Builder's Open - Any Thoughts?

owners class

Well, Fig, I've already told Trevor I couldn't possibly build a boat in this class-now anyway-too much going on. Even if the class did allow movable ballast most everybody that hasn't built a "normal" boat probably ought to do that first.
I think I mentioned this before but no recognized class in the AMYA or Internationally allows movable ballast. Given that this is the 21st Century and that they are fairly simple to set up and tremendous fun I think that is a shame....
I've never understood how a "modern" rc development class could exclude movable ballast. Seems to me that since the rc helicopter guys are flying 9 channel $2,000 machines upside down I'd think rc sailors could learn to handle an rc skiff with 4 channel's.
I think that racing superhetrodyne full flying foilers against keelboats isn't going to be too fair so maybe racing could be done in different classes within the class? I think the Moth class does that: allowing older skiffs ,scows and foilers on the same race track and , I think, scoring them differently.
PS- at this length I don't think it's a "given" that any particular type of boat will always win-even the foiler is subject to wave height limitations and movable ballast boats are more subject to crew error than are good old leadbellies that just keep on keepin on.

 

I have considered your critisism.

So I made a spread sheet to do a little experiment on.
I decided to noodle with only the cardinal dimensions to see what kind of sail area penalty they would net. Budget is 5625.
'c' is for canting ballast (taken as 2.0 * actual draft) and
'm' stands for multihull (taken as 1.50 * actual Beam.)

Boat A: Length 75, Beam 25, Draft 38, Sail area 4331 scm. 100
Boat B: Length 75, Beam 25, Draft 38c, Sail area 3984 scm 092
Boat C: Length 75, Beam 40m, Draft 38, Sail area 4003 scm 092
Boat D: Length 75, Beam 25, Draft 75c, Sail area 3261 scm 075

As I hope you can see, the penalties are rather light until the design starts getting really extreme. I doubt that an 8.0 to 9.0 percent reduction of sail area is going to hurt anyone that bad. And that's assuming that the original sail area is the least bit realistic. I would gladly be docked even 15%, if I had a real chance of planing on a good day and leaving everyone else behind. But this is mainly to prevent what happened in Australia. Boats that are as deep as they are long.

This may also discourage someone from building a boat that has no chance at all of working. Like a multi with a 75cm beam and a 75cm draft.

Bob

 

Dates

We've got a long weekend here in May ... the 19th, 20th and 21st.

Does that rule you out Figgy ... ? Anyone else? If so, let's shoot for another weekend.


Trevor

 

I'm afraid I will have to compete 'in absentia'. If you let me have details of the course and weather conditions on the day, I will time my entry over a similar course on the waters near here.

We can then compare times and you can send me my winner's trophy.

All it needs is a little bit of trust.

 

Crag Cay

Brilliant idea, Crag!
Just forward the registration fee, entry fees, absentee race fees and perhaps a little extra on the side ASAP and I'll ship the trophy right over! No wait ... the plastic coating is delaminating ... let me glue it back together

 

On further reflection sharpii I do see your point. The racing itself is made more fun if the capabilities are similar and your proposal still leaves lots of room for creativity and originality. Saving people from themselves is also admirable!

As to the canting rig idea, Wow! Has that been done on a big boat? I was just reading about that harken boat with the A frame mast and they claimed significant weight reductions. With your plan you could also reduce ballast no? Sounds like a recipe for a rocket!

 

It has been done on a full sized boat. The Brazilians have been using this idea for a very long time on their fishing rafts. The mast step has one hole on top and several holes on the bottom that splay out side to side. When they want to cant the mast, they just raise the butt out of one of the bottom holes and set it into another. These rafts were approximately 20 footers. They are being replaced by 'V' bottom decked over scows now, because the big balsa logs they used to make the rafts out of are running out.

I don't expect to save much on ballast. That's because the ballast is ment to keep the boat from turtling from a 90 deg. knock down.

As for the Harken boat. Was the wieght savings due to the mast design? Or was it due to the high tech matterials being used? I strongly suspect it was the latter. Even though I have advocated such a mast on other posts, I always caution that it will be significantly heavier than a standard stayed mast for the same sail plan. Its two major graces are that it doesn't stand smack in front of the leading edge of the main and that it is much easier to raise and lower on a windy day. It has other virtues too. One of which is that the compression loads imposed on it should be roughly half of those of a standard stayed mast.

I will now try to attach a drawing I did a while back to illustrate what I'm talking about.

Bob

 

Canted Masts

On a model, at least, it strikes me that engineering an unstayed canting kinked mast such as discussed on the swing-rig thread (I think) has a certain simplicity to it. Pivoting towards windward would require that the rig be mounted on two bearing systems, one to control direction of cant, and the other to control trim. Applied loads for a model are easily within the bounds of available bearing systems and weight can be in the hull. And by using a wing mast, or pocket luffs with camber inducers there is no longer a benefit to removing the mast from the main's leading edge.

Engineering such a system to handle the loads of a large sail, is well beyond my ken ... I've looked at the Sponderburg (sp?) masts but if I'm not mistaken they do not cant ... I'm guessing that as loads increase, practicality decreases and thus the system Bob is utilizing in his drawing ...

Question ... perhaps for Bob ... let's say one were to engineer a rotating canting mast, what would be the best means of determing angle ... windsurfers will sail up to 30 degrees or more off vertical ... and the boats designed for speed records appear with masts anywhere from vertical to steeply canted (flying wings). Any thoughts?

 

canting mast

Trevor, here is one guy's solution. You might also go to the US One Meter site(modelyacht.org should list it) and look for the information on Hank Robinson's canting mast solution.
Bernand-Ettel Sailing Technologies
Address:http://cantingmast.com/ Changed:1:24 PM on Tuesday, September 26, 2006
-----
And some comments here:
Seahorse Magazine February 98 - Tri-man of the year
Address:http://seahorsemagazine.com/9802-feb/tri.htm Changed:4:53 PM on Tuesday, September 24, 2002

 

45 deg. if I could. That way I would get half lift and half propulsion. But you have to be careful to keep the center of lift over the center of gravity. And that can severely limit your sail design choices. (tall, jib headed rigs need not apply.)

I, myself, would never build something that sophisticated. The only reason I even thought of the idea was because the design concept I have in mind would make such a cant as, say 15 deg. conveniet. On further examination, I discovered that I would only need one additional channel to make it work. The only catch is that the sail will allways have to be canted.

My major concern in this endeaver would be to successfully complete the course. And, maybe, not be the last in the fleet to do so.

I'll leave the fancy design work to the real engineers.

As much as I have hated the Soviet way of running their society, I have always admired their creativity in making simpler, cruder, but still very effective weaponry.

I always try to keep that in mind when designing boats.

If I spent more than anyone else and won, I would only feel I was getting my due. If I spent way less than most and did not even win, but merely did well, the taste would be infinitely sweeter.

Bob

 

TBLEAD design concept

Here is the crude drawing I promised Tmark a while ago. The math has only generally been worked out. The ballast bulb (not shown) will be 3cm wide and 8-10 cm long and will have 750gm of mass.

I will, once again, make my pitch for some general design limitations. It is a very big danger that an 'Open' class will quickly become a matterials science contest where only one design concept will dominate.

Here are my latest proposals. They are designed to be easily measured and checked with a cheap calculator.

1.) Ballast limited to a percentage of total displacement. (I recommend 50%)
2.) Draft limited to 40cm (slightly more than 1/2 the Length limit. And a nice round number)

And that's it.

For those who might be interested in a crude handicap, designed mostly to discourage real freaks, here goes:

1.) Area budget = Length squared, or 5,625 scm,
2.) Tax multiplier = Length/7.5,
3.) Tax = Tax multiplier * Length * Beam * Draft.
5.) Sail Area = Budget - Tax,

6.) Multi's and canting keels, could suffer an additional tax of Beam being taken as 1.5 * actual Beam, for multi's, and draft being taken as 2.0 * actual draft, for canters.

This would make Multi's and canters slightly less endowed with sail area than fixed keel mono's of the same dimesions.

For instance, the design I'm attaching will have 3875 scm rather than the 4000 scm originally planned due to this extra tax.

Bob

 

Bob,

It's interesting reading your comment about all boats ending up looking the same and then viewing your drawings ... I seem to be on the same track you are and have been working on a multi with canting rig.

"It is a very big danger that an 'Open' class will quickly become a materials science contest where only one design concept will dominate."​

There is a fastest boat for every application If however, a boat had to win a series, lets say 7 races in 7 venues over a 7 month period, the designers could not rely overly on a single-application built boat. Whatever was built would have to sail in a chop, light winds, gusts, do well to windward as well as downwind. In short, the design with the most versatility would be the design which came out on top at the end.

The Builder's Open (and just to re-iterate, it's still just a contest betwixt friends and other liked minded folks, nothing more) is about more than the race. Let's be honest, to a certain degree, it's a boat-geek pissing contest (who can design the coolest, best looking, fastest boat). A 7 race series was NOT in anyone's mind when the project was conceived and I don't thing anyone is particarly interested in it.

Given the fact that no one knows what race conditions are going to be, or what course the independent race committee is going to set, the same effect applies ... the boats will have to get around a course regardless of conditions. Of course a builder can gamble but so what ... either she loses spectacularly or wins ... in either case the beer at the end of the event will be cold.

Trevor

I'll post my thoughts on what this hypothetical boat should look like, later today.

I'll try and post pics in the next couple of days.

 

Allow anything withing the limits of what you have said already.

e.g allow multis and movable. they will weed themselves out fast enough if youmandate that no rescue boat will be available.

I can say the good mono with a fixed keel will do just fine around a course over a few races.

Tmark, good look on the wing design, close to waht I had been considering. I would recommed a rounder section up front of your foil. It will be way more foregiving to sail, trust me.

MC

 

Builder’s Open – Design Excercise

Bob’s posts about canted rigs, along with Doug’s links to the Weymouth Speed Week, prompted me to ‘blue sky’ this in the middle of the night. What follows, warts and all, is the thought process that’s brought me, like a fool, to a sliding rig, canting mast, foiling multi.

CHALLENGE
Design, build and race a boat.
For the 2007 race she must be 75cm LOA.

GOAL
Go fast. Stay upright. Negotiate an unknown course. Finish first.

WHAT I THINK I KNOW
Those who are seeking to go fast irregardless of class are campaigning sailboards, multi-hulls or some sort of foiling contraption. These craft fall roughly into two categories.

Group A
Boats that use mass to counter the heeling moment. They include sailboards, 49ers, Class C Cats, VO70s, foiling Moths, the Macquarie boat etc … Complexity varies, but for the most part they are easily understood. They represent the bleeding edge of speed technology as derived from a ballasted monohull.



Group B
These boats depend on counteracting sail and foil forces to create zero heeling moment, and zero vertical lift. They are represented in part by the Sail Rocket, Monofoil and Jelly Fish Foiler Projects.



Of these two groups, the fastest theoretical speed belongs to group B. Fastest recorded speed belongs to group A. Of the fastest boats, all are asymmetric and none can make their way around a three buoy course. But ….

But … what if we step sideways and take a second look at these fast asymmetrics. What makes them go fast? What makes them stay upright? What can we apply to a boat that will tack, gybe and run with the wind?

Macquaire Innovation

So far the fastest of the lot. It balances mass against heeling moment by using a low aspect sail and pushing a counter-weight way out to windward.



Even if you could engineer a sliding proa type platform and thus enable it to get around the buoys, it remains incumbent on the driver to adjust instantly to gusts and shifts. As discussed elsewhere, this is extremely difficult at scaled down (rc) sizes … get it wrong and you’ve got a spectacular tumble. None-the-less, you’d end up with something looking like this … outriggers slide thru hull:





Sail Rocket / MonoFoil / Jelly Fish Foiler

More experimental. Theoretically faster. These boats, like the Macquairie are asymmetric, one way speed machines. Each uses different methods to achieve the same ends. Essentially they attempt to balance vertical lift against opposing keel/foil force. And, if done right, a gust or shift will not topple these boats.



The symmetry required to get one of these around a course would require a bloody wide stance. Not sure either about fore/aft stability. They look fragile. And there’s no way one could win a tacking duel (though it probably won’t need to).

That said, remembering that this is a blue sky exercise, sooooo ..... here goes

The NARES BLUE SKY.v1
What if it were possible to get one around a course? What if she didn’t trip all over herself? What if she could actually be engineered to hold together? What if she could sail in a variety of wind-speeds and water conditions? She wouldn’t necessarily look much like a boat. Lead lovers won’t like her. She won’t adhere to a single existing class. But … she will be fast, it will exercise the brain, she will epitomize the spirit of the builder’s open … and who knows, she may win a race … thus, why not?

Summary

Canting Sliding Rig
Foiling Multi
Uber Light
Zero Heeling Moment
Zero Vertical Lift​

Theory

Rig slides to lee. Mast cants to wind.
Downwind, mast also cants to wind but rig centers between hulls.
CE remains over LCB because of curved rig track.​

Design Challenges

balancing the sailplan – keeping CE low while achieving required SA
figuring out cant angles ... foil and vertical lift MUST cancel each other out
foils … another bloody learning curve​

Engineering Challenges

weight: required bearings are heavy
load distribution: its all focused on one spot, the mast, sliding plate joint and bearings​

Mechanical Challenges

bearing systems, trim mech, canting mast mech and sliding rig systems all have to be sorted​

As I lay awake last night, I couldn’t see why it couldn’t be engineered. But that said, you are the designers, I’m the guy with insomnia and no history … bring on the guns all you lead lovers … there are bound to more objections than hot air in a foiler thread.

And for everybody else, I freely confess I don’t know enough to know what I don’t know … before I begin the drawing process, I’d appreciate this group's input into what I’m missing, and obvious first steps (I'm thinking I'll prototype the rig before even beginning to think hulls) … And even though Doug and others have already tried (thanks guys, I'm just pig-headed), maybe somebody else can STOP ME before it’s too late.

Thanks for reading, Trevor

btw ... I'm still with you Magnus ... no new rules ... just to refresh

owner designed
owner built
owner sailed
75 cm loa

1 meter min depth on course
course determined by independent committee​

applies to rig appendages hull and sails ... its ok to pull fittings, hardware etc out of your parts box ... any questions, post them here or pm me

 

OK then, my design is finished, I picked up some carbon arrow shafts at walmart for misc parts, cheapo stuff at Wal-mart in the sporting goods section, like swivels and dyneema in the fishing section.

I'm looking like a cat of some kind, just balsa and epoxy and soft sails. Dirt simple, light as possible against my own advice for a boat with decent mass to keep moving through the waves.

T-foils to keep it upright downhill.

It won't go fast uphill but it won't tip over either.

I'll start builing in January.

I hope to spend less than 40 hours building it. Too many other boats to work on right now.

When's the first race?