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johnharch 02-20-2012 08:19 PM

Depth sounders
 
While we're on the topic of electronics, how reliable do you find your depth sounders. I have a Simrad IS-15 unit and it has a nasty habit of cutting out just when I need it most--in shallow water. Its kind of hard to figure for sure when it is going to lose the bottom, but shallow, turbid water and a soft bottom seem to be contributing factors. Am I just asking for too much?

svjobeth 02-21-2012 04:34 PM

Is the transducer externally mounted, or is it a shoot-through? This sounds like a transducer issue although it's a bit puzzling why it drops only at shallow depths.

We have an ancient Datamarine Corinthian (rebuilt once) that continues to work just fine - and the waters on the SE GA and SC coasts are about as turbid as they come - while that may (and does) cause some infrequent erratic readings, we've never lost it completely.

niftynickers 02-21-2012 06:24 PM

depth finder
 
I agree that it sounds like a xducer problem.First where is the exducer located?
Ideally it should be in front of the keel so that you see the shoaling before the keel finds it.My xducer was originally installed next to the raw water intake behind the keel okay if you are at sea or sail in deep water but not good for shallow water sailing.
I think your depthmeter goes erratic when the keel starts hitting bottom and stirs up the mud,sand ,etc.
I moved my xducer forward of the keel and shoot thru the hull with a Humminbird fishfinder that shows a pic ot the bottom as well as depth and as a bonus fish.
Good luck,
Dianne and Chuck Burke S/V NiftyNickers C37#139

johnharch 02-21-2012 06:40 PM

My transducer is locate on the starboard side of the forward edge of the keel to starboard of the head, it thru hull transducer, not a shoot thru the hull. It is at quite an angle there and I thought that may be affecting it. I'm sure it is not an issue of the keel stirring up the bottom because some of the wost performance I get is when I'm tied to the dock at my home port in 10' of water. It is also not a dirty bottom issue because it can have problems right after I have had a diver clean the bottom.

I sure hate to go down the road of replacing things until it works.

Niftynickers, how and where is your thru the hull transducer mounted?

John
'91 PSC 34

wsmurdoch 02-21-2012 08:04 PM

I have a Simrad IS15 system as well. The depth sounder is Simrad (actually an Airmar B774VL triducer) mounted through the hull under the forward end of the cabin sole plate outside the head. The triducer (like the wind sensors) is connected to an IS15 Transciever before the displays. It functions very well. On occasion it will not start when the system is powered up, and I have to turn the depthfinder off then back on again to get it started. Its absolute maximum depth is about 150m. The minimum is less than the 5 feet that it takes to float the boat (about 2.5 feet below the sensor). I have twice in 8 years had the water temperature sensor fail. That has been fixed by replacing the insert. The bottom of the triducer must be kept free of growth. Water reducable bottom paint is good for a little less than a year, then it must be scraped with a plastic putty knife.

We have sailed in places where the bottom is soft enough to sail through. You know, when you go over the side and swim down, it is hard to tell where the water stops and the bottom begins... sort of a gradual decrease in fluidity. The depthfinder seems to sort it all out and give as good an indication of the depth as can be managed.

Bill Murdoch
1988 PSC 34
Irish Eyes
Irish Eyes to the Bahamas

svjobeth 02-21-2012 08:32 PM

Quote:

Originally Posted by johnharch (Post 834917)
My transducer is locate on the starboard side of the forward edge of the keel to starboard of the head, it thru hull transducer, not a shoot thru the hull. It is at quite an angle there and I thought that may be affecting it. I'm sure it is not an issue of the keel stirring up the bottom because some of the wost performance I get is when I'm tied to the dock at my home port in 10' of water. It is also not a dirty bottom issue because it can have problems right after I have had a diver clean the bottom.

I sure hate to go down the road of replacing things until it works.

Niftynickers, how and where is your thru the hull transducer mounted?

John
'91 PSC 34

It would seem the sharp angle would affect the readings, but again, I'm confused as to why it's a shallow water issue.

Our depth transducer is located in perhaps the least ideal place; a shoot-through under the galley sink on the outboard side of the sink drain and refer intake seacocks. And yes, we have run aground on occasion, but in all honesty, it's because I wasn't paying attention to where I was in relation to the ICW channel. The sounder works fine and accurately. Still, we'll definitely relocate it to the through hull forward of the keel, which was occupied by the old knotmeter paddle wheel transducer when we do our electronics replacements.

johnharch 02-21-2012 08:57 PM

Bill, it sounds like you have pretty much the same system and transducer location as me except that I have separate transducers for speed and depth. I regularly get depths to 300'and often to 400. But it's really frustrating when I'm looking for just the right place to drop the hook and the bottom is at 15' and rising and depth sounder goes out. I suppose it's possible that it happens in deeper water too and I'm just not paying as close attenetion to it, but I don't think so.

I'm not sure of my exact transducer model number, but I was just looking at the Airmar site and see that tranducers that look just like mine are internally compensated for various installation angles. So the angle probably isn't the problem.

Maybe I'll just replace the transducer insert and see what happens. Fixing this is on my priority project list for this winter.

niftynickers 02-22-2012 04:35 PM

depthfinder
 
My location for the xducer for the Humminbird on my 37 may be different than is possible on the 34. It is epoxied directly to the hull just in front of the keel and shoots thru the hull.Since we have solid glass boats (not cored) it's possible to do so.The hull is curved in that area so I had to grind a little and build up the epoxy to level the xducer.

Good luck,
Dianne and Chuck Burke S/V NiftyNickers C37 #139

seabum 03-09-2012 11:22 AM

Re: depth finder
 
Quote:

Originally Posted by niftynickers (Post 834912)
My xducer was originally installed next to the raw water intake behind the keel okay if you are at sea or sail in deep water but not good for shallow water sailing.

Our transducer is located behind the keel, too. It seems like an odd choice to me, but there must have been a good reason for the original location choice, even if we decide sometime to move it. Can anyone shed some light on the thinking of this placement?
We sail in deeper depths so for the most part this transducer location has not been a problem.

johnharch 03-09-2012 11:47 AM

Re: Depth sounders
 
Elena, I have come to the conclusion that on the 34, there is no ideal location and having talked to a lot of people, the is no normal location. If you're not concerned with shallow water performance, I don't think it matters much.

On the 34, any good forward location will have too much deadrise and I have concluded that that, coupled, maybe, with my transducer being old is my problem. I have about 27 deg deadrise where my transducer is now and I can find no thru-hull transducer that will work with that much other than the fairing models which then protrude below the hull a bit.

Putting the transducer forward has two advantages that I see, cleaner water when in the shallows and you see what is happening on the bottom a little sooner. But I don't like the idea of the fairing protruding. It just seem like something to get broken by a minor collision with a log or something.

I have been testing shoot thru the hull transducers and seem to get reasonable results aft around the galley areas, so I am going to install a P79 smart transducer somewhere around there.


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