Ben wrote:Where can I locate how to determine proper wall thickness and base dia. etc for an aluminum light pole mast? I would like to hear pros/cons of using them as a mast, past failures, masthead fittings, welding, raw surface or painted, design issues, I wish I would have.....etc.etc. When using a salvaged used light pole does the entire pole need to free of small elecrical access holes or can they be plugged? How long have the poles lasted on members boats? Thank you in advance.

I think this is a convenient and sound form of unstayed mast, when it can be found. I don't know of any failures. Mine has lasted over 80,000 miles and, though the surface is getting beaten up, I believe it to be still sound. My masthead is a flat plate, welded on, with triangular buttresses and U bolts for the halyard etc. This has lasted well, too. Anodising is best, paint has a limited life-span. Some people wax their un-anodised masts, but this has to be done regularly. There must be no holes close to deck level. There must be a hole near the heel for a through-pin, and another near the heel for electrical cables, and that's fine, but don't exit cables any higher than necessary. Any pre-existing holes should be left, or covered with a bonded-on plate - welding, or screwing on a cover, will introduce further weaknesses.  Unstayed masts should be as stiff as possible, without overburdening the boat. A larger diameter/thinner wall has a better strength/weight ratio and stiffness/weight ratio than a smaller diameter/thicker wall tube - but in practice, you have to take what you can find. 3/16" or 5mm wall thickness is probably optimum.

Hope that helps.

Hi Ben.  I'm afraid it's all rather seat of the pants for deciding on your aluminium lighting pole.  There's a bit of information here: http://www.junkrigassociation.org/junkfaqs_masts (Webmaster, please note that the new linking page doesn't work on my netbook: I can't move it up the screen and lock it there, to get at the correct button.), which will help quite a bit.  If you can use that as a start and then locate some real poles, some of the better-informed members will be able to give you sound information as to whether that particular pole will/not be suitable for what you want to do.

We have also compiled data in a spread sheet, which you can download from this page: http://www.junkrigassociation.org/sails_masts_gear/.  This is necessarily far from comprehensive due to the amount of information that is available, but once again, I think it will help point you in the right direction.  Until recently, alloy light poles were a rare bird outside of the US, so they haven't been used elsewhere that much. 

Generally speaking, any holes in the mast should be avoided.  I suspect the only way they could safely be 'plugged' would be with some aluminium weldment.

I hope this helps.