Flag pole used for CS 20 mast

[Noklin]

Would 6063-T6 with 0.095 walls be OK for my CS 20 mast? I am located about 30 miles from a local supplier. This is a tapered flag pole that is in 3 sections, total length of 22 feet, with the lower 3 feet not tapered. The pole has a 3 inch butt and tapers to 1.875 at the top. How much more would this weigh than the 6061-T6 listed in the plans? I plan on using sail tracts so need a tapered mast.

[Designer]

Cs20 hull #1 had that mast and it worked ok. It was noticeably heavier than the standard mast. Beside the heavier wall thickness, the taper is only in the top section and the spun taper tends to increase the wall thickness so that from a weight comparison it is almost as if there was no taper.

My materials manual lists 6061 T6 with a yield strength of 40,000 psi and 6063 T6 at 30,000 Psi which means that your flag pole will have about equal strength with the standard mast in 6061 T6 but with a smaller wall thickness.

[Noklin]

Based upon your comments, I looked at the specs again. Only the upper 6

[Brent]

I looked briefly at the flagpole option, but did not find a good match.

For tubing check out http://www.onlinemetals.com. I believe they ship to anywhere in USA. They are usually cost competitive.

I got my alum tubing from a midwest metals house http://www.shapirosupply.com/ which gave me excellent service. Highly recommend them, but check shipping costs to where you are.

[Designer]

I would do what Brent says. I have mast material here but it is in 12' lengths which is to long for UPS. If you don't have any luck you can email me.

[Terry Dunn]

I bought mast tubing for my CS 20 from online metals in 8' lengths. The price was reasonable and the shipping was cheap via UPS. The service was good.

I used .065 all the way. So far it has been fine. Perhaps someday I will break or bend my .065 3" bottom section. This is the third season we have had our CS 20 in the water. We have been out in heavy winds but when we had a bunch of people in the boat the winds have been moderate. So we have not hit the condition of lots of movable ballast and lots of wind.

I paid $267.78 on 3/10/2003 including shipping.

[Noklin]

Terry, thanks for the info, but how did you connect two 3 inch sections into the 12 ft section of 3 inch tubing called out in the plans?

[Terry Dunn]

I used three 8' sections ( 3", 2.5", 2") and cut the top off to get the 22' length.

My masts are probably more bendy than most with the 8' of 3" on the bottom. Since I don't have another CS 20 in the neighborhood to compare too it seems to work fine. I have standard size sails with sleeves.

Graham may have some words of wisdom regarding the 8' lengths.

You could connect 2 3" sections with 18" of 2.5" with fiberglass bearings and a narrow collar in the middle.

[Noklin]

Well, I finally got a price quote on the flag poles. After 2 e-mails with no response, I called. The 22 ft pole is 27 pounds, which I figure is not too bad. I calculated a finished weight of 20 pounds for the 6061-T6 called out in the plans. The price was $295 each with me picking them up at their place of business, twice as much as the cost I have seen on this and other post for the mast made per the plans. This is way out side my budget. I guess that I will be going with the 3 section mast per the plans.

[Designer]

I have not had a chance to work out if the 8' length is satisfactory for the lower mast length yet. I have a busy day tomorrow but you can let me know what length you would like to use and maybe I will have time to work it out tomorrow night.