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ENGINE MOUNT REPLACEMENT ON A YANMAR 1GM10 WITH ELLEBOGEN 50-70 MOUNTS

CASE STUDY: ENGINE MOUNT REPLACEMENT ON A YANMAR 1GM10 WITH ELLEBOGEN 50-70 MOUNTS.

Sailboat: Beneteau first 26, moored in Dana Point Southern California

Some information of the engine

The Yanmar 1GM10 is a compact, single-cylinder marine diesel engine introduced by Yanmar in the 1980s as part of the GM series, which succeeded the earlier YSM engines. It quickly became a popular choice for small to medium-sized sailboats thanks to its quiet operation, improved performance, and ease of maintenance.

The GM series represented a modernization of Yanmar’s earlier engine lines, with design improvements aimed at reducing vibration and enhancing user comfort. The 1GM10 was especially favored for its balance of power and size, making it an ideal auxiliary engine for sailboats.

This model remained a staple in Yanmar’s lineup for many years, valued for its fuel efficiency, reliability, and the widespread availability of spare parts.

Technical Specifications

  • Model: Yanmar 1GM10
  • Type: Single-cylinder, 4-stroke, water-cooled diesel engine
  • Displacement:318 liters (318cc)
  • Power Output: Around 9 HP (horsepower) at approximately 3,600 RPM
  • Cooling System: Water cooling (early versions), with optional fresh water cooling in later models
  • Fuel System: Mechanical fuel injection
  • Weight: Approximately 85–95 kg (187–210 lbs), depending on configuration
  • Transmission: Usually paired with Kanzaki gearboxes (KM2A or similar)

Some information of the sailboat

The Beneteau First 26 is a 26-foot cruiser-racer sailboat designed by Jean-Marie Finot of Groupe Finot. It was built by Beneteau (France) from 1984 to 1991, with approximately 300 units produced. As part of Beneteau’s performance-oriented First series, the First 26 was intended for coastal cruising and club racing. 

Finot’s design emphasizes maximizing space and comfort in a small hull – notably by incorporating features like a true aft cabin and a separate forward cabin, which is unusual for a boat of this size. The First 26 is often described as a versatile family cruiser that can also deliver racing fun, embodying a blend of cruising comfort and sprightly performance

Specifications

  • Length Overall (LOA): 26.3 ft (8.02 m)
  • Length at Waterline (LWL): 22.9 ft (6.98 m)​
  • Beam: 9.2 ft (2.80 m) – provides decent interior volume for a boat this size.
  • Draft: 4.3 ft (1.31 m) standard fin keel Optional swing keel model: ~2.8 ft (0.85 m) board up, 5.7 ft (1.75 m) board down for improved windward performance when extended​
  • Displacement: 4,814 lb (2,184 kg) for fin keel version
  • Ballast: 1,455 lb (660 kg) for fin keel version
  • Sail Area: Approx. 291 sq ft (27 mÂČ)
  • Rig Type: Masthead sloop (Bermuda rig), deck-stepped mast​.

 

Construction & Design Features

Fiberglass (GRP) hull and deck. The deck is a balsa-cored fiberglass sandwich for stiffness, with polyester resin, and the hull has wood trim finishes

Interior & Comfort

The Beneteau First 26 offers a surprisingly spacious interior for its size, sleeping 4–5 people comfortably. It features two private cabins—one forward and one aft—plus an optional berth in the main salon. The central salon includes opposing settees and a fold-down table, with good natural light and ventilation. A compact but functional galley includes a stove, sink, and icebox. The layout also includes a separate head, a dedicated navigation station, and plenty of storage, all rare features in a 26-foot sailboat.

Performance & Sailing Characteristics

The Beneteau First 26 is a fast and agile boat with a hull speed of around 6.4 knots.

Its generous sail plan and balanced design offer strong light-air and upwind performance. A spinnaker boosts downwind speed, making it competitive in club racing fleets. It’s well-equipped for sail control, yet easy to handle by beginners or shorthanded crews. With lines led aft and tiller steering, it’s ideal for confident solo or couple sailing.

Initial situation of the engine

The sailboat owner cleans the engine compartment and proceeds to replace the old engine mounts. He stated, ‘Surprise! The engine mounts on my boat were not the originals; they are much larger than the Ellebogen 50-70 ones. When lifting the old ones, I found the hole where the original base screw went at some point in my boat’s history.’

Replacement to the Ellebogen 50-70

Before starting disassembly, he placed a wooden piece under the engine to keep it in position while allowing for a bit of movement. He used an empty water bottle with the cap on. He began by removing the base screws, followed by the screws that attach the engine leg to the engine. Once all four screws were out and the engine was supported by the bottle, the old engine mount and the engine leg came off together. The front port engine mount was now removed. The base was heavily rusted, and quite a bit of debris came out during removal. The base has three openings in the vertical section facing the bilge to access the screw nuts:

  • The rear opening allows access to the rear screw of the rear engine mount.
  • The central opening provides access to the front screw of the rear mount and the rear screw of the front mount.
  • The front opening gives access to the front screw of the front mount.

Before replacing the mounts, the screws at both ends didn’t line up well with the openings, making them difficult to reach. After installing the new mounts, accessing the nuts became much easier. He adjusted the height of the new mount using the old one as a reference.  He noted that at this point, one has to be careful with the positioning of the engine leg when mounting it, one must pay attention to the round hole and the oval hole, which provides the necessary play for alignment. He made a mistake here and only noticed it after tightening it to the base. He then placed the Ellebogen engine mount on the base (without tightening the base nuts) and got it ready to attach the leg screws to the engine block.

Ideally, one should replace the engine mounts one at a time to help the engine keep its position and make alignment easier. In his case, because the new base holes didn’t match the old ones, he had to shift the engine back a couple of centimeters, which meant that he lost all previous alignment reference. After mounting them all, one must wait a couple of days for them to settle well and be able to do the alignment. The Ellebogen 50 -70 mounts were levelled respecting the height of the precedent mounts being installed on the engine.

VIDEO: BEFORE and AFTER

The sailboat owner filmed a video to showcase the engine’s condition before and after installing the new mounts. The footage below compares the engine performance with the Ellebogen 50-70 mounts.

The upgraded setup is tested during engine start and stop. The Ellebogen 50-70 mounts provide effective vibration isolation and improved stability in these moments.
The sailboat owner expresses clear satisfaction with the results, which is truly rewarding to see.

The sailboat owner is from Cådiz area, in the Andalusian region of the south of Spain. This area is close to the Strait of Gibraltar, known for its excellent tuna. He presented Ellebogen with some premium red tuna products from the brand Herpac.  We took the opportunity to make a great salad with them.