- Why does it happen, how to prevent it.
Appendix Part 2 – My own rig
This is my own mast
and rigging design that prompted all the previous stuff you've been reading; in an effort to be free forever from any maintenance, any inspections, or any failures. I hit the books
and soon found out that all this was very easy to achieve.
You just have to want it.
You all know i'm building a 55 foot cat, and doing all the rigging myself because i want it done to normal modern accepted engineering standards that would have to be used by law on land.
( and not the standard unregulated capitalist offering of a cheap
shitty death trap that regularly fails, dismasts you, or injures friends and family
so the reason i actually knew all this stuff is because i've been studying for ages trying to design mast
rigging that won't screw me over in the middle of nowhere.
So here is my attempt at doing a better job than a rigging company. Easy as.
I just wish i could have given the job to a yacht mast rigging firm instead, but they are all just too silly to speak to. They all refuse to do the job to a standard that would actually be legal
on land under normal safety
I'm glad i posted, as polishing this up for you peeps ;
- helped firm my own resolve; - as marketing works
– and if there is enough bullshit, then you drown in a sea of it. Your mind finds it really hard to go keep going when every other single
bit of information out there is against you.
The impact of 316 stainless steel performance in chlorine and under stress facts; of the true reality, gets washed away by the huge FLOOD of marketing
facts, marketing words; what's true is slowly dissolved, eroded, and diluted until your motivation for decency slowly merges back to the capitalist offerings.
- Changed my own rig design; to a fully redundant design.
- I added an extra forestay; it's now a solent rig
- ensured the baby stays can easily take all the load by themselves
- have single
nested diamonds instead of single diamonds or twin diamonds.
- clarified my thinking.
Everything custom made in UNS S32550
I will never inspect my rigging ever. There is no need.
The calculations were actually real and true. I actually took alloy life expectancy under load cycles in salt water
, temperature and chlorine data into account. Is this a First
in yachting rigging history
? Yes. It is.
Every single piece will last forever in salt water
, immune from stress cycles, immune from stress corrosion
cracking in salt water
. Every single piece will last forever, and never fail. Ever.
Remember the difference between driving a dung cart and a modern car? The difference between the two is REAL.
This alloy is far beyond 316 in strength. But more importantly insanely far beyond 316 in metal fatigue, stress corrosion cracking, crevice corrosion, brittle snapping clean in half, cycles under load in salt
This stuff is utterly immune from intergranular crevice corrosion, and so will never fail. Ever.
This always seems to be the main objection. Yet compare the (SMALL damn you) extra cost with loosing your mast or replacing a friend.
If you ever have to replace your wire ropes, then it's cheaper to do it this way in the first place.
If you ever get dismasted then its infinitely cheaper to do it this way.
You already know from reading Part 2 and Appendix Part 1 that it can sometimes even be cheaper than 316 anyway.
If you buy a part from a shop you pay around 300% more than if you buy direct from the factory, and the alloy used is cheaper than 316 in bulk, and also twice the strength. So you need smaller parts
The thing you are looking at now is called the internet
. This thing allows you to communicate directly to a factory. Can you see what's about to happen?
goto eBay and look at the cost of stuff.
My last mobile phone
(inbuilt TV, 3000 nintendo games, the only phone
with true nintendo gameboy buttons flip console, radio
, dvd's, mp3s etc etc etc etc etc ) cost $1000 in a normal shop and $100 on eBay direct from the factory in china
. My exact electric
shaver cost $160 in a shop and $1 direct from the factory in china
. So we do the same thing here.
Get your quotes from small local engineering CNC firms (if you give them one part, they duplicate it exactly in the alloy of your choice), small rigging fittings manufacturers (as they will actually communicate with you, and the large boys didn't even reply to me), and small chinese rigging firms.
here's an example of the cost
316 Chainplate bought from a shop;
Pin Hole 16 mm,
Fastener Holes (5) 13 mm
Length 406 mm
Width 38 mm
Thickness 8 mm
Weight 1.13 kg
Same 1 Kg Flat Bar in 8mm x 40mm x 400mm, but you have to drill the holes yourself.
AL6XN or 254SMO - $60
Zeron 100 - $32
32550 - $56 from australia
32550 - $7 from china, plus postage.
25% of the cost of a 316 chainplate bought from a shop. So it is actually cheaper than the stuff that will dismast you, but you have to be able to drill a hole.
$7 from china. And if you look at the Outukompu bulk price
sheet in Part 11, you'll see that they are still making at least 250% profit.
Whatever happens just make sure you get the 2% copper alloy, not 2507. It's more modern. Get the modern alloy. 32550.
S32550 plate in Australia
was $5000 for 4mm x 2.4x1.2 m
so $56.85 / Kg is the rough price
S32550 is $7 /Kg from china
bit of a difference.
I've seen far too many wire rope
strands fatigue and break from thrumming under heavy load (at the swage). The copper ensures more ductility and more immunity from micro-hardening due to vibrations while under stress, and also ensures any micro cracks heal. Twice the end yield of 2507 under cyclic fatigue loads in chlorine. Not a single broken strand ever.
I'm having custom wire rope
manufactured for me, and these are some calculations
Ferralium 255SD50 Wire Rope (sold as Amminox 255) (UNS S32550)
0.2% Yield Strength = 550MPa = 55 Kg / mm2
Cross Sectional Area True Cross Sectional Area
Diameter 1x19 compaction factor; Mpa; SWL
9mm 63.6mm2 x .785 = 50mm2 x 55 Kg = 2746 Kg
10mm 78.5mm2 x .785 = 61mm2 x 55 Kg = 3390 Kg
11mm 95mm2 x .785 = 75mm2 x 55 Kg = 4100 Kg
12mm 113mm2 x .785 = 89mm2 x 55 Kg = 4883 Kg
so twice as strong as 316 wire rope, and the strands will never break.
all my stays in 12mm wire rope, all diamonds in 10mm wire rope
Amminox 255 1x19 is available off the shelf
Duplex & Super Duplex Stainless Steels
Super Duplex Stainless Steel
Stainless & Alloy Specifications - Loos & Co., Inc.
will also make it.
Basically 10mm from england
is $30 a meter, versus $17/m for 316.
but 2507Cu is cheaper than 316 in raw elements.
So it will certainly be a small chinese or indian wire rope firm that gets the order to custom manufacture due to much cheaper prices.
Normal Sailing Loads
130m2 sail, usual maximum load of 20 knots @ 90degrees = 7.5Kg x 130m2 and the load divided equally between mast base, sail tacks, and mast top (therefore stays) with 2 stays
= 7.5Kg x 130m2 = 975 / 3 = 325 Kg usual max force divided by 2 stays = 200Kg on each stay.
Note there is no mention of breaking loads.
Note that I have not included rig tensioning. I'm using an old catamaran
surveyors recommended minimum tension and adjusted while sailing only method – versus the normal “tension to 15 or 20% of the 316 wire rope breaking load” method. Duplex ropes have very little stretch so I expect the end tension to be around 200 Kg. I chose this method years ago because the old crusty cat surveyor
had convinced me with pics of deformed hulls and logic and stories and stuff.
Designed maximum load
40 knots and full sail up @ 90 degrees gives 130m2 x 30 Kg/m2 = 3900Kg /3 fixed points and then held by 2 stays = 650 Kg per 12mm stay.
Normal use max load safety
factor of 4800 / 200 = 24
Designed maximum load safety factor 4800 / 650 = 7
No rules of thumbs, no 90% of the yield, no 1 sixth of the Breaking Load. These are real safety factors. They actually exist and they are well inside the yield strength,
and despite the temperatures the cat is sailed in, the age of the fittings, and whatever stress the fittings may see in their life of use, the Safety Factors will still exist, and exist unchanged. Forever.
(For General Interest;
Europeans have a law saying very expensive escape hatches
installed in cats for if they capsize
, yet nothing like a very cheap
auto release cleat to actually stop you going over in the first place. The stunning stupidity. Astounding idiocy.
I consider the adjustable auto release cleats
and clutches to be the single most important insurance
on the entire boat. Equal to the value of the entire 55 foot catamaran
, and all the people inside it as well.
And yes, once again, I'm having to have these custom made for me by a small engineering firm. So the designed maximum of all sail up at 90 degrees to a squall will never happen anyway.
The Real and True Multiple Safety Factors
won't evaporate into thin air if you ever decide to sail for 6 months in the tropics.
There is a stunning difference in quality
between my rigging and what you get off the shelf. I'm actually using modern normal engineering standards, methods, and practices, so that the rig is totally beyond doubt,
and then, and only after that, have real and true safety factors of exactly the same quality
Compare this with yacht rigging companies around the world and their 316 misleading, total bullshit, absolutely doesn't exist “safety factor of 6” which is over the yield already, and on an alloy that gets crevice corrosion. Accident
waiting to happen.
Their big Breaking Loads data figures sound much safer than my wire don't they? Of course you'd get them to do your rigging over me doing it for you. They're professionals.
I decided to invent my own data suitable for design for everything else other than rope, 275 MPa out of a 550MPa yield. Why so high? Why not a quarter? The one quarter of the yield suitable for design is just a rule
of thumb that IS suitable for unbelievably stupid and primitive old alloys chemistry. So this is my rule
of thumb for MODERN chemistry alloys.
6cm wide x 50cm long x 12mm thick = 30000 kg yield in UNS S32550, 15000 nominal
Why so thick? the thicker chainplate is kinder to the turnbuckle fork bolt.
6 stays, so 6 individual Super Duplex chainplates.
Even i am starting to bend to convenience. I KNOW that i should put toggles in to minimise the vibration stress waves dissipating at the wire rope/swageless fitting density change area, but i just couldn't be arsed.
My brother would snort in derision were i to tell him that i was going to leave these out, but i think i am going to leave them out.
Open Body Turnbuckles.
Capitalists (ie rigging companies) always sell 316 or CHROME plated bronze turnbuckles, but the chrome ALWAYS wears off real quick and your million dollar yacht ends up looking bad in a few short years.
Sure the chrome plating looks GREAT in the packet in the shop, but is 1/100th of a millimeter thin, and just dissolves away and then looks bad for the rest of your expensive boats life.
So i'm getting these custom made. (again, i've just seen too many turnbuckles that look bad. And the reason they look bad, is because they ARE bad).
A million dollar boat with rubbish looking turnbuckles just doesn't look good. So the capitalists can keep them as well.
Wanted open body only, as dismasting
has happened due to unscrewing, and both lock nuts and pins failing, so i want to inspect them, i want them visible, i want to SEE with my own eyes any movement. I want to SEE what’s going on. Closed body turnbuckles should never be under consideration in any mast rigging, yet guys get blaise', other people do it, so they do to. They unscrew, and that's the rig gone. At least with open bodies you can instantly see any movement. See if the split pin has failed, or the lock nut moved.
Dismasting has happened due to both lock nuts and pins failing, so i'm having both.
Bugger me, imagine loosing your mast for the want of a 20 cent part, and yet it has happened.
Galling is the reason they use bronze my arse. They could easily use one thousand more expensive stainlesses. It's cheapness every time. (ie Hardness difference between nut and bolt or hard alloys where galling doesn't occur) 316 galls at 13MPa, a stunningly soft iron alloy. UNS S32550 has a theoretical galling of 300MPa (I could find no true study), so you'd have to be flogging your mast to breaking point to get galling, but i'll use a modern teflon based vacuum grease anyway, just in case, as this lasts forever, and never has to be replaced.))
I still have some design problems. Mainly difficulties optimising the rigging fittings designs for the 32550 high strength.
Pin sizes in 316 for 12mm wire rope turnbuckles are 19mm
316 12mm wire rope turnbuckles thread sizes are 20mm
32550 is twice the strength of 316, so 20mm thread size is way oversize, but it's so much easier to just order the part, or give a part to a CNC mob
and say duplicate it. (Rather than redesigning it). So that's what i'll do.
UNS S32550 Bolts at yield (55Kg/mm2)
10mm 78.5mm2 x 55 = 4317 Kg
12mm 113mm2 x 55 = 6215 Kg
14mm 153mm2 x 55 = 8415 Kg
16mm 201mm2 x 55 = 11000 Kg
18mm 255mm2 x 55 = 14000 Kg
20mm 314mm2 x 55 = 17300 Kg
I'm pondering using normal shanked bolts instead of pins and split pins. As guys have lost
their entire masts due to a 316 pin SCC/falling out, so I will probably use Super Duplex bolts with both lock nuts AND split pins. You can get Super Duplex bolts anywhere. Remember, I intend to never inspect the rig. Thus pondering the belt and suspenders approach.
All mast fittings, tangs, lugs, 2 forestay round bar chainplate toggles, bolts, and compression
tube spacers are to be made from UNS S32550. NO 316 anywhere on the mast. (Heaps elsewhere; just not on the mast)
bars are 14mm x 35cm 32550 threaded rods, with (nut, washer, plate, aluminium tang bolt doubler plate ) both inside and outside of each side of the mast. ie 4 sets on one through bolt giving 2 tangs outside, one either side of the mast.
Tangs are single 10mm x 40mm flat bar (not double flat bar tangs with pin as most shops sell) 14 000 Kg yield.
Solent rig with twin furling jibs
The options for forestay redundancy were;
Cutter/Inner forestay/Solent or just a plain unused redundant forestay - unused and no tension on it
Due to this thread, i decided to add a solent, with twin roller furlers with jibs, and only use the inner normally, unless down wind
Unique Twin Jib Rig
(would have lost
his mast if he didn't have one.)
This gives both mast staying upright redundancy, a full sail in instant reserve, a full spare roller furler
redundancy, as well as great, easy to reef down wind
ability. Much easier to control and reef in strong wind while going down hill than a spinnaker
in the middle of the night.
here's a guy that loves them
“I think it is one of the best sailing rigs for cruising.”
So there you are. That's the full story. This is what i've been doing to side step being dismasting. Getting custom fittings is easy, as this is exactly what small engineering firms do.