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Core Sound 20 Mark 3

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The Core Sound 20 Mark 3 was developed as a shallow draft comfortable cruiser/racer for two with trips like the Everglades Challenge in mind. She has a large flush deck cabin and spacious cockpit for passengers. Based on the popular and race proven Core Sound 20, the "Mark 3" is upgraded to a fully capable coastal cruiser with water ballast. In addition to the free standing cat ketch rig we are known for, additional standard features of the Core Sound-20 Mk3 include:
  • Kick up rudder and weighted centerboard.
  • A raised deck cabin with sliding companionway hatch and hinged foredeck hatch.
  • Main and Mizzen tabernacles for quick, easy and safe rigging. 
  • Water ballast tank for easier trailering.
  • Self draining cockpit and spacious cockpit lockers. 
  • Optional "cockpit reefing" which allows for reefing the mainsail without leaving the cockpit. 
Specs:
LOA………20′-0″  [6.1 m]
BEAM………6′-4 1/2” [1.99] m
DRAFT………9" - 3'-11 3⁄16" [0.23 -1.2]m @ DWL
SAIL Area………180 sq. ft.
WEIGHT………650-700 lbs [295-317]kg
*DISPLACEMENT………1500 lbs (773 kg)
Water Ballast..........430lbs (195kg)
*@DWL With people water ballast and gear
 
Video "how to" build series. Click here
Taylor and Alan are building a Core Sound 20 Mark 3 and documenting the build in a series of videos. Check them out there. 
 
Stability:
Read more about the stability and ballast of the 17 and 20 Mark 3 designs here. The boat is very stable with the water ballast and can be made fully self righting with additional ballast. A mast head float is a recommended add on for racing and gives the option of sailing the boat without the water ballast and eliminates the possibility of turtling. 
Why is it called the "Mark 3?" Click here for a history of the evolution of the Mark 3 series of Core Sound designs. If you're interested in all the same features in a slightly smaller package, check out the Core Sound 17 Mark 3Keep reading for information on all the available options and prices for the Core Sound 20 Mark 3! 

Build from Plans: BUY PLANS
While the boat can be built from plans and templates it was really designed to take full advantage of CNC cut parts. The plans set consists of full color 11 x 17 sheets that detail all aspects of construction and assembly. These are the same sheets that accompany the kit parts. We have taken almost all of the parts from the CNC kit and created a set of full size templates on Mylar and paper sheets that are used to transfer all of the part outlines onto plywood for cutting with a jigsaw. A recommended parts layout is provided in a template guide sheet. Parts such as the cockpit seat tops and cabin top are not shown in the templates to save space. These parts are patterned from the boat as built to ensure a perfect fit. Other parts that are simple rectangles are provided with dimensions only. Below, two of the 6 template sheets are shown. The templates are either 1 or 2 stage. You can see the bottom panel in the lower template with a "second stage" of parts nested inside of it's perimeter. Once the bottom shape is traced the second stage of parts can be cut out of the mylar templates to make laying them out easier. Similarly the sheer strake panel is nested inside the side panel. Bulkheads and frames are shown in "half view" meaning one side is traced and then flipped to draw the mirror image side to produce the full frame or bulkhead. 
 
Note: The assembly manual plan sheets accompany the full size templates or the CNC cut Kit. There is no table of offsets of dimensioned hull panels sheet because the templates are full size. There is no lofting or dimensioning or connecting the dots required.  template-example-2021.jpg 
Build from a CNC KIT:This is no ordinary boat kit. After years of development the 20mk3 kit is now the most sophisticated, comprehensive and highest quality 20' sailboat kit on the market today. This kit includes every plywood part we can cut on the CNC machine and then some. All parts are made of the highest quality BS 1088 okume marine plywood and the solid wood parts are clear southern yellow pine. Every plywood component is cnc cut and labeled with our custom CNC pen which marks bulkhead and stringer locations directly onto the parts. This has mostly eliminated measuring during the build. Being a complicated boat, decisions must be made with regard to all design details. Hatches, tabernacles, ports, etc. and the kit represents the best compromises in each area.  

What is included in the kit?

Plywood parts:  

  • 3/4" birch plywood cradles and cradle gussets for the building jig. Just add 2x6 rails as shown in the plans.  
  • 21 CNC cut sheet of 6mm okume.
  • Miscellaneous parts in 4, 9, 12 and 18mm okume plywood. 
  • All parts for sliding companionway hatch and foredeck hatch. 
  • Plywood coaming laminations for optional dodger. (dodger must be custom made)
  • CNC shaped rudder blank ready for sanding smooth and glassing. 

Solid wood parts: CNC cut southern yellow pine components include:

  • main and mizzen tabernacles, 
  • Cockpit hatch coaming parts
  • Rudder cheek spacer and Tiller halves. 
  • CNC shaped Centerboard blank ready for installing lead tip, sanding and glassing. 

Hardware: These parts come standard with the kit

  • Three CNC cut solid Lexan side portlights and 2 portlights for the companionway drop board. If you would like to use a different portlight let us know and we can omit the cutouts for these portlights.
  • Lexan bunk hold down turn buttons. 
  • Cast Lead Centerboard tip. 
  • Armstrong ports for the cockpit sole/ballast tank
  • Anderson bailer for the ballast tank
  • Beckson screw ports x2 for ventilation and access to below the anchor locker. 

Epoxy and Fiberglass

Our epoxy and glass package includes all the epoxy, filler and fiberglass needed to complete the boat based on good practices and minimal wasted epoxy.

Rigging and Hardware: The standard Rigging package includes the following 

  • Aluminum mast tubing as specified in the plans. 
  • New B&B sailtrack
  • All rivets for attaching track to masts.
  • Starboard (plastic) end caps for masts where applicable.
  • Blocks, cleats and fairleads
  • Color coded running rigging and sheet lines

Optionally we offer a "cockpit reefing" option which includes additional lines and cleats for routing the main reef lines aft and into the cockpit. 

Headsail add-on kit:

A bowsprit can be added to the boat and fitted with an asymmetrical spinnaker or a roller furling headsail. This add on also includes lines and hardware for the added running backstays which provide support for the main mast. 


What is NOT included in the kit: 

 In addition to the normal consumables and tools used for stitch and glue boat construction you will need...

Additional Solid wood:
You will need additional solid wood to complete the boat. We suggest southern yellow pine for stringers, cleats, gunwales, etc. We don't include these parts in the kit because they are best ripped up from long boards which are not practical to ship. This wood is used for things like "cleat stock" which is found on the top edge of parts that will have a "top" glued to them such as the top of a bulkhead to receive the cockpit seat tops or the top edge of a bunk support frame to receive the bunk tops. These are ripped and cut to length as needed. 
 
You will also need to source some good clear Douglas Fir for the sprit booms. We prefer the builder to source locally rather than cut these in half in order to ship. 

The building cradle is framed using standard 2x6's. We provide the CNC cut cradles only which sit on top of this frame. 
 
Nuts and bolts: The rigging kit includes only the blocks and cleats not the hardware for installing them. We don't have time to put together such a detailed package for a boat this complicated. Stainless steel bolts and nuts are readily available anywhere. 
 
Finishing touches: We don't include some of the finishing touch hardware like piano hinges, hatch latches, drain plugs or stainless steel hollow back. Anchor rollers, navigation lights, boarding ladder. The list could go on and on and on. These items are for you to research and purchase separately.