Garmin 178 vs 498 and question!

[bernithebiker]

I had a Garmin 178 on my old RIB and it worked very well - accurate GPS and the sounder worked perfectly at all speeds and depths.

So I bought another Garmin, the 498, for my new RIB. Essentially, it's very similar, but the screen is slightly bigger. It seems to update and redraw faster too, and the Map display is clearer with (seemingly!) more colours. It also has a 'flasher' ! mode which I haven't quite worked out yet - a kind of different type of sonar display. The highway mode is now 'inmap' which is handy. It can take the old style cartridges AND the new G2 ones (the old 178 would not take G2). Be careful if you buy one of Garmin's new range (178 and 498 now defunct), eg. 450, or 550, as they do NOT take the old cartridges......nice little earner for Garmin, especially as G2 cards are about 250 quid! I'll stick with my old one thanks...!

On my first outing all worked perfectly, until after the first 15knot+ blast, I noticed interference on the sonar display, and wrong depth readings, eg. 0.5m in 15m of water, and it flicked between 5m, 3m, 0.5m etc.

The transducer had not moved - I checked it - rocksolid, exactly where it should be. Thinking it might be a turbulence problem I slowed right down - no improvement. I even stopped and killed the engine - same problem, so it ain't turbulence.

Later coming back into port, it was wroking fine again - very odd. I can only think it's some kind of electrical interference. Garmin say to avoid routing the transducer cable with other electrical cables, but I had no choice as there is only 1 route to my centre console from the rear of the boat.

Anyone else had this problem? Is it possible to shield the 'ducer cable to protect it from interference?

I saw (too late) on this forum, that the 'ducer could be mounted in the engine bay. I would like to have done that, but too late now!

[ribfan]

I have a 498 in my boat. It works very well 99.99% of the time. It has lost it's marbles in very confused sea once or twice, but usually fixes itself quickly. If it totally freezes up, you can reboot the unit by powering it up holding the "quit" key at the same time as the power key. It will reset to as new in the box. You will have to redo your settings, and you will loose track lines and any way points. The thing to check also is the software version the unit has. The newest version is 3.10. if not, upgrade it on Garmin's site. The 3.10 version is suppost to be more stable than earlier versions. I have no problems with mine holding depth even at wot of 42-43 kts.

Good luck.

www.eclecticwonders.com uncommon art

[jwalker]

I've had something similar to what you describe....then I realised I'd accidentally set the range to something it couldn't follow. Auto works best for me.

[Biggles]

I have two Garmin transducers fitted.

Garmin 178 works perfectly all the time. Garmin 90 gives all sort of spurious readings. I guess the 90 is older technology but its very temperamental.

Both transducers are mounted to shoot thro the hull at the rear of the boat.

[bernithebiker]

Originally Posted by ribfan

I have a 498 in my boat. It works very well 99.99% of the time. It has lost it's marbles in very confused sea once or twice, but usually fixes itself quickly. If it totally freezes up, you can reboot the unit by powering it up holding the "quit" key at the same time as the power key. It will reset to as new in the box. You will have to redo your settings, and you will loose track lines and any way points. The thing to check also is the software version the unit has. The newest version is 3.10. if not, upgrade it on Garmin's site. The 3.10 version is suppost to be more stable than earlier versions. I have no problems with mine holding depth even at wot of 42-43 kts.

Good luck.

www.eclecticwonders.com uncommon art

Thanks for this tip - I'll try it if this happens again. Presumably to upgrade the unit software I need a unit to PC lead of some kind?

[bernithebiker]

Originally Posted by jwalker

I've had something similar to what you describe....then I realised I'd accidentally set the range to something it couldn't follow. Auto works best for me.

Thanks, but just to be clear - what is the range? Is it related to the sonar? Or the GPS?
(My GPS is 100% fine, it's just the sonar display that goes odd)

[bernithebiker]

Originally Posted by Biggles

I have two Garmin transducers fitted.

Garmin 178 works perfectly all the time. Garmin 90 gives all sort of spurious readings. I guess the 90 is older technology but its very temperamental.

Both transducers are mounted to shoot thro the hull at the rear of the boat.

Thanks, but not sure what a 90 is. Is that pre-178/498?

One interesting thing is that the transducer of the 498 is much larger than the 178 one. It is both wider and longer.

I spoke to Garmin on this one, who suggested;

a) checking the transducer cable for damage (it seems OK, but impossible to check inside the cable to be sure! but if it works perfectly at times, surely cable must be OK?)
b) checking the transducer cable connector plug (just below main unit) - this seems OK too
c) they think electrical interference unlikely as 1) their cable is shielded and 2) nothing else electrical was on at the time (apart from the engine! and even when I turned that off the problem was still there).
d) check the software number as suggested above - but to upgrade I need a lead I think
e) check the transducer itself by using another loose transducer - impossible, I don't have one!
f) have the main unit checked for faults.

So plenty of things to look at - I hope it's simple as this is brand new, and I would rather it wasn't a major breakdown, especially after the 178 worked so well.

[Channel Ribs]

Originally Posted by bernithebiker

So plenty of things to look at - I hope it's simple as this is brand new, and I would rather it wasn't a major breakdown, especially after the 178 worked so well.

Can you get the people you bought it off to loan you a trasducer?

[jwalker]

Originally Posted by bernithebiker

Thanks, but just to be clear - what is the range? Is it related to the sonar? Or the GPS?
(My GPS is 100% fine, it's just the sonar display that goes odd)

The sonar range can be set (or mis-set) to various depths or you can let the unit do it automatically. So, say you set the range to 10mtrs and you have 100mtrs under you, it's not going to be able to find the bottom.

[ribfan]

you can check the software level of you 498 by going to the system tab. That screen will detail the software. The easiest way to upgrade is with Garmin's Marine Management kit. It has a card, USB card programmer and software. I think the kit was $50.00 US, you can most likely find one on e-bay for less. Follow the instructions and you should be good to go.

Bill


www.eclecticwonders.com uncommon art