On a small sailboat, especially if it has a traveler, a single
control line can hold the mast
down and in position when running on port or starboard tack.
You have to suspend what you know about sailing aboard my vessel. Much of what I do is reach back to traditional rigging
. Everything is very big and loads are enormous.
In my quest to sail at a leasurely pace without high loads, I have abandoned the Bermuda
rig. Loads, and equipment
costs, are too high.
Currently I have converted to a paraw rig. I have a short solid 35 ft mast
with a foresail and crab claw
sail behind the mast. James Wharram
calls this Tiki.
The crab claw
sail behind the mast is supported by two spars. Reefing is accomplished by drawing the two spars together.
See pictures of a small one at Blogbook of the Tiki 21 » Performance of a bamboo-polytarp crab claw sail on a Tiki 21 catamaran
The lower spar, which is kind of like a boom angles upward from the base of the mast at about 25 degrees. Behind the pilot house I currently have what I term a boom cripple. This is a 18.75 ft tall support spar 21 ft behind the mast. It is on a pivot.
My intention was to control the lower spar by tilting the boom cripple. I like my boom cripple because it helps prevent the long spars from hitting my radar
tower and wind generator
. It also helps carry the weight of the sail when furled.
The lower spar is currently 37 ft. Later I intend to install a 65 ft spar for racing
The main problem is spar flex.
doesn't have the same problem as I do since his vessels are much smaller and spars far shorter.
I need to have control lines about every 8 ft along the spar.
Experience with a single
line, that turned on blocks to and from the deck
, taught me this didn't stop flex. Wherever the load was highest the spar was able to draw line from wherever the load was lowest. In theory I could add more lines to areas of high load, however, I run out of deck
and do not want to attach to the roof of my pilot house. Lifting the roof of the pilot house off during a squall wouldn't be funny
Individual control lines going to different sections of the spar needs to be my approach. 37 ft / 8 ft requires 4 control lines. Near the spar I can split each control line into 2 more which allows me to have 8 attachment points along the spar.
Still with me?
With a small rig it is possible to still use a single line and perhaps hold the spar at one or two points. The flex is tolerated and part of the crab claw look.
The problem with my boom cripple idea is how much it has to tilt when running. Running requires it to tilt past 45 degrees. The issue comes when trying to pull the spar back to the center line. Most of the load on the righting line puts the cripple in compression
. So when running, pulling in the spar requires far more load than acceptable.
The second problem is how to deal with multiple control lines. As the spar travels across the deck , a line attached to the spar tip requires a lot of line. A line attached close to the mast requires very little line.
Getting a crew coordinated to release and haul in a single line to a foresail is problem enough. Releasing and hauling multiple lines on a spar is not something practical.
In my next post I will discuss my purposed solution. It is a device that controls multiple lines that let out and take in different amounts of line depending on position along the spar.
Has anyone wrestled with this problem before?