends up to above the water line of the vessel.

Given that Tony's boat is a cat, remanufacture of the bracket will not only be expensive but will also run the risk of interrupting water flow to the props if the bracket is dropped too far. It would be possible to manufacture a housing for the transducer that can be bolted to the rear of the boat that has slots to allow for adjustment but even this is going to create a square edge at the front of the bracket that may require fairing work to get smooth water flow.

Personally I would be trying a few things with the existing bracket first - further smoothing of the weld if possible or a bit of light fairing work to try and smooth the flow of water. Try and get the face of the transducer level with or slightly protruding from the plate if it isn't already - this will be a PITA to do - maybe a dremel. A bit of angle may be able to be created by cutting the sides of the bracket right up against the hull and bending the bottom plate slightly.

Tony, just looking at the photo's again - does the bottom of the sponson actually start to rise at an angle few feet before the transom? Can you get a photo standing back a bit from the side that the transducer is on ?

[Back In Black]

Hi Scottar,
Here are a few more images. One is with the port leg trimmed right down, showing how close it is to the transducer. Its pretty smooth from the hull to the transducer, but there is a big solid weld to the port side of the transducer, which I'm sure will have an impact.
Thanks,
Tony

[scottar]

Hi Tony,

From the photo, It looks as if the hull does come back up - so that the transducer bracket being an extension of the hull is actually slightly facing backwards when the hull is sitting flat on the trailer. This is less than ideal but due to hull design something you may be stuck with. Just looking at I think the water flow as it comes over the welds forward of the transducer where the hull starts to angle back up can't be anything but disturbed and to get the transducer low enough that it will be away from the influence of the hull shape will definitely run the risk of interference of water flow to the prop. Have you tried varying trim angles to see if they make a difference? More so from the aspect of lifting the bow high enough that the section of hull that the transducer extends off is running flat to the water - worth a try just to see what happens. The other thing would be to try and get in contact with other Sailfish owners and see what they are using and if the same problems exist - it may be that a different transducer install like a tilted element through hull is the best option but getting confirmation that it works is a better option than experimentation.

[Back In Black]

Hi Scottar,
That was Deans suggestion too. Watch the screen while slowly trimming the motor to see what effect this has.
I'll get onto Sailfish & see what others are doing now.
I did query them a year or so ago about a thru hull job, but they said they don't do it due to the construction method?? Didn't make sense to me.
Thanks for your help Scottar.
Next time I'm out, I'll try the slow trim & get a video of it to show you the effect.
Tony

[Nick H]

My mate has KC with twins. He is running a TM 260 and it is mounted 18-25mm lower than the bottom of the hull. If your boat has twins the transducer should be mounted on the clean water side of the prop. If there counter rotating it might be different. He can sound at full speed, 24-28knots depending on the swell etc. he's motors are on pods you can see the transducer tucked under attached to the hull. So about the quality of the photo.
Nick

[Moejoes]

Hi Scottar,
Here are a few more images. One is with the port leg trimmed right down, showing how close it is to the transducer. Its pretty smooth from the hull to the transducer, but there is a big solid weld to the port side of the transducer, which I'm sure will have an impact.
Thanks,
Tony

Tony,
Get a flap disc grinding wheel & wear the sharp edge off it.
You will then be able to run it along the weld & clean it up dramatically.
Should only be a 5min job.
By the way, there's a hole in your weld LOL.
Must have been some pigeons around that day :P

[tunaticer]

Tony, are there any screw mounting holes in the transducer itself?
From your images it looks like the transducer is sandwiched into the bottom hole by the top plate with nothing else holding it.
If that is the case then you will need to build a new mount that is 20mm deeper set and angled 5 degrees fore.
If there are side or top screw holes in the transducer you may have a cheaper mounting option and retain most of the lower mount. Without screw holes you will be forced into removing the existing mount and lowering and modifying it.

It may be cheaper to source a different transducer that is easier to mount.......???

[Back In Black]

Tony,
Get a flap disc grinding wheel & wear the sharp edge off it.
You will then be able to run it along the weld & clean it up dramatically.
Should only be a 5min job.
By the way, there's a hole in your weld LOL.
Must have been some pigeons around that day :P

Thats a drainage hole you knob!! LOL

[Aussie123]

That's why he loses so many fish beside the boat, they get their heads stuck in that hole. ;D;D;D

[bannana]

Wouldn't of though you would ever drive your boat above 18 knots....old boy

[Moejoes]

Thats a drainage hole you knob!! LOL

Just hit it with a hammer!!!!
That'll bend it down & fix it :P
Probably won't work anymore but will look the part.......
Or go buy a new one & I'll buy that one off you ;D

[Moejoes]

Wouldn't of though you would ever drive your boat above 18 knots....old boy

Keith, when are you calling me back?????

[Fed]

Grind some off the top of the mounting bracket so the tranny sticks out the bottom by a couple of millimetres.

[Back In Black]

Wouldn't of though you would ever drive your boat above 18 knots....old boy

Not everyone feels the need to do warp speed;D.........fat man

[scottar]

I did query them a year or so ago about a thru hull job, but they said they don't do it due to the construction method?? Didn't make sense to me.

Tony

When a boat builder says that when doing a new build they usually mean "that will make my life a bit difficult so I don't want too". The only thing that would make it somewhat more difficult is if the angle of the sponson surfaces is more than 24 degrees (the maximum angle for tilted element transducers).

Now that it is built, the things that would make it difficult are foam filling, lack of access and lack of room in between stringers in the sponson. If you have inspection ports down into the sponson it would be pretty easy to make a determination as to just how hard it may be

[Moejoes]

Here Tony,
I fixed it for you. Don't say I never do anything for you ;D
Fully adjustable

107988

[Mad one.]

Evening Back in Black,
I have just come through a similar experience with my plate alloy mono and Furuno 585/P66 transducer combo. I designed a bracket which enables me to change the location and depth of the transducer with relative ease. After trying over 20 different location/angles I am now able to get some pretty good readings at speed. Aside from the transducer location I found a few settings on the unit itself that helped me remove some of the interference when travelling. Changing the 'interference' setting from auto to high was a big help and even slowing the screen speed down to 1/2 I saw improvements. I run my gain on manual and when travelling I drop it back from say 6.2 to around 5.5 which helps reduce any interference from the engine and then I increase it back up when slowed back down and searching the seabed. I think if you are able to get a good reading up to 18 knots then the location might not be that bad, however like others have said smoothing out any bumps might be a good starting point. I would have thought you could eliminate a few possibilities e.g., can you get a clean reading above 18 knots on smooth water? I would be looking at eliminating all other possibilities before chopping anything.
As I said I have gone through this and I found playing with the furuno settings, taking note of trim and how it performs on smooth water all helpful information as to how the readings performed out on the ocean.

Cheers, MO

[Back In Black]

Here Tony,
I fixed it for you. Don't say I never do anything for you ;D
Fully adjustable

107988

I'd never say that about you Rob. I might say some other things though.......LOL

Can't open it mate

[bannana]

Not everyone feels the need to do warp speed;D.........fat man

Lol

lower your transducer and make sure the rubber housing is flush with the cut out and not raised as it currently is.

Mate you still using Viagra?

[Back In Black]

Mate, how else will I stop rolling out of bed;D;D