Back Up Sonar

[egaito]

I'm looking for a simple, fish finder style sonar for a backup unit. Rather than punch a new hole in the boat, I'm going to build a small mineral oil bath and shoot through the hull.

I'm not looking to find fish, nor do I care that I get a lock in 1000 feet of water. I just want something strong enough to shoot through the hull and maintain a lock at hull speed in coastal areas.

There are a lot to choose from, so I thought I'd see what people have had good luck with on the "low end" of the scale. I'll warn in advance, that I'm not a Lowrance fan, but otherwise, I'm pretty open minded.

Thanks,

 

[GJH]

Hard to wrong with the Humminbirds. Great value.

 

[MikeP]

I did exactly that last summer with a Raymarine ST40/ in-hull sensor on our 53. Easy to do, works great, and has BIG numbers so easy to read from a distance. I used pink antifreeze as the liquid.

 

[egaito]

I did exactly that last summer with a Raymarine ST40/ in-hull sensor on our 53. Easy to do, works great, and has BIG numbers so easy to read from a distance. I used pink antifreeze as the liquid.

I guess any liquid should work....I've always seen mineral oil recommended, but I can't say I've ever seen a reason why.

 

[egaito]

Hard to wrong with the Humminbirds. Great value.

Humminbird's used to have a reputation for "locking up". The reputation lasted several years, but this was several (5+) years ago.....have you ever had issues with it?

 

[GJH]

Ed, I was around a lot of these when I lived in Texas; seemed to be "standard equipment" on bass boats and other lake/gulf fishing craft. I also know some folks who have them on their trawlers. The cheap Paranha Max units are what I am referring to and I have never heard of problems, not that that is a very scientific sample. My Airmar/Furuno shoot-through system on the Hatt will give me "---" readings now and then at slow speed in 10 feet of water with a newly cleaned bottom, so nothing is perfect, I suppose.

 

[Beckytek]

I did exactly that last summer with a Raymarine ST40/ in-hull sensor on our 53. Easy to do, works great, and has BIG numbers so easy to read from a distance. I used pink antifreeze as the liquid.

Mike, how do you hold the liquid and install the ducer? Ron

 

[MikeP]

The airmar transducer for this purpose comes with a tube that can be adjusted for various hull angles. It's all self contained and once you mount it and pour in the antifreeze (their recommendation), the transducer snaps in and seals to the top. It's the Airmar P-79. http://airmartechnology.com/airmar2005/ex20/RMProducts/ElectCat.asp?ProdID=52&Man

Worked great and really easy. It matches the depth of my through hull depthfinder at any depth I have found here on the Ches bay. Of course the Ches isn't very deep; I don't think I have seen much over 70 ft so far in my 3 years here. So I don't know if it would do well at say 100+ feet.

 

[Angela]

If you're not fishing, does it really matter how deep it reads? I just want to know before I hit 6 feet. Anything over that and I don't really care how deep it is - it's deep enough.

 

[Beckytek]

Thanks Mike, I'm going to try it on another ducer I have. I'm in the Chesapeake also and don't care about readings over 6 feet. Just want it not go blank on me like the present one does.

 

[MikeP]

Your transducer will work fine; it's just a matter of finding a way to mount it/hold the fluid. The nice thing about the P79 is that you get the parts you need to do the mounting. You can do the same thing with PVC pipe/5200 (or whatever adhesive you prefer) to the hull and an end cap.

I learned here on this site when I was researching this that virtually every transducer sold with any brand of depth sounder are Airmar transducers.

 

[GJH]

I have the P79 as well, hooked into a Furuno NavNetvx2 / BBFF1 system.

1) It will give occasional blank readings in turbid water

2) I have had depth readings of several hundred feet. I find it interesting to observe the bottom contour. Even though I don't fish from this boat (not seriously, at least), I have have an upgrade to one of their more powerful units on the very long range wish list, just because it would be cool to track actual fish and get better structure definition; but that transducer, the M260, is about 700 bucks!

You can get a decent Humminbird black and white system for about $180, 'ducer and all.

 

[Angela]

The airmar transducer for this purpose comes with a tube that can be adjusted for various hull angles. It's all self contained and once you mount it and pour in the antifreeze (their recommendation), the transducer snaps in and seals to the top. It's the Airmar P-79. http://airmartechnology.com/airmar2005/ex20/RMProducts/ElectCat.asp?ProdID=52&Man

Worked great and really easy. It matches the depth of my through hull depthfinder at any depth I have found here on the Ches bay. Of course the Ches isn't very deep; I don't think I have seen much over 70 ft so far in my 3 years here. So I don't know if it would do well at say 100+ feet.

Mike, where did you mount this transducer? The literature on the P79 says a max of 1" hull thickness and no more than 22% hull deadrise. I figure our boats, being built at the same time, probably have the same hull thickness. We are contemplating putting this in under the starboard engine room, all the way forward in that bilge compartment, sort of under the heat exchanger, essentially that spot where you stand in front of the engine. I was concerned about the hull thickness issue, but if it's working for you, it ought to work for me, too. Also, where did you run the cable. I'm wondering if it's long enough to get to the flybridge. If not, pilothouse will have to do.

We're going to the Bahamas next weekend and we just figured out that it's the transducer on our Garmin that is dying. So, we need a quick fix (new shoot thru transducer and stand alone depth gauge) until we can haul out and replace the Garmin's transducer.

So, "back up sonar" is no longer the topic here...it's no longer the back up we're looking for. It's a "I need a depth sounder NOW" kind of thing!