Raymarine i40 help - A hard (aground) lesson learned

[swhfire21]

We were beating upwind through a section of the ICW behind Long Beach Island and tacking at water depths of 12 ft (3 times my draft). We were in 14.4 ft of water and waiting for 12 ft to show when BAMM!, hard aground and stuck (needed Seatow). As I watched the depth finder in bewilderment, I realized that it took about 2 seconds for it to read 8 ft then another 3 - 4 seconds for it to read 4 ft.

At 4 - 7 seconds of delay and 5 knots my depth finder was telling me how deep the water was 32 - 56 ft behind me it appears. Not good.

After looking at the manual again I found that there is an adjustment for "depth response" or "r" as it shows on the screen (there is no explanation as to what this is in the manual). However, Raymarine's manual for the i40 really stinks. Every time I try to page through and set the response using the steps shown the damn thing just beeps at me or moves to another page. Does anyone:

1 - know how to set this?
2 - Know what the units and useable range of "r" are (factory set at 12).

I found something on another web page saying the higher "r" is the faster the response. However, I have no idea of how to set it or what the useable range is. I keep forgetting to call Raymarine from work, so I figured I'd try here.

Thanks,

[Jim Walsh]

This is the number for Raymarine technical support. I called them from the anchorage in Great Salt Pond a few years ago and the tech. stayed on the line while I followed his instructions. It was great dealing with them. 800-539-5539

[Russell]

I find it odd that "response" is even adjustable, why on earth would anyone ever want their depth sounder to respond slower? One would think it would just come pre set with the fastest possible response.

I have found their tech support though pretty good to deal with both by phone and online.

[joemerchant]

From my Navy days. The reason this can be set is for varying conditions and boat types. The longer the time between pings, the more accurate at greater depths since it pings, waits for the return, then calculates the time. If it pings again before the prior return, it will clear the prior result and not register a computation. Opposite is true in that if not fast enough, then not getting enough reliable returns to do the math and holds the last return.

I would be more inclined to first make sure the transducer is clean and clear before making any adjustments from factory. Then truly test in known conditions in clear water.

So, best to head for the Bahamas where you can do better scientific measurements. If you really needed a good excuse.

[swhfire21]

I was not too impressed with Raymarine's help desk. It took two twenty minute calls (ON HOLD) and two voicemails to get a response. Then the guy that called was apparently reading the same limited directions I had and was left at trying to guess from other parts of the instructions (same as I was doing) as to what to do.

Anyway, after talking to him and a half hour of cursing out the unit I think the i40 works something like this:

Once you page to the parameter you want to change press both the up and down arrows "exactly" simultaneously. If this button action takes you can then adjust the setting up or down individually. Otherwise it ratchets through the other pages (lots of fun!), then you get to try again. Once you have adjusted the setting you need to press both arrows "exactly" simultaneously again to lock the setting.

The highest depth response setting on the unit is 15 (15 most sensitive, 1 least), versus the factory setting of 12 (which tells you the depth about 60 ft ago at 5 knots). The tech had no idea how much faster the 15 setting was compared to 12, so I guess we'll have to try navigating the channels again and see what happens.

The one thing I did find out though (using rock on string method at dock) was that my offset setting was wrong (I measured it while boat was on land) and the depth finder was reading a foot deeper than it should have.

The i40 is a nice looking, simple unit. I just wish it was easier to program (setting alarms was no great joy either!).

[Ron Churgin]

Don't get to excersized about the depth sounder. In my experience, and I sail in a lot of skinny water, the depth sounder will tell you, in the best of circumstances, that you are about the run aground about ten seconds after you do. Thats just the nature of shoals. They come up suddenly and are usually steep sided.

The best use of a depth sounder is for navigation and to give you a general warning that depths are increasing or decreasing. I humbly submit that the sounder will not be much help in avoiding groundings. Experience and remembering local conditions are the best defence.