Planecat - design input / potential project?

Discussion in 'Multihulls' started by silvah, Jan 31, 2017.

  1. silvah
    Joined: Jan 2017
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    silvah Junior Member

    Hi all,

    I came across something rather interesting and I am trying to determine if I should look at this closer or not. I ran into the widow of a catamaran designer by the name of Richard Rogala. Has anyone ever heard of him or Richard's designs? Evidently his mark trademark designs were based around the idea of planing catamarans. It is an interesting concept, that his wife says he initially started designing while living out on the west coast, and continued to design after moving to the midwest. She showed be a few different catalogs from the 80's with his designs as well.

    Regardless, evidently her husband died about a year ago and she has one of his unfinished projects in her pole barn. It is a 24 footer, both hulls were done by some outfit in Canada, unfortunately I can't remember the name. They are glass over plywood construction. She also has the mast, and a ton of hardware, in fact much of the hardware needed to get it on the water. She also has plans for many of his different designs, from small 16 footers, to 40 footers and beyond.

    I think she would be willing to part with much of this stuff for a very reasonable price. I am trying to decide a few things:

    1) I have never seen a design like this on a cat. I feel like there is probably a reason why that is. Thoughts on this?

    2) It is worth me trying to acquire the designs for these boats? If I was able to acquire them reasonably enough, I would be willing to digitize them and make them freely available to others.

    This project is interesting to me because with minimal investment and time I could put this on the water. For playing with it, I don't really need to fit out the hulls, just join them, mount the mast and hardware already acquired by her husband, and get some sails for it.

    I have included an image of one of the articles on this boats, as well as some pictures of the hulls. I apologize for the poor images, the camera on my phone was being wonky when I went to take a look at this. Please let me know your thoughts!

    Mike
     

    Attached Files:

  2. bjn
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    bjn Senior Member

    Cool stuff. Does he write anything about the "bumpyness" of sailing it?

    How much wind does it need to go on to a plane?
     
  3. UpOnStands
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    UpOnStands Senior Member

  4. silvah
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    silvah Junior Member

    bjn - Great questions, unfortunately I don't have any answers for those questions. If I get back in contact with his window I might be able to get some additional answers, as it seemed his wife had some extensive sailing experience. She was also looking to sell a smaller (day sailing) catamaran of her husbands design that they had sailed extensively together. However she did not seem to necessarily understand the ins and outs of his designs. She had misplaced the designs for the 24' project and was supposed to send me a text message with some images of them a while ago, but I didn't hear from her and I ended up side tracked so I didn't follow up. I was hoping there might be some additional information in the designs.

    UpOnStands - Thanks for sharing those links, they confirm what I suspected of this sort of design. When I looked at it I immediately thought, well this could be fun, but it is definitely going to pound in a chop. The stability issues called out in the one article don't apply because no catamaran is coming back up from a capsize on its own anyway. It definitely seems to provide at least a few benefits namely roomier hulls, greater capacity, easy construction, and a potentially and exciting ride in some good wind. The question is how bad will it pound in a chop? It would be great to hear from someone who has built one of those flat bottomed Woods designs to get some real feedback.

    My understanding is that he was building this boat for himself and planed to use it for weekend sails on Lake Superior and Superior is fairly well known for having some fairly good chop. Although I don't know Mr. Rogala as a designer, you would think this would be something he would have considered especially if he was building this one for himself.

    I am tempted to just go for it and consider it a toy project, put to together without fitting out the hulls inside, and just sail it to see how the design performs. However at this point that would have to wait until spring, due to the fact that this far north sailing season is a few months off yet!

    Mike
     
  5. CT249
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    CT249 Senior Member

    There's a basic geometry issue with planing catamarans. The amount of planing lift that a hull creates is closely related to beam - the wider the hull, the greater the lift. A planing hull can be thought of as something akin to a wing (both create lift by directing flow downwards). When seen from the direction of flow, a 2' wide cat hull is similar to a rig that is only 2' high, so like a 2' high rig it's not very efficient. Because the cat hull is very long for its beam, it is also difficult to get it to take up the right angle of attack to the water to develop lift.

    Some of the modern small high performance cats have moved to semi-planing hulls, but they are still nothing like a flat-bottomed pure planing shape. The small boats also have the benefit of being affected by fore-and-aft movement of crew weight which is a significant factor in helping them semi-plane.

    Basically, this is an idea that has been tried and failing (in terms of being faster than a normal cat) for 50 years or more.
     
  6. UpOnStands
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    UpOnStands Senior Member

    Mike, Core Sounds is line of flat panel monohulls some of which have very flattish bottoms - there are videos of them sailing with audio, check for "CS 17" & "core sounds 20"
    https://www.youtube.com/watch?v=Pdg1o8cfErk&list=PLCnKN6s9JPgvZKhCSUhO4VsQTiR9YmN49
     
  7. sawmaster
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    sawmaster Senior Member

    planning catamaran

    there is a video on youtube sailing videos of a planning beach cat. Its called Itsacat.The hulls look like surfboards.It goes very fast, indeed.
     
    Last edited: Feb 10, 2017
  8. Scot McPherson
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    Scot McPherson Senior Member

    although not a catamaran, phil bolger designed some monohulls that got up on a plane with wind. The Light Schooner being an example of a boat when reaching will go as fast as C-Cat and from what I have heard from the people who have sailed it, that it indeed makes for an exciting ride.
     
  9. CT249
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    CT249 Senior Member

    The Light Schooner is rated only 2% faster than a 1950s design 16 foot trailable yacht, and it's regularly beaten by them.

    This is a C Class cat: https://www.youtube.com/watch?v=l7ohSVlhVy4. Compare its speed to the RIB planing fast alongside in some shots.

    This is a Sharpie that is just 2/3 the weight of a Folding Schooner Sharpie, has a spinnaker and trapeze, beats 505s, is officially rated much faster than a Light Schooner, and yet it is miles slower than a C Class cat. https://www.youtube.com/watch?v=lIO7ZhQ-IGs

    This is a Light Schooner reaching: https://www.youtube.com/watch?v=v21UUWnr7mo Surely anyone can see the difference between the speed of the C Class and the Light Schooner.

    This is a boat that is offiically rated to be FASTER than a Light Schooner reaching; https://www.youtube.com/watch?v=d_nGJSVB9Zg It's actually much slower than a Laser, much less a C Class cat.

    There is no way that a Light Schooner is faster than a C Class cat (or a Formula 18 cat, 505 or 18 Foot Skiff) on a reach. Flying Tadpole II is rated about half as fast as a high performance 18' cat. In the 2008 MASC festival race, the Light Schooner was beaten across the line by a traditional 11 foot dinghy. in the 2010 Florida small craft festival race, the Light Schooner (rated by one source as the fastest of its type) was beaten by little old Melonseeds. Those are not good results.

    Does anyone really think that a boat built as a cheap fun craft can actually beat carbon fibre wing masted racing catamarans created by some of the world's top designers? It's like saying that a soapbox derby racer can beat a Formula 1 car.
     
  10. CT249
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    CT249 Senior Member

    I sailed that a bit. It may have been a little bit faster than a standard small surfcat in ideal conditions (when reaching in a moderate breeze in flat water) but it was slow in just about all other conditions.
     
  11. bjn
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    bjn Senior Member

    A special thing about planing hulls is that the drag is pretty constant, doesn't increase with speed. It's because the wetted area decreases with increasing speed. So with a really strong wind the boat can go really fast. There are keel-boats reaching 25 knots. So this flat bottomed Schooner should be able to reach at least that speed, I think.

    Hulls of a light catamaran like the C-class does not plane. Frictional drag increases with the square of the speed increase. This puts a cap on the max speed. I think the boat will pitch-pole when the forces gets too large.

    An F1 car will also loose in a sprint against some relatively inexpensive barn-tuned streetcars.
     
  12. CT249
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    CT249 Senior Member

    But a 700lb boat with low righting moment (like the Light Schooner) would not be able to go faster than the 180lb flat-bottomed trapeze-powered racing Sharpie I linked to in the video above. The LS has no trapeze (so less stability, much more weight which means that it does not get the bow up and reduce wetted surface in the same way as the light Sharpie, and lots of drag from the low aspect sailplan. So the LS would not be able to go as fast as the Sharpie (which I use as an example of a flat-hulled racing dinghy of similar length) and the Sharpie cannot go as fast as a C Class cat.

    As skiff and dinghy designers like Julian Bethwaite say, righting moment is a key to high speeds in a planing boat, and the LS has very low righting moment; no racks, no trapeze, no wings and apparently not even any hiking straps. It's also not particularly light.

    While (as you say) cats don't have a fantastic top speed, the top speed of a pre-foiling C Class was still 23 knots. For comparison, some say the top speed of a 49er skiff was 24.1, and Emmett Lazich reckons the full carbon top-end Grand Prix 18 Foot Skiff topped out at 28.6 knots, but the more restricted current 18 Foot Skiffs do 24 knots. At the other end, Lasers allegedly top out with a peak of 17-18 knots or so (and that would only be for a very short time, IMHO; I think the 17 was surfing a wave).

    Since the LS is rated slower than a Laser, there is no way it would end up being knots faster than a Laser and achieve the same sort of speed as a 49er or 18 Foot Skiff, and that's what's required to be as fast as a C Class. Take a look at the LS again, and then ask yourself whether it could go like this.... Skiffies aren't ******, they spend 20 times the price of a LS so they can go LOTS faster!
     
  13. silvah
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    silvah Junior Member

    I think the biggest issue with this design is going to be its performance in light winds. I took a look at some of the YouTube videos others posted, and this boat is so much different and so much more heavy, I think it is going to take a lot more to get it up to plane. There is just so much wetted area.

    If I remember correctly, the mast was 30', which is pretty stout for a 24' boat. I just wish I had been able to see the plans to see if it was supposed to have keels, dagger boards (didn't see slots for them), hydrofoils.

    With the hulls, mast, and miscellaneous hardware, what would something like this be worth? She didn't give me a price. It is worth considering?

    Mike
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    With a planing cat you will need to know the ratio of weight to the water plane area to get a guide to what kind of planing action you can expect. Like the lbs/sq foot loading of a plane's wings. Early planing demands a light boat.
     

  15. bjn
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    bjn Senior Member

    The yardstick rating is based on sailing up/down in relatively light conditions. The boat needs to be fast both up and down. So they have high aspect rigs and lots of righting moment.

    But if we are only interested in broad reaching down when the wind is strong, we could use a low aspect rig, since it produces less pitching moment. And we could put a bunch of people on the gunwhale in the stern to balance that force. Then the Light Schooner and similar designs could go really fast in this type of conditions. He did not claim it would be faster than a Skiff. Only faster than a C-class. But it could probably be faster than the skiffs since the skiffs are shorter, has a high center of effort, and less crew weight. So might be first to pitch pole. But will beat the old plywood boat in all other conditions of course.
     
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