Mooring Buoy Program

Sandy Bay West End Mooring ProgramAs of 2006, there were approximately 25 functional dive moorings and one adequately marked channel within the boundaries of the Marine Park. The growing popularity of Roatan as an international dive destination resulted in an ever increasing number of dive shops, boats, and visitors. It became a daily occurrence to have several boats tied to the same mooring, resulting in eventual damage to the groundings and lines. It was apparent that the marine infrastructure was insufficient to handle the increasing volume of divers.

The Marine Park, with funding from CORAL, began an extensive revamp of the marine infrastructure in November 2006. The main focus was the installation of new dive moorings and channel markers and the maintenance of existing moorings. After three years of management, and several additional grants focusing on improving the infrastructure, there are now approximately 60 dive moorings, 15 yacht moorings, 2 fishing moorings and six marked channels.

As part of the revamp, we investigated how the old moorings had been installed within the Park. We noticed that several methods for groundings had been adopted with the most predominant and functional being sand screws, heavy duty metal pins, and chain cemented into the reef. Each method has advantages and disadvantages that should be taken into account before installation, including variation in cost, limitations in location, ease of installation, and disruption to the reef.

Sand screws

sand-screwsThe screws come in a variety of sizes and designs, ranging between four and six feet in height. They are constructed of either one continuous length of metal that is bent over to form a loop to connect the tackle. The majority of screws used in the Park have either one or two wedges/plates which secure the pin. We have found that sand screws made of Re-Bar deteriorate much faster in the salt water than those constructed of galvanized steel. The cost of each screw ranges between $80-$150 depending on material and size.

To install a screw requires time and effort, and, from my experience has been a hit-and-miss experience. The main limiting factor for screw installation is depth of sand and consistency. It is difficult to determine how well a screw will go into the sand until installation has begun. One method we have adopted to increase the success rate is to determine the depth of sand using a seven foot metal probe. The best method to insert the probe is by securing a weight belt with 20-30lbs of weight to the wrists and rocking the pole back and forth until a grating sound is heard. This is a much faster method than trial-and-error.

For screw installation, one requires a team of experienced divers, plenty of weight, and determination! Divers will each need approximately thirty pounds of weight to enable them to maneuver on the seabed. An additional sixty pound weight belt is attached to the sand screw to apply downward pressure. Finally the probe, which is used to assess sand depth, is placed through the loop on the top of the sand screw as a lever for rotation. The start is the crucial point as it is essential that the screw goes in straight, otherwise it will shift from side to side during insertion. The sand screw must be installed as deep as possible to reduce bending when in use. It is recommended to use a lift bag when bringing weights to the surface to minimize risk of rapid ascents.

sand screw installationDifferent substrates have varying complications for screw installation. Rubble areas prove to be the most difficult for insertion as the wedge(s) on the screw often hook large pieces of dead coral and require tremendous physical force to continue or relocation if this proves too difficult. Sand is a good substrate but the depth of the patch is always a problem. Even with probing there is always the chance of large pieces of coral which were missed obstructing the wedge. Muddy bottoms, like those within sea grass beds, are the simplest locations to install sand screws as they are usually deep and have few rocks present. If the wedge hits any obstacles, a member of the team can simply glide their hand through the mud and remove the object (only applies to objects arms reach away). The only down side of working with the sea grass beds is the complete lack of visibility once screwing commences. The diver’s feet stir up the sediment and vision goes from 50ft to 1ft. The deeper the site, the larger the team should be due to the physical exertion, resulting in higher air consumption. A two man team can install a screw in 10ft of water in under ten minutes, at 40ft however, a minimum of four persons should be used to ensure completion as air is used up at an astonishing rate.

Heavy duty metal pins

The only moorings that utilize heavy duty metal pins within Park boundaries were installed by the Utila Aggressor, a local live-aboard. The pins are a sturdy and durable option but beyond the Park’s financial means as they cost upwards of $1,000 per mooring and require heavy machinery and surface support for installation. If people have the funds to pay for the pins, they are a secure and reliable option and require little maintenance.

Cementing chain into the reef

This final method for installing dive moorings has been used in Roatan and throughout the Bay Islands for years. Prior to using cement, chain was simply wrapped around large coral heads, but due to abrasion, the chains ate through the coral and the lines came free. Alternative methods for making grounding include filling fifty-five gallon drums with cement or constructing large concrete blocks to act as anchors. Using cement and chain is a cheap, effective method to create mooring groundings and one that I have adopted for the majority of new moorings throughout the Marine Park.

The method originally developed by the islanders used excessive amounts of chain (15ft stainless steel) and concrete (5+ bags) and was damaging to the reef during installation. A new method has been developed by the Park, now using only a six foot long, half inch piece of galvanized chain and between one or two 42.5kg bags of cement. Ideal locations for installation are on the edges of sand patches where the reef fringes the sand. One should look for solid holes in dead parts of the reef where the chain can be fed through and secured. Wafting sand with a hand can expose new areas for cementing or provide clues as to the suitability of the location, i.e. depth of rock.

cement mooringOnce the chain has been looped and weaved through the dead coral, pieces of three inch Re-Bar are placed through the links to add additional stability to the chain, and finally the divers return to the surface to retrieve the concrete. With metal pin moorings, cement is premixed on the support boat and pumped into the holes. The method adopted by the Park bypasses the mixing and takes bags of cement down intact. The bag(s) is cut open and the cement is forced around the chain and into the holes with 1ft of chain left exposed for tackle attachment. A large dust cloud is produced when this happens, but any particles that land on the coral can be wafted off after installation. The additional advantage of working on the sand patch is that divers can maneuver with the heavy bag without standing on the coral, as well as the majority of the dust ends on the sand.

During installation, a hand should remain on the part of the chain for attachment to ensure that it is not buried during the zero-visibility conditions. The cement should be left for several days and then inspected for any holes, big cracks or other indications that the mooring will not hold. Additional bags of cement can be added at this point, otherwise a mooring line with a riser float is attached to prevent the chain from abrading the coral and the mooring is ready for use. On average, to install a chain and cement mooring, the cost is approximately $60.

Mooring lines and buoys

mooring-buoyA mooring line consist of a length of 7/8’ polypropylene rope approximately one and a quarter times longer than the depth of the site. To attach the line to the grounding, a 7/8’ eyelet, a 1/2’ swivel and a 1/2’ D-pin or an appropriately sized stainless steel quick link is used. A small polystyrene float is attached to the second last link of the grounding chain to prevent abrasion and also act as a visual aid for divers if the mooring line comes loose. The dive mooring buoys used in the Park are 14’ white heavy duty trawl buoys, able to withstand even direct hits with propellers. The Park logo is engraved into the buoy and then painted to ensure that stolen or lost buoys can be identified and retrieved. The buoys are attached to the mooring lines using a 3/4’ piece of rope 6ft from the surface loop to avoid damage from boats when moored. This method was chosen as it enables easy removal for cleaning and maintenance. Fishing mooring buoys use polystyrene buoys with a fish drawn on to avoid confusion.

Maintenance

Every month the Park has a routine maintenance program, visually inspecting each line and buoy and tightening the D-pins or quick links. The diver shop who use the moorings every day also act as watchdogs for the Park and report any damaged or missing moorings.