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  • #4005
    Anonymous
    Inactive

    Still at the early stages of the learning curve.

    I know I need to chock the mast to 1.ensure the weight is not supported just by the pivot pin and 2. prevent excessive movement of the mast. However, could someone advise the best way to go about this please e.g. do you chock the foot of the mast first to take pressure off the pin then chock around the deck level area of the mast?? Also, what are the pitfalls to avoid e.g. issues from too much/too little ‘chocking’?

    Phil
    W844

    #8551
    Fantasia
    Member

    From what you describe, mast chocks are the final part of what you need to do to set-up your rig correctly. There should be no strain on the mast pin whatsoever. This is achieved by positioning the mast heel in the mast step by adjusting the aft pin or bolt in the mast step. The whole rigging set-up procedure should be followed as described elsewhere (I or someone else will post a link to this shortly) and this may involve you in adjusting evrything several times over. When the rig is correctly set-up, you can then consider inserting chocks in front of the mast, essentially just to fill the gap in the gate to prevent the mast from over bending. I am sorry, but the complete answer to your question is rather lengthy and I am sure that others will contribute wise words.

    #8552

    Hello Phil,
    Couldn’t attempt the whole description but try this extract from the WIC site from Canada (worth browsing all the uncle Al stuff) for a quick idea of the horizontal “chocking”.

    http://www.wayfarer-international.org/WIT/race.related/SailShape.Trim.Care.Tuning/UncleAl/98MastMain.htm

    I confess I don’t do this myself.

    Then try the complex one, i.e. placing chocks in front of the mast. This one describes the reasons for it in detail. The content is also in the Wayfarer book – highly recommended.

    http://www.yachtsandyachting.com/downloads/?s=73&ArticleNumber=17

    The mast chocking bit is about 2/3rds of the way down. I read about this several times and was still a little unsure how it worked. However, if in doubt try the following:

    Rig boat, leave kicker loose and note the degree of bend at the mast head, and particularly the width of gap in front of the mast at deck level. Now heave the kicker on hard. You will note from your observations that you are bending the mast like a longbow, particularly if you have a strong kicker. The mast bows forwards at deck level reducing the gap in front. The “T” shaped chocks go into that gap to limit this, preventing overbending as per the linked article.

    The only other bit of “chocking I can think of is the possible need to shim under the mast to take the vertical strain off the pin. I don’t do this because the mast (just) sits on its foot within the track – no shims required.

    Hope this helps
    David

    #8553

    Phil,
    further to my above post. I suggest checking if there is any vertical pin load. If you DO need to shim below the mast to remove any load on the pin, that you try fixing something like feeler guage strip in the track. I have heard of coins being used but wonder if a fixed strip would make it easier to swing the mast up with no chance of hitting or dislodging the shim. On my boat the mast foot makes contact with the track just before vertical and it has to be pushed home that last few mm indicating that the foot is hard down taking the pressure off the pin.
    Cheers
    David

    #8561
    Colin Parkstone
    Participant

    David,
    The coins you talk about are used behide the mast and in front of the bolt in the mast step.

    A five new pence coin or more than one is used to fine tune the heel position in the step so that the pin is loose in a fore and aft postion.

    The chocks in the mast gate hold that position at deck level.

    The coins have also been used to buy ice cream when a the suns out!!!

    C P 😉

    #8562
    Anonymous
    Inactive

    @David Smethurst wrote:

    Hello Phil,
    The only other bit of “chocking I can think of is the possible need to shim under the mast to take the vertical strain off the pin. I don’t do this because the mast (just) sits on its foot within the track – no shims required.
    David

    Hi David,

    Thanks for taking the time to reply. I certainly need to shim the foot of the mast as at best, there is a scrape when raising the mast. The freedom of the mast to wobble was quite evident the other day.

    Am I correct in assuming that there are two elements adding the chocks, i.e. safety and rig tuning?

    #8563

    Hi Phil,
    See Colin’s reply regarding the use of coins. The use he describes is to ensure that the pin is not pinched fore and aft and the rear of the mast foot is firmly against the mast step bolt. There are only so many holes this bolt can be placed in so coins would provide intermediate positions.

    If your mast scrapes a little as it comes to vertical (like mine) I would suggest that this is taking the vertical load off the pin and the weight of the mast is on the mast step, not the pin, which is the desired condition.

    I think chocking is primarily a tuning, not a safety issue. The rig tension (or lack of it) could be causing the mast wobble. If the rear of the mast is not hard up against the bolt/coin, that wouldn’t help either. Nor would the lack of mast pin O rings, which should be a snug fit.

    The mast is intended to bend and there are racing adjustment that can make use of, or limit, both fore/aft and lateral bend, the more sophisticated of which are beyond me I’m afraid.

    Would an experience racer/tuner care to comment, I’ve peaked on this one!

    Cheers
    david

    #8568
    Anonymous
    Inactive

    Now I confess to being confused. Having check this afternoon, there is only one bolt on the mast which I the one I have been calling the pivot pin as it straight through the mast about a third down from the deck. There are no other bolts/fixings.

    Reading the comments above and the extract from WIT, am I right in thinking there should be a proper mast step at the foot of the mast with a pin for and aft to prevent movement of the foot of the mast. There is nothing that I would consider to be a mast step as seen on dinghies I have sailed before. More importantly, there is no evidence there was one resulting in pivot pin and standing rigging being the only stability to the mast.

    Increasingly thing this is not right

    Phil
    W844

    #8569
    matoi
    Member

    proper mast step at the foot of the mast with a pin for and aft to prevent movement of the foot of the mast.

    I just happen to have a nice photo on the web already which shows clearly the mast step (black thing) and the its pin (screw):

    The pin only prevents the mast foot from sliding aft. Forestay and/or jib luff wire tension is supposed to keep it from sliding forward, though it’s not that simple (at least in my experience).

    Best wishes,
    Mato

    #8570
    Anonymous
    Inactive

    Hi Matoi,

    Ah, completely different from what I have and I wonder whether there is a difference between wooden and Alu mast/fixings design?

    I would have uploaded a couple of pictures taken yesterday however, for the life of me I cannot find an ‘upload picture’ button and Bob’s Sticky example seems to be down at the moment.

    Phil
    W844

    #8571
    Fantasia
    Member

    Sorry, I had not realised that you have a wooden mast. Most of the references above are for aluminium masts, which have a similar set-up to that ilustrated. I don’t know much about setting a wooden mast rig, but I think there has been discussion on this forum in the past. Try the search function.

    #8574
    Anonymous
    Inactive

    All,

    Thanks for taking the time to reply and my apologies for not making it clear that W844 is wood mast and boom.

    Bob has quickly sorted me out with uploading pictures therefore …

    I guess I’m right in assuming that I need to remove the weight off the pin then support around the deck area and that there is no mast step???

    #8575
    Bob Harland
    Participant

    Phil, There has been some discussion about wood masts that may help …
    http://wayfarer.org.uk/forum/viewtopic.php?t=88&highlight=wood+mast

    As you suggest the weight should be off the pin, and support the mast at the deck level – both laterally and forward – so you have a snug fit.
    I don’t see much point in using removable chocks to control movement/bend as in a metal mast if you have a gap.
    I guess that wood shims all round are all you need for the mast to be snug with the deck. And set these with rig tension on.
    I suspect the rig would have been tensioned with bottle screws – rather than a tension device on the genoa halyard.

    David Smethurst has some pictures of W48 that may help;
    http://wayfarer.org.uk/forum/viewtopic.php?t=793
    You could ask him to email originals to you for more detail.

    regards
    bob

    #8576
    Anonymous
    Inactive

    Hi Bob,

    Many thanks for the link which has proved useful. I have to confess I disregarded it in an earlier search as thought it concerned just spreaders, which I am happy about.

    Now content with what needs to be done, thanks all for your guidance. Now off to carry out a bit of measuring then tailor make the handy off-cuts the nice man from B&Q let me have.

    Phil
    W844
    All wood

    #8577

    Hi Phil, sorry, made assumption about your mast step. Everything previous assumed you had the setup in Matoi’s photo. Also, don’t have detailed pic of W48 mast foot, but sounds like your on track now. Good luck
    David

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