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I've progressed on a simple F12 design #119237
10/04/07 04:02 AM
10/04/07 04:02 AM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline OP
Carpal Tunnel
Wouter  Offline OP
Carpal Tunnel

Joined: Jun 2001
Posts: 9,582
North-West Europe
This post is a copy of a post of the main forum.

Typed up a full posting but that one got lost, so here the summery

Quote

My notion is that we need a yacht club with space to park 10 of Wouter's cheap cats.


I've progressed on a simple hull design, A deep V-ed hull; not unlike a scaled Prindle 16. Hull dimensions with eventually come out closely to length x width x height = 3750 x 300 x 450 mm = 12 x 1 x 1.5 feet. Weight of the hull is expected at 17.5 kg


F12's can be stacked on top of one another. When placed in a rack like they do with lasers then 9 F12's assembled platforms will need a "space box" the size of : length x width x height = 6.5 x 4.0 x 1.5 mtr = about 22 x 13 x 4 feet. The F12 mast can be taken apart into elements no longer then 3.5 mtr in under 5 seconds.

A laser-1 rack needs a space-box of about 4.5 x 4.5 x 1.5 mtr = 15 x 15 x 4 feet.

A fully dissambled F12 will fit into its 4.0 x 1.0 x 0.5 mtr = roughly 13 x 3 x 2 feet transport box that will weigh about 30 kg itself. F12 plus its box will be just shy of 100 kg = 220 lbs. Fully assembling an F12 in 10 minutes or less is a design goal and I think that that can indeed be done. Stacking the F12's in their transport boxes will allow 8 combo's to be stored or transported in a "space box" of 4.0 x 2.0 x 2.0 mtr = 13 x 7 x 7 feet. Boats+trailer will still be under 1000 kg weight = 2200 lbs and can be pulled by a modest family car. 2 adults will be able to unload and assemble all 8 F12's so they are ready to sail in under a hour = 15 minutes per boat.

24 F12's in their transport boxes will fit inside a 40 foot container, shipment to anywhere in the world like this will cost about 300 USD per boat.

A 65 kg F16 can be car topped on any given car as typically only 50 kg roof load capacity is garanteed. 65 kg is close enough to be save, also because there is ample proof of 61 kg laser hulls being car topped.

Detailed cost estimate puts a new F12 (no labour costs) at 3641 USD when you buy your sail and dotan rudders. If you make these yourself (not too hard to do) then 2500 USD is possible. I think that I'm able to replace ply by foam/glass for simple homebuilding as well. That is more durable and cheaper in the long run as high quality ply is increasingly difficult to source.

The F12 can take the standard laser-1 rig, it has the same surface area, luff length and mast height. The Centre Of Effort will be close enough to the intended F12 rig as well. However looks are important and the battened F12 rig is much more modern in apparence, trim and performance. See attached picture. Shown is a 5.5 sq. mtr. 4.7 mtr luff sleeved sail on a homemade aluminium mast. The intended F12 rig is just a scaled up version with the same surface area as the laser-1, as such it will be 7.00 sq. mtr by 5 mtr long luff. mast height will be 5.7 mtr. mast weight is just under 10 kg = 22 lbs

[Linked Image]

I'm getting a little off track in answering the "space" question, but I felt that this could be important data with respect to club space and required investment in building the class. That is if the overall discussion concludes that a craft like the F12 has a role to play in the youth programs

Wouter




Last edited by Wouter; 10/04/07 04:24 AM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
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New updates [Re: Wouter] #119238
10/07/07 06:07 PM
10/07/07 06:07 PM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline OP
Carpal Tunnel
Wouter  Offline OP
Carpal Tunnel

Joined: Jun 2001
Posts: 9,582
North-West Europe

The basic dimensions appear to have been settled.

Using the democraphic data for children in the age range of 2 to 20 years of age, it has been confirmed that the F12 is indeed targeted towards :

-1- Girls and women from 12 years of age onwards (this includes adulthood)
-2- Boys from 12 to 16 years of age.

At 12 years of age there is no difference between boys and girls in weight, length or body strength or even the spread in either of these measurements; both are on average 40 kg and 1.50 mtr tall.

Girls and women never grow passed the average of 58 kg and 1.63 mtr of length. At 16 years of age boys reach on average a weight of 61 kg and length of 1.74 mtr. Obviously boys have grown a little taller but not heavier ! Adding mass happens mostly after 16 years of age. As such the age group of 12-16 can race eachother fairly as 0.1 mtr difference in length is obviously not significant on a 2.0 mtr wide boat.

The initial choice of designing the craft to be competitive from 40 to 65 kg was the right one. Of course the craft will carry alot more, but not in a "fair racing" sense. This is obvious as the cat much be able to carry at least 130 kg on one hull in a competitive manner. This requires both reserve bouyancy and of course a much heavier crew will put the luff hull back in the water. There is no reason why the craft can carry 2*130 kg = 260 kg in total before becoming uncontrollable. This corresponds to a combined crew weight of 195 kg or an 90 kg dad with two 52 kg kids (16 or younger).


But a far more important analysis will be righting. The required minimal righting force is determined as being 36 kgm. This means 36 kg handing off a 1 mtr long leverage. A "standard" crew of 12 years at 40 kg and 1.50 mtr length can generate 55 kgm of righting moment using the standard righting rope. This basically means that the standard crew is easily capable of righting the craft even in flat water and absolutely no wind.

The demographic data gives that 95 % of the children at 12 years of age weight at least 30 kg and are at least 1.37 mtr tall. These will be able to generate a rightig moment of 38 kgm which is just in excess of the required 36 kgm. So they too will be able to right the boat in flat water and no wind.

Naturally both waves and wind (if present) will help righting the boat, thus creating ample safety margin in conditions where safety is extra valued.

The F12 hull volume distribution will make the weight range of 40-65 kg competitive with 57 kg being optimal.

I should not be problematic to sail the F12 in a performant manner all the way up to 85 kg. The hull will have ample (reserve) volume for that because of the V-ed shape, alot of volume is found at the top.

It appears the currently designed setup will have no problems what so ever in withstanding the increased loads.

The design is a very elegant in the way the forces are all arranged such that they largely cancel one another out. For example the mast step loading is never going beyond 220 kg. Compare that to the 1500 kg's on for example a F16 or F18.

I'm quite pleased with the setup. Simple, cheap, performant and (de)rigged very quickly. Just like the laser-1 dinghy.

Wouter

Last edited by Wouter; 10/07/07 06:20 PM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
New Updates : Weights and dimensions [Re: Wouter] #119239
10/09/07 04:38 AM
10/09/07 04:38 AM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline OP
Carpal Tunnel
Wouter  Offline OP
Carpal Tunnel

Joined: Jun 2001
Posts: 9,582
North-West Europe
From comparative analysis we have found that 18 kg's per homebuild F12 hull is possible. This number comes from measuring an actual homebuild hull of slightly longer length but the same building principle and simulation analysis using PC software.

Other top boundery weights have been determined (measured) as well. A short listing will be given now :

2 hulls : 2 * 18 = 36 kg
1 unstayed alu mast = 10 kg
7.0 sq. mtr. sail with full length battens = 4 kg
2 rudders and rudderstocks = 4.5 kg
2 alu beams = 4 kg
2 push rods = 2 kg
rest (small stuff) = 4.5 kg

Total 65 kg ready to sail.

Bare platform (hulls, beams, trampoline) will be under 45 kg and thus under the 50 kg weight limit for roof racks on small cars.

These limits allow for some weightsavings here and there, but as this boat is intended to be homebuild by a large group of amateurs I feel it is best to stay conservative. No exotic materials are used. Ply/epoxy or plain glass/foam, aluminium, dacron or maxx pentex and some stainless steel bolts and fittings.


The major dimensions appear to be :

3.75 mtr in overall length
2.00 mtr wide
65 kg ready to sail
5.9 mtr tall mast aluminium and homemade from high strength alu tube
7.00 sq. mtr. high aspect sail (aspect = 3.8)
5.15 mainsail luff length
1.85 mtr alu boom
Quite a lot of trampoline area.


Texel handicap with 40 kg person on board = 135
Texel handicap with 60 kg person on board = 142

(Wave = 141, Hobie 14 = 135, F18/F16/A-cat = 101, laser-1 = 160. laser 4.7 = 173)

A different analysis method shows slightly higher performance and indicates the feel of the craft is much like a F16. Same sense of pitching and heeling. That is a good achievement as the shorter the hulls the more twitchy a boat design becomes. The F16's feel lively but not overly nervous of twitchy. I don't want to push it any further then that as the short hull length is already limiting the total amount of sailarea and with it the F12 performance to the rear of the cat fleet.


Trying to get artist impressions ready to show the world.

Now the detailing of building the hulls needs to be done.

Wouter

Last edited by Wouter; 10/09/07 04:57 AM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
Re: New Updates : Weights and dimensions [Re: Wouter] #119240
10/09/07 10:13 AM
10/09/07 10:13 AM
Joined: Aug 2002
Posts: 545
Brighton, UK
grob Offline
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grob  Offline
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Joined: Aug 2002
Posts: 545
Brighton, UK
Quote
The major dimensions appear to be :

3.75 mtr in overall length


Surely you mean 3.65 mtr

Re: New Updates : Weights and dimensions [Re: grob] #119241
10/09/07 10:50 AM
10/09/07 10:50 AM
Joined: Sep 2005
Posts: 1,187
38.912, -95.37
_flatlander_ Offline
old hand
_flatlander_  Offline
old hand

Joined: Sep 2005
Posts: 1,187
38.912, -95.37
Quote
Quote
The major dimensions appear to be :

3.75 mtr in overall length


Surely you mean 3.65 mtr

Gareth,

You don't recall the big tiff when Wouter wanted it to be 3.91m (12'10")?


John H16, H14
Re: New Updates : Weights and dimensions [Re: grob] #119242
10/09/07 02:18 PM
10/09/07 02:18 PM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline OP
Carpal Tunnel
Wouter  Offline OP
Carpal Tunnel

Joined: Jun 2001
Posts: 9,582
North-West Europe

Quote

Surely you mean 3.65 mtr


No. I mean 3.75 mtr.

And F12 stands for : "For 12 year olds and older" (I'm not getting in that discussion again !)

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands

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