Bolero's Specifications

This page represent most of the pertinent design data, specifications and some of the philosophy for Bolero, our modified Shields One Design. It is a combination of data from the current configuration as well as historical data on the Shields class. I have already posted much of the data elsewhere, but I wanted to summarize it one location.

History

Our Custom Knockabout Sloop, Bolero, was converted from Shields #9 which was one of the first 20 Shields built by Cape Cod Shipbuilding during the 1960s.

The class was conceived in 1965 by Cornelius “Cory” Shields of Larchmont, New York and designed by Olin Stephens (Design Number 1720) as a replacement for the International One Design class, IOD. 

The Shields have an impeccable pedigree and the result is a beautiful boat that can sail in any weather and is easily steered and driven. It is easy to see why she has been called "A Mini Twelve Meter".

About 257 Shields have been built by three builders.

Boats 1 - 20 (Cape Code Shipbuilding)
Boats 21 - 190 (Chris Craft)
Boats 191 - 199 (Hinkley)
Boats 200 - 257 and counting (Cape Code Shipbuilding)

Shields Principal Dimensions

LOA = 30 ft - 2 1/2 in
LWL = 20 ft

Bow Over-Hang =  4 ft
Stern Over-Hang = 6 ft - 2 1/2 in
Bow Entry Angle = 25 deg

Maximum Beam = 6 ft - 5 1/4 in
Waterline Beam = 5 ft - 8 1/4 in
LWL / Max Beam = 3.1

Draft = 4 ft - 9 in
LWL / Draft = 4.2

Displacement = 4672 Lbs
Displacement = 73 cu ft

Displacement to Length Ratio = 262

Ballast = 3080 Lbs
Ballast / Displacement Ratio = 67%

Center of Buoyancy = 54.3%
Center of Flotation = 54.4%

Center of Buoy from DWL = -0.945 ft

Prismatic Coefficient = 48.75%

Wetted Surface Area = 150.8 sq ft

Pounds per Inch Immersion = 435.2 lb/in

Sail Plan

One of the main draw for using the Shields as the candidate for a modern Knockabout Sloop conversion was her sail plan and ballast ratio. I was looking for a boat that I could easily single hand and for me that meant a fractional rigged boat with a large SA/D ratio.The following is a summary of Bolero's (almost completely unaltered from the original Shields) sail plan and rig data.

I = 29.8 ft
J = 9.3 ft
Jib Area = 139 sq ft

P = 33.3 ft
E = 13.3 ft
Mainsail Area = 221 sq ft

Mainsail Aspect Ratio = 2.5

Working Sail Plan 100%
100% Sail Area = 360 sq ft
Sail Area / Displacement = 20.8
Sail Area / Wetted Surface Area = 2.4
Sail Area / Ton = 157 sq ft / ton

Light Air - Spinnaker
Sail Area =  644 sq ft
Sail Area / Displacement =37
Sail Area / Wetted Surface Area =4.3
Sail Area / Ton = 280 sq ft / ton

Moderate Air - 1st Reef
Sail Area = 324 sq ft
Sail Area / Displacement =18.7
Sail Area / Wetted Surface Area = 2.1
Sail Area / Ton = 141 sq ft / ton 

Moderate Air  - 2nd Reef
100% Sail Area = 276 sq ft
Sail Area / Displacement =16
Sail Area / Wetted Surface Area = 1.8
Sail Area / Ton = 120 sq ft / ton

Heavy Air - 2nd Reef & no Jib
100% Sail Area = 137 sq ft
Sail Area / Displacement =7.9
Sail Area / Wetted Surface Area =0.9
Sail Area / Ton = 60 sq ft / ton

Deck Layout

Maintaining the functionality of the original Shields Deck Plan was quite difficult due to the addition of the cabin and the aft deck access hatch. The cabin extends over the location of the original jib fairlead tracks and the aft hatch cut through the structure that supported the under deck back tension system.

The jib leads turned okay mounting them all the way forward on the top of the cabintop. For optimum jib trim they would still be a bit further forward or lower (like the original).

The backstay tension system is currently above deck but needs to find a way back under the deck and routed around the aft locker hatch.


Misc Empirical Values

I calculated a few other of the well know, although some have highly debated merit, empirical ratios just for the heck of it. The values for the Shields are compare to the Bluenose Sloop (my last sailboat) and the Atlantic Class (which was on my short list for this conversion).


Links & Resources

Tim Lackey (Northern Yacht Restoration)  - What more can I say about Tim Lackey. He was the heart and sole of our Shields Knockabout conversion project. I innocently stumbled unto his site with a vague idea of a future boat and dropped him an email. The rest as they say became history. His vision, discipline and work ethic are completely responsible for the artwork that we now sail.

Kristian Martincic (Chicago Yacht Rigging) -Kristian is a Shields racer and a professional rigger who bought his own Shields and was restoring around the same time as Tim was doing Bolero. He gratefully took us under his wing and corrected some of the larger flaws in my novice rigging choices. His web site is full of great ideas even if one choose not to races.

The Salvage of Shields 231 -Proof that there is a sailing god and karma. Somehow the gods decided that old Shields #231 should be raised from the depths of the Long Island Sound and they seemed to direct H.L. DeVore and friends to get her done. This feet and the brilliant restoration makes our own efforts seem just a little easier. And in a proper dose of karma Mr DeVore took his beautiful Shields to Chicago and won the 2009 Shields Nationals.

Shields National Class Association - The governing body of the Shields One Design Class.

Orange Coast College School of Sailing and Seamanship -This is a sweet sailing school down in Southern California which operates a fleet of Shield for their Keel Boat classes. I cleverly enrolled my soon to be new wife in a beginning Shields sailing class. Luckily for me she greatly enjoyed it since the first year of our marriage was all about Tim Lackey and Shields sailboats.

Bolero Initial Inspection Report (Tim Lackey) - This is the initial inspection that Tim performed on Bolero

Bolero Construction Log (Tim Lackey) -Tim's daily work logs during construction.

Shields Brochure - Vintage Cape Cod Shipbuilding (pdf link)





































Shields Brochure - Vintage Chris Craft (pdf link)

 

Shields Brochure - Current Cape Cod Shipbuilding (pdf link)




































Bolero
Shields # 9: 1967 - 2008
Modified Custom Knockabout: 2008 -