upgrade to aluminum mast (on a budget)

Discussion in 'Materials' started by eulachon, Aug 21, 2008.

  1. eulachon
    Joined: Aug 2008
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    Location: central/north coast bc

    eulachon New Member

    Hello all!

    I am the proud new owner of a fine rugged steel double-ended cutter. It was built for offshore use, and it ain't no dandy. Everything's steel, including the mast, which is 5 inch pipe schedule 80 (!) pipe, I'm informed.

    I am concerned that the heavy steel mast will detract from performance of the boat in a stiff breeze. I had it out in a 16 knot breeze with all canvas up, and found the angle of heel to be more than what I expected from a 14 1/2 tonne boat, fully keeled and ballasted as it is. The gunwales were dipping mighty close to the drink at times, in what I would consider to be moderate conditions. The 43 foot mast (cabin-stepped) is based upon Swain's "Frameless Steel Boatbuilding" book's specs...

    I have nothing against a steel mast in principal- in fact it matches the theme of the rest of the boat: bombproof and economical. My concern is excess weight aloft, and attendant problems with performance (angle of heel) and safety (righting moment, moment of inertia) in heavier conditions.

    I'm considering switching the pole out for an aluminum one. To be feasible for me it would have to be relatively cheap of an upgrade. I am also curious about the possibility of stepping a new mast to the keel, rather than the cabin when it currently is.

    And so I come to you all seeking wisdom! I would consider sourcing a used pole, but how likely is it I will find a 43-53 foot mast, and is it a good idea anyway to put a used mast on my boat?.....

    Another option would be to order schedule 80 extrusion custom cut for me, and fit the hardware to it- a little heavier (no big deal), and possibly even stronger, but I suspect that would be at least $4K all said and done: out of reach for me right now.

    Any suggestions would be gratefully received. I'm located on the central coast of BC
     

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    Last edited: Aug 21, 2008
  2. BHOFM
    Joined: Jun 2008
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    BHOFM Senior Member

    I would think a used mast would be the way to go, you
    could have any un-needed holes welded for little or nothing!

    Also, would not most of your standing rigging be reusable?
     
  3. eulachon
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    eulachon New Member

    Yes-
    All of my standing rigging is stout galvanized, and will be reusable after replacing the mast.

    Any ideas where to source a used mast?
     
  4. Petros
    Joined: Oct 2007
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    Petros Senior Member

    Try boat yards in your area for a used mast. Before you replace your mast there are a few other things to consider.

    I would have a good sail maker look over your sails. If they are old and stretched out, or if the plan is unsuited to your rig, there may be more benefit to having them recut. Worn or poorly fitted sails will results in too much heel and poor performance. This I suspect may be more effective, and less cost and trouble than replacing the mast.

    Since you are not changing your rigging the weight of the mast alone may not have that much effect in how much heel you get. It would be fairly straightforward to calculate the change in heeling moment from loosing the extra weight, and as a percentage of the total you could find it may not be significant.

    Also consider your ballast and keel design, adding weight low under the floor can be an inexpensive experiment that is easy to undo if it does not help.

    Is the original designer still available for consult? If so you might ask him for some suggestions to reduce the heel, he should know more about the design than anyone else.

    Good luck, it looks like a very nice boat.
     
  5. alan white
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    alan white Senior Member

    Some boats heel easily and then stiffen up once a flattish section settles in. See drawings of Slocum's Spray for an example of this. Most important is how well she sails at that angle of heel.
    I'm guessing you have a Vee bottom because it lends to steel designs with a constant angle up from the keel. If you're used to a more developed (usu. fiberglass) hull, you would find that the simple deadrise hull easily heels, but to get her over past the point where the leeward bottom is horizontal would take a hurricane.

    Alan
     
  6. eulachon
    Joined: Aug 2008
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    eulachon New Member

    Well, interesting thoughts gentlemen.... I'm grateful for your input.

    In response to Petros: the sails are triple reefed offshore "Lee" sails, cut for this boat's rig and very lightly used. If I understand what you are saying, barring replacement of the rigging I may not see the drastic reduction in weight aloft that I am expecting simply by switching the mast out for an aluminum one. This raises the question: how much lighter is an aluminum mast than an equally long 5 inch schedule 80 pipe? Anyone? I haven't the foggiest myself, and I confess to simply making an assumption: that it's "a lot".

    As for the ballast, the boat is adequately ballasted with approx 6000 lbs of steel set in concrete. In fact the builder reckoned that it was slightly over ballasted for offshore cruising, and that a full cruising kitty would take closer to her water line than he preferred (not a big deal to me- a line's just a line!). But as you say, weight under the floor... truth is, the previous owner has taken all his stuff out of the boat, so when it's loaded up with all of me and my girlfriend's crap, after we've moved on... well that'll probably change things.

    The original designer told me he would switch the mast out for a wood pole!

    To Alan White: As you say, the boat does stiffen up on her ear. The topsides have a pronounced flair above the hard chine. Perhaps I should use her as she is for a while, before I consider such a major upgrade... I just can't help but think that the steel must be considerably heavier, and that less weight aloft is always a good thing, no?

    Attached is a photo of the bottom before we painted her up fresh.

    Cheers!
     

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    Last edited: Aug 23, 2008
  7. alan white
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    alan white Senior Member

    To Alan White: As you say, the boat does stiffen up on her ear. The topsides have a pronounced flair above the hard chine. Perhaps I should use her as she is for a while, before I consider such a major upgrade... I just can't help but think that the steel must be considerably heavier, and that less weight aloft is always a good thing, no?

    The steel is heavier--- how much is easily calculated. And only you, after a bit of cruising around, can decide whether the top hamper is a good or a bad thing, since contrary to what you might think, weight aloft has some effect on comfortable motion, slowing the roll.
    The designer should have done the math and you might discuss the pros and cons of weight aloft with him as applies to that particular design.
    I would definitely sail her as is for a while. A steel mast is cheapest to replace and it may be that a lighter steel mast would also be a good solution.
    It's possible that the existing mast(s) is overbuilt.
     
  8. Meanz Beanz
    Joined: Jun 2007
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    Meanz Beanz Boom Doom Gloom Boom

    Eeeekkkk don't weld Aluminum masts, it takes them out of temper and will likely cause problems later. At the very least be very careful about what you weld, where... depending on the original temper of the mast you could set up a failure in time. Often when you see masts with welding they have been fabricated then tempered and anodised later. I'm no expert but I have looked into welding Aluminum and man its a bit of a science unto itself... ask someone who really knows their stuff before you go welding it.

    I have used epoxies to fill small holes prior to painting, that seems to have worked well so far...

    Now some one come shoot me down...

    PS the steel mast sounds like a disaster... you are right to seek a lighter alternate IMO. An open frame steel mast might be a cost effective idea (triangle space frame beam thingy, that you see some times), not pretty but... $64q is what did the designer intend her to carry?
     
  9. lazeyjack

    lazeyjack Guest

    beans you are right, sort of, you can weld UP a mast but never around it
     
  10. Meanz Beanz
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    Meanz Beanz Boom Doom Gloom Boom

    On my cat the fwd beam has crush post welded in where she is bolted to the hulls. The inside bolt develops fractures around the base of the post due to flexing, these fractures travel for about one inch then stop... basically it seems its the area taken out of temper by the welding that is prone to cracks. Problem is that once started they can follow through into the rest of the beam, some SW24's have broken front beams, which is kinda crazy because the beam is massively over strength. However the simple combination of welding in the wrong spot and a beam, that while it is over strength, it is under engineered and flexes (needs a pelican striker) can lead to failure... its not really a big problem but one to keep an eye on and not one you expect given the huge beams. Anyway just by way of example of how a small weld can cause surprising problems.
     

  11. Meanz Beanz
    Joined: Jun 2007
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    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

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