4 Meter mono foiler project

[bistros]

Originally Posted by wind_apparent

looks good Doug, only thing is if I end up with an all up weight of 137lb I'll throw the whole thing in the dump (an A cat weighs about 165, and if you think about it, thats like 2 sr-71's) ..........I want to keep it under 95lb, and closer to 85-90 if I can, 80 is my dream. less then that might be scary......(cst 46mm mast, carbon boom, all cst carbon rack, carbon gantry, foam/carbon hull,) should stay under 100 easy. the boat itself is not that much bigger than a moth, only 65cm longer, about the same freeboard, the rack is actually smaller (but some thicker tubing, so a wash), the boom is going to end up only 10cm longer (Hansen short foot technology) , 1.5m taller mast, 3sqm more sail (a wash since there is no wing tramp), and the shorter but stouter foils will probably be a wash as far as weight. if it ends up 60lb heavier than an average Moth than I did something very wrong

try it again with an all up weight of 90lb and a crew weight of 180 (average size trapeze skiff sailor with a harness on, this is a big boy kind of boat, not a toy ). (it ends up a 19lb difference or like 14%)

do you have any pics of this Rave foil wand?

Thank you once again for your input and interest.....


*****just got an update for Rhino OSX with better rendering, so real boat drawings with a hiking rack coming soon******

Thoughts:

I think your weight targets are very reasonable - more so if you are vacuum bagging. Keeping resin under control is important.

The things I didn't think of were real-world tuning and failure mode issues on my boat.

1) How do you self recover from a capsize? Water starts possible?
2) How do you carry/swim the boat out to water of enough depth to foil? What do you hang on to?
3) How do you tow/drag the boat? Got places to tie on broken stuff if it breaks?
4) What's going to break when you stuff the bow?
5) What parts are fragile? Consider things happening outside the design plane of strength (many things are strong in only one dimension)
6) Can you reach vang/cunno when trapping?
7) Got a place for a water bottle/hydration? I can easily get dehydrated/winded sailing my boat for a half hour
8) Have you provided for tuning measurement and rig adjustment flexibility? Mast step go enough range? Rig rake got a broad range of adjust?

The issue is that design work is theoretical and the real world sometimes doesn't agree. Bitch is we sail in the real world.

Bistros raises several good points; one of them is a pet peeve of mine: make your foils retractable. The early Moths were fixed because they were conversions with the daggerboard curved/angled forward and the boats had to be walked out with the foils down.
The Bladerider,M4 and Jundts foiling 18 all use retractable foils.
Don't forget buoyancy pods-like the Bladerider,M4, and Mirabaud.
Go here to "hydrofoil control system animation" for an idea of the Rave system: http://members.aol.com/HYDROSAIL/

[wind_apparent]

I'll see if I can work through these.....

I think your weight targets are very reasonable - more so if you are vacuum bagging. Keeping resin under control is important.

yup, vac bag, over a skinned mail mold, was going to go female, but thats alot of work for an untested one off piece, maybe on #2

1) How do you self recover from a capsize? Water starts possible?

I'll have a lot of righting lines rigged up the first couple times till i get it sorted, I expect to spend more time in the water than on the boat first bunch of times out. It will be impossible to know about waterstarts till I'm in the water.

2) How do you carry/swim the boat out to water of enough depth to foil? What do you hang on to?

Retractable foils, have to have them, alot of times I'll be sailing off of a beach. Carrying a 70 pound moth is one thing, a 90 pound boat something else, especially after sailing all day. the good thing is I plan to have shorter foils than a moth (like on a rs600ff) just to keep from flying to high, crashing from a meter up while on the trap would be painfull. still figuring out what a good length would be. that and shorter foils don't have to retract so high.

3) How do you tow/drag the boat? Got places to tie on broken stuff if it breaks?

Tow/drag from the bow shackle, or the rack, or the stern. can always tie broken stuff on to the racks with the righting lines (and I'll probably take some rope out with me till I start to trust her a little)

4) What's going to break when you stuff the bow?

Good chance it will be me ........................................................not the rack, maybe the kingpin, but I doubt it, if anything the mast will unstep if I snap the proder, there is a chance I mess up the foredeck cone, or rip the rack off the deck itself. Luckily this boat is kind of like a hypermoth, so I took into consideration all the ways I've seen and heard of them failing over the years and designed accordingly. And I plan on overbuilding it a little, I know I could get it down to 85lbs if I wanted to, but my target is 90 just so I can beef up the places that need it. Its a proto, I can always build the next one lighter.

5) What parts are fragile? Consider things happening outside the design plane of strength (many things are strong in only one dimension)

the Proder or spreaders, the gantry and the hull skin in the stern, the rack attachment points (i am running pretty beefy full length solid cedar gunnels to spread the load). The deck itself, (already plan on putting a layer of Kevlar on the underside and a layer of 9oz glass on the top over the carbon skins to beef her up a little).

6) Can you reach vang/cunno when trapping?

I plan on running them out to the trap rack bars like on a moth.

7) Got a place for a water bottle/hydration? I can easily get dehydrated/winded sailing my boat for a half hour

I'm going to Ductape a beer cozy to the rack strut, right next to my Velocitek , I hope to stash my water bottle in my gantry, but when I'm out just sailing (not racing because I could get protested) I ware a Camelback hydration pack over my harness.

8) Have you provided for tuning measurement and rig adjustment flexibility? Mast step got enough range? Rig rake got a broad range of adjust?

tuning measurement - yes, mast step - no (don't really have one, if it needs to move I have to cut the kingpin off the rack, it is where it is pretty much).
Rig rake - as much as I want, the mast pivots on the kingpin, I can make it as straight or as raked as I want till I don't have any more room under the boom to tack.

very good questions, some of which I hadn't thought of, thank you.

on a side note, woke up to this in my inbox.......

I'm going to join the course of folks who have encouraged you to stay within an existing class framework. Your going to spend a bunch of time and money building this really cool boat, and nobody's is really going to care. The only person to whom this will be worth anything is you. A moth will still be faster. Sure, the numbers say your boat should be faster, but you've got one shot down the design spiral. Moth foilers have had dozens of clever folks working on improving them for nearly a decade. And suppose you do manage to pull off a brilliant design, how are you going to judge it? Faster than a moth - well damn, it ought to be. Better than an RS600FF? Are you going to go to Europe to find out? You're going to be playing by yourself. Is that what you want?

its nice to feel so loved blowing it up, framing it, and putting it in my work space. I feel like such a maverick

[bistros]

Originally Posted by wind_apparent

on a side note, woke up to this in my inbox.......

its nice to feel so loved blowing it up, framing it, and putting it in my work space. I feel like such a maverick

No lack of people willing to pee in your Cornflakes, is there? Join a class where your size will guarantee you will never be competitive!

Like me, it appears you are doing this for yourself, and if anyone wants to join after you are done, great. I will not lose sleep if no one else builds a boat like mine - I did it for me. It appears however that there are lots of people interested in the concept.

In my work world (I'm an open source guy working in communication security) the best apps are the result of someone scratching a personal itch without regard for what someone else may want. Funny thing is that typically, lots of people share the exact same problem and will jump at something that scratches their itch as well.

Committees build highly compromised, bloated and unfocused crap. Focus is the toughest thing to maintain in product development.

Sheep only feel comfortable in large flocks. Be a shepherd, not a sheep!

Bram Dally built a boat because he personally wanted a one man 49er training platform. There was no intention of creating a one design, but look what happened.

It will all be worth it the first instant you lift out of the water. Anything after that split second is gravy.

[wind_apparent]

Originally Posted by bistros

No lack of people willing to pee in your Cornflakes, is there? Join a class where your size will guarantee you will never be competitive!

its ok, I wasn't going to eat them anyway, I'm more of a rasinbran kind of guy....besides everyone knows that only 150lb guys like to sail hydrofoils.

and an American trapeze hydrofoil class would never catch on, it's to hard and no fun to sail.....like these guys below .............only doing it for the chicks and the money.....

[Chris Ostlind]

Originally Posted by wind_apparent

.............only doing it for the chicks and the money.....

Yes, Quite. It's the single most daunting thing my wife has to face with me designing niche product boats at my age.

The thought does have a certain, shall we say, youthfully charged ring to it, though. I kinda like that and it goes miles when worn by my inner 12 year old.

Your project, WA and the on-going work by Bistros with his skiff, are the essence of what makes this whole thing work for me. I very much admire what you are doing to pursue your own section of the far-flung universe.

Chris

Closeups of Rave foil control head:
http://www.doranoster.com/pdf/Gettin...%20System2.pdf
More from Doran: what he calls incidence control does the same thing on a Rave that the "Fbox" does on a Moth; it is a method of changing the angle of incidence of the foil(relative to the boat) to improve takeoff ,mid range foiling and high speed foiling.Don't consider using his angle of incidence numbers on your boat IF you are using asymetrical foils(similar to the 64312 section). A monofoiler with an asymetric foil could benefit from approximately -.5 degrees(high speed) to + four degrees(light air takeoff). You MUST be able to adjust this under load. It is not required to start foiling but will greatly enhance your foiling experience. If it is too daunting to consider now leave enough room to add it later.
http://www.doranoster.com/pdf/incide...020712-hto.pdf

[wind_apparent]

Originally Posted by Chris Ostlind

Yes, Quite. It's the single most daunting thing my wife has to face with me designing niche product boats at my age.

Don't forget all the crazy partys and the free trips to Dubai

The thought does have a certain, shall we say, youthfully charged ring to it, though. I kinda like that and it goes miles when worn by my inner 12 year old.

I'm trying to let my "inner 12" year old hang out with my "married with two kids and a full time job outer 32 year old more", I'm hoping this project will do that

[wind_apparent]

Originally Posted by Doug Lord

If it is too daunting to consider now leave enough room to add it later.

This first time around I'm just going to worry about getting the foils and the rig working, but keep the other stuff coming, because I want to try some of it on round 2 if I get that far.

[bistros]

Originally Posted by wind_apparent

This first time around I'm just going to worry about getting the foils and the rig working, but keep the other stuff coming, because I want to try some of it on round 2 if I get that far.

Good. It is going to get increasingly hard ignoring all the interesting possibilities.

Focus, focus, focus!

Keep things simple, and do _not_ add variables.

Perhaps you may want to consider setting some simple milestones before you get to foiling.

Idea: make a set of basic normal foils and see about sailing the hull to determine sub foiling speed sailing. This can help you a lot in determining tuning, and behavior when you do attempt foiling. It also will give you a chance to work on ergonomics and controls.The boat really needs to work pretty well in this mode or you will never get it up to foiling speed.

Small steps.

[wind_apparent]

Idea: make a set of basic normal foils and see about sailing the hull to determine sub foiling speed sailing.

Already in the hopper.....First foils without the "T"s, same Cord, just no horizontal foil, I figure maybe a couple months in this trim. or as long as it takes to make real foils

The boat really needs to work pretty well in this mode or you will never get it up to foiling speed.

Um.....6 or 7 knots, I have clocked kids in prams doing 10.......but I understand your point.

[wind_apparent]

well, alot of drawing again today. I'm a rack man if you know what I mean

so here you go............

Photo 1 - In this close up you can see the adjustable tubes, the outer rack slides into the inner rack, I will be able to adjust it for different wind strengths. Instead of depowering, just more rack.

The rest are self explanatory. The tubes I plan on using are.

53.6mm (1.8mm wall) for the outer wing bars and the wing strut tubes (the ones that get U bolted to the boat).

48.7mm (2.0mm wall) for the extension tubes (the ones that slide into the wing struts), and the kingpin.

25.8mm (1.8mm wall) for the front triangle support tubes.


The rack is 1.8m wide in the pictures, It will extend farther, but in most conditions I plan to use it at this width. I know it looks like its to far out from the boat, but its approximately 45cm from the deck to the rack bar, same as a Musto Skiff, so it should work well.. for when it is farther out than that I am thinking of some sort of buckle on tramp. we'll see how it goes.

[yachtyakka]

Wind_apparent, how far down the build track are you?

[bistros]

Originally Posted by wind_apparent

well, alot of drawing again today. I'm a rack man if you know what I mean

so here you go............

Just on visual here are some thoughts:

1) The front looks strong and the kingpost and triangles add a great amount of strength. The rear crossbeam to rack joint looks a little unsupported and possibly weak.

2) The square layout may work well for the rack width adjustability but it doesn't translate to real world well. The trap lines coming from high up on the mast don't automatically increase in length as you move back on the racks, so effectively you will be trapping higher with more pendulum forward as you move back, One of the things Bram did well on the SwiftSolo design was curving the wings to make trapping easier and not require lots of foot loops. Wing width decreases proportionately as you go back, and that makes fighting the pendulum effect easier. Real world this works, as you are typically reaching with the kite up when trapping far aft. In your case, fore/aft trim is more about main foil angle of attack than boat pitch. Foiling adds a new dimension and also limits fore aft movement as you have to keep the boat in the air. I might consider a curved outer tube, or a rack that starts wide forward and narrows aft, making the trapping easier.

3) The wide racks are fine. My Laser 5000 twin wire skiff has monster wide adjustable racks and they work fine and aren't difficult to move on. Some people add "baby bars" halfway out to give a second transitional trapping position and they would make things easier getting out. You don't need a tramp net - or at least I don't think so.

4) It may pay to mock up the layout's critical dimensions in a big garage - outlining the racks in PVC, deck, gunwhales, tiller, kingpost and especially the trap wires. Playing with this beforehand could make a huge difference in sailability. I know it is a lot of work but it is far less than a rebuild once the carbon tube is cut and bonded.

I think the human dynamics and ergonomics of your design are where you really have to get things right up front. You can tweak rigs, you can tweak foils but tweaking a hull or deck/rack layout isn't easy. Foiling and the limitations of mobility (compared to a skiff) to keep the foils working
is a real design consideration. If you watch video of Bora Gulari he really self limits his smooth, controlled movement to stay within a small "box" that allows his Bladerider to work. No wild or big motions are noticeable. Smooth and controlled movement seems to be a foiling key.

Contacting the RS600FF guys may be in order to ask about fore/aft movement requirements and how smooth the tack/gybe to rack trapeze transition needs to be. Just an idea.

HTH,

Bill

Sam, I used 2.375ID(60mm) with a .093"(2.3mm) wall for my cross(rack) tubes for my boat which had way more SA(182) with the shrouds attached to the forward tubes. I'd say yours were probably big enough but just barely.
Mine were sized for the loads of a 250lb crew jumping as well as for the shroud loads unreinforced.
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Here are some wing bar specs for the new Moth Velociraptor:
http://www.velociraptor-moth.com/sho.../3?shop_param=
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More:
http://home.arcor.de/internationalmo...n/page0005.htm