Humminbird Helix 5 losing depth reading at slow speed and when stopped

[emilime75]

Just installed this with a transom mounted transducer. It's rock solid at anything above 10-15mph, but any slower than that, including when not in motion, it looses depth readings randomly. I find this odd as it's usually the other way around.

I have the transducer mounted next to the starboard side Smart Tab, which I thought might be problematic, but I was trying to keep it the recommended distance away from the prop and clear of under hull strakes.

My theory is that at higher speed, the Smart Tabs lift up enough to not cause trubulence at the transducer, but when I slow down, they retract back down and the do cause turbulence...however, that does not explain the random and frequent reading losses while not in motion. At that point, the transducer is fully submerged and there is zero turbulence of any kind.

Thoughts?

 

[dingbat]

Just installed this with a transom mounted transducer. It's rock solid at anything above 10-15mph, but any slower than that, including when not in motion, it looses depth readings randomly. I find this odd as it's usually the other way around.

I have the transducer mounted next to the starboard side Smart Tab, which I thought might be problematic, but I was trying to keep it the recommended distance away from the prop and clear of under hull strakes.

My theory is that at higher speed, the Smart Tabs lift up enough to not cause trubulence at the transducer, but when I slow down, they retract back down and the do cause turbulence...however, that does not explain the random and frequent reading losses while not in motion. At that point, the transducer is fully submerged and there is zero turbulence of any kind.

Thoughts?

I can think of a couple scenarios where this would happen.

What is the dead rise of your boat?
How did you compensate for the dead rise to keep the face of the transducer perpendicular to the bottom?


What is your beam width?

On a normal 8' beam you should have plenty of room between the prop and the trim tabs to be nowhere close to getting interference from the tab.

Any pictures you could share?

 

[emilime75]

I can think of a couple scenarios where this would happen.

What is the dead rise of your boat?
How did you compensate for the dead rise to keep the face of the transducer perpendicular to the bottom?


What is your beam width?

On a normal 8' beam you should have plenty of room between the prop and the trim tabs to be nowhere close to getting interference from the tab.

Any pictures you could share?

It's not a big boat with a 7'-3" beam and 19'-8" LOA. By deadrise, I assume you're asking about the transom, which I do not know.

I lined up the transducer visually using a straight edge against the bottom of the hull and set the TD to be level with it. This gave me the results mentioned. From there, I tried adjusting it both ways to see if it could be improved. A small angle change did nothing(1 click up or down from where I started didn't change read results), 2 clicks up/down no longer gave any reliable readings.

The transom is inset slightly limiting the usable width.
The width between the center of the prop shaft to the inside edge of the Smart Tabs is 23". From the outer diameter of the prop to the Smart Tabs is 18"
Where the transducer is mounted now is right next to the Smart Tab, making its center line at about 16" from the prop, and inside edge of the transducer right at 15" from the prop, which is the minimum distance Humminbire suggests as a mounting location to avoid prop turbulance.

​

 

[dingbat]

I would check the installation instructions to see if that is not 15” from the center of the prop.

I see a couple of issues right off the bat. Weird camera angle, but none the less.

Follow these instructions to the tee. Read it all before starting the installation

http://www.airmar.com/uploads/Instal.../17-297-01.pdf

 

[emilime75]

I would check the installation instructions to see if that is not 15” from the center of the prop.

I see a couple of issues right off the bat. Weird camera angle, but none the less.

Follow these instructions to the tee. Read it all before starting the installation

http://www.airmar.com/uploads/Instal.../17-297-01.pdf

Humminbird definitely says 15" from the outer diameter of the prop. See this link https://photos.app.goo.gl/FPrKXJ2ZYNvPMdhY9

Either way, I will be moving/testing it closer to the prop and further away from the Smart Tab. This will hopefully fix the loss of signal at slow speed, but won't make a difference with loss of signal while stopped.

 

[dingbat]

Don’t get me started on Hummingbird’s technical and marketing deficiencies...lol

Install the transducer exactly how described in the doc from Airmar I attached earlier.

Pay particular attention to the mounting of the transducer relative to the hull outlined in the document. The proper elevation and geometry (parallel with keel) of the transducer relative to the hull surface is paramount for performing well at all speeds.

 

[achris]

If it's just a transducer (no temperature or speed readings), why not 'wetbox' it? Solves all the problems.

Chris.........

 

[emilime75]

Don’t get me started on Hummingbird’s technical and marketing deficiencies...lol

Install the transducer exactly how described in the doc from Airmar I attached earlier.

Pay particular attention to the mounting of the transducer relative to the hull outlined in the document. The proper elevation and geometry (parallel with keel) of the transducer relative to the hull surface is paramount for performing well at all speeds.

I plan on doing just that. Will report back after testing.

 

[emilime75]

If it's just a transducer (no temperature or speed readings), why not 'wetbox' it? Solves all the problems.

Chris.........

It's an SI CHIRP GPS G2 and the transducer does provide water temp. Don't know what "wetbox it" means, I assume to epoxy it in the bilge? That would result in no temp and side imaging data. Don't really need those, but if I can have them, they're fun.

 

[achris]

A wetbox is a box fibreglassed into the inside of the hull, that the transducer mounts inside and is filled with a libation of your choice...

 

[emilime75]

A wetbox is a box fibreglassed into the inside of the hull, that the transducer mounts inside and is filled with a libation of your choice...

Gotcha, thanks.