Friday, February 7, 2014

Core Sound 20 Mark III construction - part 1

[Note- This entry was done on an iPad using the Blogger app.  Let's see how it looks.]

Graham Byrnes' designs have been extraordinarily successful. He has sold over 700 sets of plans for the Core Sound designs, including Core Sound 17 kits, and there are over 1050 of his Spindrift designs out there. In the 300 mile Everglades Challenges, his Core Sound designs account for six of the top seven times in the monohull class, including three overall wins. 

In 2007 I built a Core Sound 20 from plans for the Everglades Challenge and turned in our fastest time ever (2 days and 20 hours).  This is a fast design - a planing cat ketch with a low center of effort and an enormous cockpit that is easy to single hand. The only drawbacks, in my opinion, are that it is wet going to weather, there is not a good place to sleep and fix a meal out of the weather, and raising the main mast is, as Graham says, like training for tossing the caber. I solved some of the problem by constructing a dodger, but I was still looking for more. [Many of my previous blogs cover this.]

Paul and Alan Stewart had put a cabin on their 20, and Graham's "Core Sound on steroids," the EC 22, has both a cabin and a tabernacle-stepped main. Last year, Graham designed a Core Sound 20 Mark II and then built one with Chick Ludwig in his Vandemere, North Carolina shop.  I followed the build with great interest on the B&B Forum. The boat had the cabin, tabernacle, and greater freeboard and was self-righting with a self-bailing cockpit and stabilizing water ballast.  I was hooked.

Then Graham announced that, after only one Mark II, he had designed a Mark III with several improvements, including optimization for rowing.  Graham said that he would like to sell Mark III kits for both the 17 and the 20 and asked if someone would like to build the prototype so that he could be sure all,of the parts, cut on his CNC machine, would fit just right.  I quickly agreed to be the test pilot.

This is part one in the story of that build.  I went to Graham's shop in Vandemere, NC the week after Thanksgiving to begin the build and returned the week after New Years to continue getting the boat ready to trailer back to my shop in Tennessee.  The shop is unheated, and I spent several days in insulated overalls.  It was even too cold for epoxy to set one day.

Concept Drawing

A more recent rendering

Graham working at the computer that controls the Shop Bot

 Detail of a scarf joint

Half of the hull before stitching

Going 3D

Going 3D film - note the OSB cradle that will be part of the kit.  It makes it all a lot easier than my first CS 20 build.

Graham and Alan Stewart fitting the first bulkhead 

Two more bulkheads and transom going in

Another angle 

Alan and Graham fitting baffles into the water ballast tank

Looking aft from the cabin

With other bulkheads installed, Graham checks out the boat

Cockpit details

Sheer added

The boat on the trailer headed back to Tennessee

Cabin seats being glued up in my (heated!) shop

Cabin Seats going in

Cockpit taking shape

Cockpit locker top - one assembled and one in parts

Cabin coming along

Cabin detail

Cockpit looking aft

Cockpit looking forward 


Brace for mizzen mast to go in ballast tank