The 2'6" deep hull is way too deep. THe Tornado is only about 24" deep, and you are only going to be hauling 1 person and a 150 lb boat. At one time, I had 800 lbs of crew on my 360lb T and was out in big wind, and had a problem smacking beams on 3' waves then, but you should not with 350 lbs total. You need to be careful with the volume up front. I did not do that on an A that I built (it had the max width nearly straight from the front to the 9 ft mark), and the hulls were real prone to go nose down so had to cut the bottoms off and spread them a bit. Then the next bottom was too fat up front... both great (if expensive) learning experiences. So that is 2 mistakes I will not have to make next time You will likely also want a bit of rocker on the front of the hull so that it will turn easier, like in the first 2 ft. I honestly beleive that the extreme rocker that you have on the back of your hull will cause you to go slow, by making the hulls drag along too much water. Go take a long look at a T which is a superbly designed boat, even though old. Plus take a look at the Flyer if you can find one. The back half of the hulls are a nearly flat line: meaning all the rocker curve is near the middle of the boat. My personal opinion is that the straight rocker on the back sections are required for good speed, and my next A-cat will have that trait.
If it were me building this hull, with only 14 ft to work with, I would make a high aspect ratio mainsail, using the 26 foot Carbon fibre mast as quoted. I would make the sail a square top main with about a 5.5 ft chord that would continue for a good distance up the mast and then taper to 2 ft square top. I would put a circular traveler on it, and put the rear beam about 1'8" from the rear of the hulls, so that you can have atleast a 1'4" arm on the tillers. If you use a 6 inch chord wingmast with the pivot about 2 inches from the front of the mast, the center of your main beam would be about 5'7" from the center of the rear beam if you put the traveler on top of your rear beam. Personally I would make the hulls about 13 or 14 inches wide at the top in a tapered shape similar to the T at the middle and then taper to about 10 inches wide at the transom. I am also now a big fan of the tapered top on the front of a hull that Bill Roberts pioneered, leaving the thickest part of the hull in the middle. The Taipan 4.9 does this a bit on the very front of its hull, too, and that is a great little boat.
Maybe if I remember this thread while at home, I will draft up something that I would consider way better than what you designed and post it. It only takes about an hour now after having done so many versions of the A-Cat.
I think the 14 needs to be re-thought and radical (especialy if it is someone else's time and money?)
I would try deep hulls so the boat is less prone to hobby horsing (short shallow hulls will be a disaster in this regard, even though there may be strong arguments to support planing hulls)
This could be countered with a mast well aft and large rudders, no centerboards. While twitchy and not easy to "get rolling" the boat would tack and drive really well. A cable type traveller "track" for the mainsheet from rudder gudgeon to rudder gudgeon? I believe that in the real world of chop-whenever-it-blows any, the extra wetted surface of narrow deep hulls would pay off in fore-aft stability (not "shaking the wind out the sails")
Mast aft also reduces pitch poling off the wind. While the moment produced is unchanged (center of effort is still acting at same height) the mast weight and inertia are further aft which effects the countering moment and response time.
Maybe a longitudinal center beam from fore to aft crossbeams with multiple mast ball mounting holes and multiple shroud plate mountings at the hull fabrication stage would be reasonably cheap to do, and you could learn a lot fast. Maybe you could do without a hooter pole, a savings in itself? if the mast was way back.
Are either of you familiar with the Formula 14 class specs? We've got 14'3" of waterline to play with, and 300 sq.ft. of sail. Running without the reacher isn't even being considered, especially after the H14Ms showing at Spring Fever 2004.
In the picture, the mast is shown with no rake because it was easier to draw it that way; it will be raked back a bit. The mainsail area is ~140sq.ft. The reacher will likely be the same.
The hull rocker more closely resembles the AHCP Capricorn and a few other F18s I've looked at. I only have 14'3" to work with, so I can't have the long clean straight lines they get. I have that steep rocker in the back so I can really leverage myself off the stern of the boat to keep the bows up without too much bouyancy fighting against me.
I haven't done cross-sections yet, but the hulls will have a high Cp, with the volume down very low. The bows will curve back together at the top, with pretty much no flat deck ahead of the mast beam. The reason for the tall bows is to allow me to create this curved section without compromising the shape, and to give me the extra "stuff it" ability in heavy air while carrying the reacher. It shouldn't add much weight at all, and the extra windage should be minimized by the curved shape.
On the off-chance you didn't notice, clicking on the picture takes you to a much larger version.
Concerning the rake aft of the knuckle:
The water only knows its relative speed to the hull. Therefore if the rake here is steeper than other boats of comparable speed, who have it figured out, it will be draggy (want to detach, but can't) Bernouli says the decrease in velocity must cause an increase in pressure, so the water slows to fill the hole, and its surface climbs to correspond with the increase in pressure. Now if the boat is past its hull speed, the former bow wave or trough may be back here, and so what happens then?
Personally, I theorise that rocker has no place in a short fast boat, and turning ability has to be achieved by other means. (ref previous poster) This leads to a canoe stern below waterline at keel-line elevation(bottom of boat) and a wedge shape in plan at deck elevation ( no reverse taper to stern, but taperd all the way to the bow from stern). If you can accept dxf or dwg files, I will send you an iso of one I worked out. Basicly a minimum drag at keeline, transitioning to min waveform at waterline. (Built a 1:10 model of hull form and then got side tracked)
Hi guys,
Sorry to jump in on your topic, just came across it and had a few thoughts.
Perhaps you should be looking at other high performance short boats like the Moth. As you're dealing with a very short hull length and a conceivably very high power to weight ratio, perhaps there is potential to have quite a flat bottom (in terms of rocker) that is only very narrow in width (ie 150mm) that has a flat bottomed planing area?
Two Moths strapped together with a nice big powerful rig on them is a very interesting prospect indeed. Pity they're only 11ft long.
<img src="http:/
Yep, ok. feeling pretty dumb about now 
will do some more research before posting next time so I know what I'm talking about. 
Looks like a great little boat Darryl, rake the mast a little, and whack a kite on the front and lock the feet in some footstraps down the back and off we go!
Sorry if I'm igniting the spinnaker debate again but 14ft is probably the right size for single handed with kite - get a bit intimidated by my Taipan with kite solo (with my crew its not too bad).
Have fun guys! I'll pop in from time to time and see how things are going.
Andy.
If you notice on one of the photos there is a little black cylindrical fitting of delrin in the middle of the front beam in front of the mast base! thats the supporting base for the carbon spinnaker pole (which is standard -thats why it is an F14!!). There wasn't any wind whatsoever on Saturday the 27th of November (when the shots were taken) so not only did we not sail but it seemed a little premature to rig up the spinnaker?
Very nice boat Darryl! Have you tested it much yet?
To the person comparing a Tornado to the F14, especially regarding the bow height, please remember that you have two men almost 20' from the bow of that boat which gives you a whole lot more leverage than a single person only 14' away. Especially considering the F14 is aimed at lighter crews. The heavier guys would likely be on an I17. We'd like to see the F14 class be able to cater to women and children as well as the rest of us, and are designing accordingly. I'm doing everything I can think of to keep this little boat of mine from ever wanting to pitchpole.
Shouldn't the Capricorn be slower than other boats in it's class, as it also has a lot of rocker in the stern while many other boats in it's class don't. Instead, it's kicking butt and taking names. However... I'm working on a drawing that will reduce the aft rocker to 6" instead of 12" by having the deck drop by 6" after the rear beam... I'll be posting a new drawing tomorrow (Wednesday)
Mr. Barrett,
tell us about those rudderheads, if you please.
A lot of "little" changes in Draft #5.
1)The section of maximum width was moved from being centered under the mast to being entirely ahead of the mast. The reason being to give a better foil shape to the entire hull, and to gain more leverage against the rig.
2)The daggerboard has been moved forwards 6". This puts it around 1/3 aft of the mainsail luff.
3)The mast rake has been drawn in. I set it so the sidestays go almost vertically from the chainplates to the mast hound (which is set 2/3 up the mast)
4)The deck drops 6" after the rear beam. This allows the rudders to be mounted lower and allows the aft rocker to be lessened to 6" from the previous 12".
5) The fore rocker is still only 3", but it now ends 5' from the bows instead of 6'
![[Linked Image]](http://seafarer-research-center.com/catamarans/freestyle14d5.jpg)
I might move the fore rocker back to the 6' mark, I'm not sure I like it as much in this draft as in the previous one.
I drew the boat on an oversized grid to help you all get a feel for the dimensions, and actually managed to get a pretty level picture of it this time.
Darryl's rudder design looks amazingly similar to the G-Cat system. If my original G-Cat rudder housings hadn't been destroyed, I would still be running them and loving every second of it. It's a great, simple, and very effective design.
I have designed and used many different styles of rudder stocks, rudder head shapes, and rudder lock downs, over the years, and these are as simple as I could make in our work shop using nylon turned down and shaped for most of the components with a threaded both ends, stainless steel rod as the "pull up/ push down". It was simple, works faultlessly, is strong, and most of all it is easily and quickly manufactured in house on a good cost basis.
As far as the actual "rudder head" is concerned, they are shaped with a small protruding "crane" facing aft to give the correct leverage and arc to the rudder swing in the stocks.
as previously asked in the other thread, what do you expect your F14 to be sold for darryl?
Hi Darryl,
Please could you post a pic or 2 of your boat directly on the forum, if I follow your link to the catsailor albums I get hung up for half an hour, and then see a white screen, which is not much to go by.
Cheers
Steve
well,
i must have meant rudder stock when i wrote rudder head. if they were on a hobie they would be castings. what is the black material that is on the sides? If you sold them or the plans for the stocks, how much would they be?
i dream of building a mini version of that giant cat with the seaplane hulls and 2 masts. Although the hulls of the mini may not be the seaplane type hulls, the rigs and beams i like.
cheers
I have tried repeatenly to post pictures direct onto the forum steve, but I have given it up as a "black art" that I can't seem to crack the code of.
The rudder stocks, as almost ever other part of the cat, are 100% carbon fibre (except where we have used Kevlar as well) We make the stocks from moulds that I have made in the work shop. We would sell any part of the cat as individual items to any one who was interested in them, but it is still a little premature for us to have worked out the price structure for individual items, our main concern at present is to fully test the cat as a whole over the next few months so that we are confident in it's performance as well as the structural integrity of ALL the componentry before any of it is "put onto the marketplace" besides things like rudder stocks for one cat are not necessarily suitable (due to the differences in transoms) for all other cats
Not to sound like a whiney bastard, but could you start a seperate thread regarding the rudder system you've developed? It'll bring more attention to your rudder system and not side-track this thread which is supposed to focus on hull design (though it does seem to have stagnated a bit). I should be putting another draft of the Freestyle 14 up this week. Just more work on the rocker, hoping to get a general "thumbs up" on it so I can get on to developing the cross sections.
Sorry about that but if you read back through the immediate posts, you will see that all that I have done is to respond to direct questions. Still it is your thread and I apologise for conjesting it with other matters, mind you what has been said should be of some interest and advantage to you while working on your own design, like they say "a designer can never have too much imformation"
Darryl, I actually want to hear all about your rudder system- just not in this thread. People who are looking for rudder information will likely skip this thread and the information will be lost to them. For my rudder systems, I've got two sets of Dotan Sampson 25s and two sets of Hobie 14s. Likely I'll make the mounts set for the Hobie 14 system and adjust the Dotans to fit. Then I can run whatever system will hold up better. The Dotans won't hold up at all on my G-Cat 5.7M, but I think the F14 is just the boat for them.
well sir,
i gotta say the rudder system is part of designing a cat, and the title doesn't say only the hull design. didn't mean to side track your thread.
i seek to post a side view of a c class hull which has a fast looking rocker. admittedly cogito has a curvier rocker and was faster around the course. cogito's hulls came out of the paitent lady molds which have got to be over 10 years old. so i recomend that you closely follow existing design.
the attachment seems to have worked. all i did was hit the browse button and navigate to my desktop where the picture resided. the catsailor server seems to host the picture for us once uploaded from our computers.
Mmm, is that a wooden rudder I can see at the stern??