Re: Help Needed regarding Torsion Axels and Keel Bunks
The keel is the strongest part of the boat so the boat should be supported by it with lateral support provided by the bunks. However, the location of the longitudinal frame members in the boat in relation to the bunks has a lot to do with support as well. If the boat has a strong longitudinal frame member directly over a bunk, less keel support is needed and launching/retrieval may be easier. If there are no frame members directly over or at least close to the bunks then more support is provided by the keel. So hull design has a lot to do with how the trailer should be set up.
Torsion axles are just fine for a single axle trailer but there is one issue with them on a tandem or tri-axle. That issue is there is no equalizer like there is on a leaf sprung trailer so a multi-axle torsion axle trailer must be towed dead level or there is a risk of overloading an axle/tire in uneven pavement such as leaving or entering a driveway or parking lot. Consider one wheel having to step over an object placed in front of it. With the lack of an equalizer, that one wheel picks up a considerable amount of weight in the process. On a lightly loaded trailer that's not an issue. But since most boat trailers tend to be loaded close to their maximum, that can burst a tire or damage the cords. I have seen tandem torsion axles with one set of wheels totally off the ground. The latest incident was on a paved road intersection that had a moderate elevation change from one road to the other. In that scenario, one axle must suddenly support the entire load thus almost certainly presenting an overload condition.
