sonar 

We are using forward looking sonar (Interphase Outlook) for most of our navigation.  The advantage is that you can see shape of bottom forward of
boat, that gives a good indication what to expect. It is not cheap - but probably cheaper than one serious grounding. (That was at least my justification back in 1999 when we decided to go for it...)

FAQ:

> How far forward can you see?

It depends on setting, depth, shape of bottom etc.

Claim is that it "Scans up to 600 feet forward" but in most situation I can see some 4 - 20 boat length ahead (just guess).

I am using it mostly on generally shallow Western Port and it is barely useful when "sailing" in 3 feet of water. The main limitation is that clutter
on screen may be quite severe in such conditions. It still helps though - even most unclear picture of bottom is better than nothing.

My guess is that it is a bit like radar - without experience it is likely to be difficult to interpret too.

If depth is a bit better - at least 6 feet - shape of bottom starts to be pretty clear even if bottom is mud.

The most stupid thing: there is a shape of the boat in top left corner which does not change when you change the scale. Fortunately, Outlook shows also my centreboard (it is mounted on transom) so I have always something what is to scale on the screen.

The best thing: after first disappointment (it is not as crystal clear and simple as add shows) you learn to read the screen and it becomes second
nature. One quick look and you can see if water is shallowing and how fast. You learn to react pretty quickly.

Would I buy another one if this one goes west? Yes, definitely.

> Who makes it?

http://www.interphase-tech.com/index.htm