12-15-10
O.K. so now everything below deck has been accomplished save the painting and the wiring up of the bilge pump. The past month has seen me deep in research as to methods of
stepping and
un-stepping a keel
stepped mast. This
step in the restoration process was a
stepping stone for constructing the
stepping hardware, and I didn’t want to make any
missteps as I
stepped up my efforts to
step out of my comfort zone to develop a
step by
step proceedure to
step and
un-step the mast… So I
stepped away from my work many times this last month and thereby likely
side-stepped misfortune.
…Confused yet? A very fundamental characteristic of sailboat design pertains to how the mast is attached to the hull of the boat. This comes in two flavors; keel-stepped and deck-stepped. Traditional thought on this subject maintains that keel stepped masts (masts that run through a hole in the deck and attach to the keel) are sturdier than deck stepped masts (masts that attach to the deck and do not extend into the interior of the boat). Conversely, the deck stepped mast is relatively easy to step and un-step (put up and take down). There is a logic to this theory, but it is arguable that the weakness of deck stepped masts can be engineered around, and that the theory is based on a historical context that is less relevant with modern materials.
The base of a mast receives both vertical and horizontal forces applied to it which try to push it down through the bottom of the boat and also sideward off of the mast step. An additional consideration in designing the way the mast attaches to the boat is the way that the mast imparts its loads into the boat. It is thought that the vertical and horizontal forces applied to the mast (including the motive force from the sails that pushes the boat through the water) are more evenly distributed throughout the structure of the boat if the mast is able to transmit the force down to the keel as well as onto the deck.
The down side is that having a keel stepped mast means that there will always be water in the bilge. This water comes in at halyard boxes and other openings in the mast and nothing you can do will stop that. Second, it is way harder to step and un-step a keel-stepped mast, potentially making the boat more subject to damage in the process. An internet search on stepping keel stepped masts shows that there’s a lot of grassroots ingenuity out there (example) that has been applied to making this task easier – although nothing specific to a Rhodes 19 (which has a big, heavy aluminum mast).
So, here’s my big shot at becoming world famous… I started by constructing a mask crutch with pintles that fit into the gudgeons on the stern of the boat. This was made out of an 8 ft 2x6 and a keel roller to support the top portion of the mast. With the mast at an angle, I attach an ‘A’ frame (made out of 2 x 4 and 2 x 6) to the mast with 2 x 400 lbs capacity cargo straps. I use the crutch in conjunction with the ‘A’ frame and 2 x footings into the deck connections for the mast shrouds (mirror opposites of one another – one for port the other for starboard) that are abeam the hole in the deck for the mast.
I start the stepping procedure by making sure I have deck shoes (or some other footwear that provides good traction on fiberglass surfaces) donned. I attach the aft stay to the ring on the mast crutch, and lift the mast into the crutch. With the mast at an angle, I attach an ‘A’ frame to the mast base with the cargo straps. I then attach the two footings to the shroud hardware on the appropriate side of the boat deck. Standing just aft of the cuddy, I place the feet of the ‘A’ frame into the two footings, wander aft to the Mast crutch, grasp the underside of the mast and lift the mast off the crutch, while ensuring that the feet of the ‘A’ frame remain in the footings. Walking forward, I keep lifting the mast (hand over hand) while ensuring that the feet remain in the footings.
The aft stay becomes taught at the same time that the mast is held vertically over the hole. I move forward of the mast/’A’ frame and secure the whole thing into position by tying it off to the stern dockline. At this point I loosen the cargo straps just enough to allow me to twist and shimmy the mast slowly downward through the hole, into the boat, and onto the mast step on the keel. Then it’s just a matter of attaching all the stays and shrouds.
…Just in time for running Christmas lights up the forestay and aftstay!
There is the matter (mentioned in paragraph 3) of the built in leaks at the base of the mast… Below are a couple of articles that address this topic – and my very next undertaking. Hey Santa! Ya’ got a great big block of industrial rubber in that bag of yours?
http://www.jordanyachts.com/archives/1840
http://www.goodoldboat.com/reader_services/articles/wedgemast.php
Moon entered 1st quarter Monday at 0500 PDT.
A happy and safe Christmas to all!
I saw three ships come sailing in
I saw three ships come sailing in
