Depth Transducer Mounting

[Tom.B]

I am exploring a new Raymarine i50 stand-alone depth sounder system to replace our old ST60 Raytheon. The new system comes with a plastic/nylon Airmar P319 transducer that Raymarine says works for deadrise angles up to 24*, however Airmar's documentation says only up to 11*. The deadrise on Skinny Dippin' is around 14*-15*. The current transducer is mounted through two teak wedges, one inside the boat and one outside to keep it vertical. They are a 21 year-old OEM setup (I assume) and kinda leak a little.

I would like to eliminate the wooden wedges completely and mount the transducer straight through the hull. In theory, that would introduce error into the depth readings, but at 5', it is only 2' or less and 3' at 100' depth (solving for a right triangle with a top angle of 15*). Moreover, assuming the sounders sees the closest signal within the cone of the beamwidth, an 11* beam angle that could read that with even less error.

The other more expensive option is to buy the head unit and bronze B60 tilted element transducer.

Opinions?

 

[Comodave]

I am exploring a new Raymarine i50 stand-alone depth sounder system to replace our old ST60 Raytheon. The new system comes with a plastic/nylon Airmar P319 transducer that Raymarine says works for deadrise angles up to 24*, however Airmar's documentation says only up to 11*. The deadrise on Skinny Dippin' is around 14*-15*. The current transducer is mounted through two teak wedges, one inside the boat and one outside to keep it vertical. They are a 21 year-old OEM setup (I assume) and kinda leak a little.

I would like to eliminate the wooden wedges completely and mount the transducer straight through the hull. In theory, that would introduce error into the depth readings, but at 5', it is only 2' or less and 3' at 100' depth (solving for a right triangle with a top angle of 15*). Moreover, assuming the sounders sees the closest signal within the cone of the beamwidth, an 11* beam angle that could read that with even less error.

The other more expensive option is to buy the head unit and bronze B60 tilted element transducer.

Opinions?

I put a B60 with the tilted array in our boat and it works great. That is the way that I would go.

 

[SoWhat]

Raymarine product page states 0-8 deadrise and 45/12 beam width.
If I did a lot of boating in skinny water I would replicate the wooden wedges and fiberglass them.

The manual lists a number of compatible transducers so you could buy the i50 and the transducer separately and find one to fit the deadrise.

Plan B would be to repair the hole and just shoot through the hull.

 

[psneeld]

Study the way ducers work.


Even if not mounted completely vertical, depth only types still work fine as the first echo that returns gives the depth (unless they have changed recently).


But if you do the math on the angles...the error of a slightly off vertical ducer is a small percentage. So in shallow water, say less than 10', the percentage error is in a couple of inches (the bottom irregularities usually are that much). As the depth increases, so does the error...but for a depth only ducer...if its only off 25 or so feet in 1000' of water....is it that critical?


I used to install ducers in the marine industry, and the factory reps explained all this. For certain applications, sure precision is great, for most of us, less than vertical isn't all that bad because you really have to be outside the beam angle to start seeing the error.


Look it up on the tech pages or call as it might have changed but I doubt it.

 

[Comodave]

Actually the B60 is available in 2 different angles. Our deadrise is about 13 degrees. So I used the 8 to 15 degree model. Works great.

B60 Traditional/CW Tilted Element™ Thru‑hull
600 W

The B60 is a 600 W, 50/200 kHz transducer that integrates Airmar’s popular, Tilted Element™ feature. This Tilted Element transducer has the ceramic element fixed at either a 20° or 12° angle within the housing. The transducer is installed almost flush to the hull and the tilt of the element corrects for the hull deadrise angle. By orienting the beam directly down, it ensures maximum echo returns to the transducer for more-accurate depth readings.

Available in two Tilted Element models:

Fixed 20° tilted version for 16° to 24° hull deadrise
Fixed 12° tilted version for 8° to 15° hull deadrise

 

[sbman]

I put a bronze B60 12 degree tilted element on my boat. Can't give a report yet as to how well it works, but installation was really easy and I was able to eliminate wooden blocks that were used in the old sounder installation, so it's sealed with the bronze directly to the bottom. I got the Mix-n-Match version which has a generic Airmar cable that can be plugged into most any brand of sounder by just purchasing the proper adapter cable.

 

[Comodave]

I had to cut the connectors off mine to run the cable through the chase to the flybridge. They sell a connector box to splice the wires.

 

[boomerang]

I personally wouldn't worry about the transducer element being a few degrees off of perpendicular to the bottom. Like you have already mentioned, the accuracy will only be off a little bit in deeper water and the shallower the water gets, the more accurate the readings will be. It seems to me that shallow water accuracy is what's important to cruisers.

 

[psneeld]

I personally wouldn't worry about the transducer element being a few degrees off of perpendicular to the bottom. Like you have already mentioned, the accuracy will only be off a little bit in deeper water and the shallower the water gets, the more accurate the readings will be. It seems to me that shallow water accuracy is what's important to cruisers.

Thanks, confirms what I was taught.

 

[Tom.B]

Thanks everyone. I ordered the B60 and we'll see what it looks like when it gets here.

 

[sbu22]

Actually the B60 is available in 2 different angles. Our deadrise is about 13 degrees. So I used the 8 to 15 degree model. Works great.

B60 Traditional/CW Tilted Element™ Thru‑hull
600 W

The B60 is a 600 W, 50/200 kHz transducer that integrates Airmar’s popular, Tilted Element™ feature. This Tilted Element transducer has the ceramic element fixed at either a 20° or 12° angle within the housing. The transducer is installed almost flush to the hull and the tilt of the element corrects for the hull deadrise angle. By orienting the beam directly down, it ensures maximum echo returns to the transducer for more-accurate depth readings.

Available in two Tilted Element models:

Fixed 20° tilted version for 16° to 24° hull deadrise
Fixed 12° tilted version for 8° to 15° hull deadrise

I'm replacing a transducer soon on a 43' Viking. The local marine electronics outfit (a serious commercial marine operation) cautioned me against the B60 due to boat length. Airmar's recommended boat length is "Up to 8 m (25')". I've not gotten a coherent answer as to why length would factor into the use of the B60. Dave - it sounds like you're happy with your install. Any ideas as to why the boat length recommendation?

 

[Comodave]

It has been in our boat for over 5 years now without any problems. Don’t understand either why boat length would make a difference.

 

[sbu22]

Appreciate the response. I think I'm going to return the B45 and get the B60. Good to hear it road-tested.

 

[OldDan1943]

It has been in our boat for over 5 years now without any problems. Don’t understand either why boat length would make a difference.

It is more placement and draft. Fwd 1/3 of the length, perhaps.

 

[Comodave]

Ours is a bit aft of midship.

 

[OldDan1943]

If one has a FD hull then, placement fwd is reasonable.
The idea is to keep it out of and disturbance zone.
SD, 2 sounders, one fwd would IMO would be fine provided a second sounder, further aft.