I just bought a new boat and the previous owner tossed the running rigging lines over board?

[jssailem]

What do you do? You found the perfect boat for you but on inspection the previous owner took all of the running rigging off the boat and left you with out even a manual to try and figure out how much rope/line to buy. Here is some information I have used in rigging my boat.

When boarding an older boat with no manuals and no lines on board to use as a guide, you can always use the boat and sails to fit the lines to your boat. It was what the original designer did using drawings and rules of thumb that are based on typical use.

How big should the line be?

1. Inspect the sheaves on the boat. "Sheaves" those round wheel like things that line runs over. They spin to reduce the friction of the line turning a corner. Your line diameter must fit the sheaves. To big and they will bind, not move smoothly. Sheaves serve to smooth the redirection of your line with minimal friction.
2. Touch the line, feel the line. If the line does not feel good in your hand you will not enjoy grabbing the line as you begin to work with it.

Line size is best when it feels good to your hand and is sized to fit the sheaves on your boat.

How long should the line be? How much to buy?

1. Main Halyard - for a Mast Head Rig: lines need to be long enough to go from where they terminate either at the base of the mast or in the cockpit, up to where they go around the sheave and back to the point they attach to the sail plus a couple of feet to easily secure them. You can estimate the length with a tape measure and boat data (check out your boat on Sailboatdata.com). My mast is listed as 42 feet tall. 2 times that number for going up and down the mast would be 84 ft. The boom sits about 3 ft above the bottom of the mast. I terminate my halyards at the mast. If I buy a line 84 ft long, I will have enough line to go from the boom "goose neck" where I attach the halyard to the mainsail, up the mast, down the mast and about 3-4 feet of line left over to tie the halyard off "both ends" when the sail is not on the boat.
2. Jib Halyard - This is where that high school math you said you would never have the need to use, comes into play. The Jib on a fractional rig or a mast head rig runs two sides the length of a "right triangle". You need a line that is the equal to the height and the hippopotamus of the triangle...... ("hypotenuse" just a senior moment, channeling my goof ball friend from geometry class). Start the same procedure here as with the main. Tape measure from the cockpit to the mast base (if needed). The length from the mast base to where the sheave is on the mast for the jib halyard - this is the height of the triangle - (The top of the mast for a Mast Head Rig, or to the exit sheave on the front of the mast for a Fractional Rig.). Plus down the length of the Forestay to the bow where the jib is attached - this is the "hypotenuse length". Add a couple of feet to provide ease of tie off. On my boat that length is roughly 87 feet. I will round that off to 90 feet.
3. Spinnaker Halyard - Pretty much follows the same pattern as the Jib Halyard using either the Fractional or the Mast Head calculation dependent on where the spinnaker attaches to the mast.
4. Topping lifts - Same technique. If the topping lift is used for a spinnaker pole, then it is the vertical length up and down the mast from the tie off cleat to the topping lift turning block. If the topping lift is used to hold the end of the boom up then use the same calculation as used on the jib.
5. If you want to avoid all the geometry math, a cheat is to install the main halyard. (That is the easy one just 2 times the length of the mast plus a bit for luck.) Then knowing the length of the main halyard just use it to estimate what you need for the other halyards. Stretch it out to where you are going to need the jib halyard to go and add or subtract a bit from the length to make it fit the new purpose.

The following image tells you what the codes IPJE mean from SailboatData.com

If you are going to use the same diameter halyards for all your lines then add up the length of all the lines and buy a roll of line from the rope shop. Buying a 300 or 600 ft roll is way cheaper then buying a measured 72.65' line at the marine store.

Sail SHEETS -
These lengths are measured based on the boat length and the sails to be used. Again feel in your hand is important, as is checking the sizes of any sheaves bending the line or winch equipment gripping the line. Self tailing winches have a size range for line that can be used. It is a goldilocks type problem. Too big and the line does not fit, too small and the line will not hold. You have to find "Just Right" to be happy.

1. Jib sheets run from the winch or cleat on the side of your cockpit, to the sail and around the mast to a point at or stern of the mast depending on the size of the sail (a 90% jib uses less line than a 155% Genoa - but there is no reason you can not use the same length for both sails. It just puts a bit more line in the cockpit to address.). Using a length of line or a tape measure you can get a good approximate length. Add to that enough line to run across the cockpit so you can hold onto the line when the boat is heeling and your on the up wind rail. A rule of thumb the length of the boat plus 3-4 feet should be pretty close.
2. Spinnaker sheets - Here you go with a lighter weight of line and most often a little small in your hand. You may need more then one set of sheets for the spinnaker as light weight is used when sailing in light air, but a heavier line come in handy when the breeze picks up. The length is most often 2 times the length of the boat.
3. Main sheet. - This one is a bit complex as it depends on the specific way your boat is rigged. To measure start at the point the line is secured to the boat in the cockpit. This might be your traveler or a block and cam cleat. Measure to the block. Then with the boom swung out till it touches the shroud on the port side of the boat, measure each loop around the block to the boom and back till you reach the point that the sheet is terminated on the boom block. With the boom fully extended this length can surprise you. Since the main sheet is constantly being adjusted while the line is under tension, you want to have a feel for the line that will enable you to win at the tug of war that happens when sailing in heavy winds. As big as you can based on the size of the sheaves in the sheet blocks.

One rough guide for line lengths can be found at "Premium Ropes" website Guidelines for length of mooring lines, halyards and sheets.

If all this math and measuring makes you gag, having flash backs to high school math and that day the cute girl in the next row over called you a jerk - "We are OVER!" then there is always the Rope Line Calculators like here at SBO.

Running Rigging Calculator.

Buying your precut line here helps keep the lights on and the computers running that provide this forum.

 

[dLj]

Boy John, you were busy, that was a nice write-up!

(well until I got to the part about the cute girl... that STILL is a sore subject! LOL)
dj

 

[Red_Dog]

Your write up is great! You also have too much time on your hands.

I would hate to be in this situation. I would come close to calling it a deal breaker. The boat would have to otherwise be THE boat I couldn't live without.

 

[DrJudyB]

Genoa sheets with a length of LOA plus 3-4 feet might be too short on many boats, particularly if it’s a roller furling sail. LOA plus J is a usually about right, but they may need to be even longer if the sheets go back to winches at the helm, or if the sail is a high chewed Yankee or big genoa that sheet very far aft.

the best thing to do is to actually use a tape measure, especially if you are paying somebody to finish the ends with whipping or eyesplices. I usually add 8 feet for a tail after all the measurements to get to finished length. That’s an allowance for winch wraps for boats up to about 40 feet. For boats with huge winches, you probably need to add a longer tail.

If you are planning to put eyes on the line yourself, or tie knots, you have to add extra. how much depends on the core construction of the rope and type of splice.

JudyB

 

[DrJudyB]

The following image tells you what the codes IPJE mean from SailboatData.com

That’s an informative image, but “I” is drawn wrong in that image. “I“ is not the same as the measurement from the forestay to the butt of the mast. “ I” is measured along the front of mast from the forestay down to the main deck at the Height of the sheer line. The main deck is where the deck would be if there were no raised cabin or deck house.

Unless you have a flat deck with no cabin, you can not measure “I” directly. The bottom point of the measurement is inside the cabin, on the compression post, at the same height as the sheer line of the main deck.

The best way to approximately measure “I”is to hoist a tape up with the Genoa halyard as high as it goes, close to the forestay. Then measure down to the main deck, alongside where the side deck meets the cabin, directly outboard from the front face of the mast. It’s not a perfectly accurate measurement, but it will be accurate to within a couple of inches, even on a 50 foot boat.
JudyB

 

[DArcy]

@DrJudyB I do not question your description of the proper I measurement, I do wonder why we use that number. It doesn't seem to have any practicle value but measuring to the bottom of the forestay does since that is where the sail attaches.

 

[DrJudyB]

@DrJudyB I do not question your description of the proper I measurement, I do wonder why we use that number. It doesn't seem to have any practicle value but measuring to the bottom of the forestay does since that is where the sail attaches.

I don’t know the answer to your question. Sailmakers use “I” when properly measured, as a data point to identify the boat and compare it to other boats in our own historical databases that we keep for our own benefit.

Also, I think it’s a remnant from an earlier age of boat design. You’d have to ask a naval architect why “I” has been used by them for 100 years. It’s on every famous NA’s drawIng. Sheer lines are drawn by the NA for practical and esthetic reasons, as are deck house lines. .

Naval architects don’t care about accurately predicting the length of the forestay. Bow and stern sheer lines are raised to create extra bouyancy in oncoming and following seas. They raise and lower the deckhouse height for practical and esthetic reasons,

Naval architects know that a sailmaker will measure the rig on the real boat, after the Standing rigging and associated hardware are installed. The original sailplan drawings for older boats are only approximately dimensioned. Sailmakers can’t depend on them to build an actual sail. You’d be surprised to know how common it is for real measurement to differ significantly from the drawings!

The estimated forestay length you find online sites like SailboatData isn’t reliable. It’s a theoretical number used To calculate the theoretical sail areas, and it’s useful solely for comparative purposes. Those calculated sail areas are off by 10-30% compared to the sail areas in the real world.

As a sailmaker, I’m very familiar with the limitations of using data published online. Or sailplane drawn by the Naval Architect. We don’t rely on it. Never. Not Ever. We measure every important dimension so we don’t make expensive mistakes. In most cases, the customer can do the measurements too, as long as the designer checks them carefully against our own database.


Judy B

 

[jssailem]

I am with Dr Judy on the exactness needed in the design and building of a sail for your boat.

Sails are the power source of a sail boat. You should devote as much focus on the prep for a new sail as you would on the repowering of an auxiliary power source on your boat.

While the "spec's" of your boat may be in the manual and your boat is a production boat, an older boat of that design does not mean that a previous owner or even the build team has not made an alteration (improvement) to the boat. Having the company who is going to build your new sail physically measure your boat's rigging for the sail just makes practical sense. Yes it may mean you spend a bit more for the sail, but you a likely to get that back in better performance.

Thank you Dr Judy for sharing your skills/knowledge with us sailors.

 

[DrJudyB]

While the "spec's" of your boat may be in the manual and your boat is a production boat, an older boat of that design does not mean that a previous owner or even the build team has not made an alteration (improvement) to the boat.

I couldn’t agree more! It happens all the time!

Having the company who is going to build your new sail physically measure your boat's rigging for the sail just makes practical sense. Yes it may mean you spend a bit more for the sail, but you a likely to get that back in better performance.

It’s not clear to me that that is correct. For example, the SBO sail loft does a high quality job on cruising sails. You measure your boat yourself using their forms. You can buy from them with confidence you are getting a well designed and built sail, made with quality materials.

While every every boat should be measured individually, most owners can do it competently. If the sailmaker checks it against the internal database, and the measurement form should be designed to catch mistakes. Our forms have redundancy and internal checks built into them.

Measuring a boat is a time consuming job if the boat is big, but most owners can measure their boats themselves, as long as they are willing to do what the loft asks. If the customer makes a mistake, the sailmaker/designer will catch it before it’s too late.

The horror stories about buying a sail online are often from when you hire a loft that offers to sell you a sail but doesn’t require you to measure. The only boats that you do this for are strict one design boats. Even common boats like a Catalina 22 or Potter 19 or Hunter 260 need to have a couple of dimensions measured and confirmed.

I won’t mention any names here, but if an online loft offers you a price that is 30-50% lower than name brand or reputable independent loft (warning sign #1), and offers to sell you a “standard” sail without any measurement (warning sign #2), I recommend that you look for another sailmaker.

JudyB