With today's mapping cards

Is really that big of deal to add a second transducer or thru hull transducer to keep depth readings while on plane...seems you can use your cards for that?

For me I am looking to get a SD card lake map for my GPS Nuvi to use as an aid. But I guess because I was a soldier for most of my adult life my mentality is, "I don't care what the map says:.....accurate on the ground info is what I always needed. For boating and fishing an accurate depth finder on the lake provides that.....I would give up my trolling motor before I gave that up.

But this is just me.......

Neither Navionics nor Lakemaster survey the whole area of a lake down here. So if you get in some of the back waters, your map won't do you much good. ( Then again, if you're in unfamiliar shallow water, who wants to be going 30+mph )

From what I've seen on my local waters, the insight maps ( at least Wheeler and Guntersville ) are from the original surveys done over 80 years ago. Some of the shallower ditches shown have silted in, so the map shows 11 foot ditch, but reality is 5 foot water, just no stumps.

I feel more comfortable having the map tell me what sposed to there and my depth finder telling me what really is there.

I actually used a map app and GPS on my Android tablet to help me navigate through a dense fog once. It had a better map than the chip on my fishfinder. ( Arrowhead Creek on Wheeler Reservoir )

I think the chips are over looked far as a safety feature..............sure you don't want to depend on them solely...but they give you insight what it is like many yards ahead of you and showing you the channels and markers .

On plane depth is a must. These cards are good but not always spot on.

Lakes do go up and down. The bottom stays the same. Rofl

What about humps or shallow points................The card is going to show contours and if your running 30 mph while on plane with a depth reading and come up on a shallow area it's to late.

True. Your map is not gonna show stumps and obstacles, and the FF is gonna show what you just ran over. Best thing for me to do is go slow if I don't know the area. I got boat insurance and health insurance, but I'm not trying to find out how good either one are. Please, for the love of God, don't use your gps/map card, and run, like it's radar in the fog. Foggy morning, you won't find me nowhere near the river channel for that reason.

Yep. Was on a new flood control lake once, drawn down to winter pool. Had the map card. Had the good sonar. 30 foot of water under the keel, 300 yards off shore. Opened it up, went about 60 feet---and drove my 17' boat 15' up onto a finger reef not shown on the maps with no marker bouys on it. Darn near went through the wind shield. No other boats on the lake, by myself, in March, 40 degree water. Got out of the boat and walked around on the reef. Barely covered my boot soles at the boat. Had a heck of a time getting that boat off that reef. Good thing it was aluminum--no real damage.

Take away just like others have said--go slow on lakes you don't know, don't trust your map card, and remember the sonar shows what's in your rear view mirror.

We hear folks roaring by at our place all the time with minimum visibility. Amazing. Our dock got hit about 20 years ago. Bent the crap out of a metal walkway stanchion. The boat owner had no insurance. Lucky he had a head left. If the water hadn't bee above summer pool, his head woulda rolled. Several members here have seen the bent pole and heard me bitch about it.

I believe something like this happened to a football player in Fla a few years ago. He didn't make it. Can't remember details.