Looking for modern and tradional design

[BlueBell]

@Luke Bryan

Are you going to build to a proven design plan or is this a one-off design project?

 

[Luke Bryan]

A one off most likely, if i can find a design and modify it it would be good. Ideally i would find abmodern available design and modify it for traditional construction

 

[Luke Bryan]

Fixed ballast or centerboard? The fundamental problem is that caulked carvel is heavy, so you must go to tight seam, batten seam or double planking of maximum 1/2 inch (12mm) thickness to lighten the boat. Not many people left willing to do that.
The australian 18ft open boat would be a possibility, it's reported to plane in the right conditions. Definetly an inspiration for the rig. About https://www.openboat.com.au/about.html

 

[Luke Bryan]

This is a great lead and resource, thanks!
I will be ordering the books and going deeper into these boats

 

[Dolfiman]

You can also have a look at the 6m50 SI class, very old class (bien in 1907) but still popular in Swiss with modern designs with generous sail area (Rule : Striangles = 30 m2) and 2 trapezes authorized :
Découvrez ce Voilier 6.5m SI - Swiss 5 https://www.6m50.ch/bateaux/swiss-5

 

[philSweet]

A one off most likely, if i can find a design and modify it it would be good. Ideally i would find a modern available design and modify it for traditional construction

This isn't a very good idea. The change in shapes that represent modern designs are the direct result materials and methods of construction. The problem of hull optimization can be stated as the hull material and strut specific strength, the spar specific strength, the sail material specific strength, the cordage specific strength, and ballast density. Years ago I wrote a simple parametric hull shape optimizer, and it would kick out anything from Napoleon's *L'Orient* to the supermaxi *Comanche* just by varying those inputs and given a box rule (And believe me, I wasn't expecting that - I had no idea what it was going to kick out - It wasn't trained on any actual hulls). Conventional carvel method is not suitable to modern cored composite shapes because you can't get the weight down low enough. Clearly, if you put a carbon keel strut and lead bulb underneath, and run carbon spars and modern sails and cordage, you can get the lower cg at less ballast than was attainable in the past, but the hull is still going to be a lot heavier and less stiff in racking. You will need to modify modern rigs' stay arrangement and use composite grid structures for the keel bed and mast supports if you want a planked hull. Glued strip planking with a veil of glass is much closer to modern composites in the smaller sizes. Cold molded and longitudinal-over-diagonal planking is even better. High performance carvel was edge bonded and/or diagonally strapped a century ago. Herreshoff's and Nevin's scantling rules were nearly a composite structure, but lacked durability because there wasn't an allowance in the frames to permit refastening the planks with the next size screw the second go round - you had to sister the frames and then remove the old ones.

You might want to look at the Delft series yachts. They have developed a new series based on modern composite sailboats, and you can probably morph something between the older series and the newer one with an eye to what weight and strength you can expect from the planked hull.

 

[sharpii2]

To get speed, you need light weight and high stiffness for your hull. This is hard to get with Carvel planking.

The next thing you need is a relatively flat run aft to encourage semi-planing, or even full planing.

Then, you need a relatively large sail plan to deliver the needed power. Unless you are content to sail fast only down wind, you will need high aspect ratio sails, as, the faster the boat goes, the further forward the apparent wind moves.

Finally, you need enough form stability and/or moveable ballast, such as hiking-straps and trapezes for the crew, to keep the boat upright.

It is possibly to design this all in and have "traditional" styling above the Waterline. Everything below it will have to be modern.

Sharpie style boats, that are kept very light and have very shallow hull drafts, can be very fast. But these are essentially unballasted dinghies.

Adding a drop-keel, with a ballast bulb on the end of it, can change that. But speed requires light over-all weight, so your carrying capacity may be quie limited.

 

[Waterwitch]

John Atkins designed a planing sail boat Flying Saucer. Atkin & Co. - Flying Saucer https://atkin.mysticseaport.org/Sail/FlyingSaucer.html

 

[luckystrike]

Hello Brian,
Sharpii2 is absolut right! To get the desired Speed you have to build light. It can be done with wood, but not with traditional plank on frame. Even the desired LA 28 ist a (relativly modern) cold molded build with Veneers and epoxy.

If plywood chine or multichine is an option for you, I have some designs on my drawing board, that could fit your bill and length of 22' to 24'. If you are interested send me a PN. There are some french designs that are also available, but again in Plywood.

More information about plywood multichine? See https://forums.sailinganarchy.com/threads/re-plywood-multi-chine-sailboats.244415/

Why Do you want to build it with traditional plank on frame, a inferior building technique from ages ago?

Have Fun, Michel

 

[skaraborgcraft]

Why Do you want to build it with traditional plank on frame, a inferior building technique from ages ago?

Have Fun, Michel

Why do some people still build that way and find buyers if it is "inferior" ?

 

[luckystrike]

Why do some people still build that way and find buyers if it is "inferior" ?

Imho: Because if you love and want to build with traditional plank on frame you should choose a traditional design that is based on traditional building techniques. This is not the case in this thread, where performance in today's standards is the target. In this case "inferior" is the right term.

Have Fun, Michel