How to Install a Multihull Net

A Boltrope is a hard, non-compressible rope sewn into the border of a net that will slide into a track, mounted on the structure. It holds the net without requiring any lacing or providing any means of tensioning. Nets with boltrope on one or more sides will need to insert the boltrope into the tracks before any lacing is done. Make sure the track is clean and free of burrs. The ends of the track should be rounded, not sharp, use a file or sandpaper if necessary to round any edge that might touch the boltrope or the net. A lubricant can be helpful if the boltrope is a tight fit, WD-40, Silicone or soap will work. If the net has boltrope on opposite sides these will need to be inserted simultaneously, easier with 2 people, but possible with one alternating sides pulling just a few inches or cm at a time. Once all of the boltropes are in the tracks follow the general tensioning procedure for the tensioning sides.

Nets can be attached to cables by lacing or with sleeves. If the net laces to the cable you would just follow the General Tensioning Procedure as described above. On Nets with sleeves for cables you will need to disconnect and insert the cable through the sleeves and re-connect it before attaching any lacing sides (but after inserting boltrope if your net has both). The amount of tension to put on the cable will depend on the amount of Catenary curvature designed into the net. If the net was designed with a minimal amount of curvature (around 40:1 length to cord ratio) then you should tighten the cable hard and straight. If the net was made with more than the minimum curvature (i.e. smaller ratio) then you should tighten the cable until it has about half of the curve cord measure with the loose weight of the net hanging on it (no lacing).

This will be a starting point and you may need to adjust the cable turnbuckle or lashing as the net is tensioned. Tie the remaining corners of the net with temporary lines to hold the net in place and start lacing the tensioning sides of the net as described above but monitor the cable curve as the net stretches out. It would be best to have a tight reference line (small cord) drawn from the Cable pad eyes to measure the curve. If the cable is curving too much and needs to be tightened you may need to loosen up the lacing on the net to do this and then re-tension the lacing. If you are using synthetic lines be aware of elongation. Dyneema lines should be pre-stretched to get to their elongated length before final tensioning of the net.

Internal Tension Lines support the net similar to a Cable in a sleeve, across an unsupported side to strong Pad Eyes at the corners of the opening. They are usually finished with spliced eyes and stainless steel thimbles at the ends. These ends will need to be lashed to Pad Eyes at the corner of the opening before the rest of the net is attached. Using a slightly smaller line than for lacing, 7/64” or 1/8”, tie a bowline to the eye on the end of the tension line and run the loose end of the line through the Pad Eye. Run the line through both the Tension Line eye and the Pad Eye 3 more times, passing through each in the same direction, so that you have 7 lines total running between the 2 eyes. Tie the line off with half hitches around the bundle of all 7 lines. Do this loosely on both ends before trying to tension the lashing.

Just as with Cables, Internal Tension lines will have a catenary curve. The lashings at each end should be gradually tightened, with the gaps between the net and the opening equal on both sides, until the curvature of the tension line, with the net hanging loose on it, is about half of the designed amount of curvature.

At this point, using the general tensioning procedure above, begin lacing the remaining sides of the net. Monitor the increasing curvature in the Tension Line, and if necessary adjust the lashings so that the curve ends up near the designed amount when the net is completely tensioned. Note that it will be nearly impossible to tighten these lashings when the net is tight, so any adjustments should be made before the net gets completely tight, and if necessary the net may need to be loosened in order to adjust the Tension Line lashings. Finish the lashings off with 3 or more half hitches around the bundle of lines snugged up tight to the Pad Eye.

Nets with Rope Borders have rope woven through the netting at the perimeter, and spliced together to form a closed loop around the net. Since rope borders have practically no stiffness when loose, in order to support the netting between lacing points, they should be under significant tension. This tension must be applied from the corners where the rope border makes a turn. At every point where the perimeter of the net makes a turn, lash the rope border to a lacing point on the opening with 6 or 7 passes of line. Do this loosely at first and then gradually tighten up the lashings so that all corners of the net are an equal distance from the opening. These lashings should be tightened as much as possible so that the Rope Border is hard and stiff and not easily bent. It is important that the lacing points that the corners of the net are lashed to be strong enough to hold the extra stress. After all corners of the net are lashed tight then the sides of the net can be laced and tensioned as described above in the Standard Tensioning Procedure.

With the new net laid out on top of the old net, insert the battens, one at a time, through all of the webbing loops on each side of the net. The 1/8” lines attached to the battens will be tied off to lacing points on the boat to control the batten rotation and movement. The battens should be cut slightly longer than the side of the net they are intended for, so that when all battens are inserted they should overlap in the corners. Position the battens so that the rotation control lines are free of the net webbing loops, there should be an extra hole nearby if the line needs to be moved to clear a webbing loop.

Begin lacing the net up, loosely at first, until all sides are laced. Then gradually tighten the lacing around the net, working the slack line toward the corners. Tighten most on the sides with the largest gap, so that the net becomes centered in the opening with an even lacing gap on all sides. As you tension, keep an eye on the battens to be sure they remain overlapped in the corners, the battens will become difficult to move after the net is fully tensioned. Repeat this several times until the net seems tight, walk around on the net and then repeat the tensioning again.

The overlapping battens will need to be cut back to install the End Caps. Measure back from the center of the overlap 1-1/8” and cut the battens off square with a hand saw. If the space is to tight for a saw, a hack saw blade will work.

Unbolt the set of End Caps if they are bolted together, slip the End Caps over the batten ends so that the set screw holes face inward, and line up the bolt holes. Insert the shoulder bolt and attach the lock nut. Tighten with the wrenches. The End Caps are designed to fit loosely over the battens so that the net can be retensioned as necessary.

A 3/16” hole can be drilled near the end of each end cap for a #8 x 1/2” set screw. In most situations, where the batten is held by end caps at both ends these set screws should Not Be Used. If both ends of the batten are not fitted with end caps, these screws should be installed, on that end cap only. To install the set screw, drill an 1/8” hole into the batten through the hole in the end cap, and then screw in the set screw.