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What type / size of aluminum should we use for the prod (maybe a non marine grade that I can buy at the local steel supply company). I may build out of carbon, but looking at options and did not see it listed on here.

A pretty good rule of thumb when switching between Al and CF is to match the section and wall thickness. The difference in density then accounts for the weight savings between the two material choices (of course, with CF you can save further by tapering the pole or laminate, in ways not possible with a uniform Al extrusion- which doesn't apply to a straight prod tube).

So, if you're articulating with guys and bobstay, there's no bending loads and you can use something like 1.5" dia x 1/8" wall or 1.75" dia x 3/32 wall.

For a fixed (or internally/back end controlled articulator), you'll want some more diameter. Say, 2.5-3" dia x 3/32" wall. So thin wall spinnaker pole tubing off a bud's 30'er probably won't work, it'll take a heavier wall to resist buckling at the exit.

No calcs here, just comparing what I think I saw with the pro-specced prods, and I've personally bent a couple of 30'er spin poles in their normal use....

if you want , I can make a copy of the drawing of another make of a 18 footer that shows the layout and size of aluminum tubing that they suggest to use. Let me know.

...you can also use the lighter sections that Chad mentions,but sleeve the high stress area,,
,,and the bobstay helps a lot,,,makes a more responsive set-up whatever you use.

...you can find some pictures of my on-deck,ugly but works well setup..... http://www.flickr.com/photos/59103003@N ... 076955693/
...click on the pics for details

Marino wrote:if you want , I can make a copy of the drawing of another make of a 18 footer that shows the layout and size of aluminum tubing that they suggest to use. Let me know.

I would like to see them, thanks Marino

On the same subject, I just picked up an older sailboard mast I thought I could cut and use for my articulating sprit. could this be used without the bobstay? I am planning on using one, and setting it up like josh did on Shazza, but I was curious if it would work without one.

slowpoke wrote:On the same subject, I just picked up an older sailboard mast I thought I could cut and use for my articulating sprit. could this be used without the bobstay? I am planning on using one, and setting it up like josh did on Shazza, but I was curious if it would work without one.

...I'm not sure what Shazza has,,,,but from what I've seen with the well reinforced W'surfer tube on my boat,,you'd -definitely be wanting a bobstay.....another benefit of the bobstay is it firms-up the gust response,,where the pole otherwise bends-off in a puff,,about when you -least- want it to!