Sunday, September 5, 2010

Mast, Boom Gaff and Standing Rigging

I have made several changes to the mast furniture design.  The spars are nearing completion so it is decision time. 

Just to recap the mast is Sitka Spruce and measures 45 ft end to end or 39 feet above the main deck.  The diameter at the base is 6 3/4 inches.  At the 32 foot mark the diameter is 6 inches and from there up the mast tapers down to 3 inches.  The headstay, cap shrouds and runners will be synthetic Dynema from Coligo but the forestay and lower shrouds will be 5/16 inch stainless on 5/8ths inch rigging screws on bronze chain plates.  

The Dynema headstay will be bridled to the mast against an aft thumb 6 feet below the top of the mast at the 39 foot mark. Since all head sails will be free flying the headstay's job is confined to mast support. And its only companion at this altitude will be the spinnaker halyard block on a strop.

The Dyneema 9mm cap shroud terminates 2 and and a half feet further down at 36.6 feet.  Since the jib halyard block, the upper peak halyard block and the topsail leader line all attach at this same height, a bronze mast band would serve best for an attachment point.  The mast band ears for the peak halyard blocks should be horizontal  not vertical so that the blocks don't get in a strain and rest comfortably regardless of gaff twist. 

Next at 35 feet the two running backstays and the lower peak halyard block will attach to a mast band with three ears. The ears for the back stays will be vertical but peak halyard block ear horizontal. 
Three feet further down at the 32.3 foot level the forestay is pinned to the mast band,  the throat halyard block is attached to a crane and the staysail halyard block is attached on a strop over the mast band.

The single set of spreaders, the port and starboard topping lift blocks and the forestay share the 28.5 foot level on the mast.  To save the weight of another chunk of bronze the forestay will be bridled and the topping lifts will be on cheek blocks.

The gooseneck is 9 ft 4 inch above the keel step or 40 inches above the main deck or 22 inches above the house top.

Make sense?

2 comments:

Tainan said...

Hi, I congratulate you on your work! I have one comment. I notice in the first photos the raw water filter to the engine.It is the type with the two wing nuts on the cover I believe? PLEASE GET RID OF IT! I had the same one on my Mason 43 in Victoria Canada One of the nuts fractured at the swivel pin, the top came off the filter and the boat sank in 20 mins.Luckily it was a neap tide and she went down about 2' but enough to trash the inside furnishings,electrics,etc etc.
I now have a much larger GROCO with a screw top.
I love the BCC's having been born in South Wales and witnessed the original BCC in Barry Glamorgan where my Grand father was Pilot for many years and sailed on the originals.
Good luck.
malcolm page.
Calgary Alberta
Canada.

David Kent said...

Malcom,

Thanks for that heads up. After Ike I am all about keeping the water on the outside; I will definitly be replacing my strainer with a Groco threaded model.

Best
David Kent