Originally Posted by lhowemt
The thing i remember wondering about those fittings is that it kind of looked like the bars would not all be at the same level. Meaning the bars that go over the end, vs the ones it sits on top of. The bar at the end of this fitting won't have decking on it, but The far fore/aft cross bars won't have these fittings, correct? If so you'll need to shim on top of those cross bars so the decking is level, sitting on top of these fittings at the rest of the cross bars. I suppose you could use these fittings everywhere buy i'd skip the weight in those outer corners of the frame.
I'm not exactly sure what you're asking because if I was trying to save weight I'd only have the double rail fittings on the ends. Only having 4 instead of 6 for a 4 bay frame.
The top of the cross rails are the same as the top of the fitting. The side rails and the cross rails are at different heights so you'll have height differences between the side piping and deck. The cross rails are about the pipe outside radius (0.83" or 1.66/2) above the side rails. Thus, if you are not using these fittings at each location then yes your deck will need shims to maintain a flush bearing.
However, I don't think the weight savings by only using the double fittings on the ends and low pros at the others along with shims would save weight. You can see an example of using the fittings at all locations here
. The oar tower set up there is strange to me. That is why ZtG and I made some towers that were offset allowing for one whole plate or bleacher seating (as I used). You can kind of see this in my picture at Tequila Beach.
There could possibly be some modifications to limit this height difference. I would be slightly concerned about fitting deflection (flexing) on the ends negating the rigidity added by having a double rail. Whether this is a real concern would take some analysis and even if a double rail is really necessary added strength.