I've got my design for my A-frame mast-raising system (sick and tired of stepping the mast by hand). Looking for some advice with the following:

1. What material to use. I'm thinking T-6061 Aluminum or 316 stainless steel. Corrosion resistance will be important since it sits outside year-round.

2. A cheap place to get the tubing. Naturally as a cat-sailor, doing this cheaply is paramount. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

3. The thickness for each tube. I've calculated the angular loads on the frame to be no more than 200-pounds (140-pounds is a more realistic number). The design calls for 2" square tubing for the A-frame and then a 2-piece telescoping part welded on top. The P-18.2 mast hinges sideways and I want to get the mast on the "gin pole" up high enough to limit the stress on the forestay mount, but be able to retract it on down to unclip from the frame and attach to the bridal wires. I don't know how strong say, 1/8" T-6061 is.

Appreciate it! This will actually be a fairly cool project if I can get it off the ground on budget. I can e-mail some scale pics if anyone "in the know" thinks it would help. Thanks! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Without seeing the actual design, it's a little difficult to say, but the basic premis of an A-frame is that the two main members of the structure are in either tensision or compression. 2" square tubing of either stainless steel or aluminm would be plenty strong (I'd probably shoot for aluminum since it's lighter). Painted carbon steel would be pretty cheap, but would be subject to rust. If it didn't have to telescope, I'd say look into using pressure treated lumber. As for wall thickness, you're going to be limited to what you can actually find- probably about 1/8".

For reference, take a look at you trailer. The cross beams are probably 2" steel square tubing and they're capable of carrying the entire weight of the boat (or boats + people, etc.) in bending. Additionally, the main frame of the trailer is probably only channel.

sm

If your pieces are less than 8' long you can get any tubing you want delivered to your door. Google is your friend. Most any tubing of either material will stand up to the loads you are talking about in 2" sizes. I have a EZ stepper that is aluminum box shaped and light. It uses straps instead of an a frame, but really anything should do it.

Dan

perhaps i am missing the point, but why not go with an Policies E-Z STEP MAST RAISER (from Murray's) for under $200 instead of building a new mousetrap?

http://www.murrays.com/mm5/merchant...ore_Code=MS&Product_Code=13-9280

Try a local metals supplier. The local shop here ended up being cheaper than the online places for aluminum tube, and I didn't have to worry about the shipping either.

Some of those places have scrap piles in the back where you can find what you want for nothing or next to nothing.

Sorry for responding so late. The reasons why I chose not to go this route: 1.) The P-18.2 mast steps sideways which the E-Z Mast Stepper says it is NOT recommended for. 2.) I wanted something without a gin pole that could simply stay attached to the trailer. 3.) The E-Z Stepper is $200 and I'm trying to do this for about half that or less.

THANKS! I see three places in the Charlotte area. I'll check them out and see if they have scrap pieces of T-6061 that they're willing to give away. I don't need much. It worked for me with my 18" PVC piece of sewer pipe tube on my trailer (storage tube AND new hull cradles). I got that scrap piece for free at a construction site. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

I've already lined up a friend who can do the welding. So far, so good. If I can pull this off, I'll post pics.