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  1. #99
    Senior Member tooold2dance's Avatar
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    Quote Originally Posted by Gorgesailor View Post
    Wow! Allot of posts over the weekend... This one has been done. In fact it was the very first RDM extension available - built by Streamlined & shipped with multiple plastic composite spacer sleeves circa 1990 or so.. Not a bad idea but not very elegant with all the spacers.
    You could very well be correct on the 1990 and Streamlined. My first RDM purpose made I am pretty sure was Windsurf Hawaii , late 90s or 2000.It was not very long, and I think GOLD in color, aluminum, the adjustments were by the spacer sleeves that were alloy as well, some were taller, weird thing it was. It very well sucked, big time. Worked only maybe better than the collar adapter on a SDM for fitting a RDM into.

    the concept I rekon could be refined.

    The volcano and lip thing that was used with a SDM extension to fit a RDM mast on/into, didn't really work badly

    Last edited by tooold2dance; 25th November 2013 at 10:35 PM.


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  2. #100
    Senior Member tooold2dance's Avatar
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    someone probably Basher mentioned when the Carbon ext broke it did this:




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  3. #101
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    Quote Originally Posted by Distinctly Average View Post
    I still think my idea has a lot of merit. You have an extension with no holes, no ridges, just a decent quality tube. To set extension length you have a set of tubes that simply slot onto the extension, think of them as just off-cuts when they make rdm masts. For me it seems all of my sails that fit on RDM masts (5 of them) require either 0, 5cm or 10cm of extension so I would only need 2 of these tubes. All it takes is the sail designer to be careful when thinking about how much extension is needed. The extension this way would not be compromised by any of that silly mucking about with holes, ill fitting pins and collars or ridges cut into it. To some it may sound like a bit of a backward step engineering wise but I do not think so.
    I like this idea. The sail manufacturer could provide you with a tube of the correct length when you buy your sail, if they were confident in their recomended settings. Theoretically the extension would be no weaker than the ferule that joins the two pieces of the mast in that case. However, in a wave sailing rinse cycle incident when the mast is under extreme stress it will eventually just break at the weakest point - likely to be just above or below the boom clamp. We then may all be clamouring for aluminium extensions that are engineered to bend under extreme load and still be able to sail back to the beach in recovery mode, rather than experience a much more expensive and session ending / sail damaging mast break

  4. #102
    Senior Member lostboy's Avatar
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    Quote Originally Posted by GlynRS2 View Post
    I like this idea. The sail manufacturer could provide you with a tube of the correct length when you buy your sail, if they were confident in their recomended settings. Theoretically the extension would be no weaker than the ferule that joins the two pieces of the mast in that case. However, in a wave sailing rinse cycle incident when the mast is under extreme stress it will eventually just break at the weakest point - likely to be just above or below the boom clamp. We then may all be clamouring for aluminium extensions that are engineered to bend under extreme load and still be able to sail back to the beach in recovery mode, rather than experience a much more expensive and session ending / sail damaging mast break
    That won't work. Not everyone uses the manufacturers masts and that can make a big difference to the amount of downhaul needed. A fixed length extension could therefore provide a potential problem keeping the cringle/tack block clear of the mastfoot block. You could obviously be happy with the compromise of having a big gap between the tack and the mastfoot and just use "the next tube size up" but it could be a big compromise.

    Oh, and I'm sorry DA but the idea certainly isn't new. I got my first alu tube extension when F2 made a series of very high aspect sails called the Wing Cut. They provided an adjustable alu extension, a custom length 60 cm alu tube and specially reinforced mast (with more and lower boom attachment reinforcement because of the position that you were putting the boom on with that much extension) as there weren't 520 masts around in those days (mid 80s). You used the extension set at almost zero, slid the alu tube over it and then the 460 mast over that to create a 520 mast suitable for the sail. It was, as you say, very light, didn't ever get broken despite being used for race, speed and freestyle sessions and still resides in my kit bag - but it hasn't been out for years.
    Got an opinion? Great. Guess what, so's everyone else!

  5. #103
    Senior Member /Vico's Avatar
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    Going back to bike technology they used to have handlebar stems that were infinitely adjustable for height but infinitely crap for strength i.e. quill stems. Even road bikes eventually went over to spacers simply because this meant the rest of the mechanism was better and stronger, and Joe Public soon accepted that he or she would have to have a few spacers around the place. It wouldn't be necessary to have manufacturer-supplied extension spacers - just some standard sizes which could be combined to make the same adjustments currently available with the holes.

    I think this is a bit of what has become known as a "first-world problem" - masts break far more often, for those who push things a bit in the rough stuff, and for Johnny Freeride the main strength and durability issues remain with board dings.
    It is what it is.

  6. #104

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    Quote Originally Posted by /Vico View Post
    Going back to bike technology they used to have handlebar stems that were infinitely adjustable for height but infinitely crap for strength i.e. quill stems.
    Indeed, when I was about 15 we were riding around the local BMX track when I heard a scream. A mate of mine was laying on the floor the down track side of the whoops with a broken stem. We all stood laughing until we realise one of his love plums was still attached to the broken off stubby bit of the stem, 3 feet away from where he was screaming.

  7. #105
    Senior Member SteveE's Avatar
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    I like the hydraulically adjustable seat stems for mountain bikes. perhaps something like that could be adapted? Not enough pressure to adjust downhall though, although you could let some off with one.

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