Re: Wheel assembly for trailer tongue to pull boat?
OK, I know this thread is over a year old. But, I thought I would post an update to the solution I have been trying to engineer. The original design was lacking in a number of respects. The caster wheels would turn too freely upon encountering any kind of resistance. So, I created a rudder system to steer the wheels. However, the rudder had too much play in it and required that someone stand close to the cable to steer it.
This was not satisfactory when pulling the boat up from the lake. The wheels would dig into the clay and gravel and the cable would be under signficant tension. I don't want anyone near the cable when we are pulling the boat trailer with the boat up into the boat house. Safety first!
So, to lessen the stress that was caused by the wheels sinking into the clay and gravel, I added two more wheels to give a surface area equivalent to about two car tires to help the wheel assembly float better on the gravel. I also put the wheel assembly on a larger caster. It raises the boat tongue a couple of inches higher than the previous one. Given the weight and pivot angles involved, even a couple of inches should make a difference in the weight pressing down on the wheels and assist in providing better wheel floatation on the gravel and silt. I also fixed the rudder system (a square aluminum tube) rigidly to the caster to make steering as responsive as possible.
Finally, I added a locking mechanism to the caster to lock the wheels firmly in place on demand so that they will not swivel, removing the need for some one to stand close to the cable to steer the wheel assembly as long as the boat is aligned properly.
In the attached pictures, you can see some details of the new design. I just put this new caster on the trailer and have not launched the boat yet. I will follow up with my experience with the new design later this summer.

