Anonymous wrote:
As a thought experiment, I'd like to pose the following.
Drawings often help point out thought errors or improvements.
There is a great deal of engineering, welding, materials and structural considerations involved with installing tabernacles for free standing JR masts. This is largely because the foredeck is bereft of structures to make such solutions fit with the purpose and aesthetic of most boats.
All of these engineering and material costs must be considered when considering the "price" of the mast.
Most tabernacles I have seen have been wood, those of metal are generally made by people who have the tools already. So _costs_ is a word that is hard to define. Cash money, is for most of us, hard limited. So materials from the scrap pile, while having value, are free. Engineering, for most people is free too. They are already engineering their mast and sails. The time spent does have value but often it is available where cash is not. Trees for some people, can be cut and dried for no cost. Aluminum pipe is available ready to go and in some cases may be had for recycle prices.
But assuming the mast and fittings are hired out:
I have used several small boats which utilize two piece carbon fiber masts to permit easy stowage of a mast which can be raised by an individual for a trailer sailer. There is an internal aluminum sleeve over which the upper section that joins the two parts slides.
And so my question: could the cost of an upper carbon tube be justified by creating a system using a mizzen mast which tilts forward to act as a crane which lifts the forward mast off a lower section braced at hull and deck partners?
Why not use two batons to lift for a more generic solution?
The lower section would be made of aluminum, and would be long enough to retain the sails, parrels and such of the sail when the upper section were removed.
The lower potion in this case sounds remarkably like a tabernacle :)
Obviously, the design of the two main mast sections and the sleeve between them would need to be carefully engineered and the mast professionally built. This cost would be either justifiable or not, and estimates would be crucial, but the result could be a way to avoid requiring a crane for a once or twice a year evolution.
"carefully engineered and the mast professionally built." Also means impossible to repair on a deserted island... or maybe even not so deserted but lacking a carbon fibre builder.
I think that a person used to working with carbon fibre would already use this for their mast because they are the professional builder and understand the material well enough engineer it.
There are lots of people in these forums and not all of them are willing or able to trade time for cash. There are others who have the means to have various parts of their yacht built for them and not the time to do it themselves. For those people they would still need to do at least some preliminary engineering on both (or all three) kinds of mast just to get to the point where they would have enough information to find out what the parts would cost. So there is some up front cost (either time or cash) just to find out if it may be cheaper.
My sense is that the missing part of the equation in the beginning is vessel size. For a 22 foot (6.75 ish meter) boat like the one I am working on, carbon fibre is just not in the cards... I started off with a free hull and intend to finish good enough for camping in. I am sure I can deal with things with no crane required... still not sure about the tabernacle :)
For a 40 foot Ketch (I presume), the whole thing changes. No one is going to spend the money for a 40 foot vessel and _not_ finish it much more like a home. The size and weight of the mast(s) will be much bigger and the cost of the mast(s) while much more expensive than the 22 ft version, are a much lower part of the overall cost. Everything changes. Now the wood or aluminum mast cost has gone up, if a crane is needed the size of crane may be higher too though I expect the crane the fisher's use for lifting there load onto the local dock would lift a pretty big mast from the deck of a boat to vertical for a minimal cost... some places may not be so lucky to have something like that.
So I think that there may be a particular size of vessel with a particular size of mast where carbon fibre may pay for itself. Smaller would be cheaper to use aluminum or wood and bigger may still need a crane even for carbon fibre. Each vessel would have to be assessed for it's own best solution.