I know this is a vague question but I'm trying to get a ballpark figure for an arch for a 40ft sailboat. I was thinking of supporting two eighty watt solar panels on top with the radar slung below, and a post off to the side for an airx. I have always been thinking in terms of stainless but could aluminium be used or would the welds just crack and fail? I'd call a fabricator but I'm away from the boat and out of town for a few months. Just trying to think if it should be on the "to buy" list or the "wish" list. If anyone had designs they could post I'd appreciate it.