F12 impression

So here is the first 3-D impression of the F12 I've been working on, with many thanks to Grob who was kind enough to create it :





I'm trying to give you all a 3-D viewer and the 3-D drawing so you can all move it about and rotate it to your own will.

Okay here it is, everyone can downlaod the viewer from :

http://www.solidworks.com/pages/products/edrawings/eDrawings.html

and download the file to be viewed from here :

http://www.xs4all.nl/~whijink/F12/F12_impression_29_oct_2007.easm


The mast is bend to its maximal position, which coincides with maximal mainsheet tension. The mainsheet itself is a combined with the downhaul into one single setup. Basically the mainsheet is sheeted of the boom and its bottom part attaches to a line strop that is tied off to the same attachment points on the hulls as the mast support rods have. This way the F12 basically has a centre sheeting setup allowing the rear beam to be fully clear. The tillers of the rudders can protrude over the mainbeam that way. When the mainsheet is slackened then the mast will straighten out. The mast is of course unstayed (free standing) and be more straight up in normal sailing.

The bows are fully clear as the mast support rod keep the mast were it is. Interesting enough this setup is extremely efficient in the way it handles the rig loads. The situation is even so efficient that at maximum mainsheet load the main beam is actually pushed upward ! Nearly all forces cancel one another out and therefor no dolphin striker is needed, saves weight and saves cost. This also allows the platform to be placed on top of the car or trailer more easily. It can now slide along on its beams over two parallel planks and eventually be held by cut-outs in the plancks.

Some elements in this design may appear strange but there is a very good reason to have them. Most are not immediately obvious.

At this time I'm not to happy with the hulls as soon and I'm working on some alternatives. One of which is a deep V-ed hull.

I hadn't realized it myself early on but since then the designs I've been working on don't have skegs or daggerboards in any way of form.

What alot of people aren't realizing yet is that a small lightweight catamaran like the F12 will have a relatively large hull area for a given enclosed volume. Much more then say an 18 or 20 footer version. You are getting this (very low) aspect sideways resisting area practically for free as you have have it in order to float the craft anyway. This situation is made more pronounced by the fact that other dependencies make the F12 rig relatively small in comparison to 18 and 20 footers and the fact that oversize rudders are to be used (coming of larger boats like the Hobies and Dotans). Basically the whole situation is going towards hulls with a large sideways slip resisting area, fitted with a small rig producing little sideways force, on a platform with oversized rudders. I'm thinking lets go the supercat 15 and supercat 17 way on this design. Let the rudders and hulls combine to resist the small sideways forces and reduce complexity and cost ones more.

Interestingly enough the F12 as it is designed here will have MORE sideways resistance without skegs or boards then the boarded Laser-1. And that is when only looking at the hulls and not including the rudders. Of course the F12 will both have larger rudders and two rudders when compared to the Laser-1. When these are made part of the equation then things will start to happen.

Strange as it may seem but I expect this design to be an very good pointer. Its relatively low boat speed will positively impact on this as well. Ever seen laser-1 points in relation to a large beach cat, think along those line but with more speed.


The beams are made from the same tubing as the bottom section of the mast, again saves costs. The beams are spaced wide apart this will improve platform stiffness and space on the trampoline.

As of yet I have not designed a quick release system for the beams and I'm still satisfied with using the conventional 8 bolt setup where the nuts are welded to a plate inside the hulls. Basically you can fasten and release the beams by turning the bolts from the outside. That should be easy enough. Rigging everything else is a matter of seconds, this includes the whole rig. The only exception will be the trampoline. Currently it is sleeved over the mainbeam then a zippered sleeve goes over the rearbeam and it is attached to the sides of the hulls using a line and a handful of eyestraps. As the trampoline is relatively small and the span between the hulls is narrow I don't expect this trampoline to need much tension. I estimate under 5 minutes to fit the trampoline and I'm convinced rigging the rest takes less then 5 minutes as well. So 10 minutes from completely disassembled into major parts like sail, mast, hulls, beams, trampoline, rudders to ready to sail. Significantly less if the platform is transported in one piece.

Performance is identified as superior to any of the laser-1 versions, slighly faster then the Hobie wave and sligtly slower then the Hobie 14.

Optimal weight range 40 - 65 kg, basically making the target group 12-16 year old teenagers and light adults like women.

Wouter

Forgot to mention, that the wetted surface area of the F12 is 10% larger then the Laser-1 when both hulls are in the water and 20% less when only one hull in the water. Of course at a certain point the laser starts planing but this point is pretty far away on the upwind leg as the laser-1 crew can't acquire enough righting moment to get to the sail drive that allows planing.

Of course the F12 has much larger righting moment and when the winds start blowing the F12 will generate easily twice the amount of saildrive then the laser-1. That is where the F12 performance comes from.

Wouter

Wouter that all seems easy and practical with the external bolt system for the beams, could you slide the tramp into the tracks with the bolts loose then tighten the bolts pulling the decks up straight thereby tightening the tramp in the same movement.
regards

Have you ever tried to get the bolts to line up with the whole while there is a force pulling the beam sideways ?

Wouter

Yep on an old A class a mate had it was the only way to get the tramp on and off
regards

Not going to impart my impressions, but tonight I have my Dad staying over because tomorrow he gets to race his grandson for the first time, both are sailing Paper Tigers (not bad for an old dude who is 71). Anyways saw this post and showed it to both of them and my son (13) commented "geeze, not even grandpa chooses to sail something that clunky"....from the mouth of babes
Aerynt

Wouter,
was not trying to diss your idea's, infact your efforts are quite commendable, my comment was just supposed to show what a gut reaction from your target audience was albeit he has been on cats since he was big enough to walk.
Other comments that were heard tonight were, I wouldn't be caught dead taking a girlfriend (if and when he gets one) out on that and what I want is sharp, that thing is blunt.

My one and only observation is that perhaps you find someone to help you with some commercial styling sense to make the package more appealing and then your probably onto a winner
Aerynt

I'm sorry to say that there is nothing there that I can use.

Define clunky, especially in relation to a paper tiger that is presumably not cluncky ?

What does he feel is blunt that should be sharp. The hulls are actually much narrower then the paper Tiger and the bow profile is sharper then the Paper Tiger as well.

Also I'm bet he will be on there is his girlfriend want one. Remember the Ford Ka or the Smart car automobile. Males hated it but Girls loved it, the car went on to be a succes.

Besides styling have not been performed on the design yet. That is mostly the smart use of colours and some cool fittings. First we need to get the concept right and this is a concept drawing. It must be appreciated that way.

Also ask your son how he feels about the Laser-1 ? What does he think about the Hobie 14, wave or Dragoon. That would also be an interesting comments. I'm sure many don't appreciate the fact that there are some very tight design goals for this craft. It must cost nearly next to nothing, be easy to homebuild and very quick to rig and unrig and not be in the way when stored in the garage or the attic. Sure enough he want to have a smaller copy of the newest A-class but it will be many years of bring the newspaper around before he or his parent can affort that. In the end, the decision will be between not sailing, sailing the F12 or sailing a more expensive larger cat like the paper Tiger, H16's or F16's. It can never be totally perfect.

Don't get me wrong, I appreciate every comments that I get but in order to make effective use of it, it must be well defined, rational and elaborated upon.

Not sure I attempted to give you anything to use other than a 13 year olds opinions which from recent experience is not always the most reasonable or understandable for that matter.

I think his reference to sharp & blunt was more inline with style and about being cool verses the opposite.

As for his opinions on the other designs, I'll encourage him tomorrow to get an account here and you can do battle with his opinions yourself, and probably the other 10-20 sailor friends of his who will no doubt join in. Beware, their spelling is terrible and its easy to get serious eye strain trying to figure out what they mean.
Aerynt

That is a good idea, lets do it !

I'll do my best to understand him.

Wouter