My take on high speed proas (as of 28/3 2013)
I have been devoting considerable time thinking on all aspects of high speed sailing the last couple of years.
My primary interest is a safe, stable cruising proa with enough speed to sail across the atlantic in about 2 weeks time. That will take an avarage of 10 knots over the course of two weeks. Its a quite stiff target, but I don’t think its impossible.
This is what i’m working on here in my different threads.
When i start thinking about a brutally fast speed machine without any pretens of comfort or accommodations, things change….. A lot…..
This thread is about speed. Only speed and the way to get more of it…
Johannes
( See coming posts)
(Disclaimer: This is my view, and my way of understanding this subject. Things might be false, missunderstood, have the wrong order of importance and so on.. Take it for what it is - one persons view on a hugh and complex subject… Please comment if you agree or disagree, but rember that this is my way of seeing things. I’m not trying to prove anything. I just want to post this to hopefully encourage other people to give their views and thoughts). The only “right” there is here is “happily sailing at the incredible speed a proa is capable of”. The only wrong there is, is “not sailing at the incredible speed the proa is capable of.)
First some of the basic underlaying ideas for fast proasailing. Most of the stuff is very well known, and in many ways much too obvious. Things that are “obvious” are seldom properly assessed and compared to other data to find the correct “rank” or relative importance.
LENGHT:
I believe that lenght is the senior fact. Lenght is more imporant than weigh (within reason as everything else).
Greater lenght gives a higher hullspeed. Greater length gives a smoother ride with less pitching and less disturbance of the sails and foils proper function. Smoother rider makes it easier for the sailor to maximize speed at all times. A smoother ride create less stress on rigging, hulls, attachment-points and so on. Low stressed parts create a safer sailing and more confidence, where one does not need to be careful and conservative, but more willing to push things hard.
A high average speed is much more important than peak speed, and with a higher hullspeed (longer hull) it is much easier to keep going at a high average.
WEIGHT:
I know this is controversial, but I don’t consider the weight to be very important (once again within reason). I know a lighter boat will be faster in many ways, and especially within a boxrule, where most of development of racing-boats occur today. If one limits the length and driving power, than low weight becomes a very important factor. A proa is happily free from such limiting constraints….
If we look at what positive effects some weight gives, we find more of the same as length. Less pitching, less impact from waves or general state of the sea. A slightly ( we are not talking tug-boats and 3 inch solid steel here) higher weight gives more mass inertia, resisting pitching and unwanted wasetful acceleration in the wrong directions (less impacted from waves), keeping a clean flow attached to the sails and foils driving at all time. All the stored kinetic energy enabling the boat to punch through waves and keep the average speed high. A very light boat will be much faster in light winds, but if we want to sail brutally fast we need power. Power comes from the wind, so we have to optimize the proa for relativly rough conditions. A very ligt proa could become totaly airborn in a hard blow. People have found their 50 foot catamarans several hundret feet up on land after a hurricane. We want speed, but we don’t want to actually fly. A airborn proa is very hard to control.
A high weight is mainly a problem in light winds, but since we are not within a man-made boxrule we can always use a larger spinaker. Its much easier to control a medium-heavy boat in a gale than move a light boat and small sails without any wind.
More tomorrow.
Cheers,
Johannes
OK, Johannes, I am going to play the Devil’s advocate here. Understand, it’s just an act. Think of sharing a pint or a glass with a friend, and he says, “Speed? Seriously? Well, you need to just get over any affection for proas and look at exactly TWO choices: A planing hull—like a windsurfer, or a hydrofoil. Plus, you need a canted rig which works in exactly ONE wind condition. Less wind, and it’s a dog. Too much wind, and it slams you over like Thor’s Hammer. This affection for proas is just a a Romantic affectation. Get over it.”
Thus, when you say “speed and speed only” then limit the discussion to proas, well. Hmmph.
Me, well, I rather prefer the limit to be “joy.” Give me a tough, simple boat I can take girl out sailing and show her the rush of gliding along—fast—with hardly a hand on the tiller or sheet. Now THAT’S a boat.
A planing hull—like a windsurfer, or a hydrofoil. Plus, you need a canted rig which works in exactly ONE wind condition. Less wind, and it’s a dog. Too much wind, and it slams you over like Thor’s Hammer. This affection for proas is just a a Romantic affectation. Get over it.”
Thus, when you say “speed and speed only” then limit the discussion to proas, well. Hmmph.
I can’t find a hull-configuration better suited to hydrofoils than proas, so this might not be so far of…
As I tried to say earlier, this is my take on what I would build if I only wanted speed. Carbon, epoxy-infusion, high pressure and high temp autoclave baking is not a possibillity for me. (costs, equipment…) It will have to be within my reach, otherwise its only some theoretical rambling.
I’m not very interested in flat out speed-records on a set course. I want to sail fast whereever i want to sail, so “canted rig which works in exactly ONE wind condition” is out of the question as well.
Cheers,
Johannes
SLENDERNESS:
More of the above. A slender hull makes less wavemaking resistance and even more important, makes a lot less resistance cutting through waves. It is less affected by waves and spray. It will be more directionally stable and needs less additional control to keeps its course. Smaller rudders makes less resistance. Lower loads on the rudders enables thinner sections. Less use of the rudder makes less turbulence and less drag. I have read that there is some optimum L/B for low drag and low wet area at around 15:1. That might be true in flat calm water. I believe that when sailing hard on open waters the dynamic properties is more important than theoretical measurements of low drag in a controlled enviroment.
ASPECT-RATIO:
There is a very big focus on high aspect ratio in almost every aspect of sailing today. Tall rigs, deep fin-keels and high aspect rudders.
I don’t like it…..
They create very high loads and difficult to engineer structures, very dependent on exotic and expensive materials. The are prone to bending, tip vibrations, stalling and breaking. Vibrations exhausts materials, causing sudden and often unexpected failures. This is fine when backed by a hugh team and lots of money, but can all be life-threatening for me and my family. If you get into the water in late april in sweden, you have about 10 minutes before you loose controll of your body due to the cold climate we have. This does not give confidence and encourage pushing the boat hard in heavy wheater. I does not matter how fast your boat is if you don’t dare to push it…
There is more on the way….
Cheers,
Johannes
Yeah, I know what you mean about limits. And don’t think I was being too challenging. It’s just that I find it useful to question everything, including whether or not one might even want a proa.
And, actually, after looking through your designs, I see where you are going. I think you are right. If you want to extract the maximum speed from a proa, a planing hull (maybe combined with foils) might be, maybe, is JUST the thing. And if you can build it out of plywood, even better!
So I get it.
One of my favorite books, The Gougeon Brothers on Boat Construction, has a lot of pictures of the proa Slingshot. I did not know how low and wide the hull for that boat was until I saw the build pictures. From the bottom, it looked almost like a surfboard. My impression was that it was intended to be a like giant windsurfer, and, naturally, once you add a hiking board and a float, well, you have a proa.
(I do not know the back story on the design of Slingshot. That’s just what I picked up looking at images of the build.)
Cheers,
Rick
And don’t think I was being too challenging. It’s just that I find it useful to question everything, including whether or not one might even want a proa.
You were not at all too challenging. I very much appreciate your questions. Without anyone else questioning what i write, i’m just a eccentric guy with to much time behind my computer. I really appreciate everyones questions. Without opposing ideas and questions there would not be any development at all. Its the questions that drives me to more clearly define my ideas and goals. They are the nutritient for progress.
Praise and approval is the enemy of progress. It makes us content and dull.
Thanks!
Johannes
Its the questions that drives me to more clearly define my ideas and goals. They are the nutritient for progress. Praise and agreement is the enemy of progress. It makes us content and dull.
Agreed!
So here’s a problem. Really fast boats tend to be wet boats. In the cold, that can kill you. So you have, maybe a higher sheer or a deeper cockpit, but in doing so, you add weight and windage, so your boat is then not so fast. So you add sail area, and that means adding more weight for all the new stresses induced, so, in the end, you compromise. You just have to. You have to accept that a safe, fun boat will not be the fastest possible boat.
Or, refusing to compromise, you get into exotic, expensive materials, so the boat scales up in cost and complexity.
Thus, “speed and speed only” lead you down very different design solutions than a boat you can take your family out on. You might, on the other hand say, “Fine! Let it be wet! I will wear a wetsuit. Who cares about comfort?” Further—like my brother who was an avid windsurfer—you don’t even sail unless you have a least a twenty knot wind, and you build the boat and design your sail plan for those conditions only.
No matter how you slice it, when you want to play the speed game, you end up with a different boat. It is, I am sure, a fun game.
One of the other contributors here, Sven Stevens, has made some very persuasive arguments about how a cruiser differs from a racer. I can think of many, but here is a really good example: A deep V hull will suffer from excess wetted surface compared to a U shaped hull. But what good is a hull when its bottom is all scratched up by rocks? And that’s what will happen to a pretty U shaped hull; also, if you’ve built her out of foam sandwich, it it’ll delaminate in a hurry from the beating the bottom receives from beaching. So a racer might decide that he or she is just not going to beach his or her boat, and that’s just how it has to be, but what fun is a multihull you can’t beach? Shoot, that’s one of the multihull’s best selling points. You do not need a harbor. You do not need an anchorage. So I was sold on V hulls. Yep. The Pacific Islanders were right about that.
In the end, I realized that my own design goals required a sturdy, trustworthy, safe, predictable, easy to handle boat. Fast is fun. Fast is good. We all love to go fast! But without a seaworthy craft, we won’t go anywhere.
[edit: Why does this post look like a big giant quote?] [edit2: Uh, never mind, I had an unclosed “open quote.”]
Thus, “speed and speed only” lead you down very different design solutions than a boat you can take your family out on. You might, on the other hand say, “Fine! Let it be wet! I will wear a wetsuit. Who cares about comfort?” Further—like my brother who was an avid windsurfer—you don’t even sail unless you have a least a twenty knot wind, and you build the boat and design your sail plan for those conditions only.
No matter how you slice it, when you want to play the speed game, you end up with a different boat. It is, I am sure, a fun game.
This is a fun game.
With this proposal/idea/project i don’t care about being wet from spray or solid green water washing over the hull(s) and crossbeams, but I don’t want to end up swiming 3 miles to the nearest shore, as I would probably not survive that 9 month out of 12.
This is as much speed as possible within the boundaries of my knowledge, economy, available tools and materials.
This is the proa i would like to build right now and use this summer, only optimized for raw speed and lots of fun.
20 knots is more fun than 15 knots. 25 knots is better. 30 knots is the (most certainly wet) dream we all have.
A sustained speed of 30 knots would be fun. I know there is much faster sailboats than that, but probably not within my economy or abillity to build.
Cheers,
Johannes
This is a fun game.
With this proposal/idea/project i don’t care about being wet from spray or solid green water washing over the hull(s) and crossbeams, but I don’t want to end up swiming 3 miles to the nearest shore, as I would probably not survive that 9 month out of 12.
This is as much speed as possible within the boundaries of my knowledge, economy, available tools and materials.
This is the proa i would like to build right now and use this summer, only optimized for raw speed and lots of fun.
20 knots is more fun than 15 knots. 25 knots is better. 30 knots is the (most certainly wet) dream we all have.
A sustained speed of 30 knots would be fun. I know there is much faster sailboats than that, but probably not within my economy or abillity to build.
Well, there you go. You have your design parameters clearly defined and goals to achieve within the limits of your materials and knowledge.
Sounds perfectly do-able. And fun.
Cheers,
Rick
When i start thinking about a brutally fast speed machine without any pretens of comfort or accommodations, things change….. A lot…..
This thread is about speed. Only speed and the way to get more of it…
Johannes
I am enjoying this but can you just clarity the brief, is it a 500m record breaker, a day sailer, 3 week cruiser or a Jules Verne contender?
Tink
I am enjoying this but can you just clarity the brief, is it a 500m record breaker, a day sailer, 3 week cruiser or a Jules Verne contender?
A daysailer for most but with some camping-gear one could do a weekend or more. Even though i’m not overly afraid of weight, i want ALL weight to contribute to strength and durability of the boat. Bringing 20 kgs of water and 50 kg extra gear is not beneficial for speed. Think “the nose (el cap) in a day” and your on the right track.
Cheers,
Johannes
Hello, my 2cents on this subject…
Thus, “speed and speed only” lead you down very different design solutions than a boat you can take your family out on.
I think this is true, but on another hand, if you think about cars, it is very clear that we are not driving formula one cars on the road, but lots of the development and concepts used come from them.
With proas we can think the same way, and after an exercise like the one proposed in this thread we might find that the kind of solutions developed to work and survive a “speed, speed, speed” proa applied to a family friendly proa can make it much safer, comfortable and maybe even faster!
I find it an appealing idea to think about extremes, and then scale concepts and ideas to a sensible point.
Saying this… I don’t really have anything to add to the thread right now, but think it is an interesting one!
cheers!
I find it an appealing idea to think about extremes, and then scale concepts and ideas to a sensible point.
Saying this… I don’t really have anything to add to the thread right now, but think it is an interesting one!
You have just added to this thread.
I agree with your method. It is very educational and fun to think of and design extreme stuff, than use the knowledge gained to build something more usable. When you push the limits, you often gain an understanding and intuitive feeling for the complex relationships between different parts.
Cheers,
Johannes
I find it an appealing idea to think about extremes, and then scale concepts and ideas to a sensible point.
Saying this… I don’t really have anything to add to the thread right now, but think it is an interesting one!
You have just added to this thread.
I agree with your method. It is very educational and fun to think of and design extreme stuff, than use the knowledge gained to build something more usable. When you push the limits, you often gain an understanding and intuitive feeling for the complex relationships between different parts.
Cheers,
Johannes
Again I fully agree, I like to think where a design would go if there were no limits, supper strong material etc, where will the design be in 5, 10, 20 years etc. In my live that pays the bills I have developed the creativity skills of high school kids and graduate enginineers and found the SCAMPER technique a good starting point.
SCAMPER is a mnemonic for
Substitute.
Combine.
Adapt.
Modify.
Put to another use.
Eliminate.
Reverse.
I also was involved in trying to identify the difference in approach of the young engineers with the senior ones. Young engineers are always confident they have the solution straight way, a senior engineer never stops asking
WHAT IF? (Sometimes very frustratingly and never actually finishing the design long after deadlines have passed)
So what does a what if proa look like
Tink
I also was involved in trying to identify the difference in approach of the young engineers with the senior ones. Young engineers are always confident they have the solution straight way, a senior engineer never stops asking
WHAT IF? (Sometimes very frustratingly and never actually finishing the design long after deadlines have passed)
...Tink
That’s interesting. I’m a “young engineer”, and I seem to always think a problem to death. Never happy with a solution, always find faults or drawbacks to everything. Sometimes you just have to draw the line in the sand and build something.
-Thomas