C-80 Speed calibration

Sealife · Posted: Fri Nov 25, 2005 9:46 pm Post subject: C-80 Speed calibration

Got a pecuilar problem with my Raymarine C-80. On my Data screen, my SOG appear to read correctly, but my SPEED reading is only about half what it should be. It's my understanding that the SOG comes from the GPS, and the SPEED from the paddle wheel on the fathometer transducer. I've checked the paddle wheel and it's free and clear. Raymarine tech service talks about calibration of the speed, but darned if I can find in the manuals how to do it.

Anyone experience this problem?

Lil Rascal · Posted: Sat Nov 26, 2005 1:09 am Post subject:

Mike,

Check out page 7-21 in the manual. Its the fish finder section. There is something called transducer calibration. Maybe that is what you are looking for. See ya,

Scott

Byrdman · Posted: Sat Nov 26, 2005 7:03 am Post subject:

Great question Mike... Same issue on the electronics on FreeByrd... I can not find it by just pushing the buttons....but

my ..... Grand-nephew... Crook

my older brother Mikes grandson... found out how to "uncalibrate" mine as they were enjoying the boat one day.... and I have simply not messed with it. Good little winter project when I'm trolling about watching the sun come up one morning.

But all said... I am simply greatful that they were together having a good time on the boat!

Sealife · Posted: Sat Nov 26, 2005 10:23 pm Post subject:

As Scott pointed out, actually on page 7-17 in my manual, when the fishfinder screen is active, press Menu, and select Fishfinder Setup. One of the options is Speed Offset (1-200%). That should do it.

Mike - Sealife

Island Ranger · Posted: Sat Nov 26, 2005 10:29 pm Post subject:

Factory setting according to Les was recommended at 150%. From what I can tell on Two Lucky Fish, you can "calibrate" to be correct at one range of speeds only. I've chosen 160% to match low speeds, and just ignore the fathometer speed (use GPS instead) at high speeds

mac

Byrdman · Posted: Sun Nov 27, 2005 7:54 am Post subject:

Fishfinder screen... There is/was my problem. I am generally in the Landfinder screen... Mr. Green

So far, the fish have not hurt me when I ran over them cooken up a good time... Mr. Green

I need to try out some re-worked rods anyway. Thanks Guys!

Byrdman

flapbreaker · Posted: Tue Nov 29, 2005 5:23 pm Post subject:

Are you navigating in a river, lake, or ocean? My understanding is your paddle wheel speed won't equal the gps SOG if there is a current like in a river or ocean. Or if the wind is blowing and your course is more diagonal rather than straight then the paddle wheel doesn't reflect this. Or I could just be misunderstanding things....

edit: Put differently, the paddle wheel only measures water speed which might not reflect actual watercraft speed over ground.

Sealife · Posted: Tue Jan 10, 2006 4:16 pm Post subject:

Over the past month or so, I've calibrated the sounder's paddlewheel according to the manual, and find a particular calibration only helps at a particular speed range. For instance, at about 150% calibration, I get somewhat close to accurate speed at cruising speeds, but it's still way off at slower speeds. I've taken to totally disregarding it. It's a mystery to me whey there should be such a big difference, since on my old Sealife, I used the paddlewheel speed on my Lowrance sounder for MPH, and my Garmin GPS for KPH, and they were always very close within the mathimatical difference between statute & nautical. And that without any adjustments.

lloyds · Posted: Tue Jan 10, 2006 4:36 pm Post subject:

All: I don't have much experience with the modern paddlewheels on the speedometers, but the ones on my sailboats were pretty simple, just a paddlewheel with some fins that contained magnets. If you lose a magnet or two you can easily have your speed cut in exactly half. And the magnets fell out pretty easily, just by striking a stick or something else floating. Just a thought.

Captains Cat · Posted: Tue Jan 10, 2006 5:25 pm Post subject:

I think it depends on where it's mounted and the water flow over the wheel. If it's the same all the time, it should be accurate at any speed. If cavitation enters into it, it's a new ball game. It needs to be somewhere out of the way of the things that cause stuff other than pure water flow over the wheel....

Charlie