Would this work?

Rcsailing.net General Discussion
1

Hey there,

I played around with a few idea about a planning hull design and ended up with a weird looking concept, that I am wondering if it would work. I guess it has a good chance of being a total flop. So I thought, I get some feedback before I step right in…

http://www.digitallightfactory.com/Private/Concept_1.jpg

http://www.digitallightfactory.com/Private/Concept_2.jpg

I didn’t like the drag that is caused by the steps at low speed in the hulls of the hydraplaneur, so I thought of a way to get rid of them.
Its basically a powerboat concept adapted for a sailing vessel. Its not a Cat, its not a Tri, but rather something in between. Its should be able to plan upwind. At full speed it would be planing on the stern of the floats and the stern of the pod.
The floats could be mounted on a hinge, to be able to adjust there angle of attack depending on heel. It would use cambered daggerboards and the central pod could be used for a gennaker…

Any feedback welcome. [:-basketball]

Marcus

2

looks like a Starwars Y-wing…nice…

Wis

_/ if it isn’t broken, don’t fix it! _

http://wismerhell.esmartdesign.com/index.htm

3

I think it will work very well as long as you can keep the heeling to a minimum.
Our fast electric outrigger designs are among the fastest model boat designs in the world.
The concept design is similar.

Give it a shot. You have my interest.

Peter R.
www.cliamtemodels.com

Visit www.climatemodels.com

4

From what I see, if it heels at all… it will flip over. If the rudder section is in the water enough to be effective, then the whole thing will fall off pivoting on the aft section… if the rudder section is not in the water enough you will have no control. Balance would be critical to maintain, and it would almost need to be a fly-by-wire system like I had in the F-16 to compensate for me. If you got a hull out of the water… with your remaining hull and rudder out of plane with each other… that would produce some interesting results as well. The cross section of the hulls would be a bear to design to maintain the desired planing effect, and have to compensate for the difference in weight distrubution as the boat sits on the water under different points of sail. It would seem that the amount of rudder input would not only have to be so fast and so critical, but also enough that it would act so much as a brake countering weather helm with the mast so far aft that it would defeat the purpose of the boat (assuming that to be speed) Good Luck with it though.

5

Larry,

I am picturing that this thing would tend to heel like and iceboat rather than like a tri: The aft end of both the main hull and the ama would stay in contact with the water as it heels. Heeling in an iceboat is still table that way, so I think you would not flip over. And as you heeled the bow of theama would tend to come up giving you more margin for pitchpoling as you pressed down on the ama.

If it does heel like an iceboat instead of like a tri, then the righting moment would depend on how far the CG is away from the axis that the boat heels over (a line between the transom of the ama and the transom of the main hull). The righting moment will probably be a little bit lower than a tri but perhaps not as much as you think especially if the amas carry quite a bit of weight as the windward ama is going to be further from that heeling axis than it would be in a tri.

My overall impression of this creature is that it would probably work once it was planing. but the short hulls are going to cause a lot more wave drag at low speeds and that would certainly cause the boat to suffer as an all around design.

  • Will

Will Gorgen

6

This design raised a question: Why are the ice-crafts and as well land-crafts made so that they have the 2 wheels behind and one wheel forward? Wouldnt it be much more effective to have 2 skates / wheels forward? At least the support points would be more “under” the rigs force vector?
Also the grip would be better for steering even when heeled etc. Also all the tripod designs have the pods forward.

  • HJ

“Expertice is gained trough mistakes. However repeating
same mistake is not learning but stupidity.”

7

Will,

That’s exactly how I pictured it. It would heel over a line between the rear end of the main hull and the float.
The daggerboards could be used for additional righting moment positive as well as negativ.
The planing shape of the hulls would add dynamic stability too.

Larry, I actually thought of using a Heli-Gyro that adjusts the angle of attack of the amas for automatic stability.

Since the hulls are rather short, they could be buildt pretty light. The ship would have 1.8 m LOA, but weight only around 5-6kg. It would have a beam of maybe 1.8 m too, but should tack real fast.
Of course it is not ment for bathing regattas - if you know what I mean - but I think it would start planing real early. - Maybe as soon as a solid A-rigg condition.

The biggest challenge is probably to get the relation between Hull width and lenght right to get into planing stage as early as possible.
Since it doesn’t have the submerged step that Parlier has in his cat, it might be faster in slower conditions too.

To avoid heel, a solid wing rigg might help to get the CoE as low as possible. That way it would actually get close to a ‘yellow pages endeavour’ configuration, but in a way that makes it possible to race triangles…

Marcus

8

HJ,

The iceboats of the 1920s were built in the opposite manner - 2 runners forward on a plank and 1 runner aft. These were called stern steerers. An A class stern steerer still holds the outright speed record for iceboats which was set on Lake Winnebego back in the 1930s.

The crew would ride laying face down on a small flat platform near the back of the boat. One guy would steer and 2 others would work the sails. Sometimes a 4th person would ride along.

Here is a stern steerer built in 1929 that still sails every winter on Lake Minnetonka:

Download Attachment: Allen-111_A.JPG
33.37KB

Here was the problem with those boats: When you get hit with a puff, the boat wants to accelerate. The CE of the rig is pretty high up and the CG of the boat is down low. So the “pull” of the rig during an acceleration tends to cause the boat to pitch forward. Sometime there would be enough pull to actually lift the rear runner off the ice. Since the rear runner was used to steer the boat, if it left the ice, you lost all steerage. The boat would usually end up in a massive spinout. And spinning out on a boat that big when travelleing 70 or 80 mph is not exactly a fun experience. The crew gets flung across the ice (usually sliding on their backs for several hundred yards unless they were lucky enough to hit a snowdrift), the boat will usually flip over.

The modern configuration with the steering runner forward and the plank in the back fixes that problem. It also adds a bit more righting stability since the skipper’s weight is lifted when the boat heels so this weight goes into the righting moment of the boat. You also have a better feel for when the boat is starting to heel. You can sail the boat in the very fast configuration of the windward runner just barely tapping the ice as you sail. It is just awesome when you are sailing downwind at 60 or 70 mph to feel the boat swell underneath you and then respond with rapid accleration to 90 mph as you carve the boat down.

  • Will

Will Gorgen

9

Will,
Maybe I am missing something…Why didn’t they put the mast further back and add front steering?

Marcus

10

Marcus,

Are you referring to the boat in the picture? The boat is about 42 feet long. The runner plank for the forward runners is about 10 feet back from the bow. So, to change it to front steering, you would have needed to redesign the entire boat to move the plank to the back and set the steering runner and crew pod to the front (basically sail the boat backward).

If you look at stern steerers of that generation, you will see that the thinking in those days was to keep the rig centered over the front runners so that the weight of the rig would maximize the righting moment as the boat heeled. The stern of the boat was made progressively longer and longer to move the crew weight back to try and add as much leverage as possible to counteract the tendancy for the back to lift up in the puffs.

Despite their main flaw (spinning out), these boats remain the masters of the ice. The widely acknowledged current world record speed of 143 mph was set by a boat that looked almost exactly like this one (except that they were using a gaff rig, wooden mast and cotton sails) back in 1937. Every attempt to break that record with modern looking dragsters with wing masts and carbon fiber hulls has come up short.

  • Will

Will Gorgen

11

Will,
You’re entirely correct about the tendency of the big stern steerers to “spin out” & the same thought occured to me when I saw Marcus’ (very cool looking) design. BTW, it’s fairly widely acknowledged in the modern iceboating community that the speed record claim of 143 mph is dubious at best. A more recent claim from the early '80s is of Ken Whitehorse sailing his Skeeter “Warrior” to a speed of 156 mph, supposedly documented by Sherrif’s Dept radar, but that is also questionable IMHO.
Regards,
Bill
http://www.iceboat.org

12

Hey Bill,

I had the local sheriff “certify” my own personal best with his radar gun on Lake Minnetonka back in 1990. As you may know, the lake enforces a 45 mph (day) speed limit (used mainly to control powerboaters in the summer and snowmobilers in the winter). I was quite surprised when I had my best day sailing of the season cut short by the sheriffs flashing lights as he pursued me in his patrol car across the frozen lake. The next surprise I got was when he handed me the speeding ticket for 120 mph in a 45 mph zone (the fine was inflated by the manditory “reckless” charge that kicks in if you are more than 20 mph over the limit). I elected to fight the ticket in court. I’m not sure what surprised the judge more; the speed listed on the ticket or the description of the vehicle. He was not sure what an iceboat was so he asked me to describe it to him. I told him it was a sailboat with blades on it to slide across the ice. The word sailboat caught his ear so he asked me if it was powered only by the wind to which I replied “yes sir”. At that point he turned to the sheriff and asked “you pulled over a sailboat for speeding?” The judge ripped up the ticket and I was on my way free and clear. I kinda wish he would have let me keep the ticket as proof of my speed record. Oh well…

  • Will

Will Gorgen

13

Dear Will,
thank’s a lot for this cool story! -
I would have loved to see the face of that sheriff at that particular moment! -
Ernst

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls

14

Dear deckard,
would it be of any help, if you had three identical semicircular hulls of 6 x 66 cm made of carbon/epoxy for a first test of this suggested configuration? -
I had been playing around with an idea quite close to yours - that’s why I made those hulls.
the hulls are identical fore and aft (actually double enders), as I thought about a proa concept at that time. -
This boat maybe could be built between 122cm and 152.5 cm overall width and length - just to get started -…-
Ernst

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls

15

Will,

Did you wear cross country biker protection during your run?
I would have sh***t my pants at that speed…

Bill,

I think the only reason why a ship like my concept would have a higher risk of ‘spinning out’ is because it misses the weight of the longer sterns of conventional amas. I believe thou that this could be compensated through the mastposition moved back and the radio gear mounted further back too.
The ideal configuration would have the battery pack movable between the stern of the main hull and the stern of the amas. That way you would have optimum weight distribution for upwind and broad reach.

Ernst, thank you for your great offer, but I think, that the dynamic stability of planing hulls is quite vital for this concept to work. If this ship does not plane, it will be slow like a lead belly because of its short hulls.

Marcus

16

Dear deckard,
you may be right about the dynamic stability of planing hulls, but please consider, that semicircular hulls can be planing as well - and most of the righting moment would come from the foils. -
so I think, it would work - at least for a first test, to profe the workability of your basic concept! -
Ernst

Professional shipwright - boatbuilder/-designer with 25 years of experience and a special interest in multhulls

17

Ernst,

I was actually thinking of shaping some stepped foam hulls by myself as a first step. Building is two thirds of the fun for me.

I would then connect them with fibre glass rods and put an airplane propeller on a one meter long stick right where the mast would be, to test the concept. The propeller would point in the same direction as the force vector of the sail. That should give more controll about when the stepped hulls start to plane. I could test different rigg heights and even reproduce the force at my workshop (even thou I have no idea right now what to do with that knowledge.[:D])

Marcus

18

Hey Marcus,

Have you ever done any iceboating? If the conditions are just right (black ice, warm windy day) these boats just glide along. 90 mph is quite common on days like that. Iceboats sail fastest downwind. Your aparent wind is on the nose at 10 degrees of the bow or so. If it is blowing say 30 mph and you are going downwind at 90 mph then you feel a 60 mph headwind (well not quite because you are not going dead downwind, but you get the idea). You are bundled up in a snowsuit with thick gloves, a helmet, goggles and usually a face mask. so you do not have any part of your skin exposed. The wind sort of whistles through your helmet, but other than that, there is no noise at all. Assuming you are sailing on a nice big lake where the other shore is several miles away and you can see a good mile or two in any direction, you are not at any risk of hitting anything. If the ice is really black, then you can see the smallest objects from a good distance off. The biggest problem is if there are any expansion cracks on the ice, but those always appear in the same spot on the lake, so any local boater will know right where they all are. So, you really don’t get the sensation that you are in any sort of peril. You are just sailing. Yes, you can tell you are going fast, but it is not like in a car where any small movement of the wheel will send you into the ditch. In an iceboat, you feel in complete control at those speeds.

The day I got that speeding ticket, the wind was blowing out of a bay on the lake. The lake necks down between a point of land on one side and an island of the other. This results in a venturi effect that causes the wind speed to increase in the channel. We called it the wind tunnel (for anyone who knows Lake Minnetonka, the wind was blowing out of Excelsior bay). So the wind speed as you blasted through that channel was probably topping 40 mph. You could feel the squirt as you hit that spot on the run. After coming out the other side, you would slow down a little bit, but the friction is so low that you really don’t feel it. The sail starts luffing a little and you need to head up to get your aparent wind back and then the sails grab again and you continue off toward the other shore at something closer to 90 or 100. I’m guessing I only hit 120 for a few seconds. But aparently that was enough for Mr. Sheriff…

To be quite honest, I don’t think I actually was going that fast. I have no idea how well radar guns work adainst wood and fiberglass boats. The only metal on the boat is the stays and the runners. I bet the radar return was screwed up and his gun got all confused and over-reported my speed. Either that or he decided to write the ticket higher because he was in a pretty foul mood and wanter to teach me a lesson.

Ernst,

Yeah, the Sheriff was none too pleased when the judge tossed out the case. But it did sound pretty ridiculous to have given a sailboat a speeding ticket…

When he had “pulled me over” I had no idea what was going on. I thought maybe there was a family emergency and they had sent the sheriff out to tell me to come home or something. It took me about 3/4 of a mile to come to a stop and the whole time I was thinkng the worst. By the time he got out of his car, I had my helmet off and was walking over to him fully expecting him to have some bad news. The first words out of his mouth were “Son, do you know how fast you were going?”. I was not expecting that at all. After a stunned momentary silence, I replied “No. My boat does not have a speedometer on it.” He asked me to take a guess. I know the speed limit on the lake so I said “Maybe 40 or 45?” He got a pretty grumpy look on his face and said “I don’t think so! try 120!” and started writing up the ticket. I figured I was in some deep trouble at that point so I just shut up and waited for him to hand me the ticket. Then I sailed back home - slowly.

The worst part was there was about 5 or 6 more good sailing days before the snow finally came and ended the sailing season. I was so scared of that sheriff that I didn’t go out sailing at all for the rest of the season. Good iceboating days are rare and that damn sheriff had ruined the remainder of the season for me.

  • Will

Will Gorgen

19

Will,

That’s what i call good story telling. If you had told me that story on a rainy day in a smoky Pub, I would invite you for a pint of guiness now.[:D]

Ice Sailing always has interested me, but I am halfway right in between the two only lakes in Austria that are big enough to do it. That’s a 5 hour drive each. [:-boggled]

Marcus

20

I would send you a picture of a Finnish boat made just on the same idea, but added with Kite. Before i do so i need a website to put the picture on and the owners permission to do so.

  • HJ

“Expertice is gained trough mistakes. However repeating
same mistake is not learning but stupidity.”