KCStudly wrote:Just a little engineering spitball here, comparing the cross sectional areas is okay for a back of the napkin kind of approach, but another way to look at it is friction in the "bearing face" of the joint. It isn't always the shear strength of the fastener that makes a joint; sometimes it is the tensile strength. If the clamping force is great enough, then the friction between the two surfaces insures that there will not be relative motion; w/o relative motion the fastener will never see shearing forces. So with more smaller fasteners you get a more uniform clamp, and therefore more uniform friction. (TLAR analysis in effect.)
Another argument in favor of several smaller fasteners is that we are dealing with wood. Wood can move around and change with humidity and temperature (hopefully less so when we do a good job of waterproofing!), so by my way of thinking a few extra small fasteners hedges the bet if one or two should happen to become compromised.
Now this has come up many times before, some may argue that you could get away with no fasteners and your cabin might never slide or fall off of your trailer, that since your trailer hitch pin is just 5/8 diameter that you might get away with just a couple of healthy bolts. I say nerts to that. I believe that the cabin should stiffen the trailer frame to prevent relative motion when the chassis would otherwise flex. By eliminating relative motion you eliminate the potential for chaffing between the surfaces and the wear that might otherwise occur to damage that precious waterproofing. So it makes sense to me to spread more smaller fasteners over the length of your trailer, than to just use a few in, say, just the corners. This is also another good argument for using some sort of caulk or bedding compound when mating the cabin floor to the trailer.
Over engineered? Maybe. That's right, I'm still not camping yet
, but I always say if it doesn't take anymore effort to do something with a little logical thinking behind it than it does to toss a dart and see what you get, then why not put a little thought into the process.
Truth is that however you get there, most methods will work one way or the other. There are no rules, except to have fun doing it!