Article by ONBOARD Magazine
WHETHER YOU’RE LOOKING FOR A SOLAS, UTILITY RIB OR A LIMOUSINE, YOU SHOULD CONSIDER THE JET OPTIONS AVAILABLE. MANOEUVRABILITY, SHALLOW DRAFT AND OVERALL SAFETY ARE JUST THREE OF THE MAIN ADVANTAGES
We can thank a young engineer from New Zealand for producing the world’s first commercially successful marine jet engine. In 1954 William Hamilton was asked to design a vessel to cope with the shallow fast-flowing rivers around Christchurch.
He investigated the American Hanley Hydro-Jet, a model which drew in water and fired it out through a steerable nozzle underneath the boat. Even when further adapted it did not work well. A colleague suggested moving the nozzle to just above the waterline. Throughout the late 50s and early 60s Hamilton continued to develop the successful business which is now known as Hamilton Jet and Hamilton Marine. However, when asked how he came up with the idea Bill Hamilton said, “I do not claim to have invented marine jet propulsion. The honour belongs to a gentleman named Archimedes, who lived some years ago. I simply refined the design.”
Waterjet propulsion has many advantages over other forms of marine propulsion, such as stern drives, outboard motors, shafted propellers and surface drives. These advantages include reliability as the waterjets have fewer moving parts and most major components inboard, minimising the chance of accidental damage and increasing the life of components. The engines give the boats excellent manoeuvrability and precise steering control at any speed. With a zero speed steering effect providing 360° thrusting ability for docking and holding stationary. The engines tend to deliver excellent speed (dependent on the vessel) with the waterjets designed to be optimised for speeds from 25-50 knots, dependent on application’s engineering variables including hull resistance and type, engine power rating and rpm, impeller rating, etc.
The drive units are highly efficient with propulsive coefficients as good or higher than the best propeller systems achievable at medium to high planing speeds, and by their very nature cause less drag and have a shallow draught with the absence of underwater appendages and propellers reducing hull resistance. In a shallow draught – the waterjet intake is flush with the hull bottom to allow access to shallow water areas and beach landings with no risk of damage to the drive.
The engines on the whole tend to have little downtime and simple maintenance routines are smooth, quiet and give little hull vibration, no torque effect and no high speed cavitation giving maximum comfort levels on board.
The jet engines offer more safety for people and other marine life in the water around the boat. The engines are simplicity personified with a single packaged module with no heavy and expensive gearbox required for many installations. It’s simply a driveline from engine to jet coupling.
More tender brands are getting on board with jet engines and with some serious developments in marine diesel outboards, Yanmar are one company who are developing some great new diesel jet packages with Williams.
There is no need to compromise on comfort when it comes to tenders. At Yachtwerft Meyer, they have found it challenging to achieve minimum noise levels for the tenders. While these are standard in the automotive industry, many tenders give you the feeling of being in a helicopter under way rather than silent comfort. One main focus for these incredibly advanced 9,2m D-Rib tenders was noise reduction; the tenders use Rolls Royce jet drives and 400hp Volvo engines. No stone was left unturned and with German engineering diligence, every aspect of the came in for close scrutiny. Working from the engine beds to the air intakes and outlets – and
the engine capsules, examining structure-borne sound airborne sound – no element was left untouched. The result was an amazing 66dBa at the helmstation when the boat is travelling at over 40 knots! An incredible achievement when you consider that at this speed the biggest noise component is wind noise from headwinds.
For more details Tel: +49 (0)421/ 98 50 39 50
or visit www.yachtwerft-meyer.com
SAY CARBON YACHTS
RIBs, or rigid-inflatable boats, are lightweight, easy-tosteer and very safe. The combination of the tried and tested RIB design and the ultra-light carbon hull redefines performance in this type of boat. At 13.70 metres long, the SAY45 RIB is very spacious and approved for up to passengers. The D-shaped air tube allows impressively easy handling in the port and maximum safety on the open water. When fitted with a Diesel inboard engine with jet drive, the low hull draught makes the SAY45 RIB perfect for shallow water. The suspension seats, first-class cockpit equipment and a comfortable sundeck make your stay on board extra comfortable. Below deck, a
relaxing rest area including bathroom creates a luxurious atmosphere. commercial use, or for use as a tender for superyachts.
For more details Tel: +49 7520 96 99 00
or visit www.saycarbon.com
Rib-X offers the world’s largest range of SOLAS approved traditional RIB style tenders in 5.0m, 5.5m, 6.0m, 6.5m, 7.0m, 7.5m, 8.0m and D-Tube tenders at 7.0m & 7.5m. Rib-X also offer a custom design service for SOLAS tenders. Using their extensive experience, they know the challenges faced in obtaining approvals for custom SOLAS tenders. Regulations affect virtually every component on a SOLAS approved tender, from the hull construction, the systems, engines, equipment, tubes etc all have to be built to exacting standards, there needs to be assurance of quality control throughout the entire build process through established and approved
manufacturing standards and processes. The standards are exceptional for a reason and they believe that working within the stringent regulations should not preclude an owner from obtaining a custom approved tender. All Rib-X tenders are designed and hand built in the UK by a specialised team of professionals. The jet option on the SOLAS tender is a Volvo Penta D3 with Hamilton 213 Jet.
For more details Tel: +44 (0)1162 477 017
or visit www.rib-x.co.uk
Designed for the superyacht market, and equipped with either stern drive or jet drive, PIRELLI tenders have a reduced height to perfectly fit the yacht’s garages. The straight line exclusive design allows full customisation, to match the mothership. Tecnorib began life in 2005, with a mission to design, build and distribute a new range of Pirelli-branded rigid inflatable boats. The first tender launched in 2006 was the 770. From 2017 the relationship between Tecnorib and Pirelli is managed within the Pirelli Design project. Jet engine options include the Rotax gasoline jet engine and Yanmar jet diesels.
For more details Tel: +39 02 72080357
or visit www.tecnorib.it
After introducing their first jet tender back in 1991 and delivering revolutionary tenders to the superyacht market, Zodiac Nautic is committed to exploring the future of sustainable boating for our industry. Together with the world leading engine manufacturers Torqeedo, Avon developed the eJet450, a 100% electric tender. No need to carry fuel, no changing the oil, low maintenance costs and great reliability. The tenders are equipped with the most advanced 55kW Deep Blue electric engine from Torqeedo and the latest generation of automotive batteries (used in the BMW 3i) The eJet gives a 90 minute range at 23,knots with a top speed of 31
knots thanks to revolutionary Hydrojest technology. The eJET 450 uses a 55Kw electric engine powering a custom carbon-made hydrojet developed by Zodiac and its partners.
For more details contact email@example.com
or visit www.avon-tenders.com
CASTOLDI JET TENDER 21
Jet Tender 21 is equipped with many exclusive features such as: the new deep V 24° light and strong hull made in Kevlar single skin construction, for a more comfortable ride in rough seas; the re-designed bow landing stepped ramp; the digital switching on multifunction 9’’ display; the recessed bow shelter with two working positions, the perimetrical recessed RGB lights and the propulsion system made by Yanmar 4LV 250 mHP matched to Castoldi Turbodrive 240 H.C. waterjet, giving a top speed of 37 knots. In , within the Castoldi range of jet tenders, there is one to suit every sized yacht.
For more details Tel: +39 029401881
or visit www.castoldijet.it
EXTENDER EXT 640
Extender are first folding tenders with rigid keel made of rubber and fibreglass designed to occupy reduced space on board and to offer more space once unloaded to water. They fold up easily in less than two minutes thanks to the patented closing system and are totally customisable in colours, finishing, accessories and lengths. They are engineered for every use, from the biggest outboard model EXT 645 (4,05 once closed), EXT 610 (3.90 m once folded), EXT 560 and EXT 520 (3.30 folded) and the family EXT 430/460/490 (2,70m – 3,00m – 3,30m folded) available also in version S with a min. height of 0,85m at aft and 0,95m at bow thanks to an innovative
Tags: AVON EJET450, CASTOLDI JET TENDER 21, EXTENDER EXT 640, Jet Tenders, RIB-X, SAY CARBON YACHTS, TECNORIB, Yachtwerft Meyer
engine rotation system. Within the Extender family is a hydro-jet engine model, the EXT 640 Idro (4.30m folded). The width of the space on board allows comfortable seating for 12 passengers plus a driver.
For more details Tel: +39 0375 968490
or visit www.tender-extender.com