How did you mount your depth finder transducer?

[OS2Dude]

The 'Maximum Deadrise' on an In-Hull is the most the provided well body can accommodate. (Each piece can go 12 degrees, so from 0 to 24) If you "MacGyver" your own well body with PVC and/or parts of the supplied body, you should be able to go higher. NOTE: The P79 and it's ilk can not scan thru a cored hull. It must be solid fibreglass. Air pockets will stop the ultrasound scanning beam.

[AZ-Oldguy]

Originally Posted by Nanamuk

On my DeKleer Endurance 35 I cut a piece of ABS (could use PVC) pipe with a diameter large enough to accommodate the transducer, bevel it to be vertical and fit close to the hull then glue it to the hull with thickened epoxy. I then melt some Vaseline, pour it in the tube, install the transducer at an angle so as to prevent bubbles getting trapped under it then shift it horizontal and support it while the Vaseline hardens. My old Lorence has both wide and narrow beam transducers. I regularly read 1000 ft with the narrow beam. My new Garmen fish finder craps out at 140 ft or less. The water temperature feature is accurate with the in hull installation.

I would love to see your boat! I seem to get to Nanaimo about once a year. I'll try to get in touch next time.

[CarinaPDX]

Originally Posted by Mike OReilly

I’m just thinking out loud here, but if you really want to try this shoot-thru-the-hull approach, perhaps you can build an appropriate sized and angled wedge (using stiffened epoxy using high density filler) such that you can create a level space. Attach this to your hull using silicon, and then mount the transducer. If it works, then Bob’s your Uncle!

I did something similar. In my case I made a temporary mold of thin, cheap plywood taped together and to the hull in place, sealed with putty, then filled it with catalyzed polyester resin. It had to be done slowly as the heat stresses could crack the block. I finished by grinding the top to a smooth surface facing slightly outboard (to reduce reflections back from the adjacent keel). The transducer was put down temporarily with K-Y Jelly to try it out; it turns out it lasted for years. Later I used silicone sealant to hold it down but that turned out to be permanent; the fit was so close that it had to be chiselled off. FWIW I would never attempt to use polyester resin for building up a fairing block again, I would use epoxy. I don't think thickeners are needed but probably wouldn't hurt either.

Greg

[crazyoldboatguy]

I have a full keeled boat with a deadrise way beyond 24 degrees. I calculated the deadrise (about 45 degrees) and made an extension block that, with the block that came with the kit, arrived at the needed 45 degrees. This arrangement only works with the long stem transducer.

My boat is wood and the hull is 1 5/16” thick.

It can be done - just requires some fabrication.

[chouliha]

Originally Posted by AZ-Oldguy

Chuck, are you saying that you just used silicone to directly cement the transducer to the hull? No oil or antifreeze no well just glue the transducer directly to the hall? For me to do that I would have to make a flat spot on the hull., or does the blob of silicon form a wedge so that the transducer is vertical?

I only used silicone nothing else. I set the transducer in the silicone so it was pointing almost straight down. Maybe 80 degrees. I have it fitting in a corner of a locker with a bulkhead on 2 sides like a “L”. .its protected that way.

I have a very step angle of hull as well. But it seems to work ok. Even if it showed bottom contour at 70 feet or less that’s perfect for us. The other depth sounders are mounted with a teak block on the exterior shaped to match the hull on one side and flat on the other so it points straight down.

Chuck

[AZ-Oldguy]

Are you at your boat? Any chance you might get a picture of that install? Also the owner's guide for the P 79 depth transducer warns not to install it where the temperature of the liquid in the tank exceeds 140 Fahrenheit or 60° centigrade. It says the transducer would fail. Have you noticed any issues with the transducer heating up?

[boatnerd]

We have two transducers both inside our fiberglass full keel hull. One is an airmar P79 puck type connected to B&G plotter installed w/ 5200. Second is a Garmin forward scanning teardrop transducer made to mount on transom. That one I set down with silicone only. Both are within a foot of each other at @45° angle and work just fine.

btw a few years ago our balmar alt regulator went out and pulsed high output current frying many of our sensitive electronics. The ST60 depth sounder was one of them. Made it challenging anchoring in BoraBora with depths of 23m. .good to have a backup when cruising.

[CarinaPDX]

The angle to mount the transducer depends on the transducer itself. The P79 has a beamwidth of only 7°, which is the angle of a cone that has a 3dB (50%) drop in strength at the perimeter. With the power dropoff that rapid you don't want to mount it much off level; something like 3.5° would be ideal. It might help to have a slightly steeper angle in order to reduce reflections off of the full keel, but that risks worse performance on a tack where the transducer is on the high side. BTW the P79 is a fairly low power sensor: the 0183 version is 60W and the N2K is 100W (RMS).

My old transducer was a Lowrance with a 22° beamwidth. I mounted it at an 11° angle. It worked great, on both tacks, and to 500' depths and more. It put out 600W peak-to-peak; I don't remember the RMS number but the high power was part of that wide beamwidth working to greater depth.

Greg

[CarinaPDX]

The P79 uses 235kHz specifically so it has minimum interference with the more typical 50kHz and 200kHz transducers that might also be present.


Greg

[leftbrainstuff]

G10 fairing blocks, don't use wood or plastic. Epoxy the fairing block to the inside of the hull and use a good elastomer to attach the external fairing block.

The above assumes you've match mounted the blocks and hull holes. Also counter bore the faces of the fairing blocks to that when you bed the transducer you get a nice compression bead of elastomer at the mating face a of the transducer.

You can order long transducers from airmar.

[AZ-Oldguy]

Originally Posted by leftbrainstuff

G10 fairing blocks, don't use wood or plastic. Epoxy the fairing block to the inside of the hull and use a good elastomer to attach the external fairing block.

The above assumes you've match mounted the blocks and hull holes. Also counter bore the faces of the fairing blocks to that when you bed the transducer you get a nice compression bead of elastomer at the mating face a of the transducer.

You can order long transducers from airmar.

It looks really pricey, and with 1/2 inch thickness would take several layers epoxied together, for both the inside and outside faring blocks, no?

[stnick]

Take the boat Out of the water have the local electronics guy mount a transducer on the bottom of the hull outside !
Stop this easy way inside stuff and just get propper depth informaton by a forward mounted transducer.
I know that not what you wanted to hear ! Its BOATS !!!!!!

[CarinaPDX]

Originally Posted by AZ-Oldguy

It looks really pricey, and with 1/2 inch thickness would take several layers epoxied together, for both the inside and outside faring blocks, no?

It is available up to 2" thick, which would make it a little easier. And yes, it is pricey.

Shooting through the hull can work very effectively, as has been my experience. Admittedly it can be a problem with low quality layups (air pockets) and cored hulls so testing the location before investing more time is advisable. Mounting through the hull is pretty much guaranteed to work well but can be challenging on steep hull sections, and there is always the haulout cost. I would be happy with either way.

Greg

[boatnerd]

P79 style comes in varying khz frequencies; 235, 50/200, and 200. The cabling gauge, connectors, pinouts, and plugs are brand specific. Airmar has pdfs showing specifications. Power output is limited to 600w rms. . a one time i worked as a abyc accedited electrician until i got tired of paying the renewal fee.

[CarinaPDX]

I should have written "P79S" for the smart transducers. The P79 is a normal transducer in various frequencies.


Greg