DIY Mast Tip Extension

My Severne CodeRED Sail

My Severne 11m2 CodeRED Sail

I own a monster 11m2 Severne CodeRED 4 cam race sail. At the time I purchased it I got it cheap because it was new old stock that nobody wanted because Severne had superseded the CodeRED in favour of their new (and very awesome) Reflex race sail. I already had a Chinook formula boom that fit the sail, but was only able purchase and second hand 530 X9 NeilPryde mast to go with it, rather than the 550 that Severne recommended. No problem, I figured I would just make do with a 40 cm extension...

A 4:1 pulley applies lots of downhaul, but it still wasn't enough

A 4:1 pulley applies lots of downhaul, but it still wasn't enough

The CODERed requires a 4:1 pulley arrangement in the mast extension to provide enough downhaul to rig the sail. Despite all this force bending my 530 mast, I just couldn't get the cams to pop nicely. The mast was just too stiff and thick at the base. So after a few frustrating sessions trying to rig and tune this sail, I got the bright idea that I could cannibalise an old mast top (one that had long ago lost its bottom) and make a 20cm mast tip extension that would lengthen my 530 mast to the recommended length of 550.

Here is how I made it...

Measure the existing tip's diameter

Measure the existing tip's diameter

Start by measuring the outside diameter of the tip of the mast that you want to extend. In my cast the tip of my 530 mast measured about 29.2mm at the tip and 29.9mm at a point 8cm further down.

Add the wall thickness of the sleeve

Add the wall thickness of the sleeve

Next measure the wall thickness of the mast top you are going to cannibalise. In my case it was about 2.4mm - you need to double this number and add it to the previous measurement.

Find the location of that diameter in the spare mast top

Find the location of that diameter in the spare mast top

Next set you calliper to the combined measurements, lock it and slide the calliper it down the mast top until you find the location of that diameter.

Now comes the trick bit. My 530 mast tip was actually narrower than the mast tip on the mast top I planned to cannibalise. So I decided to turn the sleeve upside down - its slightly wider at the top - I cut out a section that was 12cm long, 4cm for the top where the extension will be glued and 8cm for the sleeve that will sit on top of my existing mast.

Measure everything twice...

Measure everything twice...

Next I measured and marked the mast top I planned to cannibalise, 20cm from the top.

Use a mitre saw to make accurate square cuts

Use a mitre saw to make accurate square cuts

I used my shop band saw to make the cuts, but you could also use a mitre saw and do it by hand. The main thing is that the cuts need to be perfectly square.

I used a bit from the tip and a bit from further down the mast top

Above you can see the bit from the top of the mast and the bit from further down that I used as the sleeve. Lying next to it is the Neilpryde mast top it will be fitted to.

Glue the pieces together with high strength epoxy

Next I filed out the insides with a round nosed file - just enough so I could push the pieces together with a snug but not tight fit. Finally I used high strength epoxy glue, which I applied to both surfaces. The 20cm tip was inserted 4cm into the sleeve, by slowly turning it, to make sure plenty of epoxy remained. The piece was stood on its end so the glue would work its way down and fill any voids. I left it to cure for 24 hours.

Finished tip extension mounted on Neilpryde mast

The finished tip extension mounted on top of my Neilpryde mast

Conclusion

This project was actually quicker and easier than I thought it would be. It pays to be as accurate as possible with the measurements, and leave a little overlap. You can always cut the sleeve smaller, but if you cut it in the wrong place first up then you are pretty much buggered. It turned out that my Neilpryde tip was pretty narrow compared to other masts tops, so I was able to use some of the leftover off-cuts to make another tip extension for Gav's 490 mast to extend it out to 520 (actually 517 - because the leftover tip was a little short).

Posted by Henry Thomas, 6 years ago on Wednesday, August 3, 2011

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