Straps are the most widely used mean of fixation for Workboat Océan 3 fendering system. Other means of fixation are gluing with PU mono or bi component PU based Glue, less often bolting or other combination of some of these solutions
In case of fenders strapped or glued on the hull, a wire can be added, passing thru all fenders by polyethylene hose in the middle of fenders, and tightened out of them to avoid to loose one module in case of severe shock
Straps are equipped with 2 or 3 buckles of « Delta » type; made out of 316L stainless steel, Thread diameter Ø 10 mm to Ø 14 mm. Buckles are passivated under electrolytic process to prevent sea water oxidation
Less high type buckles allow fender to be compressed a bit more without risks of buckles to get in contact with hull, especially for lower diameter fenders.
Seam of buckles on straps is operated by sewing robots (for good regularity) in crenulations way (for thread to be inserted in structure of strap) not to submit thread to previous abrasion and premature breaking of sewing
Tensile strength of strap is around 8 Tons, sewing (number of stitches) is calculating to pass tensile strength of strap, distortion of buckles starts when submitted up to 2,5 Tons to break around 5,5 Tons
3 buckles straps bring axial withstanding for fenders and avoid them to slide to the stern when rubbing alongside a quay or other boat
2 Buckles straps can be inserted in grooves to preserve them a bit more from rubbing or being “hooked” by protruding things. Usually manufactured in dark grey colour, they can be also realised in more visible colours if necessary (Bright yellow, Orange or else…)
These « handling type » straps present high abrasion resistance due to textile structure and material. Weaving and material : polyester, bring low friction coefficient, and great resistance to chemical products and to weather conditions exposure (UV, sea water,…) They can be coated with additional abrasion layer of casted HAR PU 95 ShA, same kind of fender coating. At OCEAN 3 straps are coated by High Injection Molding Process to bring best bonding to the strap.
Straps are moored to hull chain plates by the mean of shackles at lower parts and tensioning system at upper parts or on deck (Jack rope, turnbuckle, or others) Jack rope is main used system and very simple to fit; It could be considered as fuse in bonding to avoid if strap is « hooked » anchoring points or hull to be damaged
High resistance Polyethylene rope « Spectra » or « Dyneema », UHMWPE type, preferably PU coated (firmly avoid mesh knitted sheath that would slide) or pre-tensioned polyester Ø 5 to 8 mm. Restrict number of round with jack rope, between upper buckle and deck chain plate, to 4 for High resistance polyethylene (Ø 5 to 6 mm) to avoid the “fuse” to be the strap instead of jack rope usually considered so; and to 6 for pre tensioned polyester (Ø 6 to 8 mm)
Duration life of straps obviously depends on use, rubbing frequency of the workboat and roughness of reaction berthing surface in contact with textile or protective coating. Nevertheless experience allows us to consider duration before changing of straps, or refurbishment every 3 to 7 years according to previously mentioned elements (approx. 5 years for Pilots with mean of 5000 hours of use per a year).
Always rightly tensioned straps increase their duration of life notably. With new set of fender, when fitted for 1st time on the boat, it is often necessary to proceed to re-tensioning of straps after a period of test for workboat, due to repositioning of fender in recess.
Tensioning of straps is easier with use of simple tensioning tool, hooked both in upper buckle and deck chain plate : 1 meter length approx. lever arm allowing to bring together these 2 elements, time to twist jack rope or place pre-tensioned shackle, before releasing tension (Tensioning tool arrangement on simple request)
Easiest way to make the straps slide on the fender, during tensioning, is to put "soapy water" on side of strap in contact with Fender to move one from the other. Soapy water will disappear during first sailings and give back to the system its original bonding.