Soundings while on plane - Maxum Boat Owners Club

PJHoffnet · 03-05-2018, 12:55 PM

I lose soundings after I get up on plane. Transducer is clean. I'm assuming it has to do with turbulence under the transducer. Any good tweaks or ideas folks use to keep an eye on the bottom at speed? I typically leave Gain in auto, but have fooled around with it while on plane, but no joy on regaining soundings.

Thanks in advance.

mmwjr · 03-05-2018, 05:02 PM

Paul typically this is either a result of loss of seeing the bottom due to turbulence around the transducer or loos of connection of the transducer to the head unit. The latter is caused by vibration at planning speed that disrupts a poor connection that work fine at displacement speed.

bman440440 · 03-05-2018, 05:56 PM

you need to make sure you have the ducer mounted properly... here are some pics of mine... and as you can see at speed mine works great!

PJHoffnet · 03-06-2018, 01:57 AM

I have a through hull mounted bout 1/4 of the way aft of the bow, so I'm still thinking turbulent flow around the 'ducer.

mmwjr · 03-06-2018, 03:22 AM

Quote:

Originally Posted by PJHoffnet

I have a through hull mounted bout 1/4 of the way aft of the bow, so I'm still thinking turbulent flow around the 'ducer.

Did you mount it there? Seems way to forward for a planning hull. It should be in the back 1/3 of the boat.

jimq26 · 03-06-2018, 11:15 AM

What Mike said - that's way too far forward. Always at or close to the stern.
The signal will not pass through wood or air, so just the tiniest amount of bubbles will kill the signal. Your planing hull will probably also be above the water when at speed, so you'll be trying to send a signal through air and it can't.

PJHoffnet · 03-06-2018, 02:33 PM

Quote:

Originally Posted by mmwjr

Did you mount it there? Seems way to forward for a planning hull. It should be in the back 1/3 of the boat.

Bought the boat in current configuration. Bottom looks fine this year, so no plans to go on the hard. Will research moving 'ducer head aft next time she's out of the water for a while.

shrew · 03-06-2018, 03:37 PM

Quote:

Originally Posted by PJHoffnet

to keep an eye on the bottom at speed?

Out of curiosity.....how would this information be helpful? It's not to avoid a grounding. At planing speed you will have hit the object about the same time you're reaching for the throttles.

I can completely understand navigating slowly in shore around channels, anchorages, etc.

Again, just curious.

PJHoffnet · 03-06-2018, 05:31 PM

Quote:

Originally Posted by shrew

Out of curiosity.....how would this information be helpful? It's not to avoid a grounding. At planing speed you will have hit the object about the same time you're reaching for the throttles.

I can completely understand navigating slowly in shore around channels, anchorages, etc.

Again, just curious.

You bring up a point worth discussing. I'm certainly not going to be running around on plane in any water I'm not sure of, but when doing long range ocean or even coastal navigation, it's comforting to have a sounding that 'checks with chart' for the additional warm fuzzy above what GPS provides. Years of training has taught me to never completely rely on only one source for a position fix.

WRT to ending up aground about the same time you'd get the bad sounding, I'd disagree. By setting 'RED' (seriously bad, stop now) and 'YELLOW' (something isn't right, slow down and figure it out) sounding as part of your navigation plan, you add in safety.

YELLOW soundings should be a value that's less than the charted soundings along your planned route. If you get a YELLOW sounding it's time to figure out what's going on - you're not where you've planned to be. RED soundings should be set such that once you receive it, you can safely stop before you run aground (based on the planned speed of advance along your route).

shrew · 03-07-2018, 02:39 PM

Quote:

Originally Posted by PJHoffnet

WRT to ending up aground about the same time you'd get the bad sounding, I'd disagree. By setting 'RED' (seriously bad, stop now) and 'YELLOW' (something isn't right, slow down and figure it out) sounding as part of your navigation plan, you add in safety.

YELLOW soundings should be a value that's less than the charted soundings along your planned route. If you get a YELLOW sounding it's time to figure out what's going on - you're not where you've planned to be. RED soundings should be set such that once you receive it, you can safely stop before you run aground (based on the planned speed of advance along your route).

Does your Chartplotter and sounder have this capability? That sounds very interesting.

PJHoffnet · 03-08-2018, 08:39 PM

Quote:

Originally Posted by shrew

Does your Chartplotter and sounder have this capability? That sounds very interesting.

I calculate a RED and YELLOW sounding for each leg during my route planning. I have it written on my chart card, and I then grease pencil that on my dash next to the chart plotter. I'll have to see if my chart plotter supports entering 'alarm' soundings ... seems fairly easy thing for a device like that to do.

Kevlar7r · 03-09-2018, 02:37 PM

Is your transducer through hull, or in hull?

I had an inhull that wasn't properly mounted, and was actually using the residual bilge water as it's connection to the hull. On plane, that water collected further aft in the hull, and now the transducer had air under it.

Sent from my SM-G930P using Tapatalk

PJHoffnet · 03-09-2018, 10:54 PM

Quote:

Originally Posted by Kevlar7r

Is your transducer through hull, or in hull?

Through hull.

Most answers are point to what I was assuming caused the the outage - turbulent flow near the transducer ... so that's something I'm not going to be able to change. Just need to be more careful and go slow when I'm not sure of the depth.

Thanks all for your replies.