Adjustable Mast Extension

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General Gps & Speed Waves Foiling Gear Reviews Lost & Found WA NSW QLD SA VIC TAS

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 11:57am

I've been racking my brains (OK, I thought about it for 5 mins) on how you could make a mast extension that, instead of having its length fixed and then have a pulley to downhaul, the mast extension itself could be adjusted in situ so that your sail is always downhauled to the bottom.
That way you wouldnt have to remember what length to set your mast extension for each sail and you could always have a perfectly rigged sail.
The only thing I can think of is a screw system, but that would get clogged up.

grumplestiltskin

2331 posts

grumplestiltskin

WA, 2331 posts

8 Jun 2007 12:15pm

I might be missing the point, but aren't you normally trying to get the foot of the sail as close to the mast base as possible?

If you adjusted the sail, and then had the option of increasing/decreasing the extension wouldn't you potentially end up with the foot really high off the board?

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 12:16pm

Can't get to the link.

tried searching or Crankin, that didnt work either...

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 12:26pm

quote:
Originally posted by grumplestiltskin

I might be missing the point, but aren't you normally trying to get the foot of the sail as close to the mast base as possible?

If you adjusted the sail, and then had the option of increasing/decreasing the extension wouldn't you potentially end up with the foot really high off the board?

Imagine just hooking your sail foot to the bottom of the mast extension I.e. where the lower pulley is.
So instead of pulling the sail down via a pulley system to meet the lower pulley you actually (some how) extend the mast extension itself to downhaul the sail.
Basically a way of adjusting the length of the mast with everything in place.
So if you want more downhaul you just wind out the base. The foot of the sail will always be at the lowest point.

Nebbian has found one (apparantly)

MJP68

QLD

145 posts

MJP68

QLD, 145 posts

8 Jun 2007 2:34pm

grinch, that's a really cool idea, and I think you're on the money with the screw idea, as you'd get the purchase you'd need and still be operable by hand (like those supports they use to lift houses off their stumps for replacement of the stumps).

so I'm thinking there'd a simple hook at the bottom to slide through the sail grommet or pulleys, then the rest of it could be two tubes, one nested snugly inside the other, and joined by the aforesaid threaded rod. then you could just operate the extension with some sort of a handle through the bottom or side of the base??

am I on the right track with what you're thinking??

MP

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 12:50pm

Yep,
Thats it in a nutshell Goldy.

If you were going to use a screw there would have to be a collar that rotated freely so you could attached the sail to it. There would be an inner and outer sleeve that would be threaded male and female. You could use a crank to crank out the inner sleeve. This could be incorporated somehouw so you could adjust outhaul up and down without taking the sail off the board.

If you were going to use a pulley system you have to find some way of pulling the extension down against the bottom of the mast. It could be done but gets a bit complicated.

The screw is simplest. The screw surface could be made from polythene or some other self lubricating material wrapped around an aluminium tube. But stopping sand and sh#t getting in there would be a bugger of a job, not to mention expensive.

MJP68

QLD

145 posts

MJP68

QLD, 145 posts

8 Jun 2007 3:02pm

grinch, some clever engineer type might be able to build the screw assembly so it was completely sealed inside the extension, much like the steering assembly in a car is sealed.

in fact, here's another idea, how about instead of two tubes, how about one tube (just like a normal extension) but with the threaded rod going up the middle of it. then as you turn the rod from the bottom, the mast collar rides up the screw and pushes the base of the mast away from the base of the extension??

ideas ideas ideas....

that's the trouble with windsurfing, not many moving parts so not much scope for inventions!!

I just wish I could "invent" some natural talent...

mp

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 1:03pm

quote:
Originally posted by nebbian

Fuggen forum code keeps stuffing up my URL...

I'll keep trying. Otherwise google "Crankin Mast Extension".

Try this:
~~http://tinyurl.com/yru2wm~~

This one looks similar to the Neil Pryde one. You still have to set the length of your extension and then pull the sail down to meet the bottom of the mast foot.

Imagine a magical mast that you just slide the sail onto to and wind the bottom of the mast out to downhaul. The foot of the sail will ALWAYS be at the bottom, you will never have a gap to the mast base.

If you want more or less downhaul you just wind it out/in. If you change sails you just wind!

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 1:10pm

quote:
Originally posted by goldy68

grinch, some clever engineer type might be able to build the screw assembly so it was completely sealed inside the extension, much like the steering assembly in a car is sealed.

in fact, here's another idea, how about instead of two tubes, how about one tube (just like a normal extension) but with the threaded rod going up the middle of it. then as you turn the rod from the bottom, the mast collar rides up the screw and pushes the base of the mast away from the base of the extension??

ideas ideas ideas....

that's the trouble with windsurfing, not many moving parts so not much scope for inventions!!

I just wish I could "invent" some natural talent...

mp

Bloody good idea!
How do you get the outer sheath and the threaded bar past the stationary cup that you have to have to press against.
Bloody good idea!

nebbian

6277 posts

nebbian

WA, 6277 posts

8 Jun 2007 1:15pm

quote:
Originally posted by The Grinch

quote:
Originally posted by nebbian

Fuggen forum code keeps stuffing up my URL...

I'll keep trying. Otherwise google "Crankin Mast Extension".

Try this:
~~http://tinyurl.com/yru2wm~~

This one looks similar to the Neil Pryde one. You still have to set the length of your extension and then pull the sail down to meet the bottom of the mast foot.

Imagine a magical mast that you just slide the sail onto to and wind the bottom of the mast out to downhaul. The foot of the sail will ALWAYS be at the bottom, you will never have a gap to the mast base.

If you want more or less downhaul you just wind it out/in. If you change sails you just wind!

You've got it wrong, the rings there are for coarse adjustment, the crank actually makes the extension get longer/shorter. So the foot of the sail is always at exactly the height you set it at.

MJP68

QLD

145 posts

MJP68

QLD, 145 posts

8 Jun 2007 3:17pm

hmmm....

what are you seeing as being the stationary cup?

I guess I'm imagining a "normal" extension, but instead of a series of holes going up the side (a la Chinook), we've actually got a slot of sorts (OK now we're talking serious instability, but lets leave that to the engineers!)

so the majority of the extension still fits INSIDE the mast (as per usual), but instead of the collar (i.e. the bit that stops the mast sliding right down the extension) being set once by hand, it moves up and down the extension via some sort of handle.

does that make sense??

mp

Tozza

160 posts

Tozza

WA, 160 posts

8 Jun 2007 1:34pm

What about an inverted "Nut & Bolt"

The nut start screwed all the way down to the head of the bolt, slide it into the mast, attach sale then start "unscrewing" the nut to increase the base length.

Hopefully this is original and not me just not understanding everyone :p

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 2:04pm

Pretty much what we are talking about Tozza.
remember it all has to be strong enough, easy to manufacture, and not get clogged.

Goldy
The stationary cup would be the equivalent of the collar.
This is the 'crunch' part of the design.

Re your idea
I think I get you. Like those winders they have to lift up sluise gates? You could have a cogged wheel and a 'track' on the side of the slider.

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 2:06pm

quote]

You've got it wrong, the rings there are for coarse adjustment, the crank actually makes the extension get longer/shorter. So the foot of the sail is always at exactly the height you set it at.

Ah,
Ok sorry, now I see. Looks good, apart from the big handle.
And the coarse adjuster, thats got to go in my design. Too fiddly...

grumplestiltskin

2331 posts

grumplestiltskin

WA, 2331 posts

8 Jun 2007 2:09pm

IF you are still going to be doing a bunch of cranking every time you want to change the downhaul, or sail, why not just buy one of the North ratched extensions.
You just hook it up and crank down your sail. Isn't that exactly what you want?

mineral1

4564 posts

mineral1

WA, 4564 posts

8 Jun 2007 2:19pm

quote:
Originally posted by grumplestiltskin

IF you are still going to be doing a bunch of cranking every time you want to change the downhaul, or sail, why not just buy one of the North ratched extensions.
You just hook it up and crank down your sail. Isn't that exactly what you want?

But I can visualize what they want, the adjustment is simple to apply, the structure to maintain the adjusting process is the part that needs to be structurally sound. Collar isn’t hard to duplicate, plenty of idea's within the marine industry to adapt. But the issue is compact, light weight so it cant damage gear and longevity with item but at an affordable price. Our PM gear we have follows same principal, but its "rooooobust"

Mackay

NSW

78 posts

Mackay

NSW, 78 posts

8 Jun 2007 4:47pm

I just posted a rough sketch in photos. Is this the kind of thing we are talking about. Sorry for crappy scan

Gestalt

QLD

14964 posts

Gestalt

QLD, 14964 posts

8 Jun 2007 4:50pm

nice one mackay,

looks like you just got the copyright....

Mackay

NSW

78 posts

Mackay

NSW, 78 posts

8 Jun 2007 5:14pm

Just call it the Seabreeze Grinch!

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 3:31pm

That looks good Mackay.

The only problem is to seal it all so the thread doesn't get cr@p in it.

I think a trip to Bunnings is in order!!

(Isnt the internet a great place. You come up with an idea and some one draws it for you).

Now my next idea is a female robot that is indistinguishable from the real thing but does everything you tell it to. Like Paris Hilton.

The Grinch

733 posts

The Grinch

WA, 733 posts

8 Jun 2007 4:46pm

I'm dissapointed in you Lauri!!

I know you didn't have long to make it but that robot looks nothing like Paris Hilton!

MJP68

QLD

145 posts

MJP68

QLD, 145 posts

8 Jun 2007 7:52pm

nailed it Mackay!

quick, what's a million dollars divided by 3???

I'm still wondering how you'd get the easy on-water adjustment (which is what's so great about the North)

could be that the one that nebs posted is the best engineering result for the concept that was suggested?

it's food for thought though isn't it? I mean, what if someone developed a mast bottom-half that had that gadget literally built in, and compensated for the engineering in the top part so you got a pefect curve for every length?? good-bye mast extensions and multiple mast sizes....

like almost everything else I spose these ideas aren't new, they just were'nt taken right through to their ideal conclusions by the people that dreamt them up. and which manufacturer is going to invest in a product that ends up meaning less eqipment?? ;-)

mp

decrepit

12883 posts

decrepit

WA, 12883 posts

8 Jun 2007 6:26pm

What an exciting idea!!!!

Haven't read all the posts carefully, to impatient to make this comment.

I don't like threads in this situation, to easy for them to jam with sand and salt.

Think you can stick with a pulley idea similar to an extending ladder.
But I think the pulley system would need to be inside the tubes.
Maybe I need to make a prototype and see if it works.

The only disadvantage I can think of at the moment, it would need a very long rope!

Gestalt

QLD

14964 posts

Gestalt

QLD, 14964 posts

8 Jun 2007 8:32pm

wouldn'yt be better to make the top of the mast extendable instead of the bottom?

DL

659 posts

WA, 659 posts

8 Jun 2007 7:14pm

> wouldn'yt be better to make the top of the mast extendable instead of the bottom?

No. Because it would be better to have the extra weight of the mechanism at the base of the mast... leverage and all that.

Gestalt

QLD

14964 posts

Gestalt

QLD, 14964 posts

8 Jun 2007 9:24pm

what i mean is just have diffenrt length sections that fit over the tip of your mast. so if you have a 430 mast and need a 450 length slip on a 20cm extension piece.

there is no weight, no mechanism etc.

just an idea anyways.

Sailhack

VIC

5000 posts

Sailhack

VIC, 5000 posts

8 Jun 2007 9:30pm

The sleeve idea is 'plausible' to quote a pair of geniuses on SBS (mythb....something???)

A twin sleeve with the internal sleeve attached to the mast-base with a cutout for a ratchet handle on the external sleeve, the downhaul lines could then be 'fixed lines' attached to the internal sleeve (base plate), and a 'ratchet' system (less likely to be affected by sand etc. also less likely to loosen and unthread-dethread???) with the mast slid to a stop (as are current extensions) by ratcheting the handle, the mast slides upward through the luff pocket increasing downhaul whilst the sail is firmly attached to the base (keeping bottom of sail as close to the board as poss.), a release button with a reversing action for the ratchet would give full adjustment whilst on the water without hitting land & looking for that pulla that keeps going missing when needed.

Great thread Grinch.

Gestalt

QLD

14964 posts

Gestalt

QLD, 14964 posts

8 Jun 2007 9:30pm

or even 2 pieces with the top piece screwing over the bottom piece.

put it at the top of the mast, insert a screwdriver and turn to get the 2 pieces to unscrew and get longer.

if you use a sail with an adjustable head you would be able to access it.

sorry sailhack, we hit send at the same time so i didn't see your post.

grumplestiltskin

2331 posts

grumplestiltskin

WA, 2331 posts

8 Jun 2007 7:34pm

quote:
Originally posted by Gestalt

or even 2 pieces with the top piece screwing over the bottom piece.

put it at the top of the mast, insert a screwdriver and turn to get the 2 pieces to unscrew and get longer.

if you use a sail with an adjustable head you would be able to access it.

Yeah, good thoughts Gesty, but imagine trying to turn the screwdriver.
Its bad enough hauling on a triple pulleed rope, how hard would it be to twist the screwdriver when the tension got up there.

Personally I think the Kranker that Laurie found is the answer, its just a pity you have to release and regrip the rope each time.

grumplestiltskin

2331 posts

grumplestiltskin

WA, 2331 posts

8 Jun 2007 8:02pm

What about a setup similar to the clamp on boom arrangement?

Pull the sail down to a reasonable tension, loop the rope around an clip it into the clamp, then force it up and over centre (like the boom clamp). One simple action!

Sailhack

VIC

5000 posts

Sailhack

VIC, 5000 posts

8 Jun 2007 10:20pm

quote:
Originally posted by grumplestiltskin

What about a setup similar to the clamp on boom arrangement?

Pull the sail down to a reasonable tension, loop the rope around an clip it into the clamp, then force it up and over centre (like the boom clamp). One simple action!

I liked my idea....but I like your idea more!!!

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