Originally Posted by Richard Selman
You have to allow for the point of the bow rising/falling between the rear rollers. If the rollers are too low relative to the roller beam or axle the bow may strike.
I got round that by moving the swing beam rollers out from the keel as far as they would let me, but spread them slowly (a few recoveries were made that day!) until I had them as far apart as the bow shape would let me. They ended up remarkably close together, but I then set the forward rollers (beam for them is about 6" ahead of the axle) on longer poles further apart - they are wide, but high enough to "catch" the bow before the hull hits the axle, and are positioned almost under the toobs, as far apart as I could get them to stop it swaying. Theory is the rear rollers hold the engine up, the "mid" rollers stop the boat swaying from side to side. There's another keel roller on the drawbar which between it & the bow snubber hold the front end up.
The good thing about trailer & boat geometries is that the cross beams (swung or fixed) of a trailer are far flatter than the V of your hull - just moving the rollers outboard by an inch can result in a spectacular drop in the height of the boat without allowing it to hit any metalwork. - Keep the rollers as close to the bar as the clamops will allow, and adjust sideways until you get a "meet".
I will in the fullness of time add another set of rollers to the swing beam to give the transom maximum support (they are not needed for launch or recovery), but as Chris says, a couple of hours setting up is well worth the effort.