Trad vs Mod - Yet Another

Discussion in 'Boat Design' started by Capt Ronrico, Nov 3, 2015.

  1. Capt Ronrico
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    Capt Ronrico Junior Member

    Firstly, I really did use the Search feature before posting. It just didn't return what I was looking for, even though there are over 11,000 threads under this file. Some of them may be old, so maybe it bears renewing anyway.
    Does anyone KNOW the origin of the trendy modern hull shape - fin keel, spade rudder, light displacement, narrow and flareless bow, and volume aft?
    I assume the very first was a racing boat - but I wonder what was the first, commercialized, mass-market, "cruising" boat? I'd like to have a name for this class of boat.
    There is a reason of sorts for my question. It has to do with the fact that I despise marketing this kind of boat to non-professional sailors.
    My animosity was most recently piqued by a YouTube flic:
    https://www.youtube.com/watch?v=jIZvq9sRKvo
    This boat sank because the spade rudder was struck by an underwater object.
    You can see the owners are retired people - not racers.
    I can't understand how boat manufacturers market boats like this to people like them. Or family types. Or party-goers. Or first-time buyers. There is something definitely un-seamanlike about that.
    Anyway - back to my question about this type's origins. I'm really looking for a single (and reasonably polite) word to designate this type of boat. Saying, "a light displacement sailboat with fin keel, spade rudder, narrow and flareless bow, and volume aft" gets a bit burdensome - and I use it a lot in my ranting.
    I'm sure that some of you think the world of this type of boat. I just don't think it's a good design for non-professional sailors going cruising.
     
  2. gonzo
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    gonzo Senior Member

    It's all about fashion. Owners want to have a boat that looks like a racer. It works with cars too. Look at commuters driving around with high performance tires and a spoiler in the back ;)
     
  3. Richard Woods
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    Richard Woods Woods Designs

    If you google yacht design history you will see that that sort of boat is over 100 years old, maybe 150. Van de Stat drew many boats like that from the 1940's onwards

    You might like to rant a while on "why don't people make/want unsinkable boats"? After all Etap, Sadler etc were doing it successfully years ago

    RW
     
  4. CT249
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    CT249 Senior Member

    Well said! I can't work out why people fight over whether it's better to capsize than to sink, when there are proven ways of making boats that don't do either.
     
  5. CT249
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    CT249 Senior Member

    For one, define "fin keel", "light displacement", "narrow" etc. Only then will we be able to work out if you mean "light" as in Cal 40 or "light" as in Farr 40.

    The boat in the You Tube clip has a DLR of over 200 - it's almost identical to a Valiant 47 and is often classified as the low end of moderate these days.

    There are plenty of heavy boats with full keels that have sunk, by the way. There are trade-offs for everything. If you presented objective data, such as an analysis of sinkings of various types relative to the miles they have sailed, it would have been of interest.

    After all, we've all got our own prejudices....I'm a bit prejudiced against people who call themselves "Captain" in relation to sailboats. It sounds like they could be master mariners (who may have no idea of sailing) or pretentious.
     
  6. FAST FRED
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    FAST FRED Senior Member

    Race boats work great to race , until the race rules change and thy are scrap.

    Cruising boats have 100% different design goals , they can be slower , but at least you do not have to squeeze out 95% OF THE TOOTHPASTE from a tube to go sailing.

    Light is great for the race folks , a cruiser will be carrying extra ground tackle , months (not hours) of food and water.

    Porche vs station wagon.

    A race boat is built to a rule , the idea is to create a slow boat in the rating that sails mediocre in fact and can win.

    With no penalty for sail area or stability the cruiser can frequently do well, but will seldom get up on a plane like the racers.

    The cruisers auto pilot or Self steering might go nuts!
     
  7. PAR
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    PAR Yacht Designer/Builder

    The modern shapes where an evolution, but revolved around advances to beat the racing rules of the era. An example was separating the rudder from the keel, which was done in the late 50's under the CCA rule, but many advances have come to be, just to reduce wetted surface and as materials and building methods evolved, lighter, stronger, thinner bits could be employed. Another example would be the progression of the cut back forefoot. The forefoot was whittled away as materials and methods improved, decreasing wetted area and permitting the yachts to turn better. Some improvements were banned from racing circuits for a time, such as fin keels, because the advantage made all the other yachts obsolete overnight. Eventually as one rule got worn out and a new one was devised, some of the innovations found their way onto boats.
     
  8. bpw
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    bpw Senior Member

    Plenty of heavy full keel "cruising" boats have sunk as result of structural failure. Most any design type can be built strong if that is what is desired.
     
  9. Capt Ronrico
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    Capt Ronrico Junior Member

    So much for the "Mod" part. No one suggested a handy term for this kind of hull. I guess something like "spade-fin" will have to do, even if it lacks verve.

    On to the "Trad" part...
    John Neal, author and mariner, made this comment on his website: "The cutaway forefoot is a faster, more maneuverable design that will have fewer tendencies to trip or broach when running under storm conditions than a traditional Tahiti ketch type of full keel boat. " His reference to the Tahiti puzzles me. Neal is a very experienced sailor, but I've never heard of the Tahiti/Tahitiana being particularly prone to tripping or broaching. Also, when I look at the lines of the Tahiti/Tahitiana, the keel doesn't look very pronounced forward. PAR touched on the trimmed forefoot in general, but can anyone illuminate this further regarding the Tahitis? I'd always heard they were pretty bulletproof.
    Neal's comment is at: http://www.mahina.com/article.html

    And, CT249, if you don't like calling me "Captain" you may call me "Colonel". I had the honour of serving in the same regiment as Harland Sanders. You can even call me "Al". Just call me for dinner.
     
  10. sharpii2
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    sharpii2 Senior Member

    Fin keel Separate Rudder

    The sharp bow started with the yacht America which trounced the British to win the cup which bears her name. She was considerably faster than the British boats, which almost all went with a full bow and a gentle run aft, the so-call "cod's head and mackeral tail". One of the reasons she was faster is that she was considerably larger than most of the British fleet.

    But the sharp bow made a real difference in parting channel chop, especially when going up wind. Interstingly, British channel cutters had a similar bow, but the full bow offered beter control when going down wind in a storm, so British yachtsmen were loath to part with it.

    The separate fin and rudder was probably inspired by center-board boats such as sharpies. IFIRC, Nat Herrshoff was at least one of the first to experiment with a fin keel and separate rudder.

    As noted in a previous post, this innovation was banned for a time, so more traditional boats could stay competitive.

    As time went on, by the 1960's, it made more and more sense to go with a fin keel and separate rudder. A major reason for this, IMHO, was the advent of what I call the harbor yacht. This was a boat which was suppose to be off shore capable, but was primarily used for relatively short voyages, not far from its home port. These were often raced in summer conditions where the wind was often lacking. This created a need to cut frictional drag as much as possible. A boat with a separate rudder and fin keel worked out quite well in this environment. Such an underbody is also much easier to hoist than a full keel one, I might add. I know this from experience.

    Since a harbor yacht was mostly making shorter trips, it was required to sail to windward more often than an ocean roaming one. For this reason, as well as for racing, windward ability was highly coveted. The airplane wing like fin keel is far better at windward work than a long, slab sided full keel.

    Lastly, as I have discovered with my own preliminary design work, the need for space increases much faster than the need for displacement, as the boat size grows. People want room to sit, room to sleep, and room to put their stuff. A high sided yacht, with a fin keel fits this requirement quite well. Extending the waterline all the way to the tip of the bow, creating a plumb stem, increases the waterline length, which, for the most part, governs the speed potential of the boat, as well as allows more room for bunks and stowage.

    The advent of wind vane self-steering gear, followed by that of electric auto pilots effectively eliminated The worse vice of this type--poor course keeping ability. This hull type now routinely completes long ocean voyages, and has been doing so for many years.

    It is possible to build a quite rugged example of this type, if light weight and speed are not the primary requirements. A spade rudder, even, can be quite sturdy. I've seen one that had a fierce arguement with a rock. Its shaft was bent a few degrees but the boat was still steerable, and it didn't develop any serious leaks.
     
    Last edited: Nov 10, 2015
  11. CT249
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    CT249 Senior Member

    Yep, there were plenty of very tough boats with separate rudders.
     
  12. FAST FRED
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    FAST FRED Senior Member

    The modern racerb is created to do two things a cruiser does not wish for.

    Big flat sections way aft allow plaining with a big enough spinnaker , in a big enough breeze.

    The fly weight hull is designed to roll to lift the rest of the boat out of the water.

    This was the concept "a single very skinny hull " while reaching ,,as the sandbaggers of the 1800s did.

    Sort of uncomfortable underway, while baking dinner.
     
  13. Capt Ronrico
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    Capt Ronrico Junior Member

    I hate to be contentious, Lord knows, but...
    Sandbaggers weren't really narrow (although some other 19th-century racers were).
    Mystic Seaport Museum has a nicely restored Sandbagger, "Annie", which you can see here: http://www.mysticseaport.org/locations/vessels/annie/
    Radical racer design, eh?
    But, back to the Tahiti/Tahitiana critique...
     
  14. bpw
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    bpw Senior Member

    Compared to anything even remotely modern the Tahiti ketch has a a lot of forefoot.

    We just spent a few years cruising on a boat with a similar hull shape. The deep forefoot combined with keep hung rudder makes steering down wind in waves a real handful compared to a fin keel boat. Pretty easy to broach if you wind up over powered or take a wave at a bad angle.
     

  15. CT249
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    CT249 Senior Member

    Some Open types may be designed to roll and lift the rest of the boat out of the water, but many other modern racing boats are not.

    Sandbaggers, as already mentioned, were extremely beamy, with a beam/length ratio of around 40% quite common. See Chapelle's detailed lines plans and many other sources.
     
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