Re: Boat slips off trailer when loading. Help!!
You don't even need that rear roller. To save money, many new trailers just come with a plastic pad over that spot on the frame. The boat never touches that roller in most cases. It is handy sometimes if the launch area is real shallow. But a pad does the same thing.
The only reason there is a roller on mine is because I took it off from the front when I upgraded to self centering rollers. I use that roller and bracket for attaching my transom saver protector. It's actually on there mounted upside down. But the pic also shows the plastic pad bow protector.
As others have said you are backing in too far so the boat slips around. You don't even need side bunks. I put them on and took them back off cause the bow line gets caught on them.
Try backing down and stop when the rear of the bunks go 6 inches under water. Then when you crank it up the boat is resting on the bunks and they guide the boat up.
Don't watch how others are launching at the ramps. Most don't know what they are doing. Search a video out on trailer launching on google. I don't power load. Power loading ruins the understructure of the launch for others and is illegal at some ramps. I nose the bow in and just crank it up with the crank. If that was an effort I would just get an electric crank.
If you power launch it is mandatory that you wear a big gold necklace and have a beer in one hand and a tatoo that says "Guido" this quailfys you as a powerloader.
Having only 3 front teeth and lighting up a cig can also get you a pass to powerload too.
And then only pull your trailer out of the water a few feet and proceed to take your time putting your straps on etc
