Telephone Pole Mast and Galvanized Wire Rigging - Why Not ?

[senormechanico]

Originally Posted by fstbttms

Certainly more of a likelihood with a telephone pole sticking the hell up out of the middle of your boat.

Sails make the boat go. Every other part makes it go slower.

[Juniper]

With steel wire or SS wire, lower cost wire and labor to parcel and serve, or more costly wire and less labor? money or time. With SS wire you pay and put it up done, repete 5 to 20 years later. Steel wire, every year you fully inspect it reapply oil as needed reserve as needed, It come back to which is better a fiberglass boat or a wooden boat.

[goprisko]

The use of galvanized 7X7 wire rope in yacht rigging is practical.

If you intend to use this wire rope you can either splice it, or terminate it
with poured sockets (capels). Poured sockets are used in elevators and cranes. They are strong, and given they are poured with zinc alloy, the wire rope is protected from electrolysis.

Galvanized rigging was traditionally coated with Stockholm tar, parceled and served. The serving was annually recoated with more tar. Rigging treated this way carried Wanderer III around the world on her first circumnavigation.

Such rigging was common in yachts during the 30's. It lasted decades.

It was slightly heavier than SS 1X19 wire rope. It has more stretch than SS 1X19 too.

A glulam mast is also a practical solution, given you have access to a fabricator, and yes, they can leave channels for internal wiring, which should be run during fabrication of the mast. The spreader bases, and other fittings must be traditional bolt on fittings.

Aluminum tapered telephone poles have been used for unstayed masts by many, as well.

INDY

[Jim Cate]

Originally Posted by pressuredrop

just so happens that one person is one of the greatest sailors/voyagers of our time...

bernards rig stood up to numerous knock downs, and if youve read his books you will know he pushed that thing 110% most of the time, i dont think a conventional modern rig would survive so many knockdowns...

If Bernard had not had so damn much weight aloft, he would have not had so many knockdowns,.

Cheers,

Jim

[David M]

Let's not forget that tall ships basically had trees for masts and steel shrouds and stays.

I'm not saying that its better than aluminum and stainless, but at one time it did get people across oceans.

[Pauls]

If you're looking for the most mast for the buck I'd suggest you look at steel tubing. Performance wise, steel is theoretically equal to aluminum, strength to weight, when used as a mast. Mast strength is calculated using the modulus of elasticity. Steel weighs about 3x aluminum, it also has 3x the modulus, so in an optimized construction they will be very similar in weight. It will be much lighter than a solid wood mast.

Steel is very cheap. It also allows you to easily make mast fittings, tangs, etc out of steel and weld them on. That is much simpler, faster and cheaper than the fittings you'll need to fab for a wooden mast. And it is a high integrity, fatigue resistant construction.

Weld it closed, check that it's hermetic, and it can't rust inside.

On a boat where a solid wood mast is viable, I think that steel will serve you better.

Regards,

Paul

[David M]

With all due respect, steel does not have the same strength to weight ratio as aluminum. This is why aircraft are built primarily out of aluminum.

Steel has a better volume to strength ratio as well as a better cost to strength ratio. Steel is also easier to weld.

[atoll]

all of these masts displayed are un stayed,not possable with a ally or steel mast

Originally Posted by atoll

a few of the boats using telegraph poles near me

[Pauls]

Hi David,

I'm familiar with strength to weight ratios for aluminum and steel, as a mechanical engineer. A stayed mast is a long, thin column under compression. The formula used for calculating the dimensions needed for the mast is Euler's. Euler's formula uses the stiffness of the material, not its tensile or compression strength. It's true that the mast must be strong enough to withstand the compression forces on it, but any typical mast has a compression strength several times what it must bear. The limiting factor for mast load bearing is when the mast fails to remain straight - ie it begins to buckle. Resistance to buckling is a function of the stiffness of the material, which is not the same thing as its tensile strength. Stiffness of materials is measured by Youngs Modulus. For aluminum this = 10,000,000 PSI, and for steel is is 29,500,000 PSI. This allows, everything else being equal, 1/3 the thickness of steel to have the same buckling resistance of aluminum. There are other factors which also come into play here (there always are), but the above is a generally accurate statement.

Regards,

Paul

[goprisko]

Unstayed masts have been successfully built from wood, aluminum, carbon fibre, and steel.

Mentioning a modulus for aluminum and for steel as a blanket value is misleading. This because their alloys vary so much in their properties.

A successful mast for a boat of the size under discussion here: 28-34 ft,
can be built of wood or aluminum, but not of steel, because the wall thickness practicalities dictate 0.188 in for aluminum and 0.06 in for steel. There is simply not enough corrosion allowance and meat in the wall to secure fittings in a steel section that thin.

A good source for unstayed masts is a builder of tapered aluminum street lamp poles. They are available in various sizes and the modulus is known.
The designer of your boat, or you should know the needed modulus for the rig under consideration. See Skeenes for the formulae.

In vesels of this size, it is imperative that their weights be kept under control, and the modifier of such a boat should always keep in mind that every pound above the waterline detracts from capsize stability and sail carrying ability. For example, it is extremely bad practice to store fuel and water on deck, and likewise for other heavy objects. This reason alone is justification for a traditional sectioned boat in this size range.

INDY

[goprisko]

Boats of 28-34 ft LOA quite often do not have ovens, only cooktops.

Yet the budget concous yachtsman can't always afford store bought bread.

What to do?

English muffins are one answer.

They are made using a traditional yeast dough recipe through the kneeding
process. The dough should be formed into a cylinder about 3 in in diameter, then the muffins should be sliced off in 1/2 in thick rounds, dredged in cornmeal or whole wheat flour, and set on a tray to rise. They need to rise until they have doubled in size.

They are cooked in a heavy skillet that has a film of oil on the bottom and a tight fitting lid. On Pegasus we use the lowest setting on the top burner and put the skillet atop a stack of two grates. They need to cook about 12 minutes per side. Once cooked, they can be eaten immediately, or stored for use as sandwich rolls or snacks.

INDY

[goprisko]

When you find the boat you seriously want, the work begins.

First on your list should be hiring a competent marine surveyor with experience surveying similar boats.

Check his references.

Insist upon both a trials survey, (in the water) and a haul survey.

Be on site when he surveys the boat.

Ask intelligent questions about the boat, ie get him to show you the problem areas, features, strengths

Make certain any offer you make is "subject to survey". walk away from any "bargains" you must buy sight un seen.

Have your surveyor estimate the cost of any necessary repairs, you will use this when bargaining with the seller, and it will give you an independent view of the cost of refurbishing the boat.

Take your surveyor out to lunch or dinner afterward, if his schedule allows. Use that time to discuss the boat in private and to get his assessment of it for your purposes.

Read the report with care, at least twice. Make notes. On significant items, call your surveyor for clarification if necessary.

INDY

[goprisko]

Kevin's SC 31 has a traditional gaff rig with a solid wood mast. Given he finished the boat from a hull and deck, he chose that rig over the marconi rig specified by the designer.

I have had occasion to observe "Ruth Avery" tacking upwind, something Kevin does often, since he has no engine. Ruth Avery is significantly less stiff than SC31s I have observed which have the marconi masthead rig with aluminum mast. This despite her mast being about 2 m shorter than that specified for the marconi rig.

Remember, boats in the size range discussed here have displacements between 5-8 tons. They are not suitable for the rigs mentioned above because they cannot carry the weight. If you are going with an unstayed mast on one of these, for example as a Chinese lug schooner, or a cat shcooner, you must proportion the mass of the masts to the boat, you cannot simply add weight aloft in an attempt to gain strength.

Overbuilding is a common failure of amateur builders. When in doubt contact the designer, or Skeenes.

INDY

[TheWatchman]

Your proposal is absolutely feasible and the most beautiful demonstration of using PUD leftovers can be seen in the vessel 'Ladyhawk' at the end of H dock in John Wayne Marina in Sequim, WA.

Gary Rainwater, renowned artist and shipwright/boatbuilder extrordinare, who lives in Port Townsend, WA., has rigged a North Sea Danish Trawler using the same materials and finished out the rigging with seizing and pine tar.

He has been a mentor and ocean advisor of mine for 18 years, has sailed from Denmark to the Pacific Northwest via the Pananma Canal in same vessel and the rigging has held for over twenty years. He continues to cruise locally, and is one of the charter members of the Wooden Boat Festival in Port Townsend, WA.

If you cannot locate his contact info on the web, I see him regularly and could assist in a connection.

Displacement is obviously a factor, so rigging must be sized to meet these ratios. And 'Ladyhawk" is gaff-rigged ketch configuration.

[Weyalan]

For those who pounced on my previous comments regarding the desirability (or more accurately, the lack thereof), of a telephone pole mast; I should point out that my comments were flippant / tongue in cheek. I would have thought that the "whys" and "why nots" would be so apparent so as to be obvious.

The advantage would be, obviously, cheapness.

The disadvantages:

To my mind would be the negative impact on performance, and I don't necessarily mean speed. In particular, consider the significant, and I do mean significant negative impact on stability / tenderness / righting moment (as pointed out by Jim Cate, above). All that extra weight aloft (and indeed, high aloft) will make the boat significantly more susceptible to being knocked down.

I am not knocking wood masts per se. In one of Larry & Lin Pardey's books (I think it was The Self Sufficient Sailor) there is a great description on how to manufacture, for yourself, with basic skills and tools, a simple (Douglas Fir) wooden mast that would weigh a fraction of what a telephone pole would weigh.

Bear in mind that it is a matter of simple engineering principles, that the loads on a structural member tend to be concentrated towards the outside, such that a hollow member of a given section can be almost as strong as a solid member of the same section, at a fraction of the weight. For what it is worth, I am a qualified Mechanical Engineer, and have worked as a Design Engineer for well over 20 years, To me, the engineering disadvantages of a solid pole mast are obvious & significant.

Also, while there can obviously be exceptions to any rule, why is is that 99.9% of yacht designers specify aluminium (or carbon) hollow spars rather than solid telephone-pole type solid members? The designer doesn't get more money for specifying one type of spar over another, so they will specify what they think is best. Obviously, manufactureres would like to reduce manufacturing costs, but they don't, in general, build solid pole spars, preferring to use hollow aluminium (or carbon) spars.

That 99.5% (or more) of saling boats choose hollow spars (be they wood, aluminium or something else) is compelling evidence, I think.

So, for me, the advantage of a telephone pole mast is that is is cheap, versus the many mechanical / structural and sailing disadvantages. These disadvantages, in my opinion, far outweight the advantages. Some people obviously disagree, and such is their priviledge.

On the matter of galvanised wire versus stainless (or, indeed rod rigging, or exotics such as Dynex or carbon fibre) for standing rigging: I am moderately familiar with most of the advantages and disadvantages of one over the other. I don't see that there is a particularly compelling argument for using galvanised over any of the other options, but neither do I see anything wrong with using galvanised wire, if you want to - I see that as a personal preference thing, unlike the solid timber mast, which I think is bad engineering and bad design.