What's the best "high speed" transducer?

[1kwik72]

I've got a SeaRay 220 Cuddy that I'm looking to put a FF/GPS combo unit on this winter. I'm completely renovating the panel and I've got an in dash 3" depth finder that works at all speeds from idle to 40+MPH, it has a transom mounted transducer. I had a Lowrance Elite 5 in my last boat, it had a through hull transducer that only worked below about 10MPH. I've never ran a transducer that is mounted through the hull. If anyone has used a late model FF/GPS combo unit that's getting good depth readings at speed, I'd appreciate the information. I'm trying to avoid having the basic depth finder in the panel if I don't have to have it in there.

 

[dingbat]

Re: What's the best "high speed" transducer?

99.2% of the problems with sonar units not reading at speed are installation issues. Transom mounted transducers are the worst offenders. A properly located and installed shoot thru installation will provide good bottom detection at the expensive of sensativity performances. Thru hull installations offer the very best performance

 

[1kwik72]

Re: What's the best "high speed" transducer?

99.2% of the problems with sonar units not reading at speed are installation issues. Transom mounted transducers are the worst offenders. A properly located and installed shoot thru installation will provide good bottom detection at the expensive of sensativity performances. Thru hull installations offer the very best performance

Great! Thru hull installation it is! Thanks!

 

[UncleWillie]

Re: What's the best "high speed" transducer?

I have a Hummingbird 798ciSI side scan unit that must be transom mounted because of the Side Scan Transducer.
It reports Depth just fine at WOT at near 55 mph.
I hope you are not expecting to find fish or see bottom detail at 40 mph. Not going to happen.

Any unit you install must be in bubble free, non-turbulent water to receive the sonar pings.
That means it must be below the hull and not behind the transom.



If properly installed, there is no reason that any transducer should not be able to dispay solid depth readings while on plane.

A picture of your installation would help.

 

[1kwik72]

Re: What's the best "high speed" transducer?

I have a Hummingbird 798ciSI side scan unit that must be transom mounted because of the Side Scan Transducer.
It reports Depth just fine at WOT at near 55 mph.
I hope you are not expecting to find fish or see bottom detail at 40 mph. Not going to happen.

Any unit you install must be in bubble free, non-turbulent water to receive the sonar pings.
That means it must be below the hull and not behind the transom.

View attachment 214368

If properly installed, there is no reason that any transducer should not be able to dispay solid depth readings while on plane.

A picture of your installation would help.

It's not installed yet, the transducer that is in your pic is about like the position of the one on my depth finder.

I'm not expecting to see the bottom or find fish while on plane, but I am looking to get accurate depth readings while underway. You touched on another thing that I was planning to ask you about. Side scan and a thru hull transducer, do I have to transom mount for side scan transducers?

 

[Auger01]

Re: What's the best "high speed" transducer?

My garmin (airmar) p39 transom mount works great at 40 mph

 

[UncleWillie]

Re: What's the best "high speed" transducer?

It's not installed yet, the transducer that is in your pic is about like the position of the one on my depth finder.I'm not expecting to see the bottom or find fish while on plane, but I am looking to get accurate depth readings while underway. You touched on another thing that I was planning to ask you about. Side scan and a thru hull transducer, do I have to transom mount for side scan transducers?

"About" doesn't count!
If the transducer were to be another 1/2 inch higher it would be in the turbulent back-flow water of the transom.
It must be below the hull to work properly.

As far as I know, Side scan is only available as transom mount.
The side scan transducer must be able to see 85 degree to each side, so it must be mounted near the keel to be able to see the other side without looking through the bubble filled water behind the transom.
The photo shows the old mounting screws where the transducer had no display to the Port side.
It must also have nothing to either side of it blocking the view.
Another member had the problem of the OB's drive too close to the transom to be able to see in front of.

 

[1kwik72]

Re: What's the best "high speed" transducer?

"About" doesn't count!
If the transducer were to be another 1/2 inch higher it would be in the turbulent back-flow water of the transom.
It must be below the hull to work properly.

As far as I know, Side scan is only available as transom mount.
The side scan transducer must be able to see 85 degree to each side, so it must be mounted near the keel to be able to see the other side without looking through the bubble filled water behind the transom.
The photo shows the old mounting screws where the transducer had no display to the Port side.
It must also have nothing to either side of it blocking the view.
Another member had the problem of the OB's drive too close to the transom to be able to see in front of.

I just took a better look at your transducer mounting location. Yes, "about" will not cut it at all. So now I have a new issue...to side scan or not to side scan? It may be overkill for the 2 weeks per year we go to the beach to fish. A clear down image might be more than enough for our needs and that would allow us to use a thru hull transducer.

 

[dingbat]

Re: What's the best "high speed" transducer?

I'm not expecting to see the bottom or find fish while on plane, but I am looking to get accurate depth readings while underway.

WOW....awful low expectations. I have no problem with bottom detail or seeing fish on the fly (40 mph).

FWIW: side scan doesn't include heave compensation? Pretty useless on your typical "beach" day.

 

[1kwik72]

Re: What's the best "high speed" transducer?

I've had consistent problems with depth finders and bottom machines on various boats that don't read below about 10mph...so yeah, my expectations are low.

 

[UncleWillie]

Re: What's the best "high speed" transducer?

There should be no issues with determining depth a planing speeds.
The general bottom contour will be displayed but bottom detail is going to be an issue.

At 40 mph you are moving 59 feet per second.
At 10 sonar pings per second, each ping is going to be about 6 feet apart.
A 30 foot log is only going to appear in about 5 pings if you cross it in the long direction.
Anything smaller than a large shark is only going to be in 2 pings at best.
Even if you could positively identify the catch of the day, by the time you returned back to the spot it would be long gone.
You may be able to locate whales and large bait balls at 40mph, but not much more.

Contour is one thing, Detail is something else.
Fish finder sonar is best used at speeds below 4 mph. Not at 10 or 40.

 

[1kwik72]

Re: What's the best "high speed" transducer?

All I want at speed is accurate depth...I'll use the GPS to navigate to wrecks or structure. The sonar is for pin pointing the fish at slow speeds. Main goal is accurate depth numbers at speed

 

[UncleWillie]

Re: What's the best "high speed" transducer?

All I want at speed is accurate depth...I'll use the GPS to navigate to wrecks or structure. The sonar is for pin pointing the fish at slow speeds. Main goal is accurate depth numbers at speed

There should be no problem getting accurate depth at planing speeds up to WOT.
The Transducer must be in non turbulent water for this to happen.

This means that a transom mounted transducer need to be mounted so that it is below the hull and out of the backwash of the transom.
I suspect that many installations do not take into account what happens back there when the boat is moving.
Many people fear that a transducer sticking down under the hull is going to get destroyed by passing debris or dragging the bottom.
The drive unit sticks down much farther and survives just fine. Most transducers will fold up if they actually hit something.

If you are going to miss, mount it too low rather than too high.
The one shown in post #4 has survived sticking down for over two years so far.

 

[1kwik72]

Re: What's the best "high speed" transducer?

Thanks for the insights! This is great food for thought.

 

[dingbat]

Re: What's the best "high speed" transducer?

There should be no issues with determining depth a planing speeds.
The general bottom contour will be displayed but bottom detail is going to be an issue.

At 10 sonar pings per second, each ping is going to be about 6 feet apart.

Wow.......no wonder you say that bottom details is an issue. If that is the case, you need to invest in a new bottom machine.


My unit varies pulse length and rate by depth. At 5 meters it's running 50 pulses per second. Your 6 feet is now down to 14.5", as if those numbers meant anything.

Your not taking into account the beam is a 3 dimensional cone, the output power of the unit and the huge role the transducer's sensitivity plays in all of this. I can guarantee you that I have no problems picking up fish running at 40 mph, let alone a large shark:laugh:

Picking up bait on the bottom at 25 mph, no problem.....
Furuno Sounders Reading at Speed - How To - BCF - YouTube

30MPh, nice detail..notice the bait on the bottom
Airmar B164 High Speed Performance - YouTube

50mph, no problem
AIRMAR High Performance 1kW Transom Mount Transducers at 50 MPH.AVI - YouTube

 

[UncleWillie]

Re: What's the best "high speed" transducer?

My unit varies pulse length and rate by depth. At 5 meters it's running 50 pulses per second. Your 6 feet is now down to 14.5", as if those numbers meant anything.

Your not taking into account the beam is a 3 dimensional cone, the output power of the unit and the huge role the transducer's sensitivity plays in all of this. I can guarantee you that I have no problems picking up fish running at 40 mph...

Even though I can see that this going to be a no-win discussion...

Assuming that that you have a really big display that has 600x800 resolution; at 50pps the display can show 16 seconds of returns. That 40 mph that is over 900 feet of bottom compressed in to 9 inches. Any fish under a foot will be a single pixel and be indistinguishable from random noise.

That being said, once you blow 5 meters or less over the top of the fish at 40 mph, they are going to scatter so whatever you saw in passing is no longer useful information, or even timely considering how long it would take to stop and return to the spot.

While see something at speed can be interesting in itself, identifying what was seen in detail is just not viable.
Looking at the three videos, showed that it quite feasible to display the bottom profile at speed, but I didn't see anything identifiable in any of them. Was that a bait ball or a pile of branches?

The OP just wants to display the depth on plane, that is quite doable!
Telling the Bass from the BlueGill is another thing.

 

[dingbat]

Re: What's the best "high speed" transducer?

Assuming that that you have a really big display that has 600x800 resolution; at 50pps the display can show 16 seconds of returns. That 40 mph that is over 900 feet of bottom compressed in to 9 inches. Any fish under a foot will be a single pixel and be indistinguishable from random noise.

A digital Sounder is a wonderful thing. I have the ability to adjust the signal averaging for display 1:16, 1:8, 1:4, 1:2, 1:1, 2:1 and 4:1. How long do you want to spread that 900’ of bottom out?

That being said, once you blow 5 meters or less over the top of the fish at 40 mph, they are going to scatter so whatever you saw in passing is no longer useful information, or even timely considering how long it would take to stop and return to the spot.

Bait schools are not particularly skittish and fish are not skittish when working them. Bait will not scatter. They move vertically when startled and are not hard to find in the 10-15 seconds it takes to get turned around. If you loose them, look a bit down tide of the area. You'll find them.

While see something at speed can be interesting in itself, identifying what was seen in detail is just not viable.
Looking at the three videos, showed that it quite feasible to display the bottom profile at speed, but I didn't see anything identifiable in any of them. Was that a bait ball or a pile of branches?

This is where experience, good observation skills and a good machine come into play.

Everything puts off a distinctive sonar signature. A Bluefish gives a much different return than a Striper. A white perch gives off a much different return than a croaker. In the case of the silverside/ mud minnow, you can't tell the difference because of their small size, but the different returns given off by the turbulence caused by their tails is very distinct. An extremely valuable observation while flounder fishing.

You need a machine with the sensitivity to pick up these signatures and you need the time on the water to put a face to the signature. A good fish finder in the hands of an experienced "observer" is hard to hide from, at any depth.