Like a bowling ball in the back of a stationwagon

race car straps..

I use 4 car tie downs too. I ordered mine from Summit racing. I think the ones on the front are more important than the ones on the back. i love it when i see a 40+ foot boat with jon boat straps on the transom.

Car straps as well.

http://www.jegs.com/p/JEGS-Performan...48171/10002/-1

As said, the forces in a collision are huge. No reasonable strap will hold that force, let alone the rear d-ring/swim platform the strap is connected to.

The main purpose of straps is to keep the trailer and boat connected so the load acts as one. Ratchet straps are ideal vs the simple lock over type but if you are the in hurry/lazy type using what ever will be used more frequently is better in the averages game than a heavy duty style that is infrequently used.
A decent 2" strap is fine.
The chances of an S-hook having a problem on the transom are minimal but more solid hook styles are a relatively cheap upgrade.

Dont over look the bow strap. Illustrated by boattnt.
It makes a noticeable difference in keeping the bow planted solid to the trailer.
The recovery strap only exerts horizontal pull. The safety chain many use has its purpose as a quick piece of insurance against the recovery winch failing when leaving the ramp but does nothing to secure the boat.

Boatnt, can I ask where you purchased your straps from, they look very nice?! Thanks!
Steve

I have the same set up as you except the bow eye.

http://boxertiedown.com/wholesale/-c...ety-latch-p-98


http://www.uscargocontrol.com/Tie-Do...Flat-Snap-Hook



http://www.multiprensusa.com/hardware/snapHooks.php



http://www.s-line.com/Products/hw.html

D ring was already mounted on the trailer,would of liked alittle angle on it,This cut out alot of the tongue bouncing

http://www.ebay.com/itm/4-AXLE-STRAP...334f1e&vxp=mtr

You are right straps are needed. But lets be honest. you get in bad enough wreck it aint going to matter what you have on there