VESSEL REVIEW | Compact recreational pontoon built for Spain's inland waters

Spanish builder Moggaro Aluminium Yachts has delivered a new electric pontoon to local vessel operator Guadaluxe.

The vessel will be used for entertainment and leisure trips, primarily in inland waters throughout Spain.

“This vessel is the largest pontoon-type boat ever built by our shipyard, with a length of 12 metres (39 feet),” Moggaro told Baird Maritime. “By pontoon-type, we mean that the hulls are cylindrical, and the platform connecting the cylinders, which supports the deck, is constructed from welded aluminium profiles.”

Moggaro said that, unlike the recreational pontoons that it manufactures under the European Directive 2013/53/EU, this model is registered as a passenger vessel, certified to carry 36 people. This then necessitated adapting the design to comply with commercial passenger vessel regulations.

“The vessel will operate in the dock area of the Guadalquivir River in Seville, carrying out one- to two-hour cruises with 100 per cent electric propulsion. It has been specifically designed to host events such as corporate functions, catering services, and private parties on board.”

Pontoon design offering space and stability

The client’s brief called for a pontoon vessel for 36 passengers, arranged on two levels to create two differentiated areas, and with the capacity to accommodate 10 solar panels providing sufficient autonomy for operations on the Guadalquivir River.

Moggaro said the choice of a pontoon-type design was driven by the space and layout advantages it provides, since the entire deck area would be usable.

“The client was specifically looking for a wide and comfortable space to host corporate events, catering services, and private parties. The client already owned a larger single-level pontoon vessel built with box-shaped hulls, which was considerably heavier due to the weight of the material.

“What the client was looking for this time was a more versatile vessel: smaller in size, with two levels to optimise space while offering two distinct areas and the experience of an upper deck. At the same time, the new vessel reduces energy consumption and provides far greater manoeuvrability.”

The vessel is equipped with two Bellmarine 10kW inboard electric motors with shaft drives. The builder said this setup satisfied all the performance requirements for operations under equal or reduced load conditions up to half load.

Electric propulsion allowing for continuous navigation

The vessel is also fitted with 10 solar panels of 550 W each, 10 Pylontech 5kW lithium batteries, and a Victron 250Ah solar charger that regulates the solar panel output to charge the batteries at 48 V. A Victron 5.5kW inverter/charger converts 48 V DC into 220 V AC for onboard use, while also allowing shore power at 220 V to be converted into 48 V DC to recharge the batteries.

“The maximum expected speed is five knots at the continuous maximum power of the motors, with a clean hull, tanks at 50 per cent, wind below Beaufort Force two, and only the two crewmembers on board,” Moggaro said. “During trials, the vessel’s displacement was estimated at 8.2 tons. At maximum displacement (i.e., 10.84 tons), the maximum achievable speed is estimated at five knots.”

For the shaft exits, the stern sections of the cylindrical hulls were modified with a conical shape. This was in order to improve water flow towards the propellers and to enhance manoeuvrability.

The vessel’s key features include a bathroom with a washbasin, toilet, and blackwater and freshwater tanks; aluminium seats; a custom-built aluminium spiral staircase providing access to the upper deck; a sliding canopy on the main deck and a bimini top on the upper deck; and an onboard sound system for entertainment.

Reconfigurable onboard layout

“The benches on the main deck have been specifically designed to be moveable, allowing for two different seating configurations,” Moggaro told Baird Maritime. “The deck surface, laid over the structural aluminium profiles, is made of high-quality polymer composite planks with a wood-like finish, offering excellent abrasion resistance and durability.”

As the planks are installed with a 6mm gap between each one, wash-down water drains directly through the slats into the sea, making cleaning easier and ensuring the deck remains dry at all times.

The electronics consist of an Icom IC-M330GE VHF radio with DSC, IPX7 protection and integrated GPS together with an Em-Trak B953 class B AIS transponder with a 5W splitter, Victron smart chargers, and a Mass Plus DC/DC converter charger.

The safety equipment meanwhile includes 16 lifebuoys and a fire detection and alarm system. The latter has a central control unit and detectors installed in the engine compartments, the bathroom, and the wheelhouse.

Additional features to enhance safety

“The greatest challenge [in designing the vessel] was meeting the stability requirements,” Moggaro remarked.

”In order to provide a spacious area for passengers and ensure comfortable and safe access to the upper deck, most of the equipment had to be positioned aft (including the bathroom, the electrical and battery room, the upper deck, the engines, the rudders, and the helm station). For access to the upper deck, we chose a spiral staircase, as it offers greater safety against falls when compared to a traditional staircase.

The builder explained that, with cylindrical hulls, the very geometry of each cylinder means that the initial immersion offers little buoyancy until nearly 30 per cent of the diameter is submerged, which can negatively affect stability.

“Since the vessel was more heavily loaded at the stern, we had to design external box-shaped extensions that embraced the cylindrical hulls, giving them a nearly rectangular profile from midship to the stern. This solution improved stern stability and allowed us to meet the required stability criteria.”

Since the vessel was built from independent units (three cylindrical hulls joined by aluminium profiles) and required extensive welding to connect the cylindrical hulls to the deck, one of the main challenges encountered by Moggaro was maintaining precise alignment and positioning of these elements in order to avoid deformations that could transfer to the deck.

"On this type of pontoon vessel, the deck must remain completely horizontal," Moggaro told Baird Maritime, "and any misalignment is far more noticeable than on a monohull, which is built as a single block where deformations are less evident.

"In addition, as the vessel also incorporates a superstructure built entirely from straight aluminium profiles, it was essential to prevent any deck distortions from being transmitted to the superstructure. For this reason, we took extra precautions to ensure the most accurate possible layout of the hulls and deck structure, allowing us to continue with the superstructure construction in line with the project’s exact dimensions.”

Moggaro learned through this vessel project that with such long cylindrical hulls and extensive aluminium profiling, not built as a single block but as an assembly of independent pieces, it is crucial to carefully control the welding processes to avoid unexpected deformations.

The company also learned the importance of anticipating the joining solutions of the aluminium profiles by designing removeable parts that facilitate assembly.

“In this particular vessel, because it had to be transported by road, it was necessary to dismantle the entire upper deck railings and the spiral staircase. This required us to create a kind of ‘puzzle’ with the profiles so that everything would fit together precisely during construction, while also planning the areas that would need to be dismantled for transport and later reassembled at the destination.

“All of this was designed so that the operation could be carried out in the shortest possible time and with minimal impact on the installed systems.”