Homemade mast tip external skinny extension

[manuel]

It often happens that luff lengths require 26-28cm extension. I don't like running my base extension near the top (although doing it on streamlined at the second notch) and wanted to further test an old sail to see if I like the size or need something a bit smaller.

Anyway, first I cut off 11cm (1a.) of an old snapped top mast section (1.).

Then I fit the top I want to extend (2.) in the broken section (1.) until I get a resistance. I measured from where it started rubbing a cut 1b there.

After, I measured the cap depth (4cm) and therefore I need to have the extension (1a.) stick out at least 4cm (or it won't fit). 11-4=7. I need to have 7cm of the sleeve (1b.) below the tip (1a). 7 + 11 = 18cm, perfect, I'll cut (1b.) at 18cm !

Tips and tricks to avoid any issues ? 1a and 2 are perfectly square. Should I have good resistance between 1a and 1b or is it fine if it pivots freely? Will the 1b sleeve not stress too much the top of the mast (2.) ?



I sanded the cuts so they don't damage the sail.



My weapon of choice to accomplish the work (looks are so deceiving):

[nw30]

I would run a bead of epoxy all the way around 1a where it fits into 1b for a solid and permanent bond, that way you won't have any issues with anything shifting during use.
Some of the newer sails have mast sleeves that are very snug around the tip, so fitting that into one of those could be a problem.
Other than that, it reminds me of a mast tip extension that I used to have for my old Ampro masts (ancient history), but the sleeve was on the inside, much like how two piece masts go together. It broke after one season of use, right where the inner sleeve went into the tip extension, but we're talking pre-carbon days, all fiberglass.
Also that will definitely stiffen up the tip of the mast which could change the characteristics of it. I personally would prefer a stiffer bottom of the mast (using a long base extension) than a stiffer top.

Which brings me to something else for anyone.
NEVER add more holes to the top you your base extensions to get more height adjustment out of them, NEVER! They are designed to go into the bottom of the mast at the minimum amount without the holes (around 5").
I've seen too many people split the bottom of their masts because they didn't have enough base extension into them, they cheated by adding holes and then paid for it.

[manuel]

Cool thank you, yes sand could get into 1b without anything, at a minimum some electrical tape there. It's true that 1a and 1b really go together so they could be permanently glued together. The fit between 2 and 1b is snug until it hits 1a.

What length did you have your extension running? It would be a cleaner looking design but I'd be afraid that it splits the top of the mast apart since it's not meant to have any leverage on the inside at this point. I have heard from many people running internal version of mast tips without issues but I wouldn't take those sails in the waves.

[U2U2U2]

Read your explanation , several times, how much length did you gain ? And using 3 different masts to accomplish this?

If I read this correctly, this is a test to see if you like the size sail?

There is no way to make a judgement of strength, much would be influenced on how long the mast was/is, the size sail.

[isobars]

If by "test" the sail you mean see how it performs, this is gonna be one misleading test. You're defeating the twist the mast and sail designers built into their products, which changes everything from the top to at least the clew of the sail. When just using the wrong brand of mast in some sails can make them handle downright evilly, imagine the impact of using what is now, comparatively speaking, a rigid, thoroughly splinted section of pipe in the top of your sail.

Why not just borrow a more suitable mast or base extension, for a much better test and less risk to your mast and sail? This ain't no Ampro (I've used my Ampro with > 10:1 leverage to straighten out a badly bent exhaust pipe on my 4X4).

[manuel]

I used only one damaged mast top (1.) to make the tip and the sleeve. The mast to be extended was left intact (2.).

The extension is 11cm which helps bring down a 28/26cm base extension to 18/16cm.

The sleeve length being 18cm, is covering 7-8cm of the tip above and 10-11cm of the mast tip below.

I wanted to try the sail more for its size than its abilities so it's not a problem if performance is affected at all. The sail has a vario top (see below - not my sail) so I doubt the flex properties up there are important to the sail. Although it's been tried with good result I wouldn't trust this with much longer extension!

[U2U2U2]

Sounds like you have it all worked out then.

17cm of extension I agree would probably not change the sail by much.

Neither would using a longer mast or the 28cm of extension.

A bit of overkill to test someone else sail.

They , in the past have made top extensions, bottoms work better and safer.

[manuel]

+11cm top extension (17cm was referring to extension setting at the bottom).
There's 4-6cm of mast sticking out of the sail itself, so only 7 to 5cm of the tip extension makes it inside the sail per se.

I guess we could debate, is it safer to run this design or run the base extension at full length !

[U2U2U2]

Is it safer to make a top extension , or use the proper size mast to begin with, or an extension that is designed to go , probably 32 or 30cm?

My sails I can answer , the later.

If using someone else's sail I would have to make judgements likewise.

This falls into a home shed modification that if it works , great, if not
Then it ain't my parade.

[bred2shred]

I wouldn't be concerned about the impact on mast bend up there. What I would be worried about are 1) the fit of the luff sleeve around the now much larger diameter mast tip and 2) sand migrating into the tip extension joint and causing the tip to get stuck on the mast.

sm