Ordering Your New Mainsail with the Dutchman Flaking System

Below are several points you should consider for ordering a new mainsail with a Dutchman System to get the optimum performance. Not all can or will apply to every boat. All points also apply the the SailCase Boom, which needs the Dutchman System. We also operate the largest adult sailing school and shared use membership program in Norwalk, Connecticut, www.soundsailingcenter.com, with over 15 boats from 23 feet to 47 feet, so we have lots of experience ordering new sails, all with Dutchman Systems!

a. Loose footed sails

90% of new mains with Dutchman systems today are loose footed. With a loose footed main, we are specified that the Dutchman Tabs are installed above the straightline from the tack to the clew, to prevent the lines from ‘skirting’ the foot (there is a slight amount of upward pull on the lines as the sail is raised). Typically, the aft tab is about 3” above the straight line, the 2nd tab 5”, the next tab 6” (if 3). To avoid this from happening, in August 2013  we introduced the type L system, which incorporates a new foot attachment where the control lines are clamped to a translucent silicone tube, to avoid the problem of skirting the sail. The L System is only available with the A style topping lift clamps for boats with halyard style topping lifts.  We recommend you order a loose footed sail.

b. Full Length battens

Full length battens help a sail last longer, since it will not flog as much, and it is also easier to handle. Another advantage is that you do not have a ‘hinge’ in the sail at the front of the batten, which inevitably happens, even if expensive tapered battens are used. Note that full length battens are often less expensive than long tapered battens, although the track and end fittings can add considerable expense.

Full battens may be problematic if the roach extends more 3-4” past the backstay. Also, the friction may be considerable on older boats with slug type slides, especially if the mast is painted. A low friction track system may be needed. UHMW tracks, such as made by Tides (Strong Track) or our Dutchman track are the best solution on boats under about 50’, unless you have a recent Selden mast that can take the MDS cars. The Dutchman track system runs about $28 a foot (of luff length) complete w all hardware. Full battens and a low friction track system are required with the SailCase Boom.

We suggest batten spacing not be equal, as this is more likely to lead to harmonic leech fluttering in strong winds, and will require extra leech line tension.  Speaking of leech line tension, I certainly do not enjoy pulling in the leech line after pulling in the reef, which is what you are supposed to do.  For offshore boats, each reef should have it’s own leech line, which generally will only need to be adjusted one time.

c. Fabric Weight

A stiffer or heavier fabric will be easier to handle with a Dutchman System. We recommend going up one oz in weight for most cruising sails, especially with boats under 35′. Performance fabrics, which are more tightly woven and quite a bit stiffer, will hold their shape better than softer ‘cruising’ dacrons. This extra stiffness will also make them easier to handle with a Dutchman System and more durable.   Bainbridge Ocean Plus, or Dimension Polyant Square Weave are examples of excellent high tenacity, high performance Dacron fabrics.

Laminate sails will be easier to handle and will longer lasting if Dacron taffeta is applied to one or ideally both sides. To save weight, only apply in the leech area.

d. Batten / Slide Spacing

We are looking for about 30” spacing on a typical 35’ boat,  36” on a typical 40 footer,  and 40” on a typical 50’ yacht as a rough guide. The spacing should be as even as possible. However, we often suggest the batten spacing be somewhat unequal. If the leech is divided into even segments, there will be more harmonic flutter, and you will need to use the leech line more.

It is also preferable to have 2 slides between each batten, so the battens drop to alternate sides of the boom. We often make the spacing from the foot to the first batten a little bigger and use 3 slides that are 2-3” closer together  than elsewhere. This makes the lower folds a little smaller, so they do not hang down and rub on the dodger or bimini. We drop the batten spacing down  so as to have  2 slides between the remaining battens. The spacing between the top batten and the headboard should also be decreased somewhat, so as to have closer slide spacing, as the slide loads are much higher near the head of the sail. This is particularily important with the SailCase Boom.

e. Tack Angle

The topping lift should NOT need to be adjusted after the sail is initially set up. To do this, set up the topping lift so that as the sail is raised the last 3-5”, the boom is picked up a little. This automatically slackens the topping lift. Of course, when the sail is lowered, the boom will drop a few inches. The tack angle may need to be decreased, with the end of the boom a little higher, to allow this boom movement without impacting the dodger or bimini.

f. Reefs

Traditionally, reefs have been placed at 12% and 24% of the luff length. However, given that 90% of all sailors wait a little longer than they should to reef, and that most boats in 20 knots of wind will sail just fine with a deep reef at about 20% of the luff length, we strongly advise most cruisers to stick with one deep reef at around 20-25% of the luff length. For offshore boats, we place the 2nd reef at about 40% of the luff length. The slide spacing  should take precendence over the reef locations.

Pulling in a reef is often destructive to the sail, as the sail generally lands over the reef line, resulting in extra chaefe and difficulty in pulling in the reef. With the SailCase,  the reef lines are incorporated in the upper booms, with the sail dropped below, so the sail can not jam or catch the reef lines. The reefs are set at 20% and 40% of the  foot length, unless other locations are specified.

With conventional booms, run the reef line so that the vertical portion, after it passes through the reef cringle, comes down on the side of the sail opposite to the side the Dutchman is pushing the sail towards. In other words, if the sail is folding to the port side of the boom below the reef cringle, the vertical portion on the reef line should run through the cringle onto the starboard side. Our favorite solution is adding non swiveling blocks lashed or webbed to rings in the sail at the luff, and use specialized clew blocks (which are expensive) at the leech. This keeps the reef line entirely on one side of the sail, and makes reefing much easier.

g. Upgrade the Luff Rope

The thickness and stiffness of the luff rope actually has a significant impact on the ‘memory’ of the main. We recommend using at least a 3/8” luff rope for boats up to 30’ and a 1/2” luff rope for larger boats. The best luff ropes incorporate a stiff, as opposed to a traditional soft three strand rope.