Thursday, October 31, 2013

The new rig

The last thrilling experience sailing Aerie on Lake Erie ended with a cracked mast: the mainmast bent so much in strong winds that it delaminated at a scarf joint four feet above the mast step.  I was faced with a choice among several not too satisfactory options, all discussed with the good folks at the Wooden Boat Forum.  The masts were too slender for unstayed operation in strong wind.  I could repair the mast and reinforce it with fiberglass tape at the joints, but that would create stiffer parts that could lead to breaks elsewhere.  I could use a fiberglass sleeve (too expensive and would lead to cracks down the line).  I could use a forestay and shrouds, which would interfere with the turning of the yard and negate the simplicity of the unstayed cat ketch rig.  I could build a thicker, stronger mast, which would be hard to drop into its partner hole in the foredeck.  I could replace the masts with aluminum tubes, which would be expensive and require new tools and skills such as pop-riveting.  Or re-rig the boat completely.

I had already had many problems and confusions with rigging the two masts: two each of halyards, snotters, downhauls and sheets that had to be lying on the correct side and not fouling each other.  So I thought, if I have to build a new mast, why not be bold?  In the end I decided to switch to a gaff sloop rig, which will take a good amount of time to set up before launch, but will be sturdy and less prone to confusion and mishap during launch and sailing.

I went back to pencil and paper and designed the new rig to be balanced, with only the slightest bit of weather helm.  Here’s the sketch, a bit messy but fine for my purposes.  Mainsail is about 80 square feet (7.2 square meters) and jib about half the size.

16 foot studs being a readily available size of lumber, I settled on a 16-foot-long, 3-inch thick mast made from two studs glued together.  The bottom tapers to 2¼ inches to fit into a mast step secured to the keel batten.  The top has only a very slight taper since the hounds are quite high up.  Forestay and shrouds will be 1/8-inch synthetic rope (amsteel blue, which is stronger than steel and does not require expensive tools such as cutter and crimper) with eye splices at both ends: the top ones loop around the mast through oak pad eyes, the bottoms around steel thimbles, attached to steel turnbuckles.  The turnbuckles attach to steel straps bolted to the hull or bowsprit (everything is stainless of course).

The mast partner has a jaw-shaped slot for the mast, and will be secured with bolts and glue to the main bulkhead.  It is laminated from three layers of 1x8 pine and one of 3/8-inch plywood.  The mast will be secured with an oak piece bolted through the partner.

A gaff sloop needs a jib, so I designed a 78-inch-long, 2¼ inch thick bowsprit laminated from three layers of 1x3 lumber.  It has a slot that fits over the bow extension which I had built in for just this eventuality.  It will be secured to the bow extension with a pin.  Its aft end fits into a brace bolted to the aft end of the foredeck.  The forestay will be attached to its forward tip, which is secured to the lower bow with more line.
The mainsail is a classic gaff trapezoid, attached to an 8-foot gaff and an 11-foot boom.  It will have two sets of reef lines.  Since my original main mast came apart right near the 8-foot mark (second photo), I decided to cut it to 8 feet and repurpose it as a gaff, with jaws made of oak and plywood and a parrel line with plastic beads.  

The mizzen mast, shortened only slightly, will serve as the boom.  I will be reusing a leftover gooseneck I experimented with on my original boat.  The boom will have a sheave at the clew end for a clew outhaul, and will be controlled by a mainsheet with a 4:1 purchase just aft of its middle.
The jib is a simple triangle and will be clipped onto the forestay.  The running rigging will consist of three halyards (throat and peak for the gaff, and jib) and two sheets (main and jib), plus a topping lift to assist with rigging and reefing.  A total of seven blocks (three for halyards and four for mainsheet), eight snap hooks and assorted cleats will be needed.  Most hardware will be repurposed from the original rig; I only had to buy one block with a becket and two open clam cleats.  I decided that it is important to have different-colored lines so inexperienced crew can be given simple directions.

I have already bought most materials and hardware except for some sailmaking supplies and line for the running rigging.  My new suppliers (and they are good and responsive) are LFS Marine & Outdoor (good purveyors of amsteel rope and related hardware) and Duckworks Boat Buiilders Supply (who stock parrel beads for gaff jaws, of all things, sailmaking supplies and good, inexpensive chandlery).  The budget is about $350, or more if I run out of epoxy.

Next I’ll be talking about adventures in boat carpentry, so keep rading 176inches.