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While engine mounts may appear alike, they do not necessarily deliver identical engine performance. The mounts’ design significantly influences the vertical, horizontal, and longitudinal stiffness since the amount and sections of rubber per direction vary. Although this may seem trivial, low mounting positions can lead to engine instability and easy movement, even with manual exertion.
In this article, we will examine a scenario where we experimented with three different types of mounts until we arrived at an effective solution. Mr. Victor Canela from Sistemas Navales (http://www.sistemasnavales.es/), a company specializing in the restoration of high-end sailboats in Barcelona, made this article possible.
The Oyster Yachts shipyard, based in the UK, is one of the most well-respected yacht builders in the world. With a long history dating back to 1973, Oyster has built over 400 yachts, ranging in size from 40 to 125 feet, and has won numerous awards for their craftsmanship and attention to detail.
The Oyster 435 is a classic sailing yacht that was first introduced in 1983 by the renowned British yacht builder, Oyster Yachts. This model was produced until 1988, with approximately 60 vessels built during that time. The Oyster 435 was designed by Holman & Pye, a renowned naval architecture firm, and was intended to be a bluewater cruiser, capable of sailing long distances in comfort and safety. The yacht has a sleek and elegant appearance, with a distinctive low profile and a spacious cockpit that is ideal for entertaining and enjoying the outdoors.
At 43.5 feet in length, the Oyster 435 offers plenty of space for living and sailing, with a beam of 13.5 feet and a displacement of around 28,000 pounds (12700Kg). The yacht is constructed of high-quality materials, including hand-laid fiberglass and a teak deck, and features a classic sloop rig with a fully battened mainsail and a roller-furling genoa. Inside, the Oyster 435 offers a comfortable and well-appointed living space, with teak joinery throughout and a spacious saloon with plenty of seating and storage. The yacht has three private cabins, including a spacious owner’s cabin aft, and two heads with showers.
One of the standout features of the Oyster 435 is its sailing performance. The yacht is designed to be easily handled by a small crew, with all lines led aft to the cockpit, and features a powerful rig and a deep keel for excellent upwind performance. At the same time, the yacht is comfortable and stable in a variety of conditions, making it an excellent choice for long-distance cruising.
The Perkins 4.108 is a popular marine engine that was first introduced in the late 1960s and continued to be produced until the early 1990s. It was designed specifically for use in marine applications, including in sailboats, trawlers, and small commercial vessels. The 4.108 is a four-cylinder, naturally aspirated diesel engine with a displacement of 1.8 liters (108 cubic inches). It is known for its reliability and durability and has a reputation for being one of the most reliable engines in its class. With regular maintenance, the 4.108 can provide many years of trouble-free service.
One of the key advantages of the Perkins 4.108 is its simplicity. It is a straightforward engine with a mechanical fuel injection system, making it easy to maintain and repair. It has a reputation for being relatively easy to work on, and parts are widely available.
The 4.108 is rated at 50 horsepower at 4000 RPM and has a torque output of 100 lb-ft at 2000 RPM. It is often paired with a reduction gearbox to drive a propeller. Overall, the Perkins 4.108 is a well-regarded marine engine that has stood the test of time. Its combination of reliability, simplicity, and durability make it a popular choice among sailors and commercial vessel operators alike. While it may no longer be in production, there are still many of these engines in service around the world, and they continue to provide reliable power to a wide range of vessels.
September 2022. Mr. Victor Canela from Sistemas Navales is doing the refurbishment of the Oyster 435 and is experiencing some problems with the Perkins 4.108. The original mounts are not easy to find, and an external company has recommended to install some mounts that dimensionally seem similar. Below some pictures of the mounts in place and those who could fit in place.
Based on the calculations conducted on the new mounts, they are capable of withstanding the vertical load. Additionally, the metrics are comparable, and although the footprint is similar, adapter plates can be used to fit them, as illustrated in the image below.
Below a picture of the new mounts installed. The mounts are fitted although the hole centers of the mounts are not fitting ideally.
The below video shows the movement of the engine when moving it with his hands.
On a 6 degrees of freedom calculation, we can make a mathematical model of the engine, including the height adjustersâ height and input forces, and get the displacement of the suspended element on the Centre of Gravity.
Based on a force 3G at 20 ms of duration we get the following displacements with the original mounts that victor was testing (similar to the Ellebogen GTS 65). The displacements show +/- 8 mm of radial movement (Y Direction)
If we do the same exercise but with the Ellebogen GTM 55 and with the lower height adjustment that we have on these mounts. We get the following results:
As it can be seen the displacement is reduced to the half, especially in lateral direction (Y direction).
The Installation of the Ellebogen GTM 55 mounts allowed a much lower levelling. Althought the overall stiffness of the mounts are higher, the isolation values are correct for the sailboat owner and the movement of the engine is reduced. On the below video we can see an steady behaviour of the engine.
The renovation of a >35years old sailboat is a serious project. These types of projects require time, skilled knowledge, patience and constant work. All these adjectives can be summarized as the name of the sail vessel, âPerseveranceâ. A very appropriate name for this beautiful Oyster Sailboat.
The level of exquisite work that has been done on the engine mounts, is a representative example of how this Sailboat has been refurbished by www.sistemasnavales.es and particularly by the naval engineer, Mr. Victor Canela.Â
For those interested in following his work, you can find their social media details on the below links.
