Archive for the ‘Running Rigging’ Category
My 21 year old boat is performing like a brand new one! I just got the new sails from Neil Pryde that I ordered last fall and went out for the afternoon. Performance improvement is so incredible I can’t believe it! Pointing ability is significantly better, and at the same time, speed is better while pointing! Now all I need is to replace the miserable Crosby Rigged mainsheet with a traveler and everything will be fantastic!
I knew my old sails were overdue for replacement (they were the original sails to the boat), but I didn’t realise just how much performance improvement I was going to get! Read the rest of this entry »
Previously I covered the installation of the 1″ T track on the mast for the pole ring. The next step of the installation was to install a deck organizer block under the companionway hood to route the halyard back to the cockpit. Since I can forsee no reason that I would ever need to run another line back to the cockpit I opted to save a little expense and install a Schaefer Series 3 cheek block instead of a regular 2 or 3 line organizer block. At the cockpit I installed a Spinlock XAS rope clutch to control the halyard with.
Cheek Block Installation
To install the cheek block I had to remove the 9 wood screws that hold the hood on, and then break the solid bead of 3M 4200 that hunter originally used all the way around the hood. To do this I ran a small knife through the bead cutting through it as best as I could, and then pulled the hood up.
Once the hood was off, and the old 4200 scraped and removed, I cleaned the underside of the hood with Tilex Mold and Mildew remover as the fiberglass had alot of dark mildew spots from years of damp sea air and perpetually being in the shade. To clean it, I simply sprayed it on, let everything sit for about 5 minutes, and then hosed it off, it looks brand new again.
To install the cheek block I positioned the block so the halyard would run straight back to where the rope clutch was to be installed, marked my 4 holes, and then drilled them. I first tried using stainless tapping sheet metal screws from West Marine as Hunter had the foresight to install at the factory a aluminum backing plate under the mounting pad, but the screws ended up snapping off under the simple leverage of a screw driver leaving me a useless set of holes with screws embedded in them that I was unable to remove. After re-drilling new mounting holes about 3/8″ outboard of the original holes I opted to tap the holes for a #10 machine screw, bedded the back of the block and holes with 3M 5200, then screwed it down tight, and cleaned up the excess 5200 with an acetone soaked paper towel. I have no expectation that this block will ever be removed for the life of the boat, otherwise I would have used 4200 or lifecaulk.
Rope Clutch Installation
The installation of the rope clutch was pretty quick and easy. I ligned up the clutch on the factory designated installation / mounting pad and marked my holes, then removed the clutch and pre-drilled the holes for the #14 tapping screws, and then cranked the screws into the holes by hand with a large screw driver (this time the screws didn’t break off). I chose the tapping screws with the large sheetmetal style thhreads as they have more holding power than a machine screw because the threads are so much wider and cut much deeper into the metal. Once everything was ready to do the final installation, and the surface of the deck was cleaned with a acetone wipe down, I applied 3M 5200 into and around the holes, then screwed the rope clutch down tight, and cleaned up any excess 5200 that leaked out with a acetone soaked paper towel.
All that was left after this was to re-install the companionway hood, and reseal the edges with 4200.
Once everything else was complete, it was time to go up the mast and install the halyard. This was pretty straight forward, I went up the mast in a climbing harness and fed the bitter end of the halyard through the already existing spinnaker halyard exit directly above the forestay, and let gravity feed the line down the inside of the mast. When the halyard was visible from the exit gate at the base of the mast I used a hook shaped piece of wire and pulled the halyard to the exit, and then used a screw driver inserted past the main halyard on it’s exit gate which was opposite of the spinnaker halyard exit to push the line through. Here is the Finished product. You can clearly see the V cleats for the lazy jacks that sit on either side of the T track.
Installed my new halyards earlier this week, took the time to calculate the size I should be installing as opposed to just guessing. built a excel sheet to calulate the percentage of working load on the line based on the square footage of the sail, and the tensile strength of the line.
according to the American Cordage Institute the Safe Working Load of a line is 90% of the tensile strength, minus a safety margin of at least 5 times the load you are expecting to put on the line gives you the Maximum Safe Load. Put simply, take 90% of the tensile strength, and divide by 5, and that gives you the Maximum Safe Load you can use that line for.
then to calculate your wind loading of the sail, use the following formula (Square ft of the sail)*((wind speed in kts)^2)*0.00431
I created a Halyard Size Calculator in Excel to do all the number crunching for me… to use it, look up the tensile strength of the line you are considering using, enter the values in row 4, and enter the square feet of the sail you are looking to replace the halyard for in cell C7.
The table below will give you a percentage of the Safe Working Load the line will be at in a given wind speed. You then need to determine what the maximum wind speed you intend on having the sail hoisted in, before you reef it (for most people this will be around 15 or 20kts). Then you need to look down the wind speed row, and find the smallest line that is under 20%. This will be the smallest halyard (or sheet line) size you can safely use on that particular sail.
The other thing you will want to factor into your decision is the working elongation, or stretch of the line. Look at the line specs and see what the stretch specs are for the line you are considering. Most companies will give you percentage of stretch at a given load. so if you are operating the line at the maximum 20% load, and the line has 1.75% stretch (such as the New England Ropes Sta-Set X line that I just bought) you need to calculate the length of your halyard, for example I’ll use 100 feet, you would have 1.75 feet, or 21 inches of working elongation, or stretch of the halyard. You will probably want to minimize this as much as reasonable, and to do so, you will need to use a larger line, so you are working at a lower percentage of it’s safe working load.
For my halyards, to reduce stretch as much as possible, I went with the 3/8″ line, and assuming I am always reefing my 165sq ft main any time it is blowing over 20kts, that gives me a maximum load of 5.75% of the safe working load of the halyard, and roughly .35% working elongation, which over the roughly 40 feet my main halyard that is not coiled in the line bag in the cockpit when the sail is hoisted, gives me roughly 1 3/4″ of working elongation / stretch of the line when a gust of wind blows, thus keeping the sail shape as best as possible.