[Public-List] Hinged Mast Step

George Dinwiddie gdinwiddie at alberg30.org
Thu Dec 28 08:29:02 PST 2017


Yes, the use of the A Frame is described starting at 
http://alberg30.org/maintenance/SparsSailsRigging/UnsteppingMast/ The 
key is that the lifting force is applied at the balance point of the 
mast, greatly reducing the force at the foot. This allows the foot to be 
moved aft as the mast is lowered.

Yves Gelinas is an extraordinary sailor and mechanical engineer. The A30 
mast is much heavier than most that are engineered with hinged mast 
bases. I suspect that the off-the-shelf mast bases are not designed with 
the loads of such a heavy mast in mind. There is more to this equation 
than size of mast base. I am not a marine architect, but I suspect that 
the horizontal force at the base will be huge when the mast is half down.

  - George

On 12/28/17 10:05 AM, Wes Gardner via Public-List wrote:
> Hi Gerard,
> 
> Would you consider just building the A frame as you’ve suggested and leaving everything else the same? I know some of the folks here on the East coast have such an arrangement...I think it DOES Require more than one person.
> 
> Wes
> 
> 
> Sent from my iPad
> 
>> On Dec 27, 2017, at 11:37 PM, Gerard Kuperus via Public-List <public-list at lists.alberg30.org> wrote:
>>
>> Hello all,
>>
>>
>> Inspired by Yves Gelinas (as well as by my fear of heights) I am thinking about installing a hinged mast base. It would allow me to inspect once in a while and to do maintenance or solve problems up there. I would use an A-Frame (two 10' galvanized pipes bolted together) attached to the forestay or jib halyard, take the front lowers off, and ease some tension on the uppers (I guess) and slowly lower with a block and tackle (possibly the mainsheet). I am sure some of you have a system set up, so here are my questions:
>>
>> - the existing baseplate (the aluminum piece on which the mast sits) is rather large. I found Ballenger makes hinged mast steps, with a topplate that is 8" x 5.5" (see http://ballengerspars.com/) .This looks like a sturdy unity with the top and base plates on top of one another, but how do I attach the alluminum base to this (mine is the standard one with 4 big bolts). Having the nuts under the topplate would make it non-functional.
>>
>> - If I could somehow figure out how to attach these (or get another mast base that can be screwed on) it seems that the hinge should be as close to the mast as possible. If the pivot point is far aft the shrouds would need to be loosened quite a bit (since the mast would first go up). Or do I not get that right?
>>
>> - So, it seems I need a smaller mast base. Ballenger does have a smaller hinged mast step. Not sure where I can find a mast base for a 6 x 3.6 extrusion, but I am sure it is out there.
>>
>> - Another option is the hinge made by Dwyer (see for example here: http://www.downwindmarine.com/Dwyer-Hinged-Mast-Plates-Stainless-Steel-p-90890668.html). Now the biggest one is 6.5. The Alberg 30 mast would just fit on that.
>>
>> - A custom option is possible, but I think Ballenger makes a pretty solid product.
>>
>>
>> Any thoughts on my thoughts? Would I be right in getting a smaller mast base and then go for a hinged mast step that is about 6.5 x 4?
>>
>>
>> Thanks,
>>
>>
>> Gerard
>>
>> Skye Mist
>>
>> San Francisco Bay Area
>>
>>
>>
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-- 
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   When I remember bygone days                         George Dinwiddie
   I think how evening follows morn;            gdinwiddie at alberg30.org
   So many I loved were not yet dead,           http://www.Alberg30.org
   So many I love were not yet born.                          also see:
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