Damage to aluminium masts

  • 04 Jul 2014 00:18
    Reply # 3037604 on 3031939

    If I do have structural problems with the top of my mast I can always cut it off and put in a timber topmast!  So far so good.  Arion is in Gladstone now and we had a blistering beam wind when we left Bundaberg, 20 gusting 25 knots.  The mast stood up fine but the crew suffered a bit - it was freezing cold, around 0 degrees C when we left at 0400 hours, and every second wave sent a blast of spray across the deck.  I would have loved to be sheltering inside the boat with just my head poking up out of a Jester Pramhood.  The lesson I have learned is that you've got to zealously guard against chafing aluminium masts.  This is probably true of all masts but a laminated timber mast with epoxy resin and cloth sheathing would at least be easy to fix.  Repairing the damage to Arion's mast is not possible without weakening the structure further (you cannot weld aluminium without weakening it).

    Off topic just a little - Gary, I think your partners will be fine as the decks of the Benford dories are structurally very solid.  When you build something yourself though it is easy to wonder, at least it is for me!  I also trust your masts are secured in their steps with bolts or some other system.  Arion's mast is secured in its step with a 10mm bolt.  It would also need to jump up about 200mm to get out of the steel tube I used as a step.  10mm is a bit light for a bolt and I should have used 12mm but it is probably ok.  David Lewis lost his junk-rigged Taniwha off the coast of NZ when his foremast broke out of the mast-step and punched a hole in the hull.  Interestingly, the mast was stayed.  I tried to advise him that stays would only increase stresses on the mast due to the inadequate staying angle.  His mainmast, which was unstayed, had no problems. 

    Last modified: 04 Jul 2014 00:22 | Anonymous member
  • 03 Jul 2014 21:28
    Reply # 3037520 on 3031939

    I suspect you don't need to worry about your foremast too much: Badger's was still like new after 110,000 miles! But you do sometimes wonder how they stay there - another reason for tying them down!

  • 03 Jul 2014 11:40
    Reply # 3037099 on 3031939
    Deleted user

    Interesting issue Graham.  At least its at the top of the mast where structural stresses are a much smaller issue. Our foremast takes an absolute hammering from all the pitching over waves so the mind boggles at what it will look like up there after a few years.  May be a case for composite masts, the top third of ours is oregon sheaved in glass. But i worry more about the mast staying in its partners than anything else. Good luck with that. 

  • 03 Jul 2014 10:44
    Reply # 3037078 on 3031939

    Oh, Graham, what a shame.  I'm sure that it won't be a real issue, but this type of accident is a bit distressing.  I can imagine that it might be an issue at the slingpoint.  Could you make a cone of leather or plastic to cover the block, eye, shackle etc there?  And/or put more fendering on the yard.  Is the fendering screwed on and might a screw have backed out (and gone altogether by now)?

    But it's the sort of thing that makes the argument for going slightly over-size even more convincing.  I hope your cruise is going well.

  • 26 Jun 2014 12:21
    Message # 3031939

    I note that elsewhere David Tyler mentions that the surface of Tystie's aluminium mast  is getting as bit beat up but that he still thinks it is structurally sound.  That gives me some comfort as I recently discovered, the day before setting off on a coastal cruise north along the QLD coast, that I have managed to score some deep grooves in the upper third of my beautiful spar.  I am unsure of how it happened.  I have renewed some of the batten fendering that was getting a bit threadbare in places but cannot imaging an alloy batten could inflict such damage, and also the highest groove looks suspiciously like the location of the yard against the mast in the fully-hoisted position.  There was nothing amiss with the yard's fendering but I wonder if somehow the stainless steel shackle and block for the yard hauling parrel might be the culprit.  I had been in the habit of pulling the yard in really snug and it may have surged forward in the rough weather sailing I did last October heading south, especially when hoisting or lowering while the luff hauling parrel was slack.  This situation may be exacerbated by the fact that my yard is shorter than the battens (4m as opposed to 4.6m), so the sling point is further forward than it would be with a full- length yard.   I just don't know, never heard anything, though wonder how you could score the mast so deeply without hearing it.  I suppose when the boat is crashing along in 3 metre seas and 30 knots of wind you may not.  The grooves look like some maniac has been up there with a rat-tail file!  They must be 0.5mm deep in places.   Luckily my mast has a 5mm wall-thickness.  So it is a mystery and a deeply pained one at that.  I am now making sure to keep the sling point well away from the mast, am watching the fendering carefully and hoping that my mast is still structurally sound.  If I have to replace this spar I will be tempted to build a solid timber one, but hopefully it won't come to that.

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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