4 Meter mono foiler project

[Doug Lord]

Sa/ws hullborne and foilborne?

[wind_apparent]

whats your goal weight?

90lb all up

[wind_apparent]

Sa/ws hullborne and foilborne?

Its a secret :P

[bistros]

Why would OSX cause problems with dxf files?I would have to say that I would expect the parts to be seperated out rather than presented as a stack,as shown in your attached jpeg.In fact if you had them nested on eight by four sheets you would have helped considerably.Your old school methods will work admirably but a bit more slowly.I have no familiarity with the adhesive you are proposing to use to attach your plots to the MDF but would urge caution as moistening the paper can cause the paper to stretch.Drafting film is much more stable and unfortunately rather more expensive.How are you proposing to fill the gaps between the sections?

OS/X files are different from Windows files in a bunch of ways.

Generally where windows uses carriage return/line feed pairs to end a line, OS/X just uses a linefeed. Numbers in previous MACs were stored as big-endian, not little endian as in PCs. It was a processor architecture thing from the 68000 that just kept going forward for years. Intel processors are little endian.

Compression on MACs is different as well.

Generally, there are lots of file translate/transfer utilities for moving files from MACs to PCs. A quick inspections of the file with a hex editor will give some clues fast.

When porting software between processor architectures and platforms, this kind of stuff happens all the time - the core C libraries in each platform may differ in how they implement basic functions like file I/O - each platform tends to use it's own rules. This means files written out by the exact same piece of source code may differ across platforms.

New software ports have these things show up, and usually in a couple months they have to replace the dynamically linked library elements with statically linked functions that force the system to generate compatible files, or the build in a file translator/transfer utility.

Hope this clears things up a little for you. I've simplified things a lot but you should get the picture.

[Doug Lord]

Heres a vid you may not have seen. The boat has 7 sq.ft. less SA than your boat with the same all up weight as your target weight:
http://www.dailymotion.com/related/x7ngs_foil-surfing_extreme/video/x24hz_m4-dinghy-foiler_extreme

[wind_apparent]

Heres a vid you may not have seen. The boat has 7 sq.ft. less SA than your boat with the same all up weight as your target weight:
http://www.dailymotion.com/related/x7ngs_foil-surfing_extreme/video/x24hz_m4-dinghy-foiler_extreme

nice vid


(from the M4 site)

Specification
Waterline length: 4m
Overall length: 4.25m
Beam (hull): 0.4m
Beam overall: 2.4m
Mast height: 6.5m
Sail Area: 9-10 sqm
Hull Weight: 20kg
Sailing weight: 45kg

well, the all up seems to be about 10lb more, and the sail area looks to also be about 11-22sqf less. so if the M4 goes, so should the SR-71. It almost makes me want to put more sail on it, but having more canvas than a MPS would be silly.

[Doug Lord]

Your SA is 10.75 sq.m, right?

[wind_apparent]

Your SA is 10.75 sq.m, right?
11sqm

[wind_apparent]

I was talking to a windsurfing buddy today about a new sail that he just purchased (he now has a quiver of 9 different sails), it got me thinking, what do you all think about having three sails available for a boat like this? maybe 12.5sqm 11sqm 9.5sqm like windsurfing. So instead of 1 max sail size. 3 different sail sizes. I know its alot of $$$$$$ to start off, but after your buy in, all the sails would last longer. I was thinking about it because this is a foiler, so you want it to foil, 12.5sqm turns a nonfoiling day into a foiling day, 9.5sqm turns a overpowered day into a ripper, and the average 11sqm will work real nice in your 10-15 blow. Just a thought.

[Doug Lord]

Good idea,but why don't you come up with a viable reefing system? The RS600FF rig is reefable-when the boat was sailed as a seahugger that system was hardly used -now that it foils they're finding it invaluable.
----------
"So we started developing the RS600 and seeing how it would convert to being used for foils, and I have to say Clive Everest [the original designer of the RS600] designed virtually the perfect boat for foiling, although he probably didn’t realise it at the time! Now with the RS600FF, we have a foiling boat that works for people weighing between 70 to 95kg, it’s one-design, and with the original RS600 reefable rig you can sail the boat a long way up the wind range.”

[wind_apparent]

Good idea,but why don't you come up with a viable reefing system? The RS600FF rig is reefable-when the boat was sailed as a seahugger that system was hardly used -now that it foils they're finding it invaluable.


a reefable sail is an option, but I do see it having some drawbacks:

A) don't think it would work very well with the Pocket luff/camber induced sail technology
B) windage windage windage
C) the 12.5sqm would only be used on the lightest days, so the sail would be reefed a lot.
D) I hope to move back to the Portland,OR area soon (within the next year), so I probably won't be needing a bigger sail myself. (read GORGE)

[Doug Lord]

12.2 sq.m would be the same as the RS600FF-what a power to weight ratio you'd have then....

[wind_apparent]

12.2 sq.m would be the same as the RS600FF-what a power to weight ratio you'd have then....

Read; Scary

[Doug Lord]

Fear breeds courage(sometimes)

[wind_apparent]

Fear breeds courage(sometimes)

so does stupidity. (sometimes) :D

[Paul B]

a reefable sail is an option, but I do see it having some drawbacks:

A) don't think it would work very well with the Pocket luff/camber induced sail technology
B) windage windage windage
C) the 12.5sqm would only be used on the lightest days, so the sail would be reefed a lot.
D) I hope to move back to the Portland,OR area soon (within the next year), so I probably won't be needing a bigger sail myself. (read GORGE)

But if YOU don't design a working reefing system for this type of boat then how will the **** **** be able to use it on his imaginary foiler?

Design it himself you ask? I'll wait for the laughter to die down now...

[wind_apparent]

well, It has begun again, cut out the strongback/frame today (the real one this time). Scott "Murf" Murphy doing what he does. Hopefully I'll put it together tomorrow.

[yachtyakka]

here are the latest images of the R class

[wind_apparent]

here are the latest images of the R class

that's a great boat, very nice renderings. Hope it has a wide enough appeal to where I can take a spin on one in the States some time. Do you know who is heading up this project?

[foilman24]

It looks like the revolution is on its way, and none of dougs "boats" are anywhere in sight. We have a single handed dinghy (moth), a singlehanded trapeze dingy (Sr-71), a two handed foiling skiff (R class), and an all out 3 man super foiler (mirabaud). so where are you going to fit in doug? better start your dumb canting keel sports foiler before theres nothing left for you. :D

[foilman24]

So Sam, with all this electronic wand control talk thats been going on today, would electronic control be allowed in the proposed SR-71 foiler class?

[RHough]

So Sam, with all this electronic wand control talk thats been going on today, would electronic control be allowed in the proposed SR-71 foiler class?

From the RRS:

52 MANUAL POWER
A boat’s standing rigging, running rigging, spars and movable hull
appendages shall be adjusted and operated only by manual power.

The Class rule can change this, but unless the class rule specifically states Rule 52 does not apply, the boat cannot use electrically powered systems.

[wind_apparent]

I have been following this through out the day, I would be very much for it. My everyday job is in Electronics R&D and production, so I don't really have a problem with electronic control. I think it would be a great development if it meant the boat would be faster, more efficient, and easier to sail. And as stated before. I could just write in the class rules that rule 52 would not apply to this class, although I would stipulate that "flap control" would be the only accepted use of Non manual power. (I know firsthand how out of control unregulated electronic craziness can get almost right off the bat, and how things that were originally created to make things easier often become more of a hassle than the original system.) I would like to congratulate Clive Everest on his fantastic development in foiling technology, keep up the good work.

[Chris Ostlind]

I agree with your points here, Sam...

While the electronic potential exists for some kind of flap control be it forward or aft foils, or whatever... there also exists a potential for wholesale expansion of this entire electron based medium for other significant component monitoring and adjustments while under sail. This represents some real problems from where I sit.

Example:

While I do see the canting keel business as a logical, technological extension of the monohull realm FOR RACING. I do not like the full-time powered engine approach for the rest of the sailing environment. In fact, it disgusts me.

If the big boys want to push their, apparently unlimited, dollars out the window of technology, hoping for the best against their equally wealthy adversaries, then, by all means, get it on boys. Just do the sailing world a favor and also create a contained, unlimited class for your boats. In a gentlemanly fashion, you might also acknowledge the magnificence and the presence of the most elementally connected form of sailing (the non-engine powered canters) in each and every race in which you enter, paying them their due.

Once the engine powered nonsense invaded the scene, then the ridiculous, no-holds barred expressions of "hmmm, let's see just where can we next dedicate this freaking' engine in the hold, idea" And soon, my friends, probably within your lifetimes, you will see boats out there with but vestigial remnants of their once proud sailing heritage.

I do not want to see that same kind of developmental inevitability, hit the smaller boats, where most of us dwell with our fully humanized budgets and realistic time constraints. Want to push the next average Joe right out the window with his desire to get engaged in the sport, the best way to do just that is to instill a hardware war, where an ever-escalating dollar figure is attached the beauty of what once was.

Over the hill to their X-Boxes and leaving behind only a small bit of dust upon their exit, they will scatter.

Big bucks electronic and engine driven racing for the he-men of the sport... Sure, knock yourselves friggin' out.

Just leave my affordale meanderings in the beauty of sail alone and give some of the new guys a chance to get into it without having to be graced by wads of cash and a patient gal who absolutely knows that we are all crazy.

It is for that reason that I'd like to see the Mothies become even more regulated and completely cancel out their wayward love affair with the foil boys. Create a new class of boats, with all kinds of sizes and purposes, don't call them Moths and let them be on their way for whatever the future will grant them.

Rant Over...

Chris Ostlind
Lunada Design
Www.lunadadesign.com

[wind_apparent]

I agree with your points here, Sam...

While the electronic potential exists for some kind of flap control be it forward or aft foils, or whatever... there also exists a potential for wholesale expansion of this entire electron based medium for other significant component monitoring and adjustments while under sail. This represents some real problems from where I sit.



I would agree to the electronic flap control because it takes the slop out of the wand system and I forsee it being contained in a box about the same size as a Volocitech, probably about the same price as well. So not really a problem. I bet it wouldn't be "that" much faster than a wand boat, at least at first anyway. (it would also be cool to hook your volocitech to your electro-wandamathingy and let it change its control settings based off of the GPS speed data.)

[foilman24]

(it would also be cool to hook your volocitech to your electro-wandamathingy and let it change its control settings based off of the GPS speed data.)

you better TM that whole electro-wandamathingy name before someone else does. :D

[wind_apparent]

(I've had some requests for me to start posting by blog posts here like I did at the beginning, so I will...:cool: )


So, spent the last couple nights gluing and cutting and sanding my stanchions. They are looking good. Still need to dado the notches out of all the stanchions, and also biscuit together my two piece frames, but aside from that I hope to start getting stanchions mounted to the support structure in the near future.

[wind_apparent]

Decided that it would be best to use a jigsaw to cut out the frame tabs instead of gang clamping the stanchions and using the dado on the table saw. They have turned out pretty nice I think. I used an old crap desk as a clamping surface (only flat skinny thing I had around.) I now have to biscuit together my remaining 2 piece frame sets and cut the tabs on them, and it should be time to start mounting stanchions on Monday. (Tonight's picture was provided by my daughter Melody)

[wind_apparent]

It's late and all the stanchions are done. All glued and biscuited, all trimmed, all tabbed. Stacked them all together to show what my hull should look like. Monday I can start mounting them on the strong back frame.

[wind_apparent]

I've had some (including myself) question the safety of this project, well I've found the answer to that. While out and about I found a cheap ($20) Bell bike helmet on sale, figure it might be a good thing to add to my sailing gear for the "tuning" stage. It was the right price, was yellow (for safety) and has an image of the Virgin Mary on the back (I'm not what you'd call a "God" fearing man, but at speed, up on the foils, and out on the wire, lets just say every bit helps).

[Paul B]

I've had some (including myself) question the safety of this project, well I've found the answer to that. While out and about I found a cheap ($20) Bell bike helmet on sale, figure it might be a good thing to add to my sailing gear for the "tuning" stage. It was the right price, was yellow (for safety) and has an image of the Virgin Mary on the back (I'm not what you'd call a "God" fearing man, but at speed, up on the foils, and out on the wire, lets just say every bit helps).

My old Bell cycling helmet has the logo of the band FEAR on the back.

I am not a "God" fearing man, but I do believe in Lee Ving.

[wind_apparent]

Stayed up late drilling out all the 1'' dowel support holes in the hull stanchion frames, and started mounting them this morning. Mounted five first break, and five second break, and stayed after work for a little while and mounted eight more. Only have a couple left, which should get finished tomorrow. Then I need to glue in the dowels that support the upper portion of the frames and its time to start stapling on 1/4'' plywood for the skin. So excited.......(I am a lot farther than these pictures show, these are from this afternoon, I'll have bigger, up to date ones tomorrow)

[wind_apparent]

Woke up early, started mounting the last couple of stanchions, didn't get them all done because I had to do some special treatment to #22 (the bow) to get it on just right. got everything mounted though except for that one. I also spent 30min anchoring all the frames to the dowel rods, tried to use wood glue and spring clamps but the clamps kept slipping from not enough pressure and the glue was just really slick, so after fighting with that for a while, (the frame/dowel placement is what makes everything square vertically) I finally just grabbed some 1'' deck screws and pinned the frames in place from each side (I realize now that I don't have a picture of this, so I'll put one up tomorrow) worked really well, all the frames are "dead nuts" square and don't move at all. I mounted the final bow stanchion and trimmed the dowels on my way out the door but didn't have time to snap any pictures, I'll post some first thing tomorrow of the finished mould skeleton.

(pictures files where to big, if you want to see them just click on the blog link in my signature)

[wind_apparent]

Here are the pics of the finished skeleton and also of my deck screw centering system (I know its not pretty but it works great.) I'm thinking of moving on to my other two mould skeletons before I skin anything.

[Paul B]

Then I need to glue in the dowels that support the upper portion of the frames and its time to start stapling on 1/4'' plywood for the skin.


My experiences with this sort of thing have always been with thinner materials. With the compound curves near your sheer will 1/4" ply take the contour?

[wind_apparent]

My experiences with this sort of thing have always been with thinner materials. With the compound curves near your sheer will 1/4" ply take the contour?

I plan to cover all the flatter area's first, then steam the ply onto the easier curves, anything with a steeper curve than that I plan on using thin strips or 1/4'' bendy ply. I have some scraps of both 1/4'' ply and bendy ply around that I've been messing with a little today, seems like it should work well enough. I think that I would lean more towards the strip method because I'm not sure if the bendy will be able to take the stress loads of the vacpress without getting a bit tweaked. (if anyone out there has any experiance concerning this I'd love to hear more about it)

[Chris Ostlind]

Strips. Cleanest build, easiest to fair.

[Paul B]

I plan to cover all the flatter area's first, then steam the ply onto the easier curves, anything with a steeper curve than that I plan on using thin strips or 1/4'' bendy ply.

Thanks. I couldn't wrap my head around 1/4" ply bending to that shape.

[wind_apparent]

Strips. Cleanest build, easiest to fair.

Thanks Chris, that's what I've been leaning towards in my mind, I'm sure that's the road I'll take. On a related note, what is everyone's favorite "domestically" (USA) available fairing compound?

[kprice]

Drywall compound, from Home Depot. $10 for 5 gallon pail. Not very durable, but easy to fair.

[wind_apparent]

Drywall compound, from Home Depot. $10 for 5 gallon pail. Not very durable, but easy to fair.

I'm thinking epoxy thickened with westsystems microlight.

[Chris Ostlind]

Epoxy thickened with microballoons will certainly provide the most durable fairing compound, but it will likely also be the most expensive.

For fairing a tool, I'm thinking that you do not need to go the full tilt route for long term durability unless you are really sure that this particular hull iteration is going to be The One.

Otherwise, you could use a mid point product, such as Bondo and see how the boat performs as formed-up and then, if you plan to pull more parts from the tool after testing, you can sand away the Bondo and re-fair with epoxy for a longer lasting tool. The part, itself, cares little about what kind of tool material was used, as long as the part can be pulled without messing things up and the surface is the of the quality you expected.

This is your project and you should do it any way you want. The above are merely options on the table and in no way give meaning to your personal goals.

Chris Ostlind
www.lunadadesign.com

[Doug Lord]

First sand* the wood/foam as much as practical. Then I'd suggest coating the wood/foam with poly/vinyl ester laminating resin and then using cabosil and resin as a rough fill-put it on smoothly with no edges.Use a fairing board(like a sanding board but with a sharp edge) to apply. Follow that with bondo(use the board to apply), then sand* with 36 grit and get it nearly perfect then glass with polyester/vinylester resin. Follow that with 20 mills of white(exterior-no wax) gel coat sprayed very fine. Wash with acetone.Then use Blue Dykum mixed 50/50 with acetone to coat the gelcoat(apply with an acetone proof rag). If done right you should be able to start with 80 grit dry paper then proceed to 220 wet sanding.The dykum gives you a sanding guide so you can see that you've sanded the whole part to the same level. Don't go beyond 220 since this is the inside of the hull. Then wax with partall #2 and spray 3 FINE coats of PVA on the part and layup.
Epoxy will bond to polyester but the reverse is not true if the epoxy is fully cured.Bondo is polyester.You don't need the expense of epoxy on the plug. Fairing the hull is a whole different story. This method of plug construction is simple and relatively inexpensive and can produce a perfect surface.
* Make sure to sand double diagonally-never just back and forth. Use the longest board you can from the initial sanding on.
-----------------------
If you have people who smoke around you when you work with acetone or polyester you will die. If you have machinery that is not ignition protected you will die. I can't stress enough how important it is to use these chemicals in a safe environment! You can use epoxy as the base resin but then you have a VERY time sensitive application regime to follow: if you allow a layer of epoxy to fully cure before applying a subsequent layer the next layer may not bond. This is even more true when using bondo over an epoxy substrate.
Have you ever worked with epoxy? It doesn't smell like polyester does but epoxy sensitization is very nasty. Be sure to wear gloves and a respirator no matter which way you go.
-----
In my experience(50 years of tooling): for a plug polyester is the way to go,for a mold epoxy is the way to go. For all practical purposes your tool is a "plug"-I'd do it with polyester/vinylester to do it at a reasonable cost.
If you go with epoxy be aware of the critical timeline and look at "super fil" from Aircraft Spruce and Specialty...Also get the Freeman catalog-they have epoxy gel coat and fillers. Try to avoid bondo on an epoxy substrate.
----------------------
If you have to fill the final gelcoat surface DO NOT use bondo- use gel coat plus cabosil.MOST IMPORTANT: Do not mix two different consistencies on a sanding surface-you will CREATE unfairness when you sand rather than eliminating it!. Do not mix your own batches of epox+ micro balloons unless you mix all you will need at the same time: mixing individual batches leads to different consistencies on the sanding surface which leads to unfairness. Try to only use pre mixed fillers. Anything mixed with micro ballons should wind up UNDER the glass to prevent surface problems with the microballoons gassing off.

[wind_apparent]

Epoxy thickened with microballoons will certainly provide the most durable fairing compound, but it will likely also be the most expensive.

For fairing a tool, I'm thinking that you do not need to go the full tilt route for long term durability unless you are really sure that this particular hull iteration is going to be The One.

Otherwise, you could use a mid point product, such as Bondo and see how the boat performs as formed-up and then, if you plan to pull more parts from the tool after testing, you can sand away the Bondo and re-fair with epoxy for a longer lasting tool. The part, itself, cares little about what kind of tool material was used, as long as the part can be pulled without messing things up and the surface is the of the quality you expected.

This is your project and you should do it any way you want. The above are merely options on the table and in no way give meaning to your personal goals.

Chris Ostlind
www.lunadadesign.com

Thanks Chris, you win again..........I'll bondo the sucker, I'm pretty sure this is just the beginning as far as SR-71 tooling goes, I've never seen anything I've ever made or been a part of making go from prototype to production without some updating and changes. If I do the impossible and nail this first iteration perfect (ya right) I can always make a fiberglass and foam plug off of this mould the same way I would lay up another hull. If I ever was to make a real tooling set for this thing, I really would want to go full blown female in gelcoat.

(I really like your open ended way of providing information, thanks again)

[wind_apparent]

First sand* the wood/foam as much as practical. Then I'd suggest coating the wood/foam with poly/vinyl ester laminating resin and then using cabosil and resin as a rough fill-put it on smoothly with no edges.Use a fairing board(like a sanding board but with a sharp edge) to apply. Follow that with bondo(use the board to apply), then sand* with 36 grit and get it nearly perfect then glass with polyester/vinylester resin. Follow that with 20 mills of white(exterior-no wax) gel coat sprayed very fine. Wash with acetone.Then use Blue Dykum mixed 50/50 with acetone to coat the gelcoat(apply with an acetone proof rag). If done right you should be able to start with 80 grit dry paper then proceed to 220 wet sanding.The dykum gives you a sanding guide so you can see that you've sanded the whole part to the same level. Don't go beyond 220 since this is the inside of the hull. Then wax with partall #2 and spray 3 FINE coats of PVA on the part and layup.
Epoxy will bond to polyester but the reverse is not true if the epoxy is fully cured.Bondo is polyester.You don't need the expense of epoxy on the plug. Fairing the hull is a whole different story. This method of plug construction is simple and relatively inexpensive and can produce a perfect surface.
* Make sure to sand double diagonally-never just back and forth. Use the longest board you can from the initial sanding on.
-----------------------
If you have people who smoke around you when you work with acetone or polyester you will die. If you have machinery that is not ignition protected you will die. I can't stress enough how important it is to use these chemicals in a safe environment! You can use epoxy as the base resin but then you have a VERY time sensitive application regime to follow: if you allow a layer of epoxy to fully cure before applying a subsequent layer the next layer may not bond. This is even more true when using bondo over an epoxy substrate.
Have you ever worked with epoxy? It doesn't smell like polyester does but epoxy sensitization is very nasty. Be sure to wear gloves and a respirator no matter which way you go.
-----
In my experience(50 years of tooling): for a plug polyester is the way to go,for a mold epoxy is the way to go. For all practical purposes your tool is a "plug"-I'd do it with polyester/vinylester to do it at a reasonable cost.
If you go with epoxy be aware of the critical timeline and look at "super fil" from Aircraft Spruce and Specialty...Also get the Freeman catalog-they have epoxy gel coat and fillers. Try to avoid bondo on an epoxy substrate.
----------------------
If you have to fill the final gelcoat surface DO NOT use bondo- use gel coat plus cabosil.MOST IMPORTANT: Do not mix two different consistencies on a sanding surface-you will CREATE unfairness when you sand rather than eliminating it!. Do not mix your own batches of epox+ micro balloons unless you mix all you will need at the same time: mixing individual batches leads to different consistencies on the sanding surface which leads to unfairness. Try to only use pre mixed fillers. Anything mixed with micro ballons should wind up UNDER the glass to prevent surface problems with the microballoons gassing off.

Thanks for the input Doug, If in the future I make a nice female production mould, this info will come in very handy. (and yes I work with epoxy and solvents everyday, thank you for your concern) If you have anymore info on sanding boards and fairing techniques I would love to here about them. (I'm not really sure how I'm going to fair out the super steep inside curve where the hull meets the deck)

[Doug Lord]

Sam, do not let microballoons or similar material wind up on the finished surface or it could lock the part even if you use pva. Make sure you DO use PVA: it will wash off the part leaving no wax residue on the inside.
-------------
And once again: make sure that - whatever your final surface material is- that is 100% consistent-fillers from the same batch etc. or else the finish will be compromised.

[Chris Ostlind]

Microballoons can wind up on the surface of a faired tool, or part and it's really no problem as long as you fill the opened microballoon cavities with the chosen resin (epoxy?) and sand smooth. It makes for a perfectly fine tool surface.

I use Chemlease 15 Sealer on all my tooling and have had wonderful results. This stuff really responds to a heat gun or placing the tool in a heated environment when applying the release agent. (I've even used the sun for smaller part production) evaporates quickly and allows repeated applications (3 coats are suggested from my experience) which insure good part removal success.

You might also look at this product, Chemlease PMR-90, as it is especially formulated for deep draft part release applications.

Call this guy:

PAT MCGILL
TMI
6122 Stratler Street
Salt Lake City, UT 84107

Phone: 801-265-0111
Cell: 801-652-2792

Tell him that you are building a tricked-out foiling boat hull in carbon laminate and ask him if these suggestions will work for your needs. Pat has a terrific understanding of high tech composite part production, to include some of the most hairy carbon procedures for existing aircraft production. He's also a great guy who has a strong background in sailing and will steer you in the right direction.

Chris

[wind_apparent]

will do Chris, thanks again..

[wind_apparent]

I use Chemlease 15 Sealer on all my tooling and have had wonderful results. This stuff really responds to a heat gun or placing the tool in a heated environment when applying the release agent. (I've even used the sun for smaller part production) evaporates quickly and allows repeated applications (3 coats are suggested from my experience) which insure good part removal success.

Chris

so would this work for the bondo plug process? bondo the plyskinned moulds that I'm making, than fair them, seal them with the Chemlease 15, than release agent, than go nuts?

[wind_apparent]

Finally got to Kinko's today and got everything I needed for the rest of the boat project printed (except for the foredeck stanchions). So I'm cutting everything out. over the next couple days I hope to get the Bulkhead templates mounted and cut out, the Deck mould stanchions glued to MDF and jigsawed, build the Deck mould structural framework, and start skinning the hull mould. Its going to make for a very busy week, but it should make up for the work I didn't get to last week. Sometimes its good to just take a week to think about things and formulate a plan before jumping in to the next phase...........

[bistros]

Sometimes its good to just take a week to think about things and formulate a plan before jumping in to the next phase...........

I've always found ready, aim, fire is faster than ready, fire, aim.

Thinking time always reduces execution time.

[wind_apparent]

Since I wrote last I have cut out my Kinkos stuff, traced the Hull mould decking and sheeting, cut a pile of ply strips that very from 1/2'' to 4'' to mount on areas that have deep bends. I also mounted the Kinko's prints for the deck mould stanchions and have them rough cut. So things are progressing. I'm really excited to get back to work monday so I can start skinning stuff. I'll post some pics of that when I have some, right now it just looks like a boat skeleton with a bunch of funny shaped ply pieces piled on it.

[wind_apparent]

So I started to mount skin today, My friend Murray picked me up some 16mm x 5/8'' upholstery staples so I was able to start gluing and stapling some plywood (thanks Murr), got signed off on our big Altandorf saw last week as well, so no more bugging people to do my dirty work. I borrowed a line bleeder from my buddy Cliff so that I could adjust how deep my staples went, (wanted the crowns exposed so they would be easy to extract) but found that it was easier to just turn off the compressor and bleed the tank till the pressure was about right, a little stapler doesn't seem to run through much air. Made some good progress, hope to do more tomorrow. The plywood has some slight waves in it, so I see some fairing in my future, but all in all I think its turning out pretty good.

[Paul B]

I borrowed a line bleeder from my buddy Cliff so that I could adjust how deep my staples went, (wanted the crowns exposed so they would be easy to extract)

Some people have used plastic strapping material (like people use to hold big, heavy corrgate boxes closed) under each staple to allow the staples to be pulled out easily after the glue sets. May not work for you, but thought I would mention it.

[wind_apparent]

Some people have used plastic strapping material (like people use to hold big, heavy corrgate boxes closed) under each staple to allow the staples to be pulled out easily after the glue sets. May not work for you, but thought I would mention it.


Damn, I have thousands of feet of that stuff, didn't even think of it. Thanks for the tip, I'll experiment with it a little tomorrow. It would work good for keeping me lined up as well, because I have missed a couple times.

[wind_apparent]

So mounted the big piece of ply for the bottom today, its definitely the easy way to do it. 1/2 of the bottom done in one foul swoop. Also did the side strips in the stern. Looking very boaty as of late. Tomorrow I want to do all the stripping for the aft bottom area. If I can I would love to get to the bow as well. We'll see what happens. I also tried the nylon strapping idea for the staples, it worked for staples going the cross grain of the strap, unfortunately since I used 1/2'' Mdf for my stanchions, all my staples are put in the long grain, so the strapping just splits right around them when pulled.

[Paul B]

So mounted the big piece of ply for the bottom today, its definitely the easy way to do it. 1/2 of the bottom done in one foul swoop. Also did the side strips in the stern. Looking very boaty as of late. Tomorrow I want to do all the stripping for the aft bottom area. If I can I would love to get to the bow as well. We'll see what happens. I also tried the nylon strapping idea for the staples, it worked for staples going the cross grain of the strap, unfortunately since I used 1/2'' Mdf for my stanchions, all my staples are put in the long grain, so the strapping just splits right around them when pulled.

Why can't you run the strapping at 90 degrees to the orientation that splits it? The straps would then look like "waterlines". Should still work.

[wind_apparent]

Why can't you run the strapping at 90 degrees to the orientation that splits it? The straps would then look like "waterlines". Should still work.

I could, and I did try it that way a little bit, but it ended up being about the same amount of "pain in the ass" setting up the strapping and keeping it in place as I stapled as it was to just leave the crowns exposed and pull them out the old fashion way. I'm sure I will find a situation where I will use this technique, it's just not for the panels I've been doing lately.

[wind_apparent]

26522

I mounted the stern strips, it's a combination of 1'' and 3/4'' strips, It turned out well. I did end up with a couple of extra low spots, but I'll easily be able to bog and fair them out (I guess these little "surprises" are to be expected, I have never built a plywood strip mould before, so, all part of the experience....)

26523

I finally got around to adding the bow piece. I needed to get this on before I could start the bow stripping. (for obvious reasons)

26524

Here is the bow stripping in progress, I couldn't get it done because I ran out of time and strips. Can't cut any till Monday so I guess I'll have to go back to working on the Deck mould a little bit at home over the weekend. I used three levels of stripping on the bow area. It starts with wide 1'' strips, than 3/4'' in level two, and finally 1/2'' strips for the tight curve of the bow.

26525

Here is a closeup of the 1'' stripping. I'm trying to find the balance between enough/to many staples. I'm still not very good at that, I tend to just start shooting and see what I have when the dust settles (I'm starting to get blisters and sore wrists).

26526

And this is what the mould looks like as of now, I trimmed up the overhanging strips on the stern and sanded the bumps out a little to see what its going to look like, i think its pretty good. Not bad for a rookie, No?

(for bigger pictures visit the blog)

[yachtyakka]

Your progress is fun to watch.

The R Class is up

[wind_apparent]

Your progress is fun to watch.
Thanks, I'm getting pretty hooked on building boats, think I'm going to keep doing it for a long time......
The R Class is up
I saw that on SA, I'm a little jealous, but hope to be joining them before to long. (then we can all sport our ultra hip sailing helmets ;) )

[wind_apparent]

I'm going to stop updating this thread (unless there is some kind of public outcry, which I doubt.) Its time I could spend building and has served it purpose, which was to help me solidify the ideas for this project, and to get the technical help I would need to get it rolling. The thread has gotten pretty stale over the last couple months becoming mostly a secondary home for my Blog entries. By now most people that are interested know where my blog is. I will still be posting there as much as possible (don't be afraid to comment). Thanks to anyone who provided input or inspiration. I will still be posting on Designforums but on a "need to know something" basis. See you around...........( I might revive this thread at some later date, but probably not until I have some proof of concept pics).

-

http://sr-71monofoilerproject.blogspot.com/

wind_apparent@yahoo.com

[wind_apparent]

*********shameless self promo*************



I just got a new Gadget for the blog that makes it possible to sign up for e-mail updates. So if your one of the People who have been following this project, just sign up and all updates get sent to your e-mail inbox.

http://sr-71monofoilerproject.blogspot.com/

[yachtyakka]

whats the latest with this project?

[bistros]

whats the latest with this project?

Go to Sam's build blog (http://sr-71monofoilerproject.blogspot.com/)

He got tired of the hype here.

[wind_apparent]

I'm basicly trying to keep this project low key (away from the forums) for the most part......until I have some pictures and video to post of me flying along up in the air and out on the wire. Everyone has seen build pics before. All the really interested people seem to keep track of whats going on through the blog. I get E-mails everyday full of idea's and questions, so thanks to those sailors for their support, Its coming along and will be done when its done.

Sam

[wind_apparent]

After hearing that doug has been banned I am rearing my ugly head again. A lot has happened since I've been around these parts. I have finished the hull plug and just glassed the deck tool as well. Just need to build the foredeck plug and it will be on like Donkeykong. I have a couple questions for all you spray buffs out there:

After all the moulds are built and glassed I want to coat them with Duratec sandable primer as my tool finish. Is this brush or rollable or do I have to shoot it? Are there any issues with humidity (some of these coatings have bonding issues even with low humidity levels). And Do I have to buff it all the way to gloss or would sanding to 400 or 600 do the job? Thanks.

Sam

[yachtyakka]

I was talking with Paul Mac today at the Onetangi Sports park. I taped a interview where he talks about the foil being the future..

I will post it once its uploaded to youtube.

Did you know that Dan is selling sets of foils?

[wind_apparent]

I was talking with Paul Mac today at the Onetangi Sports park. I taped a interview where he talks about the foil being the future..

I will post it once its uploaded to youtube.

Did you know that Dan is selling sets of foils?

I would love to see that interview. Who is Dan? is he selling moth foils? where can I see them? (Pricing?). I'm looking for a set of foils (mach 2? Illiet? aardvark? Used?), the new plan is to put a square main foil box in the hull instead of a foil shaped case so that I can switch out foils at will. I plan to start with a moth foil set based on the fact that they are working well on Bruce Gaunt's 16' trapeze foiler in Aus and all the controls have been sorted. Then move onto my own optimized foil set.

[yachtyakka]

Dan Leech, designed the foiling RClass L3 and is now selling sets of Foils for the RClass.

Interview here


http://yachtyakka.co.nz/2009/05/yachting-news-may-part-13/

[wind_apparent]

Great stuff.....I don't think that the R foils would work very well on the SR because the numbers don't match up very well. To much lift area (drag) for this projects weight/sail area. I'd rather have a little less lift area than I need(moth) than to much (R). Using the moth foils I might give up a little on early lift off, but higher top speed is an alright trade off I think. I often kick around the idea of building an R mould when I'm done with this frankinstien. I think it would be a great class to introduce to the States. (***Yes I'm crazy :D ***) Well, I'm off to sand fresh fiberglass.






31994

[wind_apparent]

Haven't been to these parts in a while, but the tools are done and ready to lay up, spent the day looking into vacuum infusion. Really leaning that way.

[Doug Lord]

Are you going to lay up a hull off the hull plug or lay up a mold and then a hull? Good luck!

[wind_apparent]

Are you going to lay up a hull off the hull plug or lay up a mold and then a hull? Good luck!

Lay up off the plug for this first one, I know its not ideal, but its the easiest as far as tooling is concerned. Just want to get this first boat up and running, so I can get a feel with whats going on with it. I have plans in the works to build a female clamshell mould next. (to a new design from the same formula)

[Doug Lord]

wind, you should see post 1030 here:
http://www.boatdesign.net/forums/sailboats/moth-foils-30-31-knots-34-86-mph-11209-69.html

[Doug Lord]

He did it! Congratulations!

http://sr-71monofoilerproject.blogspot.com/

[Doug Lord]

=====================================
I realize it's too late on your current boat but it's been bugging me for a while: I would hope you would be amenable to modifying the rule to allow the LOA to be 4.55m and allowing a potential designer to eliminate the gantry.
The gantry(in my opinion) is a rule induced abberation which is NOT necessary for a successfull foiler design. In fact, there are really good reasons why it should be eliminated:
1) by allowing the hull to be a bit longer the available hull buoyancy is increased so the L/beam ratio can be increased reducing resistance and allowing the boat to achieve takeoff a bit sooner.
2) In my humble opinion, it is somewhat ugly and help creates a "contraption" appearance to some onlookers.
3) When taking off without an F-box(angle of incidence control) a gantry (and transom)drags when the boat is pitched bow up.
4) The ONLY reason for a gantry is to allow the foil footprint to be better on a boat NOT DESIGNED FOR FOILS IN THE FIRST PLACE.
---------
So whataya say,can the rule be amended to allow "gantry-less" designs 4.55m LOA?

===========================
I've totally changed my mind on this -at least for small multihull foilers. Are you going to use a gantry, Sam?

[wind_apparent]

===========================
I've totally changed my mind on this -at least for small multihull foilers. Are you going to use a gantry, Sam?

Yes, a 50cm gantry. The hull has also been cut down to 3.85m proper, so should be 4.35m with gantry. It was just a little long, so I cut it down some. 10cm off the stern and 5cm off the bow. I am also cutting the beam down from 70cm to 55cm. And adding tramps.

[wind_apparent]

I'm also working on the class rule. I'll post it here soon for input

[Doug Lord]

I'm also working on the class rule. I'll post it here soon for input

---------------------
Looking forward to it. Suggestion: allow the same total overall length with or without a gantry. Allow sliding seats-whats the harm? Allow more than two foils-again-whats the harm? Don't restrict beam-maybe just restrict crew movement?

[wind_apparent]

---------------------
Looking forward to it. Suggestion: allow the same total overall length with or without a gantry. Allow sliding seats-whats the harm? Allow more than two foils-again-whats the harm? Don't restrict beam-maybe just restrict crew movement?

Sorry doug, still no dice, though surface piercing foils are within the rule as it lays right now. (as you know, extra beam is a double edged sword on these things, seeing as you need to beat the boom across the boat on tacks and gibes)

[foilman24]

News on the street is this project took an abrupt left turn towards a cliff. Sad.

http://sr-71monofoilerproject.blogspot.com/

[Doug Lord]

What a damn shame! And what about all his "sponsors"-seems like that is real unfortunate.

[wind_apparent]

What a damn shame! And what about all his "sponsors"-seems like that is real unfortunate.

Well Doug, It comes down to I'd rather sail/race than build right now. As for the trapfoilers future, I will gladly donate the tooling to you if you want it. As for the sponsors, I'll still be plastering them on the hull, As long as I'm showing people how to use their products, they could give a rats ass what I build. tell you the truth, most people thought it was a moth anyway.:D, bigger fish to fry right now. First off getting on the water by spring.

[Doug Lord]

Well Doug, It comes down to I'd rather sail/race than build right now. As for the trapfoilers future, I will gladly donate the tooling to you if you want it. As for the sponsors, I'll still be plastering them on the hull, As long as I'm showing people how to use their products, they could give a rats ass what I build. tell you the truth, most people thought it was a moth anyway.:D, bigger fish to fry right now. First off getting on the water by spring.

----------
I'm sad to see this end this way but I wish you the best of luck!

[Doug Lord]

A bit more on Sams site: http://sr-71monofoilerproject.blogspot.com/

Sam , any idea what your all up weight will be?

[wind_apparent]

A bit more on Sams site: http://sr-71monofoilerproject.blogspot.com/

Sam , any idea what your all up weight will be?

The hull shell is 5kg, the deck is 1.25kg, and the foredeck is .25kg (approx for all). Still needs transom, frames, bulkhead, and case. It won't be the lightest build around, but it might be the widest..... also has some of the least freeboard out there, especially in the stern.

[CutOnce]

The hull shell is 5kg, the deck is 1.25kg, and the foredeck is .25kg (approx for all). Still needs transom, frames, bulkhead, and case. It won't be the lightest build around, but it might be the widest..... also has some of the least freeboard out there, especially in the stern.

You've been reading too many canoe threads, hence your disregard for Jennifer Lopez sterns.

Under 15 pounds isn't exactly heavy. I don't think the slight additional width is a bad thing - it may reduce the lumberjack log rolling balance pre-requisite somewhat and actually allow you to spend more time upright. Some of these "trends" that get accepted as best practices become standards without anyone questioning why they really are still done. I think a lot of the skinny development was done pre-foiling for weight and prismatic co-efficient optimization as a displacement hull, and moving those hulls to foilers was evolutionary.

It will be interesting to see if your design proves to be competitive when foiling without the narrowest hull in the water. I think there is a lot more development to do in rig and wing aerodynamics, that will affect performance more than hull width at sub-foiling speed. The additional width should reduce the problems associated with tramp tube attachment and flex.

--
CutOnce

[Doug Lord]

The hull shell is 5kg, the deck is 1.25kg, and the foredeck is .25kg (approx for all). Still needs transom, frames, bulkhead, and case. It won't be the lightest build around, but it might be the widest..... also has some of the least freeboard out there, especially in the stern.
--------------------
Thanks. Interesting that Mirabauds new hull is a bit wide as well. The only question I see with it is how it will affect lite air take off. I doubt there will be any serious negative to it at all.
I see you expect to be sailing by spring-hope it works out.
----------------
I found this quote from Bill Beaver very interesting when commenting on the tests of his Hungry Beaver design-which was tested at several displacements simulating the unloading of the hull as the foils began to work: "At the light displacement over half the wetted surface area is retained despite shedding 3/4 of the weight". I guess a wider hull might have a higher percentage of the total wetted surface retained as the hull is unloaded?

[wind_apparent]

Obviously this hull wasn't designed to be an 11' moth, but I have always had interest in moths even as I was trying to do my own thing. I started messing with wider moth hull form idea's because of many of the points that have been brought up in the last few posts. at some point it dawned on me that the shapes and widths where starting to be very close to what my project hull would be if I cut it down to the moth rule. It then became apparent that I would never finish the Sr-71 project just based on the amount of time I have to work in the shop. The two idea's met and created the current concept. I had read Bills moth paper, and that wider hull blip always stuck in my head. I have also always thought moth hulls might be better with a bit more form stability, and wider is always better as far as wing support is concerned. I apparently wasn't the only one thinking of these things, because when the Lister Monstro came to light, I noticed a low freeboard, wider hull form and thought that I may be onto something. The current design is far from optimal, but I think is a good enough jumping off point to gain some pretty good intel. Should be a nice solid and stable boat to learn on and hopefully I will be able to pass it on as a good starter boat to someone else when it has served its purpose. (or maybe I'll still stick a 9.5sm rig and a trap on it and see what happens.)

[waynemarlow]

Um, I've always felt the wider the hull the better, one only has to look at the 49er to see wide fat almost oracle style shape hull shapes which in light air seem to simply glide along. The Moth seems to have gone ubber narrow which then poses a problem for the larger sailor. The sailboards have gone all flat and wide but with some almost tunnel hull shape. The sailboards seem the fastest to me ( try paddling a long sailboard and see how easy it glides ) and easiest form requiring least energy to move.

Why then simply not take a 3.5 m sailboard, fit on some wings and foils and your hull is made. weights are not unsimilar

[Doug Lord]

Um, I've always felt the wider the hull the better, one only has to look at the 49er to see wide fat almost oracle style shape hull shapes which in light air seem to simply glide along. The Moth seems to have gone ubber narrow which then poses a problem for the larger sailor. The sailboards have gone all flat and wide but with some almost tunnel hull shape. The sailboards seem the fastest to me ( try paddling a long sailboard and see how easy it glides ) and easiest form requiring least energy to move.

Why then simply not take a 3.5 m sailboard, fit on some wings and foils and your hull is made. weights are not unsimilar
------------------
I don't know ,Wayne. The Moth beats a 49er anytime the two race when the Moth can foil. The "skinny" theory is low wavemaking drag on the way up to foiling. The boats are foiling earlier now so the hull-whatever it is- is less of a problem. But a wider hull is likely to have higher wetted surface and wavemaking drag than a skinny hull and if that is combined with excess weight it could prove to be slow. A wide hull with an all up weight toward the light end of Moth sailing weights-say around 220lb- will probably not be too much of a problem.It will be interesting to see how this plays out-if it plays out......

[waynemarlow]

Wetted surface is influenced by the total of the combined weight of the jockey and boat, whether that is spread over a narrow hull form with greater depth or a wider hull with less depth in the water. The old nutmeg of a dolphin being long and sleek doesn't quite hold true as it is totally under the water, and yet the average flat bottomed barge is a bitch to push through the water until it starts to ride on the surface where it has one of the least resistive hull forms of all.

The Moth just wants stability for the jockey to get on board and then a hull form that gets itself out of the water as fast as possible at lowest speed. I thought that is what wind surfing boards were good at. Its something that has pondered me for some years.

Perhaps its time to have a more careful look, anybody have any data on drag resistantance of a displacement hull such as the Moth to that of a tunnel hulled windsurfing board.

[Doug Lord]

Wetted surface is influenced by the total of the combined weight of the jockey and boat, whether that is spread over a narrow hull form with greater depth or a wider hull with less depth in the water. The old nutmeg of a dolphin being long and sleek doesn't quite hold true as it is totally under the water, and yet the average flat bottomed barge is a bitch to push through the water until it starts to ride on the surface where it has one of the least resistive hull forms of all.

The Moth just wants stability for the jockey to get on board and then a hull form that gets itself out of the water as fast as possible at lowest speed. I thought that is what wind surfing boards were good at. Its something that has pondered me for some years.

Perhaps its time to have a more careful look, anybody have any data on drag resistantance of a displacement hull such as the Moth to that of a tunnel hulled windsurfing board.
=================
I think the lower the takeoff speed the better the wider hull sounds.

[waynemarlow]

Which then leads me onto my next query, does a semi planning hull ( ie a windsurfing style hull with an its bitsy teeny foil back and front ) that doesn't totally come out of the water, but semi planes and traps air under its tunnel hull form, have less drag than a fully foiling boat relying on total foil support. The Moths are no where near as fast as boards yet, perhaps a cross over between the two.

One thing though it would be tough on structures and bodies as the slamming and skimming at 20 + knots is going to be something else.:p

[wind_apparent]

Wetted surface is influenced by the total of the combined weight of the jockey and boat, whether that is spread over a narrow hull form with greater depth or a wider hull with less depth in the water.

The old nutmeg of a dolphin being long and sleek doesn't quite hold true as it is totally under the water, and yet the average flat bottomed barge is a bitch to push through the water until it starts to ride on the surface where it has one of the least resistive hull forms of all.

The Moth just wants stability for the jockey to get on board and then a hull form that gets itself out of the water as fast as possible at lowest speed. I thought that is what wind surfing boards were good at. Its something that has pondered me for some years.

Perhaps its time to have a more careful look, anybody have any data on drag resistantance of a displacement hull such as the Moth to that of a tunnel hulled windsurfing board.

You have to remember there are foils under the thing adding their own plot to the story. The flatter wide hulls (49er, 18fter) are great for plaining, but a foiler lifts off before plaining speeds are achieved, so we are dealing in a sub-plaining area here. The game is changed to the fastest hull shape in a closed 0-7/8 kt window. My reasoning behind the wider hull was this, 1. I was interested in testing a theory i'd been throwing around with a NA friend: If you take 2 moth hulls that are the same weight, one skinny and deep and one wide and short, which one is faster? Went back and forth on it a while, but everything seemed to come down to which is worse, the parasitic wave making drag of a current skinny moth hull, or the wetted surface area drag of a wider low freeboard hullform with less wavemaking drag? Since I'm not a CFD wiz, and I wanted a moth anyway, I figured I could test it out. 2. I am no lightweight by any means, (185lbs) I was thinking as the skipper weight gets heavier, the skinny hull sinks more and more, causing more drag for a longer period as the sailor weight goes up. They already have a disadvantage when it comes to take off speeds, so maybe heavier helms would benefit from a wider hull. 3. I'm just learning, so stability might be nice. 4. I had all the hull parts sitting in the shop ready to cut down and glue together, which would get me foiling much quicker by using some off the shelf moth kit.

We'll have to wait and see what happens, or as doug said, if it happens. (I know, I couldn't believe he of all people said it either.) Anyway, hull-shape is not even relevant if your fois are sh!T. Right now I just want to put a boat together so I can go sailing instead of building. Off to the shed.

[waynemarlow]

I think we need to totally rethink the way the moth hulls need to be thought of, they are only there to get up enough speed to let the foils work, what they don't need to be is displacement type hulls with lots of energy wasted pushing the water aside.

I know that canoe body shapes have the least resistive shape of all and now with the Moth jockey being more and more in one central position then it too must have merits.

Would love to get involved in the Moth class but at 95kgs it would be a problem, pity they don't have a form of equalisiation of some kind, but that in itself would create so many problems. Perhaps just for fun.

[Doug Lord]

of a wider low freeboard hullform with less wavemaking drag? .
==========
Less wavemaking drag than a skinny hull of the same length? Really?

[Doug Lord]

Perhaps just for fun.
---------
Wayne, the Moth can carry the weight-just doesn't do so well in light air or marginal foiling conditions.....

[Doug Lord]

Sam is making progress thru bouts with Real Life-looking good:

FoilWRX Moth Concept
A blog dedicated to the construction and development of the R1 moth

http://sr-71monofoilerproject.blogspot.com/

[CT 249]

Um, I've always felt the wider the hull the better, one only has to look at the 49er to see wide fat almost oracle style shape hull shapes which in light air seem to simply glide along. The Moth seems to have gone ubber narrow which then poses a problem for the larger sailor. The sailboards have gone all flat and wide but with some almost tunnel hull shape. The sailboards seem the fastest to me ( try paddling a long sailboard and see how easy it glides ) and easiest form requiring least energy to move.

Why then simply not take a 3.5 m sailboard, fit on some wings and foils and your hull is made. weights are not unsimilar

The 49er is a narrow hull by comparison to older skiffs - all of the skiff classes have moved away from a planing-style hull to a narrower "displacement" hull designed to reduce WSA and waterline beam. Bieker, Morrison and all the Aussie skiff designers are all on record as saying this.

The flatter and wider a sailboard is then the slower it is in light winds. At the ISAF trial at Garda a few years ago, in light winds the very fat and wide (7'6" long x 3' wide) Formula boards could not get to the first mark before the longer and skinny (12'6" x 2'3") Raceboards finished the two-lap race. That's despite the Formula board carrying 11-12.5m of sail compared to the 7.4 to 9.5 of the Raceboard!

Similarly, a round-bottomed 12'9" "Division II" board, which has a narrower waterline beam and a skinny cigar-shaped hull, is even faster than the Raceboards in light winds. Before foils, a Division II board with 7.3m sail was as fast as the world's best Moths in light winds, whereas a "tunnel hull" Raceboard was definitely slower than a Moth.

The "tunnel hull" Raceboards are distinctly slower in light winds than the "boat shaped" round-bottomed Division II windsurfers. And of course tunnel-bowed scow Moths are vastly slower than skinny displacement-style Moths in light (or heavy) winds. However, some do say that in a drifter an older and wider but very round and veed Duflos-type Moth is faster still.

The proof on the water, tested time and time again, is that the narrower shapes are quicker in light winds than the tunnel-hull shapes.

[CT 249]

Which then leads me onto my next query, does a semi planning hull ( ie a windsurfing style hull with an its bitsy teeny foil back and front ) that doesn't totally come out of the water, but semi planes and traps air under its tunnel hull form, have less drag than a fully foiling boat relying on total foil support. The Moths are no where near as fast as boards yet, perhaps a cross over between the two.

One thing though it would be tough on structures and bodies as the slamming and skimming at 20 + knots is going to be something else.:p

The Moths, when foiling, are very close in performance to Formula Boards, which are the fastest windsurfers around a course in such conditions. In non foiling conditions the Moths are much faster than the Formula Boards.

The Moths are much quicker in foiling conditions than a long "semi-planing" windsurfer, if by that you mean a Raceboard-style hull like the former Olympic Mistral IMCO. In lighter winds the Moth probably still has the advantage.

When you say "perhaps its time to have a more careful look, anybody have any data on drag resistantance of a displacement hull such as the Moth to that of a tunnel hulled windsurfing board" it seems that you don't think that Moth designers have thought of these factors. In fact, many of them have a vast amount of theoretical and practical back-up - for example, the Hungry Tigers were partly designed on the computers of an America's Cup designer, who also gave some input. A very careful look has already been taken.

[Doug Lord]

The 49er is a narrow hull by comparison to older skiffs - all of the skiff classes have moved away from a planing-style hull to a narrower "displacement" hull designed to reduce WSA and waterline beam. Bieker, Morrison and all the Aussie skiff designers are all on record as saying this.

.
=============
The 49er hull and other modern hulls have not moved away from planing hulls-they have moved away from "humps" in the drag curve common to almost all planing boats-more so before the early 90's.
Frank Bethwaite in Book II* says:" In the years since 1990 one of the principal design advances has been first the recognition of the dynamically humpless hull-the realization that hulls exist that do not baulk as minimum planing speed is approached-and then the exploitation of this understanding in the design of useful boats"
Of course,THE principal design advance in dinghies since before the 90's is the bi-foiler, as demonstrated by the Moth, R Class ,Mirabaud and other one offs. The drag reduction/speed increase related to the adoption of the bi-foiler configuration is far and away the most important single advance in dinghy** design,probably, since the days of Uffa Fox.
--
The humpless design can be important to a foiler too if the onset of planing tends to occur prior to liftoff-a humpless design would be a clear advantage in that case.
In the case of the Moth with a 10/1-11/1 or so L/B ratio(at the waterline) the onset of planing occurs substantially after liftoff so a humpless design is of no consequence.
As the L/B ratio gets smaller(the hull at the wl gets wider) the consideration of a humpless design becomes more important for a foiler in order to facillitate early takeoff-depending on the waterline length of the boat. A "hump" in the drag curve just before takeoff is something to be avoided.

* "Higher Performance Sailing"
** for my purposes, dinghy= small sailboat

[CT 249]

I used the term "planing-style" and "displacement" as some dinghy designers do - as shorthand for the conceptual difference between a design intended to maximise planing lift (i.e. "Wedge" style Aussie 14, classic Aussie Cherubs, etc) and a design that chases lower drag at medium and low speeds - in other words something like the "humpless" hull. Of course all these boats plane, but the "displacement" term merely reflects a boat where there is a lower priority on maximising planing lift and a higher priority on reducing drag when in the displacement regime.

Paul Bieker described what I was calling the "planing style" like this in a piece on '80s Aussie 14s; “Most of the Australian hull designs have very flat bottoms, with a little rocker distributed evenly over the length of the boat, low chines, and fine bows. This style of boat is potent in flat water and 12 knots or more breeze, planing earlier and faster than other designs. However, in light air they seem to be relatively slow, due primarily to high prismatic coefficient and a greater tendency towards transom immersion.”

The "displacement" hull (using a term from 12 Foot Skiffs etc) has higher (if any) chines, a narrower waterline and more U-shaped sections, often with a narrower stern. It therefore has lower wetted surface area and lower form drag, at the expense of losing planing area. To quote skiff designer and NA Rob Widders, this style is “more efficient upwind and downwind in wind speeds less than 20 knots due to the lower wave and frictional resistance as a result of form and wetted area factors”. The lower form drag allows these boats to go faster in light and moderate winds. They have less of a "hump" than earlier designs because their WSA and waterline beam are narrower. Some of these features were seen many years before on MRs and N12s. OF course, the lower drag at displacement speed increases speed which then increases dynamic lift and therefore allows the boat to plane early despite having less planing area.

Some say that the 9ers adopt a different approach to achieving the same effect. That is, because they are not constrained by class rules they can be considerably longer and/or carry more sail, thereby dramatically reducing their DLR and form drag and increasing their hull speed and reducing the drag hump around the forced regime. The fact that 9ers are free of class rules means that they don't need the same high-volume sections to achieve the same result, like shorter and heavier skiff types do - however there remains the same intention of reducing drag at lower and medium speeds rather than on increasing planing lift at those speeds. Julian for example referred to the development in his 18s as moving more to a "displacement" shape and away from the Tasar hull that could be called more of a "planing" shape.

The May/July 2007 report from Simon Watin confirmed that the 49er DOES have a hump when trimmed with crew weight to achieve its maximum performance. The humpless drag curve came when no such trimming was done - the boat is faster WITH a "hump" caused by a reduction in drag.

[Doug Lord]

The May/July 2007 report from Simon Watin confirmed that the 49er DOES have a hump when trimmed with crew weight to achieve its maximum performance. The humpless drag curve came when no such trimming was done - the boat is faster WITH a "hump" caused by a reduction in drag.
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A "hump" caused by a reduction in drag??? CT, forgive me but that just doesn't make any sense: a "hump" is, by definition, excess drag that occurs just prior to planing!
Can you provide a link to the report by Simon Watin?

[CT 249]

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A "hump" caused by a reduction in drag??? CT, forgive me but that just doesn't make any sense: a "hump" is, by definition, excess drag that occurs just prior to planing!
Can you provide a link to the report by Simon Watin?

Imagine a boat that has the following drag figures;

1 knot - 2 lb of drag
2 knots - 4 lb of drag
3 knots - 6 lb of drag
6 knots - 12 lb of drag
8 knots- 16 lb of drag
10 knots - 20 lb
12 knots - 24 lb
15 knots - 30lb etc

Plot that and you will see a straight line.

Imagine a second boat that has the following drag figures;

1 knot - 0.5 lb of drag
2 knots - 1 lb of drag
3 knots - 3 lb of drag
6 knots - 12 lb of drag
8 knots - 16 lb of frag
10 knots - 17 lb of drag
12 knots - 20lb of drag
15 knots - 22lb of drag

Boat 2 has a planing hump but has much lower drag at most speeds and is therfore a better boat in that respect.

The hump in the Watin tests came because drag at lower speed ranges was reduced by crew positioning - plotting that lower area on the drag curve created a "hump" at higher speeds.

Given the slurs you have made at me I see no reasons to send the Watin information - to ask for something from someone whose honesty you have repeatedly impugned seems rather odd.

[Doug Lord]

Imagine--- Given the slurs you have made at me I see no reasons to send the Watin information - to ask for something from someone whose honesty you have repeatedly impugned seems rather odd.
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I made no slurs-absolutely false-I merely questioned a couple of things you said-and I still do:
1) "all of the skiff classes have moved away from a planing-style hull to a narrower "displacement" hull"

2) " the boat is faster WITH a "hump" caused by a reduction in drag."

[CT 249]

(1) is a simple fact - refer to the Bieker quote, for example. There is a distinct difference in shape and philosophy between a Bieker and a Wedge, or a Nash and an O'Mahoney, or a Brownie and a Bethwaite - or a 49er and an earlier Bethwaite. Talk/correspond to Bieker, Bethwaite, Nash, Morrison, Walsh, Moore, Stephenson, Brown, etc and study designs and the pattern becomes obvious and is well known. I can't help it if you don't want to know it.

(2) is obvious - if you reduce a boat's drag below planing speed, then a low spot in the drag curve will appear at those speeds. If you have a low spot you inevitably have something of a "hump" next to it - but if the hump is caused by REDUCING pre-planing drag then it is obviously a good thing.

And you have repeatedly insulted me and my integrity in the past, so you shouldn't be surprised if I don't hand over stuff sent to me by a designer.