Multihull Structure Thoughts

Discussion in 'Multihulls' started by oldmulti, May 27, 2019.

  1. oldmulti
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    oldmulti Senior Member

    Lucifer8.5. Thanks for the input. Was the crash a boating or road accident? Also is the main hull bottom tortured ply or strip plank? It looks an interesting tri, have you any performance numbers eg what sort of speed does it do upwind and reaching under good conditions. Sorry about the number of questions but they are interesting tri's
     
  2. Lucifer8.5
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    Lucifer8.5 New Member

    It was a reef incident as a result of a navigation error - sailed into a reef which effectively tore the below waterline area of the main hull apart.
    The floats are 4mm stressed ply with 10mm foam core decks and the main hull is 10mm foam with about a 600gsm biax either side up to the flair out above the waterline. Above that the flat topsides are plywood with 600gsm either side. I haven't cut into the the topsides yes (we need to fix a hole we accidentally punched in it turning it over) but it guess its 8 mm ply, maybe 10mm. The decks/cabintop are also ply.
    The keel cove and taping on the stressed ply floats separated on impact but shaped ply stayed remarkable true to shape even around the holes.
    IMG_5430.jpeg
    Looking down the hatch into the main hull -- the centreboard case was the structure which held the rest of it all together and minimised further damage.
    IMG_5423.jpeg
    Meanwhile there is some long boarding to do....
    We have also been doing a careful weight study while its all in bits, floats are around 13okg each which includes winches etc, main hull 340kg. We have a spreadsheet with all the other data so will put that up in due course.
     
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  3. redreuben
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    redreuben redreuben

    I think it’s tragic that the 8.5 class hasn’t spread, apparently the sticking point with Australia is the sailplane is too small for our apparently lighter winds. I can assure you that the summer sea breeze here in the west would work with the Kiwi sail plan no problem.
    There are two boats at Nedlands YC a Firefly cat and an 8.5 Farrier. There are a 1/2 dozen tris but all smaller Corsairs.
    It’s a start.
     
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  4. oldmulti
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    oldmulti Senior Member

    Lucifer8.5. Thank you for your input. The more we learn about these relatively cost effective boats, the more likely we will have more people out there having fast fun, with a possibility of short term cruising as well. I hope you can relaunch in a reasonable time and we will be very interested in the weight summary. The jpegs are of Lucifer. Web address with further details is; Demon 85 http://www.blairboats.com/demon-85.html
     

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    Last edited: Apr 21, 2022
  5. oldmulti
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    oldmulti Senior Member

    The Inclusion Catamaran is a modern wheelchair-accessible sailing catamaran that was designed by Portuguese naval engineer Frederico Cerveira. The intention of the cat is to allow people of all abilities to go sailing including those who are wheel chair bound. The cat is 21 x 15 foot over the hulls with a length of 25 foot over the prodder and rudders. The weight is claimed to be from 1800 to 2400 lbs depending on the source. The cat is certified to carry 10 people which means it can carry about 1700 lbs so I will assume the total displacement is around 4000 lbs. The 28 foot fixed aluminium mast has a fractional rig that carries a 190 square foot mainsail, 90 square foot self tacking jib and a 220 square foot gennaker. The hull length to beam is 8 to 1. The draft over the fixed low aspect ratio keels is 2.6 foot. The fixed rudders are transom hung. The outboard can be from 5 to 20 HP.

    The Inclusion Cat has a wide bridge deck that is accessible from a dock by a very good door arrangement allowing wheelchair passengers to board etc. The bridge deck also is large enough to pitch a tent for camping. Each hull has 2 single berths in its 2.7 foot wide hulls and due to the 3.7 foot freeboard over most of the hull length there is limited sitting headroom and some storage space for a camp galley and portapotti. This cat could function very well as a camp cruiser for a few weeks.

    The construction is unknown but its likely to be foam glass in the hull topsides and underwing. It may be solid glass below the waterline. The 200 mm aluminium tube cross beams are bolted to the hulls to allow disassembly for transport.

    The sailing performance is not commented on beyond saying its good. My calculator says if it has good sails it can perform well with peaks of 15 knots and capable of 8 knot averages. The self tacking jib and fat head mainsail with reasonable large keels will allow the cat to go upwind well. This cat should outperform EG a Tiki 21 at full displacement.

    A very interesting cat that could be a fun, reasonably fast small cruiser for a young family. The jpegs give the idea.
     

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    Last edited: Apr 22, 2022
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  6. jamez
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    jamez Senior Member

    I remember the rig size debate from a decade or so ago. Fact is all the competitive 8.5s have upwind working sail area in the mid to high 50 sq meters. Lucifers working sail (as designed) is 60 SqM. The nearest aussie boat to an 8.5 is probably the Firefly 850 which has about 47 sqm of working sail on a taller mast. Taller rigs are arguably more efficient but the extra area probably makes up for it. Also, IIRC, there was concern with how the boats would rate under the Au measurement rule. Anyway, I agree it was a missed opportunity a few years back to have a class that could have worked for both countries.

    Dirty Deeds, probably the winningest 8.5 Cat was sold to Australia a couple of years ago. I wonder how shes going over there.
     
    Last edited: Apr 22, 2022
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  7. oldmulti
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    oldmulti Senior Member

    An article on Dirty Deeds can be found at: https://multihull.org.nz/wp-content/uploads/2019/07/2008-10_Dirty-Deeds.pdf

    Some jpegs of Dirty Deeds including one of Dirty Deeds burying its nose. It recovered and continued racing. NZ 8.5 racing crew think this is all in a normal days sailing. Hmm.

    The last 2 jpegs are of the original JT trimaran Meltdown which became Mama Tried etc.
     

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    Last edited: Apr 22, 2022
  8. oldmulti
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    oldmulti Senior Member

    For those who need an understanding of how hard NZ sailors drive there boats. The coastal Classic is their favorite event and gets about 150 boats in it per year. Dirty Deeds was shown above but this is the 2011 Coastal Classic race "review". TeamVodafoneSailing is a 60 foot OMRA tri.

    2011 COASTAL CLASSIC - THE SUB-SIX HOUR RECORD IS SET!

    Five hours, 44 minutes and 31 seconds was all the time it took for TeamVodafoneSailing to sail the Coastal Classic racecourse, and it marked the achievement of a decades long ambition for the boat's owner, Simon Hull, who bought TeamVodafoneSailing to New Zealand, specifically for this reason. To average a speed of around 20 knots for the duration of the race, TeamVodafoneSailing peaked at 34.8 knots of boatspeed on the racecourse, and saw extended periods of over 30 knots. TeamVodafoneSailing was followed into Russell by Roger Pagani's catamaran, Triple 888, at a finishing 19.24 hours (7 24 PM) in the evening, and Taeping at 19.52 hours. The race started at 10.00hrs. Dirty Deeds finished thirty minutes outside the record for smaller multihull boats at an average of 14 knots for the 119 mile course. The under-30-foot multihull record is 07 hrs: 58 mins: 35 sec.

    The jpeg is of Timberwolf (35 foot tri) doing a NZ sail reduction by blowing the head out of its spinnaker.
     

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    Last edited: Apr 22, 2022
  9. oldmulti
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    oldmulti Senior Member

    On page 45 of Multihull Structure thoughts is the Nic Bailey designed Feral 32. Nic designed several versions of the Feral cat including this 50 foot version that was built in New Zealand. The Feral cats have a common theme of long thin hulls, low displacement and a very streamlined cabin top. It started with the 26 foot Coolcat production catamaran and extended throughout the range. The Feral 50 is 50 x 23.3 foot with a weight of 10,000 lbs. Now this cat is described as a fast cruiser, with a weight like this it will be fast especially with its 65 foot wing mast rig. The mainsail is about 900 square foot and the self tacking jib is about 230 square foot. The length of the prodder suggests a code 0 of about 1000 plus square foot could be carried. All sail sizes are a guesstimate. The draft is 5 foot overall with a draft of 2.5 foot over the rudders. The length to beam of the hulls is probably about 14 to 1. Engine power is 2 Diesel YANMAR 15HP with shaft drives.

    This design is great at doing a little test for you. Do you look at the jpegs and think it should have more accommodation on the bridgedeck or look at the jpegs and say the cat should have more beam, deeper dagger boards and a bigger headsail? I find a design like this show how much you are cruising orientated or racing orientated.

    Very few people accept the design concept of a very high performance 50 foot cruiser with a 40 foot accommodation package and beam as it is. They want a “different” concept even though this cat would be capable of 300 mile days when cruising and in the right conditions could peak at over 20 knots if the owner wanted to sail at those speeds.

    How am I confident of these statements? The Coolcat 26 was built by Cornish Crabbers (yes the producers of open and cabin clinker glass mono’s) in 2005. It was 26 x 15 foot displaced 3000 lbs with crew. It has 2 double berths and a sitting headroom main cabin. It literally could sail rings around Catalacs, Tiki 26’s, Telstar tri’s etc. Very few were sold. People either wanted more cabin space or they want pure performance. This very high performance cruiser was not a commercial success. The first jpegs are of the Coolcat 26.

    The series of Feral cat designs ranged from 32 foot to 50 foot, all had the same design concept, narrow hulls, low windage cabins, reduced accommodation, narrower overall beam and low displacement for there size. All are fast designs. The next set of jpegs is of the Feral 32 as an example.

    Finally, we discover a New Zealander has had a Feral 50 built by Waikato Marine Composites (these guys are very good) in fully vacuum bagged Carbon/Kevlar on a 15mm Core cell. The owner stayed true to the design concept and has a very fast cruising cat but with limited accommodation of 2 doubles, 2 singles, 1 toilet and a smaller downstairs galley. The main saloon has seating and a space for a laptop for EG navigation, entertainment etc.

    The final set of jpegs give the idea.
     

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  10. oldmulti
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    oldmulti Senior Member

    This is about a variety of plywood cats from 24 to 28 foot from 2 designers. Richard Woods Salish 28 and Eagle 24 and Selway Fisher Cat 25 and Cat 254. Each of these designs are aimed at a similar markets, a high performance cruiser/racer that is relatively easy to build in plywood with aluminium and/or timber cross beams. I could have included many other designs like EG Fish and Chips, Tonga Tini, Gypsy etc, but each of these additional designs have a different build concept which will take longer and more effort to build.

    The Eagle 24 is 24 x 14.4 foot with a weight if 1,460 lbs and a 2,800 lbs displacement. The 31 foot mast carries a 339 square foot sail area, The hull length to beam 10.6 to 1. The draft is 4 foot over the daggerboards.

    The Salish is 28 x 19 foot with a weight of 1,570 lbs and a displacement of 2,200 lbs if racing, 3,000 lbs if cruising. The 39.6 foot mast carries 365 square foot of sail. The length to beam of the hulls 12.6 to 1. The draft over the boards is 4 foot.

    The Cat 25 is 26.2 x 14.5 foot with a weight of 1,850 lbs and a displacement of 3,400 lbs. The 32.5 foot mast carries 270 square foot of sail area. The length to beam of the hulls is 9.3 to 1. The draft is 3.7 foot over the boards.

    The Cat 254 is 26.2 x 16.7 foot with a weight of 1,980 lbs and a displacement of 3,580 lbs. The 34 foot mast carries 375 square foot of sail area. The length to beam of the hulls is 12.5 to 1. The draft over the low aspect ratio keels is 1.8 foot.

    Each of these cats have 2 single berths per hull, 4 to 5.5 foot of headroom, room for a small galley and portapotti. The hulls are from 3.5 to 3.7 foot wide. Very similar accommodation with the Woods cats having more headroom. Each of these boats use 6 mm ply for the hull sides, decks and secondary bulkheads. The bottoms have some 9 mm ply as are main strength bulkheads and underwing. There is timber stringers and framing with bunk panels required to improve hull strength. The aluminium cross beam tubes range from 150 mm to a 250 x 150 mast sections for the mast beam on one design. The Eagle, Salish and Cat 25 are chine or multi chine hulls. The Cat 264 has a semi tortured ply hulls (good concept).

    Now we get to the choice of design. The Eagle 24 is a fast cruiser that has the accommodation in a slightly smaller easy to build package. The Salish is the latest and fastest of all these designs and was designed for the Race to Alaska. It has the most sail for its sailing weight, 15 to 30 % more beam and the longest waterline. The cabin is slightly smaller but it is still a fast build.

    The Cat 25 was originally designed at the start of the Micro racing rules and has the shortest waterline length and least sail area. A mark 2 version with a longer waterline was done to improve its performance. This cat is the most cruising orientated.

    The Cat 254 semi tortured ply hulls improve its hull shape and has the most sail area. This improves its performance but it has low aspect ratio keels and a shallow draft. Good for cruising not as good for upwind performance. As Richard Woods says (general statement about his designs) having good daggerboards will improve performance more than changing a hull from a chine hull to a round bilge hull. I do not know if the low aspect ratio keel on the Cat 254 is required structurally or is a choice for EG accommodation space. If daggerboards could be done on a Cat 254 it could be interesting.

    What I am trying to show here is these designs are all about the same length, have the same accommodation and use the same build materials. Each would take a similar time to build with the only significant difference in their mast length and sail size. The slowest may sail at 15 knot peaks the fastest at 20 knot peaks but all of them will cruise at 7 to 9 knots under the right conditions.

    The choice is yours but what is really required is an understanding of your intended sailing. The above are good to very good cats, how much cabin space versus speed do you want? The jpegs are of each boat.
     

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  11. oldmulti
    Joined: May 2019
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    oldmulti Senior Member

    This is about a production trimaran. This is also a warning to aspiring production boat builders. The CHS X19 or Trikala 19 is 19 x 13.4 foot with a weight of 540 lbs and a displacement of 920 lbs. The 28 foot aluminum mast carries a main sail of 158 square foot, a jib of 50 square foot and a spinnaker of 161 square foot. The length to beam of the main hull is 11.7 to 1 and the floats are 12.5 to 1. The draft is 0.8 foot to 3.1 foot with the board down. The tri is trailable with a sliding cross beam system which allows the tri to fold to 8 foot. The tris is conceived as a fast comfortable day sailor with some stowage forward.

    Now we get to “production” story. A man wanted to produce a fast day sailing tri, he went to Kurt Hughes who used his knowledge to produce an excellent design. The man then started on the build of the molds. He set an ambitious build target and started to promote the CHS X19 on the web stating the initial boats would cost about $16,000. (Final production tris by another company sold for about $50,000). He anticipated the molds would be ready in months. 3 years later the float molds were ready and the frames for the main hull molds were set up. During this time he was on the web being given advise by people who had boat production experience how to produce production molds. EG build registration (alignment pegs) into the mold as you go etc.

    During the 3 years there was the usual problems, a lack of money, time over runs requiring him to return to full time work, trying to build things on a part time basis, then trying to find investors. Also, Kurt was requested to do an update on the design which resulted in a different float bow shape which required a second float mold to be produced. Finally, the guy gave up and sold the molds etc a second business. That business then tried to develop the tri further. Finally, we hear that the molds ended up in Spain and about 20 Trikarla 19’s were produced. Kurt Hughes is selling the Trikala 19 plans on his web site which indicates the tri is out of production.

    The Trikala 19 could sail well with an owner saying “All in all, the Trikala 19 is a pretty versatile day sailor. She’s fun to sail even though this particular model is not rigged with any furling gear. We set the chute out of the bag from the leeward tramp. With the kite up and relatively flat water, she’ll easily sail at 14 or 15 knots. With just the working sails deployed, she’s capable of 12 knots in the right wind and wave conditions.” The tri takes about 30 minutes to unload or load onto the trailer with the only difficulty of raising the mast as it is a fairly big heavy section.

    The final production boat was foam e-glass with aluminum sliding cross beams. The plan version may have a strip plank hull option.

    A good fast comfortable day sailor. The jpegs give the idea. The first jpeg is of the original version and floats then the updated version and new strip plank float. The final jpegs are of the Trikala with old float molds.
     

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  12. oldmulti
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    oldmulti Senior Member

    We will talk about MOD 70 racing trimarans today. MOD 70’s were developed in 2009 after the cessation of the OMRA 60 class as it became too expensive. The intention of the MOD 70 was to produce cheaper more reliable one design tris that had a 10 year life. In 2006/8 the majority of the design was done by VPLP Design with several builders (CDK Technologies /Multiplast /Décision Suisse) doing the construction of 7 tris from 2009 to 2012. The MOD 70 is 70 x 55 foot with a weight of 14,220 lbs. The 90 foot carbon fibre rotating and canting wing (4 degrees either side) mast carries 3200 square foot upwind and 4,300 square foot with a screecher. Spinnakers optional for the brave. The length to beam of the main hull is 17 to 1. The floats length to beam is 21 to 1. The draft ranges from 5.6 foot to 14.8 foot with the boards down. The engine is a 50 HP diesel.

    The MOD 70’s with the same righting moment, longer floats and a shorter mast than the ORMA trimarans, the MOD 70s are designed predominantly for ocean racing with a crew of six. The MOD 70 has 5% reduced sail area compared to the OMRA 60 for better safety, the MOD 70 has a main hull 10 feet longer for avoiding pitching over the bow (which was OMRA 60 main problem) and raised beams for better passage in the waves. The main rudder can be lifted to reduce wetted surface and a MOD 70 has curved foils in floats for better performance and safety. The mast can be canted up to 4 degrees on either side. Because all the MOD 70 come from the same moulds and are built within 110 lbs of each other and started as a one design class they cost about 3.5 million Euro’s. The OMRA 60 had to have a new design every 2 years at a cost of 5 to 8 million Euro’s per new design. OMRA 60’s were very carefully built (a more detailed and experimental built than MOD 70’s).

    The performance of these designs is spectacular. Maserati did the 605 mile Fastnet course in 23 hours, 51 minutes and 16 seconds at an average speed of 24.94kts. Powerplay’s owner said “My top speed at the helm is 38.9kts, I want to hit 40 knots and I can’t sell Powerplay until I do”. And these speeds were achieved prior to several of these designs were upgraded for more performance. Powerplays skipper Ned Collier-Wakefield. ‘These boats are bulletproof. We can push them hard and they just lap it up. You can set out on a record attempt and smash it across the Atlantic and you tie the boat up at the dock at the end of the day, wash it down and it's pretty much done.”

    The construction of MOD 70’s is basically carbon fibre with all panels where there is a chance of slamming have a foam core, while the rest is Nomex cores. As an example the floats outboard sides are in foam, while the inboard side have Nomex cores. Also, the type and density of the foam and Nomex varies according to the location, flexing and slamming loads that may effect that panel. The carbon fibre is high strength and mainly pre preg with epoxy resins. The builds are post cured to ensure strength and consistency. The design of the MOD 70’s works with safety factors 2.4 to 1 versus OMRA 60 which worked with safety factors of 2 to 1. A designer of home built boats use safety factors of 5 or more in their designs. High quality designs and builder boats can outsail an average armature built design because the quality design/built boat is generally lighter and stiffer.

    The jpegs give the idea. Tomorrow we will talk about the mast and foils builds of the MOD 70’s and how it effected future tri designs.
     

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  13. bajansailor
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    bajansailor Marine Surveyor

    Re Powerplay, she capsized quite spectacularly in France in 2013 -


    Some (rather old) photos of her on Marinetraffic (she has not been seen on here since 2018)
    Ship SAILING POWERPLAY (Sailing Vessel) Registered in France - Vessel details, Current position and Voyage information - IMO 0, MMSI 228035700, Call Sign FIHD https://www.marinetraffic.com/en/ais/details/ships/shipid:180595/mmsi:228035700/imo:0/vessel:SAILING_POWERPLAY

    She was successfully recovered after her capsize, and was for a while sponsored by the Barbados Tourism Authority, and re-named Miss Barbados - she took part in our annual Mount Gay Round the Island Race in January 2016, and smashed the course record,
    Mount Gay Round Barbados Race 2016 Spectacular finish https://www.visitbarbados.org/mount-gay-round-barbados-race-2016-spectacular-finish

    She was match racing with Phaedo 3, and only 12 seconds separated them at the finish line, after sailing at least 60 miles in 2 hours, 37 minutes. In contrast, we have sailed around the island a few times on monohulls, usually taking around 10 - 12 hours......
    Ship PHAEDO 3 (Sailing Vessel) Registered in Cayman Is - Vessel details, Current position and Voyage information - IMO 0, MMSI 319076500, Call Sign ZGEP7 https://www.marinetraffic.com/en/ais/details/ships/shipid:3511541/mmsi:319076500/imo:0/vessel:pHAEDO_3
     
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  14. Dead Air
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    Dead Air New Member


  15. oldmulti
    Joined: May 2019
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    oldmulti Senior Member

    It’s interesting that the MOD 70’s have developed a lot of unique little safety features, thanks for the videos, it helps everyone understand what is required to sail really fast safely.

    The MOD 70’s after racing as a class for years, then were developed to do additional tasks such as single handed racing. They stayed close to their original MOD 70 specs (70 x 55 foot with a weight of 14,220 lbs. The 90 foot carbon fibre rotating and canting wing (now up to 12 degrees either side) mast carries 3200 square foot upwind and 4,300 square foot with a screecher) but some upgraded the C foils to provide more lift. The original C foils for the Mod 70 hydrofoils for Argo racing and Beau Geste racing were uptip L-foils designed by Martin Fischer. In cooperation with Andrew MacPherson two new sets of foils were developed and built by DNA. The basic materials for the foils are carbon fibre pre-preg in epoxy. The Mod70 hydrofoil moulds are milled in a 3D-profile and built using an autoclave-resistant carbon tooling is made. With the ‘one-shot’ production process, DNA manufacture all our continuous fiber foils under vacuum cured in our Autoclave. The production method was developed to create a hydrofoil that cures in one go, without glue joints and including internal stiffening ribs. The result are very strong light hydrofoils. The C foils are 11.1 foot long with a 4.4 foot tip length and 1.85 foot wide. The retractable curved foils in the MOD 70 floats helped alleviate the downward force on the leeward float, helping to reduce the wetted surface area of that float, but significantly also reduces leeward bow burying by providing lift forward. These foils helped develop offshore foils suitable for large racing tris that can fully fly. The foil build jpegs are from DNA.

    The carbon wing masts of the OMRA 60 tris were light and fragile often with Nomex cores. The MOD 70 rotating wing masts, made by Lorimar, were built in carbon fibre epoxy without a core (monolithic). The solid carbon masts are cheaper than cored masts but in the event of a boat capsizing it will damage the boat less. “Before you capsized with the Nomex mast, you broke all the parts of the boats because the mast floated. With these masts you are safer and you save a lot of money too.” Rigging, both standing and running, is primarily Dyneema with some PBO, while the Solent stay is Kevlar. They have avoided carbon partly because of cost but they also want a small amount of give in the rig to reduce stress.

    So, we have the MOD 70 tri that was developed to sail as fast as an OMRA 60 but with greater safety in all aspects. The mast being moved aft in the original design and the lifting C foils providing lift allowed the MOD 70 to be driven harder across a wind range with less tendency to pitchpole which was a weakness in OMRA 60 tris. The additional strength built into the designed structure, rig and foils also allowed to crews to push the tris harder across oceans. The MOD 70 provided a lot of valuable information that was designed into the 100 foot tris that now race across oceans.

    The jpegs give an idea of the tris features.
     

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