In JRA Magazine issue 97, Jeff Middleton described the sad loss of his boat Sesi on the rocks of Anglesey, and at the end of the article, he mentioned the possibility that she might be replaced by a Westerly Konsort.

Well, that came to pass, and a week or two ago, Jeff contacted me for advice on getting a mast to convert from bermudan to JR. We looked at the Hydro tapered tubes, but none was strong enough. So we looked at the concept of the hybrid mast. A wooden topmast could have been made, as has usually been the case; but at that moment, it happened that I was just getting interested in 3D printing, and it seemed to me that we might make a mast from  a series of parallel aluminium tubes with 3D printed tapered fairing pieces and 3D printed internal sleeves at each step down in tube diameters.

This does indeed appear to us to be a way to make a very good mast. The Needlespar masts were made by adding a smaller tube to a larger tube, with the taper being made by machining the top of the larger tube. Clearly, this is beyond the scope of a home workshop, and other ways of making a taper are difficult and messy; but 3D printing is clean, several JRA members have printers, and it seems to me that this is a solution to our perennial difficulty of finding unstayed masts.

I have a Prusa MK4S printer with a 210mm x 250mm bed, which is just capable of making components for a 7 inch diameter mast. The mast for the Konsort will be made from 5m of 7" x ⅜” tube, 5m of 6” x ¼” tube and 5m of 5” x ⅛” tube, giving a possible assembled length of 14m. However, it’s worth noting that the lower tube can be 7” x ¼” or 7” x ⅛” to suit boats with a lower righting moment, with the upper tube or tubes being adjusted in wall thickness and length accordingly. The deck and heel arrangements would remain same, as would the tapered sleeves. The only new components to be designed and made would be the internal sleeves. Thus, there may well be an easy mast solution for boats from 7m to 9m LOA.

We’re ready to go ahead, with confidence that we can complete the project. The tubes can be ordered. I’m engaged in designing and printing all the components for the Konsort’s mast. The .3MB files can be found at 7 inch diameter mast parts as I design, print and check them, and I will make a photo album for those interested but not able to open them with 3D printing software.  In the meantime, I’ll attach a few images that may illustrate the way I’m thinking. The masthead, with places to mount a VHF antenna and a tri-white light; a section through the heel; the 3D printed mast retainer and heel socket that form part of that assembly; and how the deck partners will look (all subject to change as we progress).

Yes, Sikaflex, Simson's or some similar flexible adhesive will be used to bond the printed  components to each other and to the tubes, where a permanent join is to be made.

I’ve been learning the hard way how time- and material-wasting it is to try and make cylindrical sleeves. There are at least three sources of problems:

1. In Fusion, if you make a sketch of the vertical cross section and revolve it, it's very easy to make the lines not quite vertical, although they might appear so on the screen. Then the diameters are not accurate. You have to check them very carefully. It's better to sketch concentric circles and extrude them (with a draft angle for the tapered sleeves).
2. The shrinkage of both ASA and PETG is variable and unclear, but somewhere in the range 0.4% to 1.5% as far as I can tell. Normally this doesn't matter too much, but in this case it does, as the difference on a 5 inch tube for example is between half a millimetre and one and a half millimetres.
3. The tolerance on the diameter and roundness of the tubes is another factor, which only disappears if you can very carefully measure the actual tubes that you'll be using.  

So having spent all day yesterday making an expensive piece of scrap that won't fit, I'm planning to make the internal sleeves more like a staved mast, in eight pieces. These images are of a sketch for the basic cross section, that will print standing up on edge on the bed without needing support, and a version with a web to support a 32mm waste pipe with solvent welded couplings, as a conduit. These need a 40mm dia hole to pass through, or mast assembly would get tricky. I can fit two or three of these on a plate, at 6in to 5in size, and these are now printing. Without the web, for the upper sleeve, I'll be able to fit more on the plate.

I've found that my new Elegoo Centauri Carbon printer will cope with ASA a lot better than the Prusa, and I've got some Flashforge ASA for the tapered sleeves, which I've found out from a youtube video has  the best adhesion between layers. I'll print these as a full cone, because anything other than a full circle warps and lifts off the bed. It's not as bad as the internal sleeves for sizing, as they only have to fit over one tube, not between two tubes.

Yes, that’s entirely reasonable. What one ought to do is stop a print when the first centimetre or two has completed, cool it, measure it and adjust as necessary before trying for a complete part. Either by changing the X and Y dimensions of the 3D model, or using the slicer to apply a scale factor to the X and Y axes. What’s rather more difficult to design out is the human error factor, which I’m getting more and more liable to exhibit.

Indeed, it would be sensible to split the tapered sleeved into more stacked pieces, where there is any doubt about the printer or material, chiefly so that if something goes wrong and a part has to be scrapped and printed again, there’s less chance of the frustration of almost getting to the upper end of a tall component that has taken all day to print, finding the flaw or error, binning it and trying again.