Location of Depth Transducer on 2016 R31?

[davez]

Hello,

Can you tell me where the depth transducer is located in the 2016 R31S? My depth reading is flashing now more often that not. Per other tugnuts posts, I am hoping a top up with RV anti-freeze will fix the problem. Do you know which make/model of transducer I am likely to have (I have the GSD 22 Sounder if that helps)?

If my transducer is the Airmar P79, the installation manual says not to overfill with glycol. How does one know what is the correct fill level, vs overfill?

Thanks
Dave

 

[Kevin Lamont]

Hello,

Can you tell me where the depth transducer is located in the 2016 R31S? My depth reading is flashing now more often that not. Per other tugnuts posts, I am hoping a top up with RV anti-freeze will fix the problem. Do you know which make/model of transducer I am likely to have (I have the GSD 22 Sounder if that helps)?

If my transducer is the Airmar P79, the installation manual says not to overfill with glycol. How does one know what is the correct fill level, vs overfill?

Thanks
Dave

Dave,

The transducer is located in the AFT compartment next to the rudder on the port side. Typically it is right behind the generator shelf which is there if you have a generator or not. Also it is right by the stern thruster motor. The easiest way to access this is by removing the floor piece under the aft seat, lift the seat so the bench is facing the swimplatform, unlock both turn latches and lift up and out to remove. Once you have that panel removed you can access your transducer. The transducer is the Airmar P79, typically you want the fluid just at or just below the transducer itself, does not require much antifreeze at all. If you add too much it will push out when you re-install the transducer.

Thank you.

 

[davez]

Thanks Kevin,

It looks like it might be fixed, at least it was better at the dock. I will test it tomorrow on the water. It took about five capfulls of anti-freeze to get good wetting.

A tip for others: The transducer twists out, no need to remove the two screws.

I did take out the screws and so spent an extra hour re-levelling the transducer (hope its right). In the process I discovered the longer screw (1-1/4") wasn't long enough to connect with the locking ring. It barely gets thru the transducer, so I replaced it with a #6 x 1-1/2" wood screw. And the shorter screw (1") seemed too long (but 3/4" was too short) so I'll look for a 7/8" screw, if they make them. For now I just didn't tighten the small screw all the way. I'll have to remember to replace the wood screw with a stainless screw.

Fingers crossed for a good test at sea tomorrow.

Regards
Dave

 

[1Harrison]

Had a similar problem. We were in the Broughtons is 1200 ft of water when the sallow warning alarm went off. It said we were in -1.1 ft of water. Refired the garman and all was normal. No problem the rest of the cruise. Then back at home at the dock with the systems on noted the depth finder was all over the map (32', 14', 5' and back). Contacted Garman and Andrew and was informed check the depth finder fluid level and that it was RV antifreeze. Opened it up no indication it was low. Chose to remove the antifreeze and replace with new. Refired the system no change. Still all over the map. Then a brain fart, let's take the boat out and shake it up. Soon as we left the dock everything appeared normal. A number of maneuvers over our own wake and back to the dock. At this time everything appears to be back to normal. Possible this will be included in the owners manual when it is printed.

 

[davez]

I took the boat out this morning to test the depth readings. It flashed blank until I reached 4.8 ft depth, then continuous readings started as I got deeper. I have a depth alarm set at 2.5' (which I believe means 2.5' under the keel), which means 5' real depth). I read somewhere that the depth guage will flash if depth is under the set alarm depth? but should it still display accurate depth right until 0 depth?

At slow speed (< 5 knots) it read depths well over 500 ft, but at 10 knots flashing readings started as I got over 350' deep. I understand the need to install the P79 transducer to account for the sideways angle of the hull relative to the waterline (i.e. deadrise angle) so the sound wave cone does not project to the side of the boat. But is there an adjustment so that when the boat is moving and the keel angle increases (bow higher than stern), the sound cone does not project too far forward? Should I be able to read depths greater than 350 ft at 10 knots?

I didn't think to try it, but at 15 knots and lots of trim tab (vs 10 knots and no trim tabs), maybe the keel would be closer to level and depths > 350 ft could be read?

To summarize, adding the anti-freeze was a big improvement. but I would still appreciate knowing what the very shallow and very deep capabilties of the system sholud be.

Thanks
Dave

 

[Kevin Lamont]

I took the boat out this morning to test the depth readings. It flashed blank until I reached 4.8 ft depth, then continuous readings started as I got deeper. I have a depth alarm set at 2.5' (which I believe means 2.5' under the keel), which means 5' real depth). I read somewhere that the depth guage will flash if depth is under the set alarm depth? but should it still display accurate depth right until 0 depth?

At slow speed (< 5 knots) it read depths well over 500 ft, but at 10 knots flashing readings started as I got over 350' deep. I understand the need to install the P79 transducer to account for the sideways angle of the hull relative to the waterline (i.e. deadrise angle) so the sound wave cone does not project to the side of the boat. But is there an adjustment so that when the boat is moving and the keel angle increases (bow higher than stern), the sound cone does not project too far forward? Should I be able to read depths greater than 350 ft at 10 knots?

I didn't think to try it, but at 15 knots and lots of trim tab (vs 10 knots and no trim tabs), maybe the keel would be closer to level and depths > 350 ft could be read?

To summarize, adding the anti-freeze was a big improvement. but I would still appreciate knowing what the very shallow and very deep capabilties of the system sholud be.

Thanks
Dave

Dave,

The transducer should read at all depths, I was testing a C30 yesterday and it was reading depths at 40+kts. I would ensure that the angle of the transducer is correct so it is shooting straight down and not to the side as that would cause it to read incorrectly or not at all.

Here is a link that describes the depth levels it reads at and all information about the transducer:
http://www.airmar.com/uploads/brochures/p79.pdf

Let me know if you have any questions.

Thank you.

 

[davez]

Hi Kevin,

Can you tell me what the deadrise angle is on the 2016 R31S? I will check that against the (hopefully visible) angle indicators on the top of the P79 and the indicator on the locking ring. When I placed two different levels on the top of the transducer (in a side-to-side orientation), the bubble in each level was not dead center, but it was within the two reference lines in each level. So I think it is close enough to perfectly level and is shooting straight down (vs side to side). If you can tell me the deadrise angle, I will confirm that the transducer and locking ring are aligned to that value.

In my test run yesterday, at slow speeds (<5 knots) the deeper depths read perfectly. It was only at higher speeds (10 knots) where the flashing depth readings occured. At that speed, the bow is near its highest lift (before the trim tabs should start to be used) so I'm thinking its not the side-to-side angle of the transducer that is the issue, but rather the front-to-back angle. With the bow so high, maybe the transducer is shooting so far forward that its reflection off the bottom can't be picked up?

In your C30 test yesterday, at 40+ kts the keel would almost certainly have been close to level (planing, with the transducer pointing straight down), so I would expect the depth reading to work. I wonder if, at maximum bow-up angle at slower speeds, the depth readings would flash in the C30?

I will be taking my boat out tomorrow and will see if the flashing readings at 10 kts and trim tabs up will change to a continuous depth reading at higher speeds with trim tabs down.

Thanks for the airmar pdf

Regards
Dave

 

[Kevin Lamont]

Hi Kevin,

Can you tell me what the deadrise angle is on the 2016 R31S? I will check that against the (hopefully visible) angle indicators on the top of the P79 and the indicator on the locking ring. When I placed two different levels on the top of the transducer (in a side-to-side orientation), the bubble in each level was not dead center, but it was within the two reference lines in each level. So I think it is close enough to perfectly level and is shooting straight down (vs side to side). If you can tell me the deadrise angle, I will confirm that the transducer and locking ring are aligned to that value.

In my test run yesterday, at slow speeds (<5 knots) the deeper depths read perfectly. It was only at higher speeds (10 knots) where the flashing depth readings occured. At that speed, the bow is near its highest lift (before the trim tabs should start to be used) so I'm thinking its not the side-to-side angle of the transducer that is the issue, but rather the front-to-back angle. With the bow so high, maybe the transducer is shooting so far forward that its reflection off the bottom can't be picked up?

In your C30 test yesterday, at 40+ kts the keel would almost certainly have been close to level (planing, with the transducer pointing straight down), so I would expect the depth reading to work. I wonder if, at maximum bow-up angle at slower speeds, the depth readings would flash in the C30?

I will be taking my boat out tomorrow and will see if the flashing readings at 10 kts and trim tabs up will change to a continuous depth reading at higher speeds with trim tabs down.

Thanks for the airmar pdf

Regards
Dave

Dave,

The dead rise is about 22 degrees, and it is important to make sure the top of the transducer is level when static in the water. It should be level all around as the deadrise measurement is to ensure the transducer is level on top in all directions.

On the C30 test i never saw it flash even when getting on plane.

Thank you.

 

[davez]

Hi Kevin,

As you suggested, I checked the front-to-back level of the transducer - it was way off (front high). I started incrementally rotating the transducer and checking both levels (side-side and front-back) and after checking multiple positions, found the best compromise between the two levels. I could not find a single position with a near perfect level both ways. So now, neither level bubble is perfectly centered, but both ways the level bubble is half within with level's centermarks. That best compromise position is at the 2 degree deadrise mark (with the transducer location as you described, but on the starboard side).

I now show a depth reading very quickly after powering on the system, and the depth no longer flashes regardless of my speed. That's all an improvement. Except that now the depth displayed is more than the true depth as shown on the (mutil-depth contour) fishing chart. When I am physically over the 100 ft depth contour on the chart, a 125 ft depth is displayed. That difference increases the deeper I go, and decreases the shallower I go. I will make a point to greatly zoom in the fishing chart when I am out tomorrow to get very accurate chart depths and then note the corresponding displayed depths.

Would the transducer being a little off level result in higher displayed depths than actual?

Thanks
Dave

 

[Kevin Lamont]

Hi Kevin,

As you suggested, I checked the front-to-back level of the transducer - it was way off (front high). I started incrementally rotating the transducer and checking both levels (side-side and front-back) and after checking multiple positions, found the best compromise between the two levels. I could not find a single position with a near perfect level both ways. So now, neither level bubble is perfectly centered, but both ways the level bubble is half within with level's centermarks. That best compromise position is at the 2 degree deadrise mark (with the transducer location as you described, but on the starboard side).

I now show a depth reading very quickly after powering on the system, and the depth no longer flashes regardless of my speed. That's all an improvement. Except that now the depth displayed is more than the true depth as shown on the (mutil-depth contour) fishing chart. When I am physically over the 100 ft depth contour on the chart, a 125 ft depth is displayed. That difference increases the deeper I go, and decreases the shallower I go. I will make a point to greatly zoom in the fishing chart when I am out tomorrow to get very accurate chart depths and then note the corresponding displayed depths.

Would the transducer being a little off level result in higher displayed depths than actual?

Thanks
Dave

Dave,

Glad to hear that there was a significant change in how it is performing. It could be possible that due to the off level it might be shooting at an angle at which it is reading incorrect. Let me know how it goes when you compare depths and let's see where it lands. I doubt it would be a setting in the system.

Thank you,
Kevin Lamont

 

[davez]

Hi Kevin

Now I'm totally at a loss. I had to go from San Juan Island to Sydney marina two days ago, and as soon as I exceeded 250 ft depth, the flashing started (while planing at 14 knots). I reduced speed to 5 knots, and still flashing. It did not stop flashing until I crossed the channel and reached 200 ft. Same thing on the trip back from Sydney. Then in the middle of Haro Strait I turned off the engine to call in to US Customs, and while stopped and floatng around I read a depth of 720 ft. As soon as I started moving again, flashing. Something is wrong.

While between Sidney marina and Sidney spit, I stopped and dropped my downrigger ball to the bottom, in four different locations. Each time the downrigger depth was 3 ft more than the depth sounder depth (which is almost right for their difference from water level), and the fishing chart depth was 9 feet more (ok since it was high tide).

So when the depth reading is not flashng it seems to be right. But it should not start flashing at only 250' depth.

I just checked the transducer level today - it seems better than before. 80-90% of the bubble in my level is between the level center marks, both front-back and side-side.

I wiil ask the Ranger guys and Garmin guys about it at Roche this weekend. Who would you say would be the expert on this?

Thanks
Dave