Is there a significant negative impact to attaching a topwater lure directly to a swivel? Cranks, paddles props etc...

 

Eric J

Adding even the slightest amount of weight to the front of a floating bait affects it.  It's just physics.  How much and if it is negligible depends on the bait and the snap/swivel.  

Are you talking about a swivel,  a snap, or a snap swivel? A single snap should not be much of an issue except on a suspending jerk bait. 

33 minutes ago, Scott F said:

Are you talking about a swivel,  a snap, or a snap swivel? A single snap should not be much of an issue except on a suspending jerk bait. 

Swivel snap...

Only thing I use swivel snap's for is pre tied leaders with snell hooks when fishing with bait. You might be able to get away with a small snap on something like a crankbait but tying directly is the best so as to not affect the action of the lure.

You are opening up a can of worms, my friend. (Pardon the pun)  most people on this site hate swivel snaps.  They don't hold up, they impede action, they are communist, sissy, etc.  At the risk of being banned, I have used them with no issues.  I used one when I wanted a tiny amount of weight fishing worms and started slaying them.