A question of depth

[wingdiver]

Hi
Need some input from folks who know about these things.
I've been having a conversation with my father-in-law about depth sounders.
He has one of the old spinning red light ones and a NASA one which has given up working.
In looking at replacements, he has been advised that, for shallow waters, he should get a dual frequency system.
Now, I have Raymarine gear and this seems to work pretty well and let me know when I am about to go aground (should pay more attention sometimes /forums/images/graemlins/blush.gif )and this seems to be a single frequncy 200khz system.
Many of the dual frequency systems seem to work on 50khz and 200khz.
As far as I can tell, the lower frequency gives a broader angle of 'view' and is good for deeper waters where the lower frequncy signal penetrates better. The higher frequency is better for shallower waters.
If that is the case, and he is obviously more interested in shallow water accuracy, why would he need to go to the expense of a piece of kit which adds a second, low frequency that helps with accuracy at depth.
Cheers
D

 

[ebbtide]

No complaints about the Raymarine ST 50 log and depth, tho one dual unit was a mistake which I couldn't live with.
The sounder reads 000 when am about to go aground, and ---- when I am!
As for accuracy at great depths, the strategy of following a contour has been superseded by gps nowadays. And I do have a 10m leadline - tho SWMBO swears I swing it more than use it!

 

[eastcoastbernie]

I have a cheap as chips NASA sounder. Cost nothing in fact as it was given to me by someone when he upgraded to B & G instruments. No complaints at all. Due to its old age, it occasionally has to be sent back to NASA for repair. Repairs are quick and reasonable and NASA are friendly people.

The only time it reads rubbish is when the boat is bouncing about in a lumpy sea, but I assume they all do that.

Other than that I trust what it tells me.

 

[Cantata]

I have a Raymarine ST60, it has always seemed to work fine, deep or shallow. Much of my sailing is over soft mud but even so it seems very precise. I'd be a bit sceptical about that 'dual-frequency' advice.

 

[johnalison]

I've used sounders from the old Seafarer spinner to my current ST60. Irrespective of any accuracy issues, the great advantage of the modern sounders is the automatic gain. I had a Nasa cheapo on my last boat when the Navico self-destructed (as did all the Navico junk) and it was absolutely fine though the gain had to be adjusted at times.

I still have a hankering for a forward-looking thingy, but don't suppose I'll get around to it.

 

[wingdiver]

Thanks for the replies thus far. Please keep them coming.
Just to clarify, the main thrust of all the drivel in my original post was to see if there is any mileage in the dual frequency thing or if it is 'buy something you don't really need' he was being fed.
My thoughts were the latter but just wanted someone in the know to confirm my suspicions.
D

 

[leomagill]

I have a forward looking thingy (echopilot bronze) and it seems to lose the plot in murky water when I most need it.

 

[sailorman]

my ST60 is very good /forums/images/graemlins/grin.gif.
the only probs Ive had is when i don't look at it & with the alarm turned Off /forums/images/graemlins/blush.gif

PS
make sure you look @ it carefully when in the vicinity of the Long Sand Hd & Mersea Island /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif

 

[Koeketiene]

[ QUOTE ]

make sure you look @ it carefully when in the vicinity of the Long Sand Hd & Mersea Island /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif

[/ QUOTE ]

Experience talking? /forums/images/graemlins/wink.gif

 

[sailorman]

to [--word removed--] up you need to leave the mooring & get passed Landguard /forums/images/graemlins/ooo.gif

 

[Koeketiene]

 

[sailorman]

Almost forgotten wot it looked like /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[NorthUp]

Dual frequency is only of real use to fishermen, unnecessary if all you want to know is the depth of water.

 

[michael_w]

Don't get a basic echo sounder, buy a fish finder. They're cheaper than a regular echo sounder and much more useful. Watch the gradients change, judge the bottom composition for anchoring, even help you catch your lunch!

Usually you get a transom mounted transducer but his can be swapped for a through hull one. This is on my jobs list once Sestina's out of the water in late January.

Mike

PS How's practice for the gig going?

 

[marksaab]

Yes def agree with going for a Fishfinder.

I installed mine last Summer, on the transom with a simple sliding bracket so I could drill the mounting holes above the waterline whilst afloat.

Watching the gradient change worked really well....I watched it right up to point after I missed my turn coming out of the Strood channel and ended up on the mud for 5 hours /forums/images/graemlins/blush.gif

Operator error!

M

 

[Noddy]

There is no bottom 'round here. The water just gets thicker!

 

[sailorman]

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[wingdiver]

Hi Mike
Rehearsals OK.
Hopefully everyone will swill enough ale for it not to matter if we make the odd lash up! /forums/images/graemlins/blush.gif
Thought we saw you come back in on Sunday.
Are you out of the water here?
D

 

[wingdiver]

Thanks again for the input - especially those with intimate knowledge of the sea bed around these parts - you know who you are! /forums/images/graemlins/shocked.gif

 

[sailorman]

/forums/images/graemlins/blush.gif /forums/images/graemlins/confused.gif