T20 -- New development class

Discussion in 'Multihulls' started by idkfa, Sep 26, 2011.

  1. rayaldridge
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    rayaldridge Senior Member

    Well, look at Randy Smyth, who beat 2 guys on a Tornado, sailing solo in his little tri, in the last Everglades Challenge.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    =====
    Thats a good one Ray. And the Gougeons beat all the C Class cats with Victor T-a C Class tri without the C Class cat beam restriction.
    My contention has always been that the trimaran "type" is faster if all the elements of the "type" are incorporated. I think a production tri 18' long and 18-22'(or so) wide could be designed that would whup all production cats. Hasn't happened yet but I bet it will. And be easier to sail and less physical than the cats it beats.

    Picture: Victor T in the old days:

    click on image--
     

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  3. dstgean
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    dstgean Senior Member

    Good point. Weight is a BIG deal though, so if the solo sailor can keep it together, he has a 200# advantage. That = speed. Randy is one heck of a sailor and competitor. His tri is pretty exceptional & quite light based on watching him dragging it off the beach at the WT start.

    Power can be similar for a given area, but the Tri will win out in light air due to less wetted surface area & maybe again in heavy air once the cat has to depower.

    I also view it similar to a triathalon. The three events are of primary importance, but one racer can beat an = competitor in transition. I'd be interested in the "transition times" of Randy vs. the Tornado guys.

    Dan
     
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  4. arekisir
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    arekisir Junior Member

    This idea has merit, a home built version (bit smaller) of an M23 for a lot less money.

    I think Chris O did some work on trimarans based around big beach cat doner parts. Not sure if any got off the ground they looked pretty sweet.

    There is the sardine run trimaran which is quite cleaver in its simplicity if some of this thinking could be used I think it would be a winner.

    One thing I'm curious on is the volume of the hulls on a typical F18?

    Some of my own thoughts:

    Since a lot of small tri's have floats that allow the rear of the float to squat (farrier etc) would it be possible to have a 20-22ft main hull with the end of the floats ending 2-4ft further forward.

    I dont think a folding system along the likes of farrier is viable for a low cost I would be happy with disassemble.

    The extra righting moment will mean boards, cases, rig needs strengthening are there any other areas that require extra strength.

    If there were a good set of plans covering the build of a simple main hull and the strengthening required I think this would be a home build within reach.

    Does anyone have an established modern design of this concept?
     
  5. Corley
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    Corley epoxy coated

    As far as I know there are no modern plans for this concept. The reason is simple, if your going all out for performance you would build floats of appropriate volume and shape for their role as a trimaran float not use a donor catamaran hull. If the rules specified that you must use a donor catamaran hull set then it may be viable. What you would find is that most of the boats that were racing would gravitate to whatever donor cat hulls offered the best performance. You would end up with a defacto one design class and everyone who was building would look to tweak their main hull, foils and fittings for maximum performance.

    I dont really see it as a cheap class to build a boat to fit. The 290kg minimum weight also seems a bit lardy to me I think you could build the boat to be 250kg without too many exotic material choices (I think that I could build a 20' main hull out of simple tortured ply that would be considerably less than 70 kg, my 25' C Class trimaran weighs less than the proposed weight (210kg-250kg depending on fittings) and was built cold molded and ply in 1962. I gather min weight for the F18 catamaran is 180kg? Thats pretty lardy in itself really but I can see the virtues as far as keeping the boats simple.

    As always the competitors with the most money will come out on top as they have the ability to buy the best sails, fittings, foils and rig and test and tweak them for best performance. I personally would like to see the option for twin trapeze in the class and no lifting foils I dont think you need them and they will add a lot to the cost of the class and require additional strengthening of the donor cat hulls and installation of special trunks.

    If I was running the race I'd handicap lifting foils back to the fleet or make them race in their own division if they proved popular (I know I'm a luddite). I've seen what foils do to club racing everyone ends up in an arms race which only a few sailors can afford also how do you handicap the damn things properly? sometimes the foils do nothing useful other times they could be the race winner in themselves they only offer improved performance in a certain window of conditions.

    If your only racing other T20's what does it matter how they stack up against cats? catamarans will probably be faster in medium winds the tri's will be faster in light conditions and in stronger winds. I see what your proposing as a kind of round the buoys sportboat and think the offshore component is unnecessary 20' trimarans handle like a sportscar and will be a nicer boat to sail than an equivalent cat you dont have to oversell the concept to make it work. I think there could be enough interest to make it work assuming the rules offer enough clarity. I'd certainly consider building a boat to race to the rule.

    I hope I dont seem negative I'm passionate about multihull sailing and think that excessive gadget adding might make our boats unappealing for the broader sailing community, when I sail I want to be a sailor first and a technician second.
     
  6. Doug Lord
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    Doug Lord Flight Ready


    Corely, thanks for pointing out the proposed weight-I missed it and it seems awfully high for an 18'-20' tri. I haven't looked at it carefully but I would doubt that ama and/or mainhull lifting foils would work well at that weight +two people.
    Idkfa, doesn't want to fly the main hull and thats probably good because using an F18 rig it would require 2.47lb.sq.ft pressure at the CE . The design
    max pressure with two people on the trapeze of an F18 is 1.8lb/sq.ft..
    I just got to see(and not sail, yet) the Bradfield Osprey(see thread). It is an 18' trimaran, 20' wide(not including foil tips) and weighs 400lb all up. It is not all carbon-it is mostly glass/foam. It does use a carbon mast and carbon beams. The difference between carbon beams and aluminum is about 50 lbs.
    -----
    The advantage foils, used for foil assist, have is to reduce wetted surface and increase the pitch control of the boat. On my 18 footer they do that by allowing the main hull to take off in very light wind drastically reducing wetted surface right off the bat. The foils I'm using are effective thruout the speed range though they do act differently as the speed increases: the main foils unload to near zero at around 15 knots and the ama foil loads up to near maximum at the same point. But then the main foils still act 100% to control pitch and maintain the riding attitude of the ama foil (and ama) which begins to act like a surface piercing foil somewhere above 15 knots depending on how it is set up.
    All this just to point out that a properly designed set of foils is not limited to this: "they only offer improved performance in a certain window of conditions".
    I don't consider foils to be "gadgets" anymore than are amas, masts etc. They are a major element of modern multihull design because they can have tremendous advantages. But using them w/o a design specifically for them can result in a marriage made in hell.
     
  7. Corley
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    Corley epoxy coated

    I like the idea of an "extreme" class within the T20 classification Division 1 if you like in that you can go nuts on lifting foils, beam up to square and all manner of wing rigs and carbon fibre stuff. The problem is not many people will build a boat thats competitive because its so expensive maybe there will be 2 or 3 teams who could put together the cash and sponsorship to make it a reality.

    I think a more limited division 2 category is a good idea this will be the class where you will have more competitors because it will be affordable for most folks to put a boat on the water that meets the criteria. I can see quite a few boats being constructed to fit this division 2 and some of the best racing to be in this section.

    The problem I see is this not many people want to sail a boat thats extreme. At our club AGM the other night we were discussing how many racing multihull boats that are classified under OMR could be described as extreme. We came to the conclusion that out of 60 boats only 7 or so could be classified as fitting that category. We came up with Trilogy, Mad Max, Indian Chief, Bare Essentials and Voodoo Spirit and KAS the previous Banque Populaire orma 60 (we thought cynaphobe might be in there as well).

    The obvious conclusion from that discussion is that if we relied on division 1 boats to make racing worthwhile we would never have any multihull nationals because it isnt worth running those races for 6 boats.

    I see a similar situation with the proposed T20 class I'm not a fan of having the same 2 or 3 boats winning all the time and like the thought of a trophy for the more basic division 2 boats.

    I'm not knocking lifting foils I like them but its not worth running races for 2 or 3 boats so there needs to be some incentive for people with less dosh to get involved in the game or somehow a subsidised system for people to get expensive gear on their boats. Its worth noting that lifting foil equipped boats are still very high end and expensive as to get maximum benefit the boats have to be light. I can think of only a few low volume production lifting foil equipped multihulls and they are all expensive the Nacra 20c comes to mind and the seacart 26 is there a production A class with lifting foils?
     
  8. Doug Lord
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    Doug Lord Flight Ready

    =======================
    You're probably right but I'm hoping that the definition most people regard as extreme will morph into "good performance". I think an 18'-20' tri can be designed that performs better than an equal length cat, that is far more comfortable and easier to sail than the same cat, less likely to capsize or pitchpole and easy to trailer and set up. It may sound ridiculous but I believe that is a realistic boat from a cost standpoint and from every other standpoint. A boat like that would redefine what people think a small trimaran is all about and would surprise a whole lotta people-in Division 1 and 2.......
     
  9. idkfa
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    idkfa Senior Member

    I do agree the weight is high, it's baggage from the F18, should be dumped...

    Keeping the F18 rig would go a long way in keeping cost down.

    Any value in the 1.25m cabin height restriction? Seems to fit into club racer - division 2.
     
  10. Corley
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    Corley epoxy coated

    I think the cabin height minimum is fine, racers being racers though unless you impose very strict rules as to the shape and size of the cabin it will be the smallest cuddy you have ever seen because everyone will want to minimise windage for racing. I wonder whether it would be economic to build a hull shoe for the main hull like the leneman L7 and a ply kit for the topsides/cabin area a beam kit would be possible probably make the cnc files available for potential builders to get their kit cut locally. The F18 rig will be fine for a club racer.
     
  11. arekisir
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    arekisir Junior Member

    "Keeping the F18 rig would go a long way in keeping cost down."

    What is estimate on cost?
    Second hand F18 complete and ready to go - 8K
    Main hull chined ply -2K
    Beam mods alumin 1K
    outboard 2-3hp 0.5K
    Unforseen - XX?

    I could see a boat on the water for 15K that would nip at the heals of an M23 is this fantasy?

    alex
     
  12. Corley
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    Corley epoxy coated

    The costings sound about right, add a bit for trailer (you may be able to mod the cat trailer) and you would be done.
     
  13. waynemarlow
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    waynemarlow Senior Member

    Are you not getting a bit over excited about the F18 donor boat, its heavy, has a very heavy mast, heavy dagger boards, heavy fittings you name it, it is over engineered for the purpose of Amas of a Tri where everything needs to be light.

    Now for about the same money you can get an older A Class with very light weight hulls, 17.5ft long, virtually all are ahead in design terms of the hull to the F18's and as a bonus you get a taller mast. You may need to beef the mast up slightly but that is no real problem. Now build a light weight centre hull and we are talking.

    The other boat to consider is a F18HT if you can find one.
     
  14. idkfa
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    idkfa Senior Member

    Waynemarlow I hate the excess weight of the F18 too, but the hulls of the A Class look a bit small, any ideas as to their volume?


    If we put a third body on an F18 what happens, it's slower, until the wind picks-up to over 18K when she would have normally been over powered?

    If that third body is a vaka, the helm and crew sit in, then she'll fly the centre hull/fully power-up in 12K?

    All that said, I would vote for a weight around 175kg and a carbon mast, but at what cost, and can it really be "a home built"?... maybe Division 1?

    We race off a lovely beach here most of the time, 18-25k winds during the Easter months. But the yacht regattas venture to the unprotected coast where the waves get up to 2m. And, we also have a round the island race thats 25K winds and 3m waves. I would like a small tri that could do all. Surely an F18 can, but there are miles of coast that would mean death if one came ashore there, so an outboard and anchor should be part off ones gear.
     

  15. Corley
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    Corley epoxy coated

    I agree with you Idkfa its easy to get the weight down if you are an accomplished home or production builder but most people are impatient and simply want to get on the water quickly.

    Alan with his 23' trimaran "the experiment" went down the A class path and ended up having to widen and increase the freeboard of his floats to get enough volume thats outside the scope of most home builders I think.

    I know from my discussions on here and looking at posts that people are absolutely terrified of the prospect of building three hulls if you can reduce that down to one main hull it becomes much easier for potential builders to conceptualize and take on. What is required is to get bums on boats and get them on the water and the quickest path to that is the most desirable once you have said bums on the water they will want to tweak their boats and will start looking for the lightest hulls, best fittings etc. You can build a class on that basis.

    We were discussing earlier the idea of a division 1 and division 2 boats I think you have to go that way with this kind of boat due to low numbers I'd much rather see twenty division 2 club race T20's on the water in a given geographical region than maybe 2-3 division 1 T20's racing alone.

    The big problem with tiny classes is that if someone loses interest or they are not able to make an event due to personal issues your class has lost 1/3rd of its numbers if half of 20 boats stay home you can still have a decent race.

    I've helped plan several events in the past and theres nothing worse than just two people turning up and deciding to go home because there is not enough numbers for a decent race it really makes you despondent when that happens. Not to mention your wasted time in providing a committee boat, setting marks and publicising the event. The most inclusive events with the broadest range of boats seem to be the most worthwhile.
     
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