Amateur Yacht Research Society

Is there anybody that has already used a cfd like javafoil or xfoil to do some prediction with the sails of their boat? I found something curious with one of this program and I really want to share it with someone.

Hi John! Thank's for your comments. What you call a yuloh, in my case I call it a sculling oar. They are smaller and also not attached to the bottom floor. In fact, it works differently but with the same principle. As soon as I will be able to finalize the design of the paddle I will surely post it ...

Hi Robert,
Marchaj mention this type of rig on page 126 in"Aero-hydrodynamics of sailing" and it seems that it's in Cowes that this boat was tested. May be there...?

The launching of the boat was a success! Great stability, perfect trim, eases for load up and down the trailer. The only black spot is that the scull I design and fully tested in static (swimming pool) stall when we reach a certain speed on the boat. So, I made another sculling oar, more traditional...

So, this concept boat is not so far from my rig! Thank's for the info.
For the hull drag test, do you thing that pushing the boat could be better than to tow it? We will not have the problem with wake disturbance and my dynamometer can be use in both direction.

Hi John! Yes this is a good summary of what the Kasala project is! Nice done! The “well known fact” comes from the famous experiments carried out by Croseck and that you can found in different books like “the Sailing Yacht” of Juan Baader or “Architecture du Voilier- tome 1” of Pierre Gutelle. They ...

Thank you for your comments. I agree with you that electronics are not essentials in this stage. Later, I planned to install a bi-data so I can get the speed/log and a dept sounder. From the GPS you can only record the ground speed and sometimes it’s not enough. The comparison between the different ...

Hull impact resistance: This matter will probably interest all the available brain in this forum! Classification rules don’t really take puncture resistance of a hull in to account. This is especially true, when you design a new light unit and when you are working with rigid hull material like plywo...

Sorry guys, it seems that the pictures don't go through. So lets try it...

Effective design appears when you can dedicate different purpose on a single element. For example, the support tube of crutches has a multifunction task: - It hold a step - It support the telescopic mast holder - It receive the strap holder - The rudder control system is bolted on - And for sure, it...

Hi John! Thanks’ for your compliments. It’s an interesting topic you bring here. For sure, that when we select a keel profile we assume that it works in a laminar flow. But it’s true that it is rarely the case. However, I don’t think that the choice of a keel profile has something to do with the sit...

Select the right keel profile. A few weeks ago I complete installation of Kasala keel inside his trunk. Everything was going fine and the simple lifting system I adopt, allows a 10 years old boy to raise or lower the keel. It’s a 6:1 pulley system install on top of the cab, completed with an externa...

Good decision! If I could help I will be more than happy to joint the team. Suggestion: when you get all size and dimension of the frame, why not propose to members a kind of design contest as a first draft or so? And after that you can decide where to go?

I’m sorry, but I never use a junk rig and I don’t know anything about it. But, what I know is that I never see any winning racing sailboat equipped with such a rig. Bernard Moitessier sails with such rig when young but he never keeps it on her later craft. A square top sail is quite specific. The to...

Hello Robert, http://i66.tinypic.com/2uhu8vr.jpg For sure a wishbone could surely do the work too! But... - Some are not so effective for fine tuning the sails. - The reefing is not as simple as it looks - With a rigid mast and a square top sails they are not particularly recommended - When the sail...

I think that if you think to build a metal hull it's mainly to increase the impact resistance, isn't it? For you information there is a coating available called Line-X that can bring any object almost unbreakable. And this is not propaganda! It works for real. And there is some representative in UK....

I'm glad that you find the boat interesting! Unfortunately, the rig is integrally part of the project and another type of rig can not be fixed on those hull without affecting balance, stability and efficiency . But sails performances can be demonstrated with polar curves. Also, competing with other ...

Few words again on roto-duplex rig: It doesn’t seem that this rig arouse much enthusiasm. But we all know that sailors are conservative and are allergic to drastic change. Wind is a free energy and trying to improve efficiency of a sailing arrangement is for poor interest for a great majority of us....

On most catamaran the rudders are vertical. By contrast on beam transom monohull, the rudders are angling about 15 or 20°. This create some friction in mechanical linkage and increase the stiffness of the tiller. Diabolo rubber are often use to realize those attachment. With a duplex rig, like with ...

Well notice! Yes there is some pressure (or traction) on side mast base. This pressure could be estimated at 5000 N (1100 lbs) per side including an appropriate safety factor. In fact the rail is a hight quality grade aluminium "U" shape channel, perfectly bend and lay on his side on deck....

http://i65.tinypic.com/t5shsp.jpg http://i68.tinypic.com/1178kk7.jpg Roto-duplex rig. Duplex rig also called twin cat rig or bi-plan rig consist of 2 masts lying side by side symmetrically at sheer line or mainly on each hull of a catamaran. This rig is rarely used on monohull due to the fact that,...

A boat is a choice of parameters and you have to keep in mind that Kasala is a laboratory. I'm the kind of helsman who like to sail with a long stick up to my shoulder and between two fingers! You can not do that with twin rudders. The tiller is often tough and not really pleasant to handle. Minimiz...

Hello! Here are the pictures of the oscillating rudder.

Rather than words, a picture will show you what I call an oscillating rudder. But if you want to rename it, feel free! And here is the explanation I give in the presentation: “I decided to use a single rudder, even if the hull shape, from a plan view, looks like a wedge. With this kind of hull, when...

Designing a small boat is not an easy task. The principal difficulty encountered comes from the weight of the crew members that could totalise almost half the entire mass of the boat it-self. The mobility of this weight compromised greatly boat lines and stability. So, imagine now, that you want to ...

Hello! I have a great project that I want to propose to Howard Fund. Is-it still active? Can we still submit some lines? If yes, will it be better to send it by mail or e-mai? Let me know. Thank you.