Mast construction for rounding Cape Horn

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  • 17 Dec 2021 09:20
    Reply # 12198439 on 12197206

    Are second hand carbon fiber masts really suitable for a junk rig? I guess at least some of them are designed to fit a wishbone rig. The occurring forces will be quite different i guess?


    E. Sponberg, page86

  • 17 Dec 2021 08:55
    Reply # 12198415 on 12197206

    Some anecdotal evidence:

    I got knocked down twice in the S Atlantic and my aluminium masts were undamaged. 
    Galway Blazer lost spruce masts in the same area. 
    Jester and Jester II. both lost spruce masts.
    Badger went to Antarctica without mast trouble. Hers are near-solid, built from many pieces of douglas fir.

    I used to have a mooring near a Freedom 40 that broke at least two “carbon” masts. There was little actual carbon in evidence at the break.

    Long ago, I raced an OK dinghy in the days when their unstayed masts were made of spruce. The usual mode of failure was horizontal compression cracks on the after side.

    For a timber mast, I would be looking for something with high compression strength and fatigue resistance. 

    Last modified: 17 Dec 2021 08:59 | Anonymous member
  • 17 Dec 2021 01:50
    Reply # 12197938 on 12197206

    I'm not that familiar with carbon fiber , or free standing masts. I very familiar with wood and fiberglass. I will keep a eye out for a freestanding mast though, and look at the specs for the aluminum. 

      What would be the downside of a wood mast wrapped in carbon fiber, or even just a couple layers of glass? I'm so familiar with wood I keep going back to it. Plus it's pretty cheap, if I can make it strong enough.

  • 17 Dec 2021 01:17
    Reply # 12197898 on 12197206

    On the East Coast US, it is probably worth looking for a good used free standing mast by contacting the numerous boatyards.  Boats get scrapped every year.  I've seen a number of Freedom carbon fiber masts listed........ of course that means getting the boat to the mast most likely instead of the other way around.   Here is a listing I found in a few minutes after reading your post...... just as an example.  Located in Buzzards Bay MA, it's a 60' carbon fiber mast, 12" at the base, 6" at the top from some  model of Freedom.  At $7500, it's a bit pricey, but so is an aluminum flagpole from what I've seen.  I've seen a lot cheaper Freedom masts, and I suspect the mast you are looking for is laying in some boatyard if only you could find it   ;-)

    60' Carbon Fiber Mast


  • 16 Dec 2021 22:47
    Reply # 12197691 on 12197206

    My experience of flagpole suppliers and manufacturers is that they run away when you talk about using their products for mast.  I think you need to do an independent assessment based on the specifications.  The section should be spun-tapered for a start, not welded, and the wall thickness should be a minimum of 5mm for a mast suitable for your boat.  It should ideally be 6061 alloy with a T6 tempering, for additional hardening.  I don't think my 10.5m mast on Arion was T6 though.  It had a diameter of 200mm at the base and began tapering about four metres up from the base to 100mm at the truck, with a wall thickness of 5mm.  It was the bottom section of a 25m flagpole, made in France.  Setting 35 sq m of sail, I hammered that rig for some 15000 miles of coastal cruising without problems.  It is hard to say if an alloy or timber mast would survive a violent capsize, which is always a possibility in the Southern Ocean.  If I was sailing there with an alloy or timber mast, I'd carry a built in jury rig on deck, like Galway Blazer did.

    Lady Pepperell, a boat with unstayed carbon-fibre masts, was violently pitchpoled in the Southern Indian Ocean in the 1982-3 BOC race.  Her rig survived, even though the force of the 'corkscrew' capsize caused severe structural damage to her keel, and the boat was abandoned.  I'd choose a CF mast for the south, if I had deep enough pockets.  Timber and alloy masts are perfectly ok for most eventualities, however. 

    PS:  If I do another junk rig conversion, I will probably make a hybrid mast, with an alloy bottom section and a timber topmast.  I have sourced a straight 6.5m section with 200mm dia and 6mm wall thickness that would suit.  I'm not planning to go into the Southern Ocean, however!  

    Last modified: 16 Dec 2021 23:34 | Anonymous member
  • 16 Dec 2021 18:11
    Message # 12197206

    Hello all, I have a Cape Dory 28 with a sloop rig. I want to convert to junk. I spoke to a extruded aluminum flag pole vender, he said after speaking to the manufacturer at length , the poles would not be suitable for a mast. Locally I can source 2x10x20 spar grade sitka spruce, I am a carpenter so am able to make a mast with wood. 

    So here's the low down...I want to head south and play it by ear, but a tentative goal is to round Cape Horn, aside from that I will be sailing to Asia , so this rig needs to be as bullet proof as possible. 

    I am open to suggestions, including steel , aluminum, wood. Also with wood I'm interested in thoughts on most sturdy construction type. I am located in NC on the east coast of the US. 

    I know there are alot of posts about masts, I hope this is enough of a different question so as not to make this a redundant post.

    Thanks!

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