MUL­TI­HULLS PER­FOR­MANCE

Shock load­ings can snatch an an­chor right out of the sea bed. Here’s how snub­bers can help you stay put

SAIL - - Experience Under Sail - Cor­sair Ma­rine, cor­sair­ma­rine.com Man­u­fac­tur­ing Inc., sail­stiletto.com Cor­sair Ma­rine, cor­sair­ma­rine.com

COR­SAIR 760 An evo­lu­tion of the pop­u­lar Cor­sair 24, the new Cor­sair 760 pocket cruiser of­fers a com­bi­na­tion of wave-pierc­ing bows and some ad­di­tional vol­ume/buoy­ancy in the amas to pro­vide that much more speed and sta­bil­ity un­der­way. Like the rest of the Cor­sair tri­maran line, the amas eas­ily fold in for trai­ler­ing, and the boat of­fers a sur­pris­ing amount of ac­com­mo­da­tion space be­lowdecks for its size. For those in search of even more speed in 24ft of LOA, a “sport” ver­sion is also avail­able, which in­cludes a car­bon mast and boom, car­bon bowsprit and a spe­cial light­weight in­te­rior for peg­ging the speedo no mat­ter what the con­di­tions.

COR­SAIR 970 SPORT/CAR­BON

The pop­u­lar Cor­sair 970 Cruze tri­maran has re­ceived a makeover with more than a lit­tle pep­per thrown in to cre­ate a pair of dis­tinctly new it­er­a­tions: the Sport and Car­bon. The new Sport vari­ant car­ries a taller 44ft alu­minum mast, and the main is trimmed via an aft trav­eler ar­range­ment that in com­bi­na­tion with the taller stick af­fords about 10 per­cent more power. A car­bon rig is also avail­able. As for the Car­bon ver­sion of the boat, it fea­tures not only the car­bon mast, but full car­bon con­struc­tion with an eye to­ward cre­at­ing an es­pe­cially light, stiff and more pow­er­ful plat­form. Both boats in­clude the same fold­ing amas for which Cor­sair is known, mak­ing the boats eas­ily trail­er­a­ble, ei­ther to dis­tant re­gat­tas or cruis­ing grounds.

STILETTO X AND XF

Over four decades and 500 hulls after it first splashed in the mid-1970s, the dra­mat­i­cally styled trail­er­a­ble Stiletto 27 is back in an “X” ver­sion that has been re­designed for the the twenty-first cen­tury with cut­ting-edge ma­te­ri­als and mod­ern fea­tures, such as wave-pierc­ing bows and im­proved ap­pendages. Bet­ter still, there is also an all-car­bon Xf ver­sion ca­pa­ble of full-foil­ing in the works. If what we’ve seen so far is any in­di­ca­tion, look for the lat­est it­er­a­tion of this clas­sic, which is now built in Columbia, North Carolina, to make just as big of an im­pres­sion as its fore­bears. Stiletto

A key British naval port since the early 18th cen­tury, An­tigua has long been a fa­vored des­ti­na­tion for sailors. When I first vis­ited the is­land in 2012, I fell in love with the place. Strolling around his­toric Nel­son’s Dock­yard, I was cap­ti­vated by the his­tory and grandeur of the 18th cen­tury sail lofts, of­fi­cers’ quar­ters and cap­stan house used to ca­reen and re­pair the navy’s old wooden ships.

At that time, I was on a two-week cruise through the Lee­ward Is­lands on a 40ft Jean­neau I had char­tered from Sun­sail in St. Mar­tin. I had just missed Sail­ing Week, but the aura of this mas­sive yearly gath­er­ing of some of the world’s best sailors and yachts still hung in the air.

I was running short on my char­ter, so I only spent two nights in An­tigua. How­ever, I vowed that I would one day re­turn and see Sail­ing Week and the dock­yard in full swing. When I heard that 2017 would mark the 50th edi­tion of this awe­some week of sail­boat racing, I booked a ticket and packed my sail­ing gloves.

This year’s event, which ran from April 29 to May 5, brought sailors from all cor­ners of the globe, racing on boats rang­ing from the mas­sive 115ft Farr mega-yacht So­jana to a 24ft Melges.

One of the more leg­endary en­tries was Kialoa III, a 78ft cus­tom yacht built by Palmer John­son that broke the Syd­ney to Ho­bart Yacht Race record in 1975 and re­tained the ti­tle for 21 years.

I had the plea­sure of racing against Kialoa III on Sap­phire III, a 76ft CNB yacht from 2016 owned by John O’Con­nor, and while it would have been ex­cit­ing to race on Kialoa III, the view was just fine from the lux­u­ri­ous decks of O’Con­nor’s CNB.

I also hopped on Hot Ticket for a day’s racing. This speedy King 40 owned by Jim Hightower is crewed by some very friendly and tal­ented good ol’ boys (and girls) from Texas. My job was trim­ming and grind­ing; thanks to the boat’s un­der­sized winches and jib-sheet twing that added a lot of fric­tion, this was a pretty phys­i­cal race to say the least.

With 145 boats in 16 classes, there are many op­por­tu­ni­ties to hop on boats and race, and for those in search of a spot, there’s an of­fi­cial crew board you can sign up on, or you can just walk the docks and ask if any­one’s short­handed. You can also grab your sail­ing bud­dies and rent a spe­cial race-rigged boat from char­ter com­pa­nies like Sun­sail and Dream Yacht Char­ter.

I met a group of Ger­mans who were racing in the bare­boat char­ter class on a boat called Klassen­fahrt, which means “school trip.” They were all cel­e­brat­ing their 50th birth­days on a 50ft Jean­neau on the 50th edi­tion of Sail­ing

choose your pri­or­i­ties wisely. I checked out a num­ber of re­sorts, and each has its perks.

For those who want to be close to the events at Sail­ing Week, my fa­vorite re­sort is The Inn at English Har­bour. This clas­sic inn is a col­lec­tion of colo­nial-style, white­washed, sim­ple but el­e­gant wooden struc­tures strewn across a lush green lawn in front of a quiet, pro­tected beach. They of­fer com­pli­men­tary wa­ter taxi ser­vice to Nel­son’s Dock­yard, and the chef is one of the best on the is­land.

If you’re look­ing for more of a clas­sic beach ho­tel, with lots of wa­ter toys and more ac­tion, Carlise Bay is also rel­a­tively close to Nel­son’s Dock­yard. While on one of my kayak­ing ad­ven­tures at Carlisle, I found an empty lit­tle stretch of sand just around the head­land on the east­ern end of the main beach that be­came my pri­vate lit­tle get­away.

One of the spots on the Caribbean coast I es­pe­cially liked is the Co­cos Ho­tel, whose cozy bun­ga­lows are perched on a hill­side over­look­ing Val­ley Church Bay and Jolly Beach, one of An­tigua’s most fa­mous and pop­u­lar beaches.

Also on the Caribbean side of the is­land is the rather up­scale Her­mitage Bay, which is set on a qui­eter and more pic­turesque, semiex­clu­sive bay. The el­e­gant beach­front cot­tages and high-end ser­vice make it a fa­vorite among hon­ey­moon­ers and ro­man­tics.

If Sail­ing Week didn’t “sail you out,” Non­such Bay Re­sort also has a full-ser­vice sail­ing school and a huge fleet of allinclu­sive sail­ing boats of var­i­ous lengths and per­for­mance rat­ings. It even has a kite surf­ing school called 40 Knots. The in­struc­tors at the school told me sailors gen­er­ally make good kite surfers, so I de­cided to give it a try. In spite of all the en­cour­age­ment, I en­coun­tered a bit of a learn­ing curve dur­ing my first les­son. That said, it was a blast, and I plan to take more lessons in the fu­ture.

I al­ways try to get in a cou­ple of dives when­ever I’m in the Caribbean, and Jolly Dive is one of the old­est op­er­a­tions on An- tigua, with owner Paul Roos a trea­sure trove of info about div­ing in the area. As the name sug­gests, his shop is on Jolly Beach, just down from Co­cos Ho­tel. As such, he takes guests mostly to sights on the Caribbean side of the is­land where you find more soft corals.

Mamora Bay Divers, on the other hand, is lo­cated at St. James’s Club & Vil­las on the At­lantic side. Here you see more hard corals, as well as some in­ter­est­ing boul­ders and canyons to dive through. I also en­coun­tered more sharks on the At­lantic side. They were mostly harm­less reef sharks. How­ever, Mamora Bay Divers man­ager Linda Swann told me An­tigua has a very healthy and di­verse shark pop­u­la­tion.

If you’re look­ing to re­ally get away from it all and en­joy strolling along end­less miles of empty beach, you’ll have to hop over to Bar­buda (An­tigua’s sis­ter is­land), which is only a 20-minute plane ride away. (Tak­ing the ferry is also an op­tion.)

The place to stay on Bar­buda is Bar­buda Belle. Sit­u­ated on a de­serted, seem­ingly end­less stretch of blaz­ing white and pink sand beach on the north­ern most point of the is­land, this sim­ple but el­e­gant re­sort is par­adise.

Be­hind the re­sort is a man­grove pro­tected area that is home to a huge colony of frigate birds. The big­gest spec­ta­cle here is dur­ing mat­ing sea­son (September through April) when the male birds show off their scar­let red gu­lar pouch on their necks. That be­ing said, it was equally amaz­ing to see these birds off­sea­son, and my guides and I were the only peo­ple there.

Sail­ing Week isn’t the only no­table sail­ing event held an­nu­ally in An­tigua. There’s also the Su­per Yacht Chal­lenge in Fe­bru­ary and the Clas­sic Yacht Re­gatta, which runs mid-April. Now that I know what I’ve been miss­ing, An­tigua’s got a spot on my an­nual cal­en­dar. Next up, Su­per Yacht Chal­lenge! s

One of the spots on the Caribbean coast I es­pe­cially liked is the Co­cos Ho­tel, whose cozy bun­ga­lows are perched on a hill­side over­look­ing Val­ley Church Bay and Jolly Beach, one of An­tigua’s most fa­mous and pop­u­lar beaches. Eric Vohr and Michaela Ur­ban have a travel web­site at trav­elin­tense.com

A 45ft, 12-ton yacht (26,500lb/12,000kg) mov­ing at 1 knot (0.5m/sec) would de­velop 6,000 x 0.25 = 1,500 joules.

We do not know how fast a yacht moves at an­chor—our equip­ment is not sen­si­tive enough—but 1 knot seems a rea­son­able fig­ure; though it might be higher for a smaller yacht with a fin keel or lower for a heav­ier dis­place­ment, longer-keeled yacht.

En­ergy is based on the as­sump­tion that the yacht veers— in our tests on rode ten- sions, we found that the max­i­mum loads oc­curred as a re­sult of veer­ing, not windage per se. So an an­chored boat that does not veer will have a lower max­i­mum ten­sion in the rode than the same boat when it veers. We want to con­sider the worst- case sce­nario, hence the fo­cus on veer­ing.

Let’s say the yacht is at­tached to the an­chor with a length of Kryp­tonite-strength piano wire. En­ergy would then be “trans­ferred” di­rectly to the an­chor in the form of a snatch load, which will mod­ify the shear strength of the sea bed in which the an­chor is em­bed­ded ( see Ground Rules in the Au­gust 2017 is­sue of SAIL).

Stick­ing with our ex­am­ple of our an­chor at­tached with a Kryp­tonite wire, we could trans­fer that en­ergy to some­thing “elas­tic” (in the same way that the im­pact of bumps on the road are trans­ferred to a car’s sus­pen­sion). If we had this “mixed” rode, the Kryp­tonite wire would give us abra­sion re­sis­tance and the elas­tic com­po­nent would ab­sorb en­ergy. Think of a bungy jumper—as his bungy cord ex­tends

This graph shows chain’s low fi­nite abil­ity to ab­sorb en­ergy. In con­trast, ny­lon stretches un­til it fails. At low ten­sions—low wind speeds—chain has a greater abil­ity to dampen the move­ment of a boat and ab­sorb snatch loads, but the dif­fer­ences are mar­ginal, and in the grand scheme of things 30ft of ny­lon and 100ft of chain are very sim­i­lar. The graphs are for 30ft of ⅜ in ny­lon and 100ft of ⅜ in chain; lighter chain will have a lower abil­ity to ab­sorb po­ten­tial en­ergy, but longer lengths (and 100ft is not very gen­er­ous, nor is a 5:1 scope) will ob­vi­ously be ben­e­fi­cial.

In shal­low wa­ter, we mea­sured the ten­sion for a 45ft mono­hull with 75ft of lighter 5/16in chain and no snub­ber, a 5:1 scope. In 30 knots of wind the max­i­mum snatch loads were around 900lb. At shorter scope, snatch loads were se­vere, in the or­der of 1,500lb. The in­creased sever­ity and fre­quency of the snatch loads beyond about 700-800lb means that the all-chain rode has no abil­ity to ab­sorb more ten­sion. More scope is the an­swer, as has been known for gen­er­a­tions; if you have the room to de­ploy more chain, by all means do so.

While chain is more than ad­e­quate for be­nign con­di­tions, the sim­ple use of 30ft of ny­lon will greatly in­crease safety at an­chor when winds are above 25 knots and room in the an­chor­age is lim­ited.

he feels al­most no shock load, just a gentle de­cel­er­a­tion. Then think of a snub­ber as a bungy cord for a yacht. The snub­ber or bungy cord are sim­ply a fa­cil­ity to store the ki­netic en­ergy as po­ten­tial en­ergy.

A ½in x 30ft length of ny­lon will com­fort­ably ab­sorb 1,500 (1,440) joules, equiv­a­lent to about 900lb of ten­sion (or a 900lb snatch load). Based on mea­sur­ing rode ten­sions with­out a snub­ber, this 900lb of ten­sion is ap­prox­i­mately the max­i­mum snatch load de­vel­oped on a 45ft, 7 ton yacht in 30 knots of wind with a 5:1 scope; 900lb is also 7.5 per­cent of the ul­ti­mate ten­sile strength (UTS) of ½in ny­lon.

Con­se­quently, if you are us­ing a Kryp­tonite wire rode—to­tally in­elas­tic and with no cate­nary effect—then a 30ft length of ½in ny­lon cordage will ab­sorb all of the en­ergy de­vel­oped from snatch load­ing in 30 knots of wind of a 45ft yacht, below the rec­om­mended limit of the WLL of 30ft of ½in ny­lon. If you dou­ble the length of ny­lon to 60ft, the en­ergy ab­sorp­tion will be the same—1,500 joules—and you will only be work­ing with 3.75 per­cent ex­ten­sion (well below the work­ing load limit of 10 per­cent).

But if you in­crease the di­am­e­ter (weight) of your 30ft ny­lon snub­ber to ¾in, then at the same 900lb ten­sion you can only ab­sorb ap­prox­i­mately 885 joules, and there will still be a snatch load— the dif­fer­ence be­tween the ki­netic en­ergy of the mov­ing yacht and the po­ten­tial en­ergy of the cordage. This sim­ply il­lus­trates that the thicker (heav­ier) the cordage, the less it stretches at a given load, re­sult­ing in a snatch load.

There­fore, there is a com­pro­mise to be made be­tween hav­ing enough stretch (with a limit to the WLL) and min­i­mal or no snatch load­ing at all, or too lit­tle stretch (with plenty of WLL re­main­ing) with the risk of snatch load­ing. (Note that ½in ny­lon has an ul­ti­mate strength of around 3 tons and ¾in ny­lon has an ul­ti­mate strength of al­most 8.5 tons.)

If we now re­turn to re­al­ity and dump our Kryp­tonite rode and re­place it with 100ft of ⅜in steel chain, how will it per­form? Our 30ft x ½in ny­lon snub­ber will store 1,500 joules at a ten­sion of 900lb with a 7.5 per­cent stretch. The max­i­mum en­ergy ab­sorp­tion of our 100ft of ⅜in chain at a 5:1 scope is around 1,300 joules, at a to­tally un­re­al­is­tic 3.5 tons of ten­sion. There­fore, at 900lb of ten­sion, still at 5:1 scope, the chain’s po­ten­tial en­ergy is around 950 joules. Ba­si­cally, beyond 900lb of ten­sion the chain is a vir­tu­ally straight steel wire. If we in­crease ten­sion to 1,350lb, then the chain alone has around 1,100 joules of po­ten­tial en­ergy, while the ny­lon has 2,700 joules. At low wind speeds chain, and cate­nary, is bet­ter at ab­sorb­ing en­ergy than ny­lon—but at low wind speeds there is lit­tle con­cern any­way.

In 30 knots of wind, our 100ft of ¾in chain at a 5:1 scope be­haves like Kryp­tonite wire and of­fers no ben­e­fi­cial cate­nary effect. We can ob­vi­ously de­ploy more chain if we have swing­ing room in the an­chor­age, but sud­denly the idea of a mixed rode—some ny­lon, some chain—looks ap­peal­ing. We can marry the abra­sion re­sis­tance of the chain (and keep some of its abil­ity for po­ten­tial en­ergy at lower wind speeds) to the ben­e­fits of ny­lon’s abil­ity to add po­ten­tial en­ergy to the rode. The big is­sue is the need to join the chain and ny­lon to­gether and de­cid­ing what length of each we need.

The al­ter­na­tive is to have an all-chain rode and a ny­lon snub­ber that can be at­tached any­where us­ing a chain hook or some form of hitch.

SET­TING UP SNUB­BERS

It is a good idea to have one set of snub­bers to use up to 35 knots and another heavy-duty set to

use beyond. Most peo­ple will never ex­pe­ri­ence winds over 35 knots in a rec­og­nized an­chor­age, so the need for “storm” snub­bers is ex­cep­tional, and the oc­ca­sional use of a “stan­dard” snub­ber in 40 knots will not be cat­a­strophic. For cruis­ing around your home port, the ab­sence of storm snub­bers is not go­ing to be an is­sue—you will have ac­cess to de­cent fore­casts and know the lo­cal bolt holes. How­ever, if you are go­ing to cruise in high lat­i­tudes storm snub­bers and spares are strongly rec­om­mended.

Though keep­ing within ny­lon’s WLL will max­i­mize their life, snub­bers are con­sum­ables and will need to be re­placed, per­haps ev­ery two years de­pend­ing on how of­ten you an­chor. If you do not re­place your snub­bers, you should fully ex­pect them to even­tu­ally fail (which they will do, with the noise of a ri­fle shot).

You will roughly dou­ble the life of your snub­ber if you in­stall one on each side and join them at a com­mon chain hook (a bri­dle). We leave the snub­bers on our cata­ma­ran per­ma­nently in­stalled—they are not in the way and the ex­cess is stored as you would sheets. They are best made from three-strand or mul­ti­plait ny­lon. Bri­dles can also be em­ployed on mono­hulls.

Another op­tion for mono­hulls is to have an “ev­ery­day” snub­ber on one side and a storm snub­ber on the other. Let the two snub­bers meet at a com­mon chain hook and only bring the storm snub­ber into ser­vice when needed by sim­ply slack­ing off the lighter snub­ber so the storm snub­ber takes the ten­sion.

We have tried all sorts of meth­ods for at­tach­ing the snub­ber to the chain, and the sim­plest is a cheap G70 cra­dle or sad­dle hook, used in the trans­port in­dus­try. Most “ma­rine” hooks are quite ex­pen­sive and are sel­dom tested (and even when tested you have no idea what the spec­i­fi­ca­tion or test data means). Hooks used in the lift­ing in­dus­try are made for spe­cific chain sizes, and in my ex­pe­ri­ence chain re­ten­tion is much more se­cure than the hooks sold for ma­rine ap­pli­ca­tion. An al­ter­na­tive is a Prusik knot (our rec­om­men­da­tion for a tied at­tach­ment), some form of hitch or a Dyneema soft shackle.

Given that snub­bers can fail, you must also se­cure the chain to a strong point on deck so that there is no chance of the snatch loads be­ing trans­ferred to the wind­lass should the snub­ber break. The best way to do this is to sim­ply at­tach a sec­ond, short snub­ber to both the chain and a strong point.

When you rig the snub­ber you need to let out some slack in the chain, be­tween chain hook and bow roller, to al­low the snub­ber to stretch. If you are re­ally clever you can es­ti­mate that slack to be, say, 15 per­cent of snub­ber stretch. This then lim­its the amount of stretch to which your snub­ber can be ex­posed. If you have an “ev­ery­day” snub­ber on one side and a storm snub­ber on the other, you can ar­range that your storm snub­ber comes into play when the ev­ery­day snub­ber reaches 10-15 per­cent—this then al­lows both snub­bers to work to­gether.

A snub­ber is not a panacea. It will not make a poor an­chor re­li­able, though it will make it less un­re­li­able. Snub­bers are sim­ply part of your ground tackle wardrobe, along with spare an­chors, spare rode, rated shack­les and so on. If your spare rode is a mix of chain and ny­lon, it does not need a snub­ber; the ny­lon spliced to the chain will of­fer the re­quired elas­tic­ity.

THE CATE­NARY MYTH

In case it is not yet ob­vi­ous, your chain cate­nary has fi­nite ben­e­fits. In fact, you should as­sume that, given the amount of chain you can carry and the lim­ited space in many an­chor­ages (which in turn will limit the amount of chain you can de­ploy) that any use­ful cate­nary will ef­fec­tively dis­ap­pear at around 30 knots of wind as the rode straight­ens out. You can choose ny­lon snub­bers for any and ev­ery even­tu­al­ity, from 20 knots to 70 knots—they will of­fer elas­tic­ity for any­thing the fore­caster can throw at you. You sim­ply need to de­cide what you think is rea­son­able.

For ev­ery­day an­chor­ing on a 30ft to 40ft yacht with G30 chain, a 30ft ⅜in or ½in ny­lon snub­ber will be ad­e­quate, up­ping the thick­ness to ⅝in for 40-50ft boats. s

Jonathan Neeves has been re­search­ing and test­ing ev­ery­thing to do with an­chors and an­chor­ing for many years

SAIL MAG­A­ZINE

Stiletto X and Xf

Cor­sair 970 Sport/Car­bon

You’re never short of clas­sic race­boats to ogle at An­tigua Sail­ing Week

A

Yes, you too can race in An­tigua— just char­ter a bare­boat for some hot com­pe­ti­tion Many rac­ers bring their fam­i­lies to re­sorts like Non­such Bay

Cata­ma­ran sailors de­pend on snub­bers and bri­dles for ev­ery­day an­chor­ing, not just for heavy weather

It’s a good idea to rig dou­ble snub­bers

A re­li­able chain hook is an es­sen­tial ac­ces­sory

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