Latest News: Forums Technical Can’t get pre-bend

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  • #4152
    Algol
    Member

    So I went to set up the mast today on my Mk II and I couldn’t get any pre-bend in the mast.

    Why would this be?

    First off, we had probs with the spreaders.

    1. The spreaders were too long. They wouldn’t adjust down below about 515mm (recommended is 503mm I think).
    2. A bottle screw broke so I had to borrow one off another boat and we had to leave the bottle screw settings as I found them as the one I borrowed was seized too.
    3. The end result was the mast to spreader-spreader distance was about 240mm (it’s meant to be 200mm)

    Now, this setting should produce more mast pre-bend than recommended shouldn’t it? But, with rig tension and rake set we still got zero pre-bend. I even removed the chocking from the fibreglass mast chock/side pad.

    The friend who helped me wondered if it had been built to have no pre-bend, that the mast foot/shroud plate dimensions might not allow for it. Could that be the case?

    Any thoughts anyone?

    #9191
    Algol
    Member

    That mast chock thing.

    Sheared spreader screw

    #9196
    Swiebertje
    Participant

    As replied before; get that “mast chock thing” out. Its is preventing your mast from bending and it is *not* a Wayfarer part. Next remove the pin from the mast step it may prevent mast foot movement. That too could prevent the mast from bending. It is later put back to line op the holes in the mast with the holes in the tabernacle. Finally, but only after the above has been done, you may need to help the mast a little by pushing it forward. While sailing the mast gets this push from the kicker and the boom.

    The only permanent chocks you need are those that fix the mast sideways at deck level. Forward movement is restricted only in very light winds by easy removable, T-shaped chocks. These chocks go in from top to bottom, the top bar of the T prevents them from falling through. Made from 4mm ply, one chock only narrows the gap by 4 mm. If we want to close the entire gap we use several of those chocks or a beefier one.

    All this is so simple and easy to explain in the dinghy park with real boats at hand, and so difficult through text messages, Again my best advice is to go out there and meet other Wayfarers! Bring a camera and make lots of pictures of rigging details on other boats. That is how I learned.

    #9201
    Colin Parkstone
    Participant

    First thing to say but a bit late is that fibreglass moulding you have is very neat,not seen that before and is a class item as it is not covered by any class rule with regards to make,just does the job neatly.

    Next, the gate does sound as though it is short to alow the mast to bend forward, have you made sure the tabanacle pin is in the right place from the transom.

    If it is too far forward that will not help !Also measure the shroud base to the class rules!

    I think I see a highfield lever on the mast for the genoa halyard, if not then you are going to need the aft pin in the heel to hold the mast against the pull of a mussel box.

    One last thing to say is, each boat can differ so be preparded to not go too the class set up measurements to get what you want in set up. If the spreaders have to be past the 200mm or so to get prebend, then try it and see !!

    CP

    #9202
    Algol
    Member

    @Colin Parkstone wrote:

    have you made sure the tabanacle pin is in the right place from the transom.

    Do you mean the mast pivot pin or the mast heel pin?

    @Colin Parkstone wrote:

    If it is too far forward that will not help !Also measure the shroud base to the class rules!

    I’m going to check the class measurements and work from there.

    @Colin Parkstone wrote:

    I think I see a highfield lever on the mast for the genoa halyard, if not then you are going to need the aft pin in the heel to hold the mast against the pull of a mussel box.

    Yes, there’s a highfield lever, and the pin is there in the heel plate.

    Re muscle boxes etc, I’ve struggled to find any info on such products on the net. Can anyone point me towards them?

    #9203
    Swiebertje
    Participant

    First hit in Google on “Muscle box“: http://www.sailboats.co.uk/Cat~RWO_Standard_Muscle_Box_4807.html

    Though a muscle box is a neat solution it does have a lot of friction because it has eight (and sometimes ten) sheaves. I use a muscle box but I have to pump the tension on with two hands. Today most W-sailors prefer a cascade system on top of the CB case. Because it has only three blocks (8:1 purchase) it has far less friction. The cascade is usually placed left and right of the CB slot leaving the slot itself free. A piece of bungee holds the cascade in place when it is not in use, without it the lines quickly become entangled. The last block of the cascade has a hook to attach the halyard or the storage bungee to.

    A cascade system for a boom vang is explained here: http://www.wayfarer-international.org/WIT/race.related/RiggingTips/TonJaspers/TJcascade_vang.html It shouldn’t be difficult to imagine a similar system on top of the CB case to tension the Genoa halyard.

    #9206
    tempest51
    Member

    In the top photo above, there is a light blue dyneema cord going through the deck. Does anyone know what the white hole plug/protector is called and where I can find them?

    #9207
    Swiebertje
    Participant
    #9209
    BluTak
    Participant

    I have that blue sleeve on the front of my mast and it was put on by a rigger friend as he noticed a small crack in the mast. I wonder if yours is there for the same reason. It works fine but then I don’t put loads of prebend in the mast. Don’t bust your mast they’re expensive! Robert
    The white hole protector looks like a pipe outlet flange. I have one on the outside of the boat for a pump albeit a bit bigger

    #9210
    tempest51
    Member

    Well done Swiebertje, spot on as usual
    Dziekuje bardzo…

    #9214
    Swiebertje
    Participant

    @BluTak wrote:

    I have that blue sleeve on the front of my mast and it was put on by a rigger friend as he noticed a small crack in the mast. I wonder if yours is there for the same reason. It works fine but then I don’t put loads of prebend in the mast. Don’t bust your mast they’re expensive! Robert
    The white hole protector looks like a pipe outlet flange. I have one on the outside of the boat for a pump albeit a bit bigger

    If you start using chocks the mast is point loaded at deck level. It may be a good idea to fit that sleeve just as a precaution. If you order a champion version Wayfarer a sleeved mast is fitted standard by the builder. Maybe that is because racers tend to use chocks all the time?

    There are ways to fix a small crack in the mast but a sleeve is NOT the way to do it.

    #9216
    Colin Parkstone
    Participant

    Yes Algol, the pivet pin holes in the tabernacle. They have a measurment postion and if they happen to be to far forward, that may not help your prebend.

    C P

    #9218
    BluTak
    Participant

    Swiebertje – thats what I thought prebend could cause problems at deck level – my boat had been previously raced and had a vicious kicker on it. My friend who is a rigger and maintains many Wayfarer training boats (he was also Flying Fifteen World Champion for a years as crew – probably still is!) said that this was quite usual on Wayfarers and that the sleeve was his standard fix – he’d never had any problems. What do you know that I don’t? I’d be interested to hear your recommendations.
    Robert

    #9219
    Algol
    Member

    @Colin Parkstone wrote:

    Yes Algol, the pivet pin holes in the tabernacle. They have a measurment postion and if they happen to be to far forward, that may not help your prebend.

    I’m going to check these measurements, as I’m a bit baffled about the lack of pre-bend right now.

    Not that the mast doesn’t bend at all. At the weekend it pointed lovely in light airs with the boom block-to-block.

    And that’s a massive improvement as it was inverting prior to this weekend, which is likely why I was overpowered on a previous couple of occasions.

    #9220
    Swiebertje
    Participant

    @BluTak wrote:

    Swiebertje – thats what I thought prebend could cause problems at deck level – my boat had been previously raced and had a vicious kicker on it. My friend who is a rigger and maintains many Wayfarer training boats (he was also Flying Fifteen World Champion for a years as crew – probably still is!) said that this was quite usual on Wayfarers and that the sleeve was his standard fix – he’d never had any problems. What do you know that I don’t? I’d be interested to hear your recommendations.
    Robert

    Cracks occur at the front of the mast where it is stretched when it is bend (the rear is compressed). The sleeve is fixed to the mast at the rear by only four rivets hence it does not take the stretching forces at the front of the mast.(The front can still move inside the sleeve). A doubler could work but only if it is fixed to the front of the mast. But if you fix it with rivets in the front, the holes may cause yet more cracks. In general you don’t want holes in the front of the mast where the stretching forces are strongest (at deck level) and this is also the spot where it is point loaded. The only good way to fix a crack is by welding it. And if it is a big crack it may have to be reinforced by doubling it. A doubler is a sleeve that is welded to the mast on all sides.

    Welding most probably changes the bend characteristics of the mast. Maybe you are better of with a new one? A new mast does not need to be expensive if you buy a bare mast and transfer the fittings yourself. Also you need to ask why the cracks are there? Has the mast been over stretched? Is it material fatigue? A crack is often a sign of something much worse. If a crack is fixed (welded) chances are a new one will appear next to the fixed one because the mast has worn out, its past its time, its a dead parrot.

    The blue collar’s sole purpose is to beef up the mast where it is point loaded by chocks or by the deck. The collar spreads the load over a larger area of the actual mast thus protecting it (a little) without influencing the bend characteristics. It also prevents chafing of the actual mast. As such it may prolongate the life of a mast by preventing damage, it does not fix damage.

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