New Design for a 17' Daysailer/Racer

Discussion in 'Sailboats' started by Cleve Motley, Oct 31, 2004.

  1. Cleve Motley

    Cleve Motley Guest

    Anybody interested in considering a design for a new 17' daysailer/racer that's a balance between a dinghy and a sportboat? Here's the background:

    I love the RS K6, and would like to see if the designers on this forum could translate a lot of the key features, performance, and looks of that design into a slightly smaller boat that two people could comfortably sail and race (as opposed to the three man crew of the K6).

    Key criteria:

    Light weight from state of the art materials
    Lifting fin keel with bulb for stability
    Kevlar glass/foam core/epoxy build
    Light, blanced helm
    Fast upwind
    Quick to plane on a broad reach
    Beautiful
    Quickand easy to rig/unrig
    Ergonomic cockpit design
    Accessible to home builders
    Carbon fiber mast and bow sprit

    I'd be interested in building a prototype and seeing if it would attract any interest in my local waters (Santa Barbara). If nothing else, I'd like to build a boat that my wife and I could race on handicap that would be fun, fast, and pretty.

    What do you guys think?

    Thanks,
    Cleve
     
  2. Paul B

    Paul B Previous Member

    What about the Thompson?

    A while ago there was one of the Thompson 590s in the boatyard there in Santa Barbara. Did you see it while it was there? Is that similar to what you have in mind?

    http://www.tboat.com/T590-gallery.html
     
  3. Cleve Motley

    Cleve Motley Guest

    Guest

    Paul,

    I didn't see the T 590 when it was here. However, the R6 is somewhat narrower . . . it's beam is just 6'. It's also quite a bit lighter. My sense is that it's part of the current school that goes for light, narrow, easily driven hulls with minimum wetted area. The web site below has some additional information on it.

    I'd like to apply those values to a slightly smaller design aimed at two normal sized crew.

    http://www.ldcracingsailboats.co.uk/rsk6.asp
     
  4. Paul B

    Paul B Previous Member

    I think the Thompson site makes it difficult to compare apples to apples at times. I belive they list the sailing weight including the listed crew weight. That would make the boat about 840 pounds, still more than the K6. However, they have a 300 pound bulb. I can't find the listed weight for the K6 bulb, but it can't be much.

    How stable or sporty do you want this to be?

    Ditto the beam. The Thompson is probably close to the same shape at DWL, but they have the flared wings for sitting out (as in http://www.boatdesign.net/forums/attachment.php?attachmentid=1577&stc=1&thumb=1).

    By the way, I saw this on the Melges site a few nights ago (while looking for data to compare to my just-rebuilt 28 foot version of what you are looking for): "New at Melges!
    Melges has all kinds of new things in development. For 2005 Melges will be introducing two brand new boats. The Melges 17 and the Melges 32." You might want to contact Melges and see if their 17 might fit your needs.

    I once worked for a boatbuilder in Santa Barbara. Be sure you have a lot of disposable cash if you want to get into this business.
     

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  5. Doug Lord

    Doug Lord Guest

    Performance 17

    I've been thinking along these lines for some time and it seems to me that if you want a 17-18' keelboat to daysail or race that a retractable canting keel could add a lot to the equation. It would be like having a third person on board and would allow a couple to sail fast.Small keelboats designed to plane carry the lead around at a disadvantage most of the time since if the boat is sailed flat- as most dinghies are- the fixed keel does no good at all. The canting keel could provide much more righting moment allowing a couple to manage the boat easily. The design can "hide" the canting keel system so that it does not intefere with the interior space too significantly and it could easily be manually or electically controlled. I like the idea of carbon tube wings with a difference: the tube,in addition to supporting the seat, would form a seat back that would allow for comfortable sitting out in real safety. The seat portion would be made of trampoline material and the whole thing would look really good and be very functional and super comfortable.
    Using the kFOIL allows the extra lateral resistance required by a canting keel to simply retract into the bulb when not needed and could be set up to deploy and retract automatically. The bulb mounted pivoting foil already retracts automtically if it hits anything. The kFOIL makes a canting keel practical on this small a boat because the extra lateral resistance won't take up any interior room.
    If a boat like this was to get started kits could be available from builders to allow much of the work to be done by homebuilders.
    I think it could be a fast,fun boat -a little bigger than most double handed dinghies- with a performance edge.
    But I can't wait to see the new Melges 17!
     
  6. Cleve Motley

    Cleve Motley Guest

    Guest

    Check this out:

    http://www.backmanboats.com/Index.html

    This guy's done a canting keel, twin rudder, carbon mast/sprit boat that has a lot of "Mini-Transat" look to it. But you could certainly apply his mechanical method of handling the canting keel to a 17'-19' boat that had a narrower beam, and less wetted surface.

    I'd like to see the Melges 17, too. They did a wonderful job with the Melges 24 and could bring critical mass to that size boat. It would be neat to see the latest advances in design applied to this size boat.
     
  7. Paul B

    Paul B Previous Member

    That Backman thing looks pretty strange. I wonder how it goes.

    I doubt you'll want any canting mechanism on a 2 person "dinghy with a keel". Two handed will have enough to do without worrying about getting the keel across. Getting it wrong might be very bad.

    The light weight of the bulb won't add enough righting moment to make it worth the added weight and complexity of the canting mechanism in a small boat. I would especailly steer clear of unproven, "Pie-in-the-Sky (TM)" ideas. All this stuff does is add so much cost to the end product that no one will pony up for one.

    Adding a trap wire will give far more RM than canting a 100 lb bulb, but I doubt you really want to do that.

    We have a group of people who are starting a Sportboat fleet in SoCal (SB to SD). PHRF won't let you play if you're less than 20 feet, but we probably will. Check it out at: http://groups.yahoo.com/group/socalsportboats/
     
  8. Doug Lord

    Doug Lord Guest

    Pie in the sky™

    P,If you were refering to the kFOIL™ as unproven pie in the sky technology you are way off base. The technology is new but far from unproven with wings being used as lateral resistance on the canting keel boat Atomic by Andy Dovell in Sydney Australia very succesfully in racing.
    The absurd admonition to avoid new technology including canting keels is nuts and a formula for everything to stay the same!
    Innovation is what will make a boat as described in the first post viable not something to be avoided. Backwards thinking like that won't help new developments in sailing at all and labeling ideas with merit as pie in the sky is the height of ignorance.
    Canting keels are used to great effect in the Mini 6.5's that are only 21' and are singlehanded; there is no question that a canting keel can be made to work very well with a double handed racing keelboat in the 17' size range.
     
  9. Paul B

    Paul B Previous Member

    "..there is no question that a canting keel can be made to work very well with a double handed racing keelboat in the 17' size range."


    I look forward to seeing the one you build to prove the theory.
     
  10. Brett (Aust)

    Brett (Aust) Guest

    I'm in the keep it simple crowd here.

    Having a canting keel for a two handed sportsboat is just one more thing to do during mark roundings, one more thing to do badly and one more thing to break. We have a 24ft sports boat and sail with 4-5 and there is plenty of things for everybody to do during each manouvre.

    If you want a giant leap in rm either give yourself a set of wings or traps. Think more dinghy ideas and less keelboat and get to line as easily as possible.

    my 2c

    brett
     
  11. Doug Lord

    Doug Lord Guest

    Performance 17

    I'm visualizing a two person canting keel boat with carbon seat/wings with an overall beam of 8' (hull beam at deck around 5'). The canting keel system can be made robust and has a long history(over 30 years) on singlehanded ocean racers from open 60's to the Mini's.
    Simplicity is good but not when it prevents (for the wrong reason) consideration of new technology. I just don't believe you are going to make a "hit" of a 17-18' keel boat unless you embrace new technology which can allow significant performance gains and offers a potential marketing edge over anything currently being produced.
    There are really exciting proven new technologies that should be looked at in the creation of new designs like this 17 footer. Doing the same old thing just will not cut it in my humble opinion. Nor should it: using a canting keel makes a 17'-18' powered up keel boat easy to handle by a couple with high performance compared to any other keel boat in this size. And this thing would be loads of fun-racing or daysailing with friends!
     
  12. Cleve Motley

    Cleve Motley Guest

    Guest

    If you look at the boat that was the impetus for this discussion, the RS K6, it seems that the qualities that contribute to it's performance are pretty classic: long water line, minimal wetted surface (from a narrow beam at the waterline), very light weight (significantly less than the Lightning, which has virtually the same dimensions), minimal weight aloft from the carbon fiber mast, significant weight concentrated in the bulb for maximum righting moment, and the asym.

    That's more what I'm looking for, but in a slightly smaller boat that's ideal for two. The idea is to achieve high performance without requiring an athletic, dedicated crew. I'm trying to get my wife interested in sailing and racing with me, but I dont' want to sail a slow boat. And I like beautiful boats (don't we all . . .).

    If you could design and engineer a canting keel so that it was simple and reliable--and had enough weight to actually make a difference--then it seems like that might be one way to increase the RM without having to go to traps or bars. I think the Backman 21 used a manual block and tackle system, if I'm not mistaken. Maybe that just becomes one more string to pull when tacking.

    Seems like that should be achievable in 17'.
     
  13. Paul B

    Paul B Previous Member

    It's fun to think about all the fancy bells and whistles that "can" be added to a boat (in theory). But at some point you have to pull out the pencil and consider how things work in the real world.

    Let's say you have this 17 foot "sportboat". I assume you'll want to ramp launch something like this. That means the keel will have to raise/lower. To have a canting keel you'll have to cant the Keel Box (well) that the keel raises/lowers through. It's been done. It adds weight and cost. You'll have to think about how to make the interface between the well and the hull watertight. It's not a simple problem to solve.

    If you're sailing in SB you might need to think about kelp. How can a kelp cutter be attached to the canting board?

    If you cant at 45 degrees will you need a canard? Probably. That's weight and cost. You'll also want to raise it downwind. Something else for a 2 person crew to handle. Gotta get it down at the leeward mark, while the kite's coming down and the jib needs trimming as well.

    How are you going to sail this boat? I'm assuming it is more "dinghy style" sitting than "big boat style". That means less power/leverage for the crew/wife to cant the keel. How much can you or your wife pull in a seated upright row? Take into account you're not at the gym, but on a heeling boat. Balance requires some effort. How much can you or the crew pull one armed?

    I did a quick sketch/study here at lunch. Best case you'll probably have to pull a 175 pound load to lift your keel (assuming a 100 pound bulb). With an 8:1 puchase you'll end up pulling about 25 pounds. However, with the 8:1 purchase you'll have to pull in about 11 feet of line. If you're doing seated arm pulls you might do it in 8-11 pulls. If you can set your feet maybe you can do it in 5 rowing pulls. All while the boat is overpowered and the crew weight is not working any better than the keel weight.

    So to tack the boat we'll assume a self-tacking jib to make things easier on the crew. As the tack begins the weather keel line is dumped, allowing the keel to drop and it is then free to move as it pleases. The crew must then balance the boat like a big, unballasted dinghy through the tack, with the keel swinging however it wishes. You can capsize to the old leeward or the new leeward side through the tack. Ever try to sail a dinghy half full of water?

    Once on the new windard side the crew sweats up the new keel line with 5 good rowing motions, or more arm curls. The boat is overpowered through this and you're losing ground to leeward. You could sweat the thing up quicker and more efficiently if you stand up to do it, but the boat isn't real stable like this.

    I see the Beckman 21 seems to sail with 4 people, and it isn't so much a dinghy-style boat. I'm sure they have a better opportunity to stand and **** on the keel line.

    The answer to all this is, "Yes" it can be engineered to function. Can it function efficiently enough for a "mom and pop" to race around the cans. I have my doubts.

    My opinion is for the stated purpose of this design you should think about having enough stability to self-right from a round up or down. That should mean a fixed keel (board) with a bulb. This can then be lifted for trailering.
     

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  14. Doug Lord

    Doug Lord Guest

    Performance 17

    One can always approach any set of problems from the standpoint that they are too difficult to solve.Incorporating new technology requires that problems be solved and I know that these particular problems can be solved relatively simply-if they are carefully designed and engineered.
    On a canting keel boat the number one question is what kind of lateral resistance are you going to use when the keel cants too far to be effective? The best answer, in my opinion, is the kFOIL™ as described in an earlier post. It develops the extra lateral resistance at no cost in interior room and is retracted when not in use. If it hits anything when deployed it retracts w/o damage.It can be simply set up to automatically deploy. This is really important on a small boat such as this. The kFOIL™ requires a TRUNK that is built into the boat and that is 100% waterproof. The method of building and sealing the trunk eliminates the characteristic "bump" common to many canting keel installations. It also makes it very easy to install or remove the keel-and to retract it for trailering; it allows the shaft for control of the kFOIL™ to pass thru the fin and does allow a kelp cutter!
    Another thing you have to consider in a canting keel installation is how far is the keel going to cant along with the weight and length of the fin. My preliminary work on this idea suggests that a 55 degree canting keel with a 5' fin(adjustable down to 4' for shallower draft) is the best solution. Using 160 pounds in the bulb the weight moves 4' to weather of the centerline at approximately the same position the two person crew is sitting on the wings in max conditions.
    The best solution for a system like this is to use an electro hydraulic(or just electric) system that moves the keel from center to windward in around two seconds. Keel control would be accesible from either side deck. An important design feature MUST be that the keel can never move freely unless it is being moved automatically by the crew or using the back up hand crank that would allow the keel to move side to side(110°) in 11 turns.If you let go of the hand crank the keel remains in position. The keel must also have a locking facility.If the control lines break,electric system goes down and in a worst case scenario the keel must have shock absorbers that prevent movement any faster than the electrical system allows(when its working).
    This stuff takes carefull engineering and the canting keel assembly including electronics backup etc. will add about $1500 or so to the boats cost compared to a fixed keel. But shorthanded performance will exceed any current boat and because the ballast is always 100% efficient in adding power -even with the boat sailed flat- performance will be very good.I've talked to an elecro-mechanical engineer that works for Disney about this concept and he feels that the electronics available today would make the automatic version of this system work flawlessly in a harsh environment for years and years using a relatively small battery.
    There are problems ,for sure, but they can be solved at a reasonable cost and in a light weight structure. I think this will be an exciting boat -I'd like to build one when I'm thru with a couple of foiler projects.
     
    Last edited by a moderator: Nov 3, 2004

  15. Paul B

    Paul B Previous Member

    Given that the "Pie-in-the-Sky (tm)" foil does not exist it might be difficult to fit it to any boat.

    The RS that was originally described as the "big sister" to the 17 footer weighs in at less than 600 pounds. I suppose something 10% shorter should weigh at least 10% less.

    So now you think in this 500 pound boat you'll have a 160 pound bulb at the end of a 5 foot fin, one that will cant magically without a bump (must be one big slot in the bottom, or a perfectly cylindrical section). Add in the battery, hydraulics, electrical system, back-up hand crank system, etc and you have..well, something that hasn't been thought out.

    But if Cleve, or anyone, wants to build the world's most expensive 17 foot white elephant I say go for it.

    I wonder if it will be as successful as "Doug's foiler that won't foil (tm)"?
     
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