New Rig #4 Sleeving the Mast Sections

The Tiki plans specify a 4"x 1/8" 316 aluminum tube for the mast section (or wood as per the original plans). The aluminum tubes come in 20' lengths so I had to sleeve together a 20' length plus the additional 5' that I wanted for my finished mast height. The standard mast height is around 21 ' but gives very little room to move around the deck when the mainsail is set - I have to crouch down low to get under the main when tacking. I wanted to add additional clearance under the main to allow easy movement and better visibility, and this produced a finished mast length of 25', so around 4' taller than a standard mast. Note that even the standard mast height of ~21' requires adding additional length to a 20' aluminum tube, and this is usually done with a short wooden section at the mast base.

Finished mast joint

 

I used the sleeve formula used by Kim on his Tiki 26 in LA, and posted on Wharram Builders and Friends (thanks Kim). The original came from Sailing Anarchy (see below). The sleeve is 5 tube diameters long, so 20" in this case. I used an additional section of the same mast tube to make the sleeve. This section was cut lengthwise (gingerly using a Skilsaw with an aluminum blade) to create a slot about one inch wide. This is so that the sleeve can be compressed to slide inside the mast sections.

One tube diameter each end (4") is cut into "teeth" so that there is no hard point transition from the sleeve edge to the mast section. Instead of using sharp angles as shown in the graphic, I cut mine into rounded shapes at the top and bottom of the "teeth" because I thought it would leave the sleeve stronger.

The sleeve was then compressed using hose clamps, and inserted into the mast sections using West gflex epoxy as a bonding agent (others recommend using 5200, but the gflex has worked out well). While the glue was setting, I drilled a pattern of holes and riveted the sleeve and mast sections together. I already can't remember what size stainless rivets I used, but it was either 3/16" or 1/4." The sleeved mast is rock solid and has been in use now for three years at the time of writing, including some long coastal trips and winds to 30 knots under full sail.

I don't usually add this disclaimer, but it should be self-evident that I am describing here what has worked for me, and I'm not suggesting that anyone should follow this design for their own use.