Movable Ballast for Small Multihulls / Self-Righting?

Discussion in 'Multihulls' started by Doug Lord, Nov 27, 2010.

  1. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    I liked the roto-pod cockpit. I figured we could put Doug in and send him over Niagra falls to test it. More fun than a barrel of monkeys! I think you'll need Pentagon funding for the development, we'll have to code name this Operation Platinum Hammer and sell congressmen in warm water states on the concept. What with the testing and TV rights it could boost almost any economy. If he sells the idea to the networks go for it wheels, they don't want you to die on camera. If the sponser is cable with a name like "The Most Dangerous Test" bail out before they film the crash!
     
  2. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ===============
    Will, just for the hell of it here is the probable type of rig I would use on a High Performance self-righting tri-only a bit taller. It uses masthead buoyancy that would assure the boat could not turn turtle. The squaretop main AND the square top jib allow the CE(center of effort) to be lower than for an equivalent conventional rig. The jib could be removed and the main reefed to reduce sail. Carbon mast and boom.


    click on image and then again on resulting image:
     

    Attached Files:

  3. cardsinplay
    Joined: Oct 2010
    Posts: 330
    Likes: 3, Points: 0, Legacy Rep: -74
    Location: Camp Plasma

    cardsinplay da Vinci Group


    It guarantees nothing of the sort. Ask Hobie if they ever experienced one of their Bob floats being broken off. Ask any cat, or tri sailor if they've ever heard of a shroud breaking during a pitchpole? Ask multihullers if having a mast head float actually puts inordinate stress on the mast in the event of a capsize, pitchpole, especially at speed, which is the angle that Doug is pushing with gusto.... and what happens should you lose the mast and that savior float thingy at the top of the rig?

    Yep, it's over you go and this idea of Doug's is not coming back on its own.

    Assurances from Doug...? Dig a bit deeper.
     
  4. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    Wheels, have you watched people on Moths foiling? If it seems doable and you want to go foiling anytime soon consider retrofitting a moth with a sliding seat similar to the sailing canoes. You seem to have the mindset and agility. with a float coat that keeps you right-side up, not all do, you should be all right. You would probably need a spotter for launches and recoveries but you could probably adapt. You don't want to be strapped in on this one ! The seat has to be able to move fast then lock in place and you need to be able to steer with one hand, sheet and move the seat with the sheeting hand. Obviously you'll develop the best techniques for yourself as the man on the scene and you'll know versus wandering. I wouldn't recommend this to anybody but after watching for a while I think you could survive trying with some helpers on hand.
     
  5. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    A self righting system should never be built around a mast. If you've lost the rig but can turn over it's time for the kite sail if you were cruising. Proas, the safer way to fly.....
     
  6. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Partial results from Hobie and the Rave: capsize or pitchpole/SRT

    -----------------
    There is not one valid reason why a mast can't be an integral part of a selfrighting system on a smallmultihull-if it is designed for it! With a carbon mast and fiber shrouds the mast can be built to be strong enough in the event of a pitchpole/capsize.

    ======================
    It occured to me the other day that the boat I propose would be very similar to a Rave(in crew seating/speed in strong wind)-only with a bit more SA and lighter. So I thought I'd ask experienced Rave sailors and the designer of the Hobie trifoiler what the dynamic consequences of a pitchpole would be.
    1) In the Hobie trifoiler there has never been a capsize or pitchpole except once during testing where an ama broke off-the result was a very slow settling with NO consequences to the crew-the crew was not thrown and did not/does not require any form of restraint.
    2) I talked to the designer of the manual control system for the Rave who has thousands of hours in the boat: in all those years the boat has only capsized/pitchpoled twice-once in heavy conditions with the boat going very fast with two crew. The crew sits in the Rave with their legs under the deck-there was NO dynamic affect on the crew whatsoever-the boat seems to go into slow motion and reaches a vertical position with the mast holding it upright and the crew simply climbs out. No danger to the crew , no dynamic effects as a result of the speed and no restraints required.
    3) added 12/12/10-heard from the third of four hydrofoil sailors I wrote to about the dynamic affect of a pitchpole or capsize. He sits on a trampoline to sail his boat and has only had a couple of pitchpole incidents with this boat. He was thrown off the boat but said that if he had been sitting in a cockpit like a Rave he doesn't believe he would have been thrown out.
    =========
    So for the design of the SRT(self-righting trimaran) this is good news. No restraint will be needed in the extremely unlikely event of a capsize/pitchpole. Of course, testing would tell the complete story but these actual experiences in similar(though not self-righting) high speed boats show that a disabled person would be highly likely to be able to sail an SRT safely WITHOUT RESTRAINT/MINIMAL RESTRAINT(depending on the disability) and with NO dynamic consequences due to a capsize or pitchpole. Good news and an important design milestone.With the design innovations included in the SRT-high dihedral on the cross arms and ballast on the hydrofoil strut- the boat should(pending testing) automatically right itself with no action required by the crew. The boat would be designed for the extra weight and its Power to Weight ratio would be better than an F-18 catamaran. The most important measure of its potential speed is the SA/WS(Sail area to wetted surface ratio) which is SIGNIFICANTLY better than an F-18.
    The weighted daggerboard/keel would be easily retractable as would the rudder and the crossarms would fold for trailering.
     
    Last edited: Dec 12, 2010
  7. cardsinplay
    Joined: Oct 2010
    Posts: 330
    Likes: 3, Points: 0, Legacy Rep: -74
    Location: Camp Plasma

    cardsinplay da Vinci Group


    This is no design milestone whatsoever. Those noted designs are not at all the same boats and using them to predict behaviors for this design is as faulty an assumption as one can make.

    Making statements in the absolute, such as, "with NO dynamic consequences due to a capsize or pitchpole." places you and your design in a position where you will be severely run over by plaintiffs lawyers in the event of an accident. Trust me, Doug, there will be accidents.

    The only thing that is going to prove the concept of this boat is to build and test models, followed by the building and testing of full size versions. Hopefully, by the time that happens, you will have learned to stay away from grand pronouncements that glorify a non-existent boat.


    Full Stop

    I'm editing my previous post to indicate that I no longer give a crap what Doug Lord does in his pursuit of pseudo boat design wheel-spinning Internet exercises. Doug can now fulfill his childhood dream to wander down the path once strode by the Emperor wearing his New Clothes. He has earned that right and it suits him completely.

    I hope to see the rest of you guys and your interesting comments and questions, on other threads. I'm looking forward to reasoned discussions where folks are open to a broad landscape of ideas and methodology that will advance the craft of designing and building boats for the enjoyment of all.

    Cards Out
     
  8. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    High Performance Self-Righting Multi Design for Disabled Sailors-and others

    ---------------------------
    A tri using the system described in this thread has the potential ,in a max power version, to at least equal the Moth- while being far easier to sail and launch. The tri ,without the ballast surely would as would the much smaller MPX-12(probably not safe for disabled sailing).
    The purpose of this thread was to try to inspire people to consider High Performance sailing to the Max as appropriate for disabled sailing and to inspire the creativity and hard work required to come up with a design that has the potential to be at least equal with the fastest boats under 20'.
    I'm convinced it can be done,should be done and will be done-the need for speed transcends all boundaries.
     
  9. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    Isn't it asking a lot of the foils to fly the ballasted daggerboard/drop keel? And what happens if it is in the up position? It seems the old power,weight spiral is getting a thermal lift. The problem with the mast isn't when it's new as much as when its been fatigued. I've seen older Lasers tear out their mast step and those are well thought out boats. Trimarans are fairly complicated to right and not really an instant achievement. A keel foiler with enough ballast to right from a 180 isn't in your targeted performance envelope. The least force in righting a tri is either rotating over the bows or over the sterns, which means flooding chambers and pumps. Flooding a ama means having the remaining one fold to avoid large amounts of ballast. Proas, the safer weigh to fly.....
     
  10. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    The thing about the moth is that it is a realistic goal for him to try now instead of waiting for all the revisions, tests and whether or not the boat is ever made.
     
  11. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ================
    Cav, the ballast is approx. 175lb in the first iteration of the proposed design-the one whose specs are printed on the previous pages. I mentioned that that design and those specs were chosen because the 18 tri was DESIGNED for two 175lb people-skipper and crew. The numbers, including SA/WS are all based on 2 crew at 175 and the boat so configured has better numbers than an F18 cat.
    But for disabled sailing the boat would be singlehanded and the "crews" 175lbs would be put into the bulb at the juncture of the daggerboard and main hydrofoil. That,combined with increased dihedral of the crossarms, would allow the boat to be self-righting while still retaining the numbers to beat an F18.
     

    Attached Files:

  12. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    You did talk about carrying a passenger. We better rename this operation Platinum Dumbo because even elephants can fly if you throw enough money at them and put them in cargo planes.......Proas, the safer way to fly.....(at sea level anyway)
     
  13. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    High Performance Self-Righting Multi Design for Disabled Sailors-and others

    -----------------
    Why don't you present some rough but detailed numbers for your idea-and show why you think it is "high performance"-and why you think it would work. You may not like what I have presented but I've at least tried to present a viable solution. Just saying it doesn't get it-show us some rough numbers to back up "Proas, the safer way to fly". Show us some comparisons to other "High Performance boats" or just standard comparative ratios-esp SA/WS.
     
  14. cavalier mk2
    Joined: Mar 2010
    Posts: 2,121
    Likes: 54, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    Go surf, the internet is full of sailing proas, quite a few of them beach cat size. Your design is not proven and your math is theoretical at best. Quit picking on the numbers and start testing, you make good models. Poor Cards exhausted himself trying to hold the smoke and mirrors approach accountable and had to go on vacation to more rational climes. The numbers don't mean a thing if they don't work. You can't define a boat as having any performance, high or otherwise, unless it is shown to work. On with my chores....cheer up though, debating has tripled the amount of hits your thread had!
     

  15. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    High Performance Self-Righting Multi Design for Disabled Sailors-and others

    ==============
    With any design idea, you have to start with numbers-if the numbers don't add up there is no point in proceeding. In the case of the SRT the preliminary numbers do add up.
    ==========
    Bull. Just what role do you think design plays in something like this? How can you build without having accurate numbers? How can you evaluate a new concept in design without comparing the proposed design to other boats using comparative ratios that you have to generate numbers for??? Give me a break.......
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.