Fiberglassing in an aluminum tabernacle?

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  • 22 Mar 2017 12:39
    Reply # 4682432 on 4663961

    All the comments from the crowd over the last few days go a long way to explaining why you see so few tabernacles on deep water cruising boats.  My original curiosity was whether they were rare because of expense or rare because of low function versus high complication.  I think that for larger masts, it's clearly the latter.  Putting the money and construction investment aside, it's still just too much bulk, too much weight, too high up, with too little utility.

    Admittedly, one of the reasons I wanted to investigate the idea is because I had always wished I'd put them in my last boat - but that was a trailer sailor where I had to step and unstep the masts every time I sailed.  Apparently not an issue with my big boy boat.

  • 22 Mar 2017 07:46
    Reply # 4682008 on 4678519
    Scott Dufour wrote:

    Yup.  That's definitely what I was missing.  A hinged mast with a sleeving tube, eh?

    Suddenly the world makes a bit more sense.

    If I went that route, I'm guessing that it would be something like:

    1) Order a mast the same length as if were a normal keel stepped mast.

    2) Cut the mast above the deck at about 10% of LOD.  Fabricate an internal hinge.

    3) Source another section of mast with an ID = the mast's OD.

    4) Sleeve this over the mast, fair the top somehow, and secure.

    The numbers would look something like:

    ft

    Mast total length from step 50.0
    Mast length above deck (LOD) 44.0
    10% of LOD (hinge height) 4.4
    Mast Length above hinge 39.6
    Sleeve extension above hinge 4.0
    Sleeve length 8.4
    Sleeve as % of LOD 19%

    It's about 120 lbs of added weight with COG 4 feet above the deck, not including the hinge materials. I wouldn't have to pay somebody to design it - I can do that myself. Sourcing the sleeve might be straight forward.  The mast is tube (OD = 10"), the sleeve can be 10" Schedule 40 pipe.  Pipe ID = 10"   My mast is the max most places provide (10" OD).  I think most pipe comes in 6061-T6, so that's way more than strong enough.

    I'm guessing the sleeve would cost maybe $1000 USD.  Figure another $1000 for the weld work fitting the mast hinge.

    Doable. 

    What d'yall think?  

    Scott I have got quite interested in this post but I want to ask how many times are you thinking of taking the mast down, The reason I ask is this on my last boat we only took the mast down once in 6 years divide that by the cost of a crane and per year it comes out at a reasonable rate. some detective work into yacht clubs may also bring good results

    in that some clubs have their own derrick that can be used by club members at a very reasonable rate, or thy hire a crane in to lift boats once or twice a year and you can slip in with that group

  • 21 Mar 2017 21:01
    Reply # 4681096 on 4680594
    Webmaster JRA wrote:
    Scott Dufour wrote:

    It may be that crane work is less expensive in the rest of the world than in Connecticut, USA.

    Definitely.  Mine cost  £80.00  = US$100! Cost me about the same in France a couple of years ago.

    How can anyone justify that much to pull a mast?

    Chris


    Depends on the size of the crane and the size of the mast.   Sometimes a HIAB would be too small to handle tall masts in a deep-draught boat out of the water. It cost me NZ$25 to put Fantail's mast back in a couple of years ago, with a mini-crane. 
  • 21 Mar 2017 20:01
    Reply # 4680981 on 4680281
    Scott Dufour wrote:

    It may be that crane work is less expensive in the rest of the world than in Connecticut, USA.  It was $1200 USD to pull the mast from my boat 

    Wow!  I'd of considered a tabernacle as well.  My marina doesn't have mast lifting services so I called a trucking/transport company and they sent a Knuckle Crane (HIAB) truck.  I still can't find my receipt, but the cost was closer to $300 for two masts and I was charged $100 per hour plus travel time.  Location: Vancouver, BC, Canada.
  • 21 Mar 2017 19:16
    Reply # 4680825 on 4680281
    Scott Dufour wrote:

    It may be that crane work is less expensive in the rest of the world than in Connecticut, USA.  It was $1200 USD to pull the mast from my boat when I brought it onto the hard last year.  

    I've had masts lifted in Canada and New Zealand, and from memory, the costs were under $200 in all cases.

    Last year, I got Weaverbird's mast stepped, using a HIAB, and the cost was based on an hourly rate of £55 + VAT. It was a quick job, but I had to pay for an hour's travelling time each way, so that made it 2.5 hours at £55 + VAT = £165. Still a far cry from $1200. 
  • 21 Mar 2017 17:45
    Reply # 4680594 on 4680281
    Anonymous member (Administrator)
    Scott Dufour wrote:

    It may be that crane work is less expensive in the rest of the world than in Connecticut, USA.

    Definitely.  Mine cost  £80.00  = US$100! Cost me about the same in France a couple of years ago.

    How can anyone justify that much to pull a mast?

    Chris


  • 21 Mar 2017 15:44
    Reply # 4680281 on 4663961

    That's a fair assessment, Darren.

    It may be that crane work is less expensive in the rest of the world than in Connecticut, USA.  It was $1200 USD to pull the mast from my boat when I brought it onto the hard last year.  But even that - how often would I need to do it?  I'm not planning on putting the boat up each year.  The mast would only need to come down for maintenance.

    I had entertained hopes of being able to lower it on my own to tuck into areas behind low bridges for a few weeks or months.  But really, how often would that happen when I've got a 6 foot draft?  Low bridges usually mean thin waters, too.

  • 21 Mar 2017 14:32
    Reply # 4680078 on 4663961

    I don't think you're giving up much Scott.  I have masts the size of yours and they come out surprisingly easy with a crane truck (assuming you have wooden wedges or a conical partners if you use something like spartite).  We laid the masts in a temporary wooden "gallows" for road transport, I think they would also have been fine like that for something like canal work.  I couldn't find my receipt for the crane truck, but it was not exorbitant.  Our driver hadn't done a mast before, but it didn't phase him in the least, I suppose a mast is a lot like a telephone pole.  If you're planning on removing the masts and laying them on deck, a stripe painted just above the centre of mass would come in handy.

  • 21 Mar 2017 12:59
    Reply # 4679903 on 4663961

    I've seen masts this large go up in a tabernacle before, though I admit, it was a full day project with a whole world of lines and a jury rigged A-frame.

    I really wanted to explore the option, in terms of money, design, and practicality so that I wasn't missing an opportunity with the boat all opened up and available.  It just doesn't trade, though.  I don't want to spend the money, I don't want the weight above the deck, and as Peter and David mention, even with a well-designed and strong tabernacle, it'll still be a bear to raise and lower the mast.

    I think I'm quite comfortable putting the tabernacle on a mast this size into the "Fully Considered and Fully Rejected" pile.

    Last modified: 21 Mar 2017 13:00 | Anonymous member
  • 21 Mar 2017 11:08
    Reply # 4679806 on 4678630
    David Tyler wrote:

    So the question I have to ask is: why do you think a tabernacle is needed? You're talking about a mighty big, heavy stick that cannot be handled with manpower alone. Even if there's a tabernacle, it would be a major undertaking to raise and lower the mast, and i don't know how I'd do it without a crane to pull it up. Why not, then, just use the crane to step the mast?

    Hi

    if i understand correctly from what David has said I would agree that any mast that two big guys can not throw around is going to become a monster when you try to set it up right.

    The cost of such a tabernacle with sufficient strength built in alone is going to cost.

    But if you are going this way use epoxy to stick it down with, you will have to etch the alli (you can get this at a good car panel place)  then coat it with epoxy let it set off then abrade with 120 grit paper mix up your epoxy with something like celli fibres these make a very strong pudding that will bed your hardware. re drill your holes as they will fill with epoxy  but it will make a barrier between the alli and stainless metals

    pete j

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