There are several different methods of fixing trampolines, which can vary from one boat to another. Often, we may even wonder if a net, a canvas or a strap will remain in place or not and this is completely dependant on the fixation system.
Our job consists of the knowledge of fabrics and the fixation system linked to the trampoline. However, we also check the anchoring points on the hull, the bridge and the other parts of the boat that are responsable for receiving tension from the net. A skipper or an owner knows their boat better then anyone else and in the most minute detail.
Certain boats have aluminium rails riveted, bolted or screwed to their hull or on the bridge. A bolt rope, which has either been sewn or soldered to the trampoline, can then be threaded through the rail. It will be impossible to add any tension the net on this side, so tension will have to be increased on the other sides of the trampoline.
Systems using steel bars or aluminum/wood tubes, that have been bolted to the hull, leaving a space forming a framework through which lacings can be attached, are also used.
Deck plates or screws with large flat heads are screwed into the structure of the hull, especially around the joint between the hull and the bridge
. These create fixation points attached to the boat. In this case, the trampoline or net either has to be highly flexible, or the lacing have to be precisely positioned all around the outside of the net, in order to fall exactly in the right place.
The forward beam on a cruising multihull, especially on catamarans, is regularly a section of the mast with the rail protruding. Depending on the shape of the rail, flat or cylindrical sliders can be placed all the way along it. It is important to choose you sliders carefully, as the most basic, low range sliders are often too weak to withstand the pressure from the trampoline.
Lacing can also be wound directly around the beam, this is not however very aesthetic and wears the ends out quickly. For very small lengths of beam, it is possible to consider shaping the trampoline into a sheath and running the beam through it. As in the cas of a bolt rope, no tension can be placed on this side of the trampoline. The net can also cover the upper end of the beam and then come and attach itself to its own netting using lashings.
If there is no solid structure on which to attach the net, a cable can be stretched across the area to fulfill this role. It is obviously not quite as solid as a piece of the hull or the bridge, which will create a dip in the trampoline, however it can in some situations be the logical choice.
For example, on a trimaran, the front ends between the central hull and the linking arms have no front beam. A cable can be used, but only in certain situations.
We will now look at the different ways of attaching the trampoline to the boat, without focussing on the material it is made from.
In order to obtain an efficient and durable installation, the trampoline has to be tightly stretched. Therefore an area of tension must remain between the trampoline and the boat (hull, bridge, rail, etc.). You should leave between 5 and 15 cm; the bigger the space, the more tension is facilitated, however the bigger the risk of dropping an object or putting a foot through the gap.
The link between the boat and the trampoline is often made using lashings or lacings. This method has several advantages and a few disadvantages. A 6 mm polyester lashing can be delivered with your product if you wish.
This type of lacing is ideal when there an alternation between eyelets on the net and swivel rings on the boat
A single lace can be used on each side of the trampoline. At either end, a stopper knot is used to maintain tension.
The lacing should be carefully chosen: high resistance, low elongation, high resistance to UV light.
Very efficient for tension, however the fixation system is very specific. It can be used with sliders that face each eyelet.
Placing the net under tension is then easy and efficient, thanks to the 90 degree angle of the lacing on each attachement point. This is also the best way of maintaining the tension in lashing.
However, it is essential to check that the lashing is adapted. The sliders must also be blocked in place on either side of the lashing.
Double lacing is a combination of the two previous types of lacing.
This not only helps to establish tension but also spread the weight over several segments of lashing.
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