Beachcat vs. Beachtri?

[Robin Larsson]

God evening, atleast here in Sweden:)

Which is really the fastest? I´ve only sailed cats at a few occansions, just once in a Hobie 16 i light airs, and a couple of times in and old NewCat 14. So not much experience i multihulls, so I ask you guys:)
I would like to build a multi, something like 16 foot, preferably plywood or some other method to build fast. Maybe the KSS method? I´m open to ideas:)But l prefer working in wood, but have experience in one off FRP to.

What would be best, a tri or a cat? Is there really a big performance differnce? I read somewhere that cats have a higher speed potential, but that tris normaly were easier to sail, and thus faster. I dont know if its true, and maybe only for bigger boats?
A cat should be lighter? But a tri would have more RM due to wider platform?

I want a boat that is a bit overcanvased, but possible to sail both single and doublehanded, maybe single without jib or something. I want a almost skiff style bowsprit and assy:)
Trapezes depending on conditions.

Maybe a skiff would be better, But it feels like a tri would be the easiest to sail?

Difficult question maybe, but you guys are experts:)

Best Regars
Robin Larsson

[Doug Lord]

Robin, a tri can be faster and more comfortable(I hate sitting on a flat tramp) but there are few sources of plans for trimarans in the size range you're talking about that are trully powered up enough to be beachcat killers. Look at some of the tri designers like Kurt Hughes.
Your description sounded a lot like Bethwaites HSP shown in THE BOOK:" High Performance Sailing". There are numerous threads here dealing with different aspects of high performance small multihulls. Good Luck!

[Robin Larsson]

Thanks Doug!
I´ve found Kurt Hughes site earlier today, his 16foot tri got me thinking about a tri again:)

Just read a couple of long threads about small performance multis:) Interesting reading to say the least!

Yeah, I see what you mean about comfort, the cats I´ve sailed were rather uncomfortable, it feels like the trapezes were the best choice:)
In a tri I guess one can have a more traditional cockpit in the mainhull. But one out hiking its the same:)

Doug, on the two trimarans I´ve read that you have built, did you use trapezes?
Btw, seems to be some problem with your site, microsail?

What is it that gives the tri the ability to be faster then a cat? It is after all carrying a bit more weight. I mean, look at the Seacart 30, really fast boat, almost always sails on one hull, then whats the point of having the mainhull? Of course, accomondation, but from a sailing standpoint?
I read about a cat called Alinghi an its "offspring" in the Swiss lakes, they built a cat with a center hull that never touches the water, they had it only to support the rigging...

I´ll have to see if I can find that book:)

But one of the reasons to why I would like o build a tri is because I like them:) Would want to build a larger(liveaboard) one one day, but would like to start with a dinghy first:)

The problem with the designs available, not being powerd up enough, isnt that easy to fix, just more sailarea? And maybe then stronger structure:)

I dont really need to kill the beachcats, just sail as good, but of course, killing would be nicer:)

Thanks for the respons so far! Hope to get more!

//Robin

[Doug Lord]

Robin, read the "Ultimate 18' tri" thread where I compare the U18 to a Hobie Tiger-that should explain what a tri can be when really powered up. In my opinion, for a beachcat killer tri the main hull must fly,the boat must be square or over square and the boat must use foils and or planing amas. Check out the comparison numbers. That takes care of high speed. At low speed or for just daysailing you have a boat that can be depowered so that it could be sailed just from the cockpit -a real cockpit where your feet hang down(!). And the main hull plus an ama just kissing will probably have less wetted surface than the two cat hulls sitting level in lite air-and way more SA. So it's faster in light or heavy air, more comfortable in light to moderate air with less chance of pitchpole than a cat that doesn't use foils for pitch stability.
Neither of my tri's used a trapeze but the U18 would use two.
----------
Thanks for the heads up but I just checked monofoiler.com and microsail.com and they were ok. What seemed to be the problem?

[Chris Ostlind]

Hey Robin,

Have fun with your discussion thread about cats and tris. Keep in mind that Doug doesn't actually build anything. He paints pictures in the air with vapor trails and makes use of your thread to promote his vacuous ideas about a boat that will never see the light of day.

If you want to see a beach trimaran that is a cat killer, look at the Nitro tri design out of France. You can see a few photos of the boat here: http://www.navaldesigner.com/en/index.html Go to the gallery section of the site and click on the image at the far right side of the page. No trick foils, no overly radical beam and structure issues, no planing amas that absolutely suck at low speed sailing scenarios, just a straight forward foam and carbon build from a well-designed boat that easily flies the center hull.

We've been around Doug's action for quite a while now and there has been absolutely no boats of any kind from Doug over the last several years... only big noises, a few vague drawings and lots of hyperbole being spread around for his benefit.

Doug was just challenged to provide photos of the boat he's been championing for nearly a year and as of tonight... nothing but more vapor.

Ask him to show you any full sized examples of a performance oriented, working tri or cat he's done in the last couple of years. Ask him to produce the name and email of the person who now owns the boat, just in case he blabbers about having sold it to make room for his next project. I bet he folds his cards and vanishes. One might say that there's a credibility issue there.

Chris Ostlind

[frosh]

HI Robin, how big a project do you want to commit to? And, what is capability as a boatbuilder, honestly? If you are looking for a fairly easy multi to build, and absolute performance is not the highest priority, I suggest that you look at the link in this thread: http://boatdesign.net/forums/showthread.php?t=17903

If you want to go all out for the highest performance and the cost and complexity of the design are not a problem for you, then I would also recommend the Nitro from France as did Chris Ostlind.
Beware of any suggestions at all from Doug. He has his own agenda which is not related at all to giving anyone good quality advice on what to build.
Good luck, and think about your project very carefully before you make a decision.
Regards, Sam

[waikikin]

Quite the uncool vibe going on, people gotta throw some ideas around to develop anything including interest even if its their own, must be more to the story on agendas. Asides that these mini tris do look like fun & more comfort than beachcats plus more space for a picnic. Regards from Jeff:D

[Robin Larsson]

Thanks for all the respons guys!

Hmm, yeah, I´ve read the U18 thread, interesting stuff, no doubt!
And the rather popular oppinion about Doug, I kinda figured that one out, but I´m to much of a nice guy to pick sides just yet:)

But as Chris say, Doug, would be nice to se some drawings, or rather, pics of your previus two trimaran builds!

As to my own experience as a boatbuilder, Well, I´m a young guy, just 24, so off course I dont have all the experience that many of you here, But, I´m schooled to become a boatbuilder at a boatbuilding school on Orust, you now the island where Najad, Hallberg Rassy, Malö, Nordwest and the most other high quality yachts are built:)
So, nowadays I dont work at a true boatyard, we build windows and other stainless stuff for boats, but we´ve just finished the build of the boss´s new 32feet penisenlarment(Motorboat) If I may use that kind of language.
I work with the cad-drawing and run the abrasive waterjet.
Berfore I worked at a small custom boatyard, we build the Swedish Match 40 yachts for Maxi, and amon other things rebuild some motorboats and did the hullplugg for Sweden Yachts new 54footer.

So okey, I definitly have somethings to learn, but I now my way around a workshop, has access to one:) I would say that I could finish a rather complicated build if I wanted to. But, cost is an issue also, as is time.
I´not going for any speedrecords here, sure, would love to build a carbon nomex boat, but I dont really see that happing now, cause of money.
The boat would have to be a bit fast, thats the point of a multi:) If I could keep up with a Hobie in the same size, I would be more then pleased:)

Oh, yeah, this I forgot, I´m already in the middle of a build, but thats a 44feet, slim monohull, a Wasa 55. So, the tribuild would probably not happen in some time, depends on a few other things to, would be nice to have a sideproject to get away from the big boat. But probably not until the Wasa is in the water, which could happen around August:)

I would like to have a set of drawings to atleast begin from, maybe just change small things, or maybe build, sail, and se what can be betterd later:)

So I say thanks for the links, I will continue to follow the progress of Frosh´s boat!

But there seems to be the opinion that a tri could perform atleast as good as a standard beachcat? With some advantages:)

By the way, Frosh, I´ve read the link about that cat you linked to, I like it, but there is something thats missing for me o really like it:) Maybe its just the missing vaka:) But thanks, could most certanly be an option.

And be the way, the really small Kurt Hughes tris, the on thats like 3meters, anyone here knows how they sail? Maybe that could be a nice compromise to:) Looks kinda cool atleast! Maybe it could be tricked out with lifting daggerboards/foils like the Orma 60 and a big assy:)
Would really like something that looked like the Orma 60s, those are incredible boats!

Was thinking about building a 2.4m (mini12) theres a set of hullmolds here in Gothenburg that one can rent for not much money. But then I rather build a small multi!

Thanks again guys!
//Robin

[grob]

God evening, atleast here in Sweden:)


I would like to build a multi, something like 16 foot, preferably plywood or some other method to build fast.
I want a boat that is a bit overcanvased, but possible to sail both single and doublehanded, maybe single without jib or something. Trapezes depending on conditions.Robin Larsson


From your criterea I would think a catamaran would give you the fastest boat, for the money and effort.

The F16 range most closely meets your requirements.I would personally go for a Blade. see http://www.formula16.org/content/view/40/57/lang,en/

All the best

Gareth

[Doug Lord]

Robin, it is possble to build a beachcat killer tri but just because you build a tri there is no guarantee that it will beat a well designed beachcat. You have to look carefully at the numbers and at how the design works. There are important factors to consider like the weight difference ,wetted surface difference ,size and design of ama, does it fly the main hull(and at what angle), if it is powered up(how much?) how is the pitch issue handled etc,etc. And the probability is that a tri capable of beating a beachcat will be more expensive than the beachcat.

[Chris Ostlind]

Hmm, yeah, I´ve read the U18 thread, interesting stuff, no doubt!
And the rather popular oppinion about Doug, I kinda figured that one out,...

But as Chris say, Doug, would be nice to see some drawings, or rather, pics of your previus two trimaran builds!

//Robin

Yeah, Doug, even Robin is suggesting that you to put your proof on the table. So, where is it, Doug? How do we know that you have even the slightest clue as to what you are speaking about if you can't present even a collection of photographs of what you have done with regards to boats of this type?

You could, at least, honor the request of a new member by showing him the photos of your past efforts in this field.

I somehow sense that Doug is about to go into hybernation and attempt to ignore your request, Robin. Welcome to the club of those who have tried to get Doug to substantiate his experience. We've asked for more than photos of the work of others and an endless stream of foamy blabber on all things technical for what ails sailboats.

Best of luck in your pursuit. If Doug does supply you with some photos of his work in the area, Robin, please share them with us here or write a private email with the images attached, so that we can all benefit from the towering intellect that is Doug Lord.

Chris

[Doug Lord]

Robin,as you know I have two websites with pictures (and some video) that show some of my work over the last 15 years but the two(non rc) tri's I built were done in the 70's(and I have a picture of one of them). And in addition to the production design and tooling of the rc models I have done numerous experimental foiler,catamaran and trimran test models as well as developed and experimented with rig design(Wing Tip Rig™) and Power Ballast Systems™. I've used rc models(microMOTH,for example) to experiment with manual altitude control, buoyancy pods etc.
I was the first-to my knowledge -to use manual control of the mainfoil flap to control foiler altitude.
However,unlike Mr. Ostlind and Mr. Frosh, I back up almost every proposal I have made on this forum with detailed numbers. I did so with the U18 in a detailed comparison with the Hobie Tiger.And I've done so in the "60'(+or- 20') Monofoiler" thread, the "Sportboats-Design for Flight" thread as well as in the "X18T"(21) thread which is the boat I am developing now. In addition to which I have 4 US Patents (and more on the shelf) and fairly recently sold a trademark( 3D SAILING). I have a proven 40+ year track record of innovative design and development-but the most important thing is as I just said: I back up what I say with numbers that anyone can doublecheck- you would be hard pressed to find anyone on these forums- most especially including Frosh and Ostlind- that have made any boat design proposals or answered any questions with as much detail as I generally present.
---------------
Ostlind-I know you're upset that I exposed your fabrication of the details of the 2006 Moth Worlds(Moth on Foils "thread) but you really should just apologise and put it behind you.

[Chris Ostlind]

It's time to breathe, Doug... There will be no apology forthcoming. If anyone is offended by my take on the events, they can always sue me in court.

Your patents for boaty things, by the way, are very nearly useless. I'm sure that you try to milk the potential for all it's worth with anyone who will listen and has no idea as to the relative value, but they are virtually impossible to defend in court. Even if they were, Doug, you don't have anything even close to the required cash to mount the proper legal process for doing so. That means they are beyond virtually worthless. A patent is only as good as your ability to prosecute the claims, as made.

As usual, you have expressed your foamy exhalations in a useless spinning of the wheels exercise, with little to show for it. It's fascinating. Just think what you might have had built already if you had used the filing fees, as well as the time to prepare said claims, in the pursuit of a finished boat such as you have been foaming about for years now? You might actually be regarded as a guy who can produce something besides hyperbole and sloganeering....

70's trimarans...? Really now. Perhaps you have something just a bit more current to show us? Something that actually worked as intended? Something that is full sized so that you don't just sit on the grass, mouth breathing, while you drive it?

Doesn't Robin deserve better than these whiffing gestures of self-importance?

[Robin Larsson]

Hi
Sorry to take so long to reply, have been without internet during the weekend:)

Doug, I cant get in to either of your websites, www.microsail.com or www.monofoiler.com have I mispelled?
You dont think you could post a pic or two here instead?

Thanks for your defence Chris!:)

But to get back to one of my previus questions, I askes wether anyone knew anytingh more about Kurt Hughes really small tris, http://www.multihulldesigns.com/stock/12tri.html or http://www.multihulldesigns.com/stock/3mtri.htmly

I´m not completly sure what size I really want, of course I´d prefer an ORMA 60, but hey, cant afford that right now:)
Seems like those two minitri´s could be fun to! Could probably be changed somewhat to become almost 1:6 scalemodels of the 60's:)

But do they sail somewhat good? Do you think we´re even talking two digit speed in good conditions?

Hope you can stand my misspelings and stuff like that, I´m from Sweden after all.

Regards
Robin Larsson

[Chris Ostlind]

I can't give you any specific info on the two models about which you inquired, Robin. I can give you this info about Kurt as general background, though.

Kurt's a pretty good guy to talk to, professional and very unselfish in his willingness to share ideas and opinions. He is extremely approachable, so an email about the two designs would be very well received. His breadth of knowledge on multihulls is astounding with design work across the board from small tri's to really big, commercially operated cats.

The 19' Trikala design was actually in production in Spain some years ago and several boats were produced before the manufacturer ceased production for a reason unknown to me. Just background on this, as the boat is outside your interest at present.

There is, apparently, a fleet of the 3 meter tris operating out of the Seattle/Vancouver area of the Pacific Northwest region of North America. They have regular races and beach party style get-togethers. The original boats in this class were designed by John Marples and I'm not sure if any of the current fleet is from the Hughes design. More possible info at: http://www.nwmultihull.org/index.htm They can probably answer your questions about Hughes boats that are sailing in the class.

[Robin Larsson]

Hi again!

All of you, thanks for all your help and links! Chris, the links about the 3m Class was very interesting! And as I wrote in my mail to you Chris, really nice boats your small tris! Thanks!

Grob, whats the Idea behind having 4(i guess) identical hulls? Is it for transportation and stuff like that or is it performance oriented?
The Biplane rigs looks really cool:)

Yeah, maybe a cat would be best? But somehow, I prefer trimarans, think they look better.

I would like to test something like the lifting boards or is it called foils?, that they have in the amas of the 60's. Or do you guys think it would work with outwards canted boards with lifting foils like the Moths in the bottom? Or is it better as on the 60's with one centreboard in the vaka and arched daggerboards in the amas?

When I read about the 3meter class I found out that they are a bit to slow, topspeed around 6knots, but its a nice concept still.

I think something like 16' high volume amas, lots of foils:), long bowsprit, two trapezes, rotaing canting wingmast, square top main, jib, and the looks of the 60's, thats what I want:) But also to be possible to go from overpowered catkiller for two guys, to singelhander sitting in the vaka. I mean, can always take a reef or to, and skip the jib and/or assy. Depending on conditions of course. Would like to singelhand trapeze to, need the exercise:) I want to both be able to sail alone and with a friend.
Would this be possible on one platform? I would be a multi in more then one aspect;)

And if you wonder, yeah, I´m a bit crazy;)

Thanks againg everyone!
Best regars
Robin Larsson

[Doug Lord]

I wouldn't try to directly scale down an ORMA 60 foil system which is very dependent on ama reserve buoyancy for pitch stability. I can go into that some other time in more detail.
Your idea of canted out foils like a Moth may be a good idea: to create a foiler that takes full advantage of the power to carry sail of the tri configuration. Of course, you should see Kotaro Horiuchi's boat in this forum and consider just adding significant bouyancy pods to a production Moth...
The boat in this picture is the first production rc foiler and designed by me with lots of help understanding the concept from Dr. Sam Bradfied. It is similar in concept to the Rave and Skat but the foils,rig,and overall beam are somewhat different as are the hull designs.
This type of foiler works on the princible that the differential altitude control systems create lift a well as rightig moment. I'm going to experiment with the idea(a VERY expensive idea, Robin) you had down the line and these are the mods to this design that I'd make:
1) the boat is already more "oversquare" than most tri's yet tacks very well so I might increase beam a bit more.LOA 56" BOA 71"
2) the foil system would be completely redesigned NOT to develop it's own RM: there would be two canted t-foil systems(one wand per ama like now) in each ama but the ama would be extended by use of a non immersed carbon tube so that the rudder foil was almost as far back as it is in this picture on the main hull. At static this tube would not touch the water. The reason for this is that the foil systems in each ama would now be designed to operate entirely separately as opposed to together(differentially). The new model would use a movable ballast system to move the weight of the battery. On a full size design using this concept the crew would move outboard using trapezes(maybe) instead of sitting in the center as they do on a Rave.
3) At static if the boat was balanced perfectly neither ama would touch the water and when retracted neither would the foils. But the new boat woud be designed to sail with the leeward foils down and the windward foils retracted.
The boat would be designed to fly in as little as 5-6 knots of wind due to the massive SA but the rig would be reefable/reconfigurable. The major advantage is that none of the foils lift is used to generate righting moment and that saves a lot of drag.Also when underway on foils there would be just two surface penetrations saving even more on the drag budget. When sailing in anything over 5-6 knots this thing would fly on just two foils. Also because the foils are not developing differential RM the structure of this boat could be somewhat lighter than the Rave/F3 type.
Probably enough to makeup for the extra foil set and rudder "gantries". Disadvantage: foils probably would not be retractable creating extra drag below 5-6 knots windspeed.
mfoilerf3_14a.jpg
http://www.microsail.com/images/mfoilerf3_14a.jpg Changed:7:04 PM on Monday, June 18, 2007

[Ray Kendrick]

Hi , I have just registered as a member, have been lurking for some time and seeing some very interesting discussions.
Re the 3 metre tris, I designed one some years ago and sold some plans in various parts of the world. Have built 3 of them one of which I sailed for a while. I decided 2 years ago that the design could be modified to make sailing it more fun. I redesigned the boat adding 500mm (1'-8") to make the overall length 3.5 metres (11'-6") and called it the SCARAB 350. The Scarab 350 can be sailed one or two up sitting on the trampoline with feet in the main hull and steered with a conventional tiller and rudder arrangement. It has a jib (self tacking) pocket luff mainsail and if required a retractable prodder with screecher. The design has been modified to cut down building time tremendously (over the previous 3 metre design) and may be built in plywood or foam sandwich. If interested have a look at the Scarab 350 at http://www.teamscarab.com.au
Regards
Ray Kendrick

[Robin Larsson]

Doug, I didnt mean flyfoils:) Thats not really what I want, I want atleast one hull in the water:) Dont know why, just dont realy like the flying och foils idea, sorry:)

Your pic didnt work, atleast not for me.

But the two curved daggarboards they have on the Orma 60s, arent they there to minimize the risk of pitchpoling? Wouldn´t then a narrow entry ama service even more from having said boardarrangement? Maybe not. But I´ve understood it as that daggerboards do the (more or less) same job as lots of reserve bouyanzy?

My idea was to have daggerboars canted outwards in the amas, pretty far forwards, with smallish lifting foils attached. So they would both do the job of reducing leeway and keeping the bows up when driven hard. Since that seems to be the most commonway of capsizing multis, atleast beachables.
Rudder on either all hull, och only on amas. No centerboard in vaka.
The vaka should fly most of the time anyways, so why bother having a centerbord that will only be half inmersed?

Thats my idea, if its any good, I dont now:)

So thats really back to my original question, why even bother having the vaka, if its going to most of the time? How can having an extra hull in the air make the boat faster than a cat? Cause that seems to be it, I mean, there arent that many Orma 60 cats, I only know of Parliers, any more out there?
Is it better loaddistrobution that makes the vaka usefull?

Ray, thanks for the info! Welcome to the forum, but I´m also rather new, so I´m not the one to say it really:)
The Scarab 350 seems like a really nice boat, so does your other boats to in fact. For a couple of years I have sailed a lot with my 4.8 meter keelboat, a small cruiser from the happy 70s:) And a tri in that size would be fun, but not now sadly...:)
How fast can a 350 sail? I wanna go fast you know:) About how many building hours would you say?


I really feel that I have to get my Wasa 55 ready, so I can sell it and build/buy myself a big trimaran instead:)

Regards
Robin Larsson

[frosh]

Hi Robin, I detect a strong sense that you are dreamer much more than a doer. That is OK, but in real terms, the sort of tri you want has not been built yet in the size range you are interested in. You might need to self design, and if the exercise is likely to be theoretical, then Doug might be the help you need to get a true radical multi purpose " Killer performance" boat on the drawing board.
However I hasten to caution that even if it is finished on the drawing board, it is HUGE step to translate that into a fully functioning trimaran in the " flesh".

[Robin Larsson]

Hi Frosh,
You detect right I´m afraid, I most certanly like to dream away at times, have a lot of ideas:) And, for sure, sometimes things dont always get done. But, I must say, when I set my mind firmly, then I get things done. Hate to leave a project half way through, so I usualy dont.

I see what you mean Frosh, and sometimes I need someone to bring my feet back to the ground, thanks:)
But I also feel, that if I´m gonna do something, then I wanna do it "right", see what I mean? dont know the way to say it english.

But hey, way better to have a small tri that sails good, then a half finished one on land that possibly could have done 1 knot or 3 more:)

If there havent been a tri like the one a envisoned built before, is it because its to complex, not enough bang for you buck, or because its a bad concept?

Feels a bit like if one should go complex, for the sake of speed, than it deserves a full carbon construction to, see where this is going? And thats something I cant do right now.
I could probably get a simpler tri built in plywood, thats far more doable right now. And thats really what I wanted, a relatively small project that could be finished "soon".

But say that I build Chrises 14footer or something like that, or Rays 350, wouldnt it be possible to test different daggerboards and such, adding complexity along the way so to say? Or wouldnt it be worth the job?

And Frosh, how is your planing tri coming along? Should be sailing soon shouldn´t it?:) Hope all goes well!

Regards
Robin Larsson

[grob]

Grob, whats the Idea behind having 4(i guess) identical hulls? Is it for transportation and stuff like that or is it performance oriented?
The Biplane rigs looks really cool:)


The principal reason for the four identical hulls was transportability and ease of manufacture. The boat was designed as an entry to the BMF 2002 Concept boat contest, it was a finalist and the brief for the competition was to design a transportable boat.

All the best

Gareth

[frosh]

Hi Robin, you have heard of KISS havn't you? "Keep it simple, stupid!"
Not a bad principle to follow the majority of the time. When an International Moth changed from a simple homebuilt scow or skiff to a high tech, all carbon, lifting foil, extreme sail boat, it became about 10 times the price, and was beyond the average sailor to take out and simply have fun.
If you can build assymetric ama fitted banana shaped foils within arced centreplate cases, good luck, most of us amateurs probably couldn't. I for one have never attempted it, and would not bother, as it is now becoming extremely difficult to build and also to sail, for minimal extra benefit. Easy to draw up for fun, even I could do that in an hour.
My planing ama tri has temporarily stopped due to very heavy other committments and should be ready before the Australian Summer. The main brief to myself was (1) Try something fairly different that might have a good chance of higher than normal performance in stronger winds, which is our normal summer weather. (2) Keep it fairly simple in concept with not to many moving parts or adjustments to be made. (3) Keep the whole structure as light and strong as possible using exotics or state of the art timber boatbuilding techniques. (4) Keep the concept simple enough that one experienced and one novice sailor could go out and get considerable performance and maximum fun without a long learning period.
Keep us informed of what you are going to do.

[Robin Larsson]

Grob, thats what I thougt, smart concept! How does it it sail?

Frosh, yeah, heard that expression, we use it in Sweden to:) Of course that is a good way to do things, will take your advice for now:)

About banana foils, I´m not sure that I could do it, but a rather think so, I do have a abrasive waterjet machine to play with, accuracy about 0.1mm. Could make jigs and or mould in alu for the boards.
But as you say, probably not worth it.

But asymetric daggerboards in the amas, that could maybe be enough, if I dont build a boat with "keels" like the Hobie 16.

Of course I´ll keep you updated! But not likely that I will start building until my keelboat has hit the water, maybe around late august. But that depends on if I can get the keel casted in time, otherwise I might start building a simple tri this summer:) we´ll see.

Thats seems like some good specs for your boat, will fun to sail I think:) Hope you get it done in time, but I think you will!

Regards
Robin Larsson

[grob]

Grob, thats what I thougt, smart concept! How does it it sail?

Thanks, its a work in progress, it has high wave drag so is not great in light winds, but once it gets over the hump its pretty quick. Still needs alot of work though.

Gareth

[frosh]

Hi Robin, as much of your postings have been about types of positions of underwater foils on the new tri (yet to be designed and built), I thought I would give my thoughts on this topic. First decision to make is whether the vaka will be regularly flying. In a small boat I can't see the point in doing a tri with only the leeward ama in the water. It is lighter and cheaper to go for a cat and the and F16 homebuild design ( such as the Blade) probably is the best way to go.
Assuming that you want a tri and that the vaka as not meant to regularly fly, then put all foils on the centre hull, otherwise on every tack and gybe when many tasks are being undertaken by the crew in the space of a few seconds, you also need to drop the plate on one ama and raise the one in the other. Think about it! Can you achieve this as well as control the tiller, and sheets for 2 or 3 sails, rapidly shift crew weight, all at the same time. My feeling is that it will be very difficult, and becomes stressful, and for what advantage?
The banana foils on the ORMA 60 significantly add to reserve bouyancy on the leeward ama almost lifting it out of the water at high boat speed. The design and placement and exact orientation of the boards will be very critical because they will be carrying huge loadings. In other words a design error can be disastrous in strong winds. I consider this an unacceptable high risk strategy, as the chances of getting it right at first attempt are small. If doing straight boards, whether canted or not, you still get all the disadvantages without the main advantage of the banana board. (leeway resistance and lift at the same time). Then it will be almost impossible to do a minor surgery to change the position, shape or orientation of a banana board. Having foils in the amas significantly increases the structure and therefore weight of each ama, which is ultimately speed robbing. My feeling for my own boat was to do an 18ft. tri, with advanced building techniques and materials at a much lower weight than the same length F18 cat. This factor alone will probably mean that on many points of sail the much lighter tri will be quicker.
For rudder blade(s), why have two when one will do an excellent job with less wetted surface, less construction, and less complexity.
You shouldn't look too closely at extremely high tech 60 footer designs when doing only an off the beach 16 footer. Hope this makes the foil(s) thing a lot clearer.

[Doug Lord]

The point of using a design that allows the main hull to fly is the phenomenal increase in righting moment and ,therefore, power to carry sail. But you can't just mimic the ORMA 60's because the scheme they use to control pitching won't work nearly as well at this size.
The increase in weight is more than offset by the increase in power. In my opinion, foils on both the rudder and a single daggerboard with planing amas or as I described in a previous post are the type of solution that would allow this kind of power to be effectively exploited. Both allow the use of smaller than "normal" amas which is a weight reducing factor while using th the foils for lift and pitch control in the one case and for pitch control only in the planing ama case.
A tri that uses the trimaran configuration to maximum advantage like this will be much more expensive than a "normal" tri. And much faster than any normal tri or beach cat in light and heavy air.

[catsketcher]

Hello all,

I watched Frank Bethwaite get the HSP going over a few years. It went from a complicated slow arrangement to a very fast simple tri. I am a trimaran afficionado having got my first tri, a Piver Nugget when I was 15. As much as I like the normal tri configuration I wonder about its use at small sizes.

The Windrider and its ilk of lower performance but wonderfully sensational sailing are very intoxicating boats. I always wonder about the need for speed on a play boat. I go sailing to feel the boat go over the waves. It is not so much raw speed but the senses the boat delivers to me that are the reason I sail. 12 knots on our 38ft cat is nice but can be mundane. 12 knots on our Tasar is a hoot.

So for a fun boat the pursuit of speed itself is problematic. It may increase complexity, cost, skill requirement and the like. If I didn't have far too many other things to do I would like to build an HSP - very easy shpaes to build - asking for KSS. Very simple and light crossbeams - alloy tubes. The engineering of the HSP setup is far easier than a normal tri as the beams become compression members rather than cantilevers.

Scaling down the ideas in large boats can be problematic in other ways too. A friend who worked for Lock Crowther told me of sailing Shotover - the 60ft cat built in the 80's. He said they could fly a hull in that safer than a smaller boat. The accelerations were much slower than a small tri and so gave more time to react. Getting a small tri up on one hull could be trickier than it looks.

Just build whatever gets your kettle boiling. Only you have to love it. If you really like sailing it, chances are someone else will buy it from you when you get over it. Then again don't put too much money into it so that you can keep it if no one else loves it enough to sell it to.

cheers

Phil Thompson

[Chris Ostlind]

Excellent set of observations, Phil.

These boats actually thrive by being less complex than is being suggestd on this thread. They are easier to build, own and sail. Can be devastatingly fast when dialed-in correctly and built from simple and easily obtained materials.

The form already has a considerable righting moment advantage over cats of the same length and when built correctly, can be every bit as light as most of the production boats one sees on the beach.

There's no need to get all tricked-up with this type of boat to have a good time on the water and your comments to that effect are spot-on. When looking at the new tri being built by Sam, I see that simple approach being developed to a logical end.

Any beach style tri that emulated the performance of the French Nitro, whether slightly bigger or even smaller in scope, would yield a wonderfully fun beach boat which could easily be towed by a smallish, economy type car.

Another issue... if one keeps the design and execution simple, then it's very easy to make any future mods to the design when one finds it a potentially fun effort. Complex boats, by their very nature, design themselves right into a corner from which it is costly and complicated to emerge.

Chris Ostlind

[Robin Larsson]

Hi Guys!

Thanks for those last answers! Sorry to take so long time to respond, but I´ve been away without internetacces, Sailing and stuff you know:)

Of course I should build a simple boat to start with, and thats what I´ll do.
The only questions then are, which modell and when:)
It will probably be a tri, as Phil Thompson said, thats what would get my kettle boiling, or for that matter, float my boat:)

About the foils, as you say Frosh, if the vaka stays in the water, its best to have the foils there.
My reasons to build a tri would be that I like tris better, and like the idea of having a cockpit, maybe even like a kayak. Altough, Im not to keen on footsteering. So maybe one should sit on the side of the vaka, and move further out as needed. That should give alot more sailcarryingpower.
And, I want the boat to be physical sail, I need some exercise:)

But just for the sake of me learning some more, on a tri like that, the mainhull stays in or atleast very near the water, would there be any real gain in having daggerboards in the amas? And rudders for that sake. Of course on a tri like the Seacart 30, which fly the mainhull easily, you need the rudders on the amas to keep control, but the still have the daggerboard in mainhull.

But as you say, build simple from the begining, and I can always and more complexity later on. gets me one the water faster:)

But againg, I want to learn things. Why cant one build a cat that is as wide as a tri? Would there be alot of downsides to it? Cause that really feels like the biggest advantage with a tri, the width and hence have high righting moment. I mean, most cats are only about half as wide as the´re long, alot of tris are almost square.

Thanks for all the help guys! I´ll keep you all posted when and if somethings happen:)

Best Regards
Robin Larsson!

[frosh]

Hi Robin, apart from the structural issues of relatively huge crossbeams supporting the mast base and the rig loads, there is another reason, why cats are roughly half the width compared to overall length. Longitudinal stability will be compromised before lateral stability. Would you rather prevent a capsize over the leeward hull by sitting out, or prevent a pitchpole over the leeward bow by hanging out over the rudders?

[Robin Larsson]

Hi Frosh, yeah, I see what you mean, but dont the trimarans have same problems? Okey, the crossbeams probably get a bit stronger in the connection to the mainhull, and maybe they dont see the same amount of twisting loads, due to the mainhull taking much of the rigloads, am I right?

But the pitchpoling problem must be the same? Or is there a fundamental difference in the shape of a tris amas and the hulls of a cat? Maybe the tri have fuller bowsections or something? But if so, why?

//Robin

[frosh]

Hi Robin, I am sure that you already understand the rig loads and crossbeam situation already. Do not forget the loads generated by the forestay during upwind sailing as well on a catamaran, which is much more easily absorbed by the large central tri hull. Then there is the asymmetric spinnaker set off a bowsprit as well. I would rather accomodate that in a tri.

The big question is why a tri is built almost square and can cope with longitudinal stability which becomes somewhat problematic only once we are flying the main hull, so near the limit of heeling stability as well.
To be truthfull I do not know all the details but will give an opinion, and also invite other forum members to give their views.
It is not to do with the bouyancy of the ama bows being greater than the catamaran bows. In fact for the same overall length ama hulls are much less bouyant throughout their length, than a cat hull in virtually every case.
One needs to study a graph of rig heeling force versus, hull resistance to heeling to get a clearer picture. It is more sudden on a cat when the hull reaches near its limit of lateral stability, and then things can happen very quickly if the rig forces increase even a small amount. On a tri the whole lateral heeling situation is more progressive and power can be reduced or maintained with more of a safety factor in reserve. I will leave it there as this is not my area of specialty.
Regards, Sam

[Hobiestoke]

Hi Robin,
im new here but have been quietly watching your thread.
Here is my 14ft. plywood/fiberglass beachcat I designed and built a few years back:
www.geocities.com/proteus_catamaran (http://www.geocities.com./proteus_catamaran)
its plenty fast & weighs approx 160lbs fully rigged. a beachable deep symetrical design i wanted to be similar to a dragoon or prindle 15. It uses "wave" type skegs and no centerboards. performs really great. Best part is assembles and dissasembles in an hour and takes up very little space in the garage. recently extended mast to 22ft. for larger performance sail setup and Hobie 14 Shroud/forestay setup. should be approx 150 sq ft of sail when shes done w/ modifications. Getting new sails ready will post new pics in a few weeks when I have time. It was hands down one of the most satisfying projects ive ever designed & completed (O:
Good luck to you!

[xarax]

If one solves the structural problems associated with the mast foot, (or if one uses a bi-mast configuration like "Team Phillips»), I see no reason why the square cat would not be faster than the square tri. It would be cheaper, too...

[Doug Lord]

Xarax, I'm not so sure about that. The tri can use one main hull with two very small ama's that together don't equal the size and weight of the main hull (or one cat hull) and can effectively sail in an OVER square configuration.
Interesting stats on two 60 footers:
----
Parliers Cat- LOA 60' Beam 49' weight 11000lb--
two partially lifting foils, two rudder t-foils,planing hulls
--------
L'hydroptere - LOA 59' Beam 80' weight 11975lb
three lifting foils(designed to fly)/movable ballast system.
---------------

[Robin Larsson]

But Doug, if a tri that sails on mostly one ama, why can that ama be smaller than a comparable cats hull?

Look at this "cat" http://www.decision.ch/ANG/default.htm find the Décision 35 there. Its said to be the fastest cat on Lake Geneva.
It uses a mainhull to cope with rigloads, but it never touches the water:)

Regarding my own build, we´ll see what it will be, but most likely a wide trimaran, cause I like them more. Since I already have a rather big mono that I´m not 100% sure I will keep for very long once its built, I think the tri build will have to wait a little while.
If I keep the Wasa 55 I´m building right now for a few years I´ll probably build a small tri, if I sell it I´ll probably buy a bigger trimaran, or build one, not sure. We´ll see that when I sell the Wasa.
It really all depends on how much I love the Wasa 55 when its in the water:)
If I´ll keep it, I need atleast a small tri:)

Thanks for all help guys!

But hey, if there will be no Tall Ships Race for me this summer, and somethings goes bad with the Wasa, I might just start building something like Chris´s 14foot tri:)

Hobiestoke, thanks for the info on your Proteus, nice boat:)

//Robin

[Doug Lord]

But Doug, if a tri that sails on mostly one ama, why can that ama be smaller than a comparable cats hull?

//Robin
Because with a boat using foils/planing amas for lift the hull doesn't have to support the weight
in the normal way-buoyancy- except in an emergency.So the total buoyancy of the ama can be used for that purpose. This is the theory behind my 18 idea and it has been proven in models-and to some extent on L'hydroptere. I think using this philosophy on beachcatkiller tri would produce a very fast boat with greater pitch stability than a cat(using the system in the url below) and, of course, we know that l'hydroptere is fast. But it is not a viable system for a cruising tri-at least not now.
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Ultimate 18' Tri ? - Boat Design Forums
Address:http://www.boatdesign.net/forums/showthread.php?t=17644