Yesterday, I chatted with a buddy of mine that is using a custom made top mast extender.
Why ?
well, first the guy is really a light weight (sub 60kg), and he is good. I mean really good, yet over his 60'. Always the first flying, makes it look as anything he does is just easy and effortless.
He explained that he needs to use softer mast, as he can't get the mast to bend so the sail is in its correct shape. As I am mostly foiling, I made the same thinking, and I usually rig one size below recommended spec. But it is sometime difficult to have an base extender long enougth. And I don't like having the wishbone clamped to low on the mast.
He explained he made a top mast extender from a broken top. He also claims the too long base mast extention makes the rig 'hard topped'.
I surfed the web in search of example and came across this :

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snides8

razzmatazz said...

anybody knows where to get one of these and how much they roughly are. I want to extend my 460 at the top to make a 490 or thereabouts. cheers

sorry i dont know where you can get them from.
i am not aware if any manufacturers make them.
a few guys here( including myself and slowboat) make them out of old top sections of masts that where broken etc.
you need to be a little handy as you will have to ensure the tip will fit over the top of your existing mast. then you just need to glue/epoxy a stopper inside the tip at the required length to give you a 300mm extention.
hope this helps.
they are ideal for lighter riders who may need a slightly softer mast.

I know it is from a distant past, but if you happen to have some pics of such a set up, I'd appreciate to have a look on how it was mad.

from many, many moons ago...

I can see that being left behind at the top of the sail when you pull the mast out, could be a real pain to get out

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Ben1973 said..
I can see that being left behind at the top of the sail when you pull the mast out, could be a real pain to get out

Sure.
Duct tape is your friend.

That's the way I imagined it was done. I am not sure it would fit easily in a narrow sleeve.

Severne used to make mast-tip extension that had the same outer diameter as the mast. The mast plug was removed and the extension was fitted inside, much like the regular mast connection, only "up-side-down".

I'm relatively lightweight myself (about 62-64kg) and it is only in the very largest sails (10-11 m^2) that I sometimes will use a shorter mast in order to make it a little softer an more responsive in light winds. On other sails I think it simply takes away too much from the top-end, and that is even worse for us that have a little less weight and physical strength.

As I said, the buddy that told me about this mod' is very lightweighted. I am also about 65kg, and for windsurfing I just use specs. I've tried out some shorter mast for foiling and I usually prefer softer. But my foil style is definitely freeride small sail. I had never heard of anything else but base extention. I just try to understand what more experienced riders try to explain me.

Here is a picture of the Severne tip extension. It was recommended for use with their race sails at around 2010, if I remember correctly.

A tip extension will make the mast relatively more flex top. The longer the tip extension the more pronounced the effect. You can experiment with different lengths but I mostly found that more than 200mm starts to not work so well. It will all depend on the sail and mast you have got.

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sheddweller said..
A tip extension will make the mast relatively more flex top. The longer the tip extension the more pronounced the effect.

This information seems to be consistent with what my friend tried to explain me : a longer base extension making the mast 'hard top'. I still haven't figure out how come, but I take it.
I still have plenty to learn about sails and rig...

From a few years old post....

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.

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6u1d0 said..
Yesterday, I chatted with a buddy of mine that is using a custom made top mast extender.
Why ?
well, first the guy is really a light weight (sub 60kg), and he is good. I mean really good, yet over his 60'. Always the first flying, makes it look as anything he does is just easy and effortless.
He explained that he needs to use softer mast, as he can't get the mast to bend so the sail is in its correct shape. As I am mostly foiling, I made the same thinking, and I usually rig one size below recommended spec. But it is sometime difficult to have an base extender long enougth. And I don't like having the wishbone clamped to low on the mast.
He explained he made a top mast extender from a broken top. He also claims the too long base mast extention makes the rig 'hard topped'.
I surfed the web in search of example and came across this :

snides8

razzmatazz said...

anybody knows where to get one of these and how much they roughly are. I want to extend my 460 at the top to make a 490 or thereabouts. cheers

sorry i dont know where you can get them from.
i am not aware if any manufacturers make them.
a few guys here( including myself and slowboat) make them out of old top sections of masts that where broken etc.
you need to be a little handy as you will have to ensure the tip will fit over the top of your existing mast. then you just need to glue/epoxy a stopper inside the tip at the required length to give you a 300mm extention.
hope this helps.
they are ideal for lighter riders who may need a slightly softer mast.

I know it is from a distant past, but if you happen to have some pics of such a set up, I'd appreciate to have a look on how it was mad.

It is a bad idea, because it puts a ton of extra weight were you can feel it the most. Besides the weight, it is very unclear what it would be the influence on the flex character of the mast. An extra ferrule and the short, unavoidably stiff, top extension would probably mess up any mast/sail combo. And just to clarify, using a long extension allows you to use a softer mast, it does not induce a "hard top".

PS For an example of the weight distribution of mast sections check out this post www.seabreeze.com.au/forums/Windsurfing/Review/Point-7-SDM-K80-K100-weight-distribution?page=1#5, which shows a 200 grams plus difference between the top sections of a 80 vs 100 carbon mast. A top carbon extension would add at least 200 grams to the top-most part of the mast, not to mention what an aluminum one would do!!!!

I'm unsure about the weight gain but I'm 100% sure it's still lighter than one size up, at least for my extension.

The mast will be slightly more flex top than using a long base extension. In one case the batten above the boom will clear more the mast than the bottom one, in the other the opposite. So the pocket moves slightly up and down.

It's great for light weights and people looking to use a bit less extension for wave riding to minimize stress on the base extension.

I have used mine for years and like it. It's a pretty firm fit so I don't need to electrical tape it or anything. Even if we lose it in the mast sleeve, it'll just fall off down.

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duzzi said..


It is a bad idea, because it puts a ton of extra weight were you can feel it the most. Besides the weight, it is very unclear what it would be the influence on the flex character of the mast. An extra ferrule and the short, unavoidably stiff, top extension would probably mess up any mast/sail combo. And just to clarify, using a long extension allows you to use a softer mast, it does not induce a "hard top".

PS For an example of the weight distribution of mast sections check out this post www.seabreeze.com.au/forums/Windsurfing/Review/Point-7-SDM-K80-K100-weight-distribution?page=1#5, which shows a 200 grams plus difference between the top sections of a 80 vs 100 carbon mast. A top carbon extension would add at least 200 grams to the top-most part of the mast, not to mention what an aluminum one would do!!!!

Not really.
Some of the ones I have made from carbon tube have been lighter than the actual mast at the top, others are the same weight and some have been a bit heavier...but none have been noticeably heavier in use. I cannot tell any weight difference when using the rig.
I have yet to break one either.

Bend curve-as I said in a previous post. tip extensions make masts more flex top.
Lengths of 100mm and below seem to have more marginal effects, lengths over 200mm can have much more pronounced effects and 150mm seems to be a sweet spot.

The main pain with a tip extension is that many masts have different diameters, so you end up needing one for each mast, that and they need taping so they don't stay behind in the sail when derigging!

Tips are certainly legitimate tuning devices, if you can be bothered.

They are not a "bad idea".

If you add an extension to the top of the mast you are not adding its full weight to the top as you have to deduct the weight of the mast that would be there if you extended it from the bottom.
so if for example your 10cm extension weighed 100grams and the top 10cm of your mast weighed 50grams your only really adding 50grams to the top over extending it from the bottom

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sheddweller said..

duzzi said..


It is a bad idea, because it puts a ton of extra weight were you can feel it the most. Besides the weight, it is very unclear what it would be the influence on the flex character of the mast. An extra ferrule and the short, unavoidably stiff, top extension would probably mess up any mast/sail combo. And just to clarify, using a long extension allows you to use a softer mast, it does not induce a "hard top".

PS For an example of the weight distribution of mast sections check out this post www.seabreeze.com.au/forums/Windsurfing/Review/Point-7-SDM-K80-K100-weight-distribution?page=1#5, which shows a 200 grams plus difference between the top sections of a 80 vs 100 carbon mast. A top carbon extension would add at least 200 grams to the top-most part of the mast, not to mention what an aluminum one would do!!!!

Not really.
Some of the ones I have made from carbon tube have been lighter than the actual mast at the top, others are the same weight and some have been a bit heavier...but none have been noticeably heavier in use. I cannot tell any weight difference when using the rig.
I have yet to break one either.

Bend curve-as I said in a previous post. tip extensions make masts more flex top.
Lengths of 100mm and below seem to have more marginal effects, lengths over 200mm can have much more pronounced effects and 150mm seems to be a sweet spot.

The main pain with a tip extension is that many masts have different diameters, so you end up needing one for each mast, that and they need taping so they don't stay behind in the sail when derigging!

Tips are certainly legitimate tuning devices, if you can be bothered.

They are not a "bad idea".

I don't see how one can claim that home made tip extensions have this of that flex effect without measuring the flex ... but besides, if it is such a good idea why you cannot buy tip extensions anywhere? Regular extensions can extend your mast up to 50 cm, and seem to have none of the problems associated with tip extensions.

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duzzi said..

I don't see how one can claim that home made tip extensions have this of that flex effect without measuring the flex ... but besides, if it is such a good idea why you cannot buy tip extensions anywhere? Regular extensions can extend your mast up to 50 cm, and seem to have none of the problems associated with tip extensions.

I do measure the flex, In 2 different ways. That's how I know the effect tip extensions have with respect to bend curve. I have also cut bits off the top of masts and measured what effect it has( makes the tops stiffer) and weighed the offcuts, which is how I know that using a tip extension can sometimes reduce the swing weight of a mast.
I have done the work and got the answers so am commenting with direct knowledge. Are you?

No, I haven't. I have very little interest in pursuing what I think are bad ideas. But good for you for making the effort, and discovering that cutting down a tube decreases its deflection for the same amount of applied force. Anyway, if you are so convinced that putting home made contraptions on top of precision designed masts is smart go ahead, you might be onto something and could even start a business!

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duzzi said..
No, I haven't. I have very little interest in pursuing what I think are bad ideas. But good for you for making the effort, and discovering that cutting down a tube decreases its deflection for the same amount of applied force. Anyway, if you are so convinced that putting home made contraptions on top of precision designed masts is smart go ahead, you might be onto something and could even start a business!

Thinking and knowing are 2 different things.
I am quite often surprised by the results of testing. That is a good thing.

What problems are associated with tip extensions?

Problem with long mast bottom extensions are:
1. Loss in mast top flex (can possibly be a pro for a soft sail and a heavy guy to be fair)
2. Added weight
3. Weak in surf
4. Added cost

For me 3. is critical and 2 is a nice bonus.

Now a light weight friend of mine liked to use his 5.0 with a smaller mast to soften the sail. He used a long bottom extension, (most likely because tip extensions aren't so popular).

It worked well for his type of sailing. No way in hell I'd use a long carbon mast extension in surf though!