About the SB20 | SB20 Class Association

About the SB20

SB20 Sportsboat world_layout_2015-04-15

  • Brochures & Boat presentation

SB20 brochure 2013[1]

Brochure Commerciale SB20  (Note: This brochure is in French!)

Click on the following links for more details:

Basic features of the SB20

Stability Checks 

Read about Yachts & Yachting SB20 Boat Test by clicking here: Y&Y Boat Test

Finally, check out our Helpful Documents page, for more reference and tips!

Tony Castro Super Yacht Design – www.super-yacht-design.com

TONY CASTRO LTDA new 3-man Keelboat – DESIGNER’S   COMMENTS

TC SB20 Sportsboat world_2015-04-15

“A One-Design boat is probably one of the most challenging and difficult jobs any Designer can get asked to do. It is also a very rewarding experience when you get it right.

It is primarily a very careful balancing act between all the client’s wishes, all the positive aspects you want the boat to have and the inevitable restrictions imposed upon you .

I am fortunate in having got-it-right with the 1720, but for many people the boat is too big, with too many crew and too expensive.

I have been thinking of designing a smaller 3-man keelboat for a couple of years and I am increasingly asked to do something about it .

Basically the intention in this case was to design a modern One Design Keelboat with the following priorities:

  1. Maximum 3 person crew.
  2. Easy to sail by anyone of any age. The winning should not depend on the size of your pocket or the physical fitness of the crew.  No seating out
  3. Modern Design, Fast and Fun to sail
  4. Very Stiff and Stable. (Capable of looking after the crew in extreme conditions)
  5. Strict One-Design rules.
  6. Simple and therefore affordable but yet High-Tech image..

The above are the key points in the design brief I think and whoever builds the boat can add his own influence.

The overall size of 6m coupled with a beam of approx 2.5 m gives us a generous small yacht/large dinghy, comfortable to sail with 3 people, economic to buy and maintain, and easily trailable behind a car.  Note: I have so far deliberately left the beam wide so that we could seat well out on a flared hull sections but I may well reduce the beam slightly when I do the proper VPP studies.

The keel will ultimately be as heavy as the weight study will allow but I am aiming for 50% ballast ratio minimum. Stability is all important because it makes the boat fast and easy to sail.

The deck layout is open and clean and as simple as possible. I think it is important the deck design is also “sexy” and much more modern/elegant than the 1720 is.

To make the boat exciting and fast we need to design a generous sail plan . The Sail Area-Displacement ratio  is about the same at the 1720.  The basic idea of having smaller sails for heavy weather in the 1720 worked very well because again it makes the boat sailable in heavy weather without scaring the users.. We could adopt a similar philosophy in this smaller design ??.

A non-overlapping jib was chosen for its simplicity and it also allows the chainplates to be set wide and support a simple sturdy mast section. (carbon ??) dinghy style…

As with the 1720 the boat should be unsinkable with the hatch closed.  The cockpit and bow sprit shelf is self draining, there are no ropes underdecks, the mast is deck stepped, and there is no way for water to get in when the hatch is closed.

The performance of the boat, especially on a beam reach will be electric, but because of the stability it is effortless.  I would like to keep this feature in the small boat as I did with the 1720

The hull prismatic coefficient is quite low and combined with a large sail area it is plenty fast enough in light airs also.

The balance of weight, sail area, draught and stability is a happy one and not unlike the 1720 this feeling comes across quite clearly as you will sail her.

My philosophy is to build from the lessons learned with the 1720 and develop the new design with the help of further R&D and input form a top class builder.

I firmly believe that this could be as successful as the Laser because there are so many people out  there that can only afford  a small keel boat but so far it has no product to buy as all the competitor boats are designed for 17 year olds ….

All in all it should provide people with the fun and pleasure of sailing a proper one-design Keelboat, with strict rules, where your ability to sail is what matters and at a price you can afford.

TONY CASTRO 16/04/01