My boat came with a Navman 4380 color fishfinder.. I have had really
poor results with this fishfinder working when I'm on plane. I was
hoping it would work at least for a low planing speed like 20-25 mph,
but the screen just goes white. I have tried tilting the transducer
forward a little, but it still exhibits this performance. The transom
mount transducer was installed by the dealer, and looks to be properly
located.

I'm scratching my head wondering if this behavior is related to the
mounting position.. or if Navman's are just sucky fish finders?

It's nice to see the SmartCraft gauges linked to my Merc Optimax... but
I'm getting frustrated with this thing.

Does anyone have any experience with Navman fishfinders?

Pics of mounting:
http://aycu34.webshots.com/image/279...6884250_rs.jpg
http://aycu17.webshots.com/image/113...8036262_rs.jpg

In article . com,
"feetwet" wrote:

My boat came with a Navman 4380 color fishfinder.. I have had really
poor results with this fishfinder working when I'm on plane. I was
hoping it would work at least for a low planing speed like 20-25 mph,
but the screen just goes white. I have tried tilting the transducer
forward a little, but it still exhibits this performance. The transom
mount transducer was installed by the dealer, and looks to be properly
located.

I'm scratching my head wondering if this behavior is related to the
mounting position.. or if Navman's are just sucky fish finders?

It's nice to see the SmartCraft gauges linked to my Merc Optimax... but
I'm getting frustrated with this thing.

Does anyone have any experience with Navman fishfinders?

Pics of mounting:
http://aycu34.webshots.com/image/279...6884250_rs.jpg
http://aycu17.webshots.com/image/113...8036262_rs.jpg


What is happening to you is your trying to beat the "Laws of Physics"
and those laws are not subject to political change. The faster you
go the more air, (bubbles) crosses the Transducer face, and the less
of the ultrasonic signal generated by the Transduser Crystal is coupled
into the water, and the less return signal is coupled back from the water
to the Transducer Crystal. You can either, SLOW DOWN, or stick the
Transducer down in clear water. (deeper by a foot or two) Should you
try the later, just remember that it is down there and anything you run
over is going to break it off. Must be a Weekend Skipper........

Me

I wouldn't give up too quickly. I have a lowrance lms320 on a Kenner
18v. The kenner is a shallow running boat and planes real well with
not much more than the prop in the water but I still get great depth
readings down to less than 2 ft. Even shallower on a hard bottom but
once you get to that depth its time to start slowing down, turn around,
or really hit the throttle to get on the other side of the hump.

Maybe the tunnel hull helps.

Now it could be that the good results are because this unit has lots of
power and the strong signal overcomes all the bubble noise etc. As I
recall its like 400 watts RMS. How many watts is your NAVMAN. Don't
be fooled by a high peak number which is like 4 times the RMS number.

It could be that if you just tinker with the angle of the mounting and
a slight depth change may make all the difference in the world.

Having said all that I'm assuming this is not an aluminum boat with
lots of rivets in the hull on the bottom making lots of bubbles, noise,
etc.

Don


Me wrote:
In article . com,
"feetwet" wrote:

My boat came with a Navman 4380 color fishfinder.. I have had really
poor results with this fishfinder working when I'm on plane. I was
hoping it would work at least for a low planing speed like 20-25 mph,
but the screen just goes white. I have tried tilting the transducer
forward a little, but it still exhibits this performance. The transom
mount transducer was installed by the dealer, and looks to be properly
located.

I'm scratching my head wondering if this behavior is related to the
mounting position.. or if Navman's are just sucky fish finders?

It's nice to see the SmartCraft gauges linked to my Merc Optimax... but
I'm getting frustrated with this thing.

Does anyone have any experience with Navman fishfinders?

Pics of mounting:
http://aycu34.webshots.com/image/279...6884250_rs.jpg
http://aycu17.webshots.com/image/113...8036262_rs.jpg


What is happening to you is your trying to beat the "Laws of Physics"
and those laws are not subject to political change. The faster you
go the more air, (bubbles) crosses the Transducer face, and the less
of the ultrasonic signal generated by the Transduser Crystal is coupled
into the water, and the less return signal is coupled back from the water
to the Transducer Crystal. You can either, SLOW DOWN, or stick the
Transducer down in clear water. (deeper by a foot or two) Should you
try the later, just remember that it is down there and anything you run
over is going to break it off. Must be a Weekend Skipper........

Me

I have since raised the transducer a little and it is now reading the
bottom while on plane. Apparently the dealer mounted it a bit to far
below the hull... which some folks (on another board) mentioned will
cause bubbles.

I had a chance to compare this unit head to head against a Humminbird
565 (hi-res) finder... and the Humminbird painted a much nicer picture
of the bottom... After that comparison, I feel that this navman is
really only beneficial for montioring structure on the bottom and
seeing balls of baitfish.... where the Humminbird will actually see the
game fish clearly.

Before I made too many conclusions I'd make an A-B comparison on the
same boat same speed.

I've never been to fond of the humminbird mfg quality but they may well
work fine now.

All I know is that the Lowrance unit I have is simply amazing at the
detail it can pick out. I think its a combination of high power and
digital signal processing to remove the noise. Now if I could only get
those fish to bite.

I took a look at your unit. It looks like they put more money into the
color display than the sonar processing side of it.

have fun

Don