VIBRATION ISOLATION OF A KEEL COOLED YANMAR 3GM30 ON A HISTORIC DUTCH SAILBOAT

Right ‘Zuiderzee’ HL38, sailing on the Dutch coast near Medemblik.

2 marine engine mounts ELLEBOGEN 75 (Ref. 128270-08341) and 2 marine engine mounts ELLEBOGEN 100 (Ref. 128377-08351)

The Sailboat was designed by J.K. Gipon and constructed by De Scheepsbouwers in Werkendam.  The overall length of the boat is 26,24 ft /8m, with a beam of 10,4 ft / 3.2 m. The displacement of the boat is 14,330 lbs / 6500kg with a draft of 2.9 ft / 0,9 m. The model of boat is called “Staverse Jol”. In early days this type of sailboat was used to fish eels, anchovies and herrings on the Zuiderzee. The Staverse Jol is an open boat with a shallow and fully continuous keel.

Although these type of Sailboats looks a bit clumsy, they have been praised for his seaworthiness. Their remarkable shape is created in consultation with the fishermen. They are very stable ships with completely smooth edges, so that the nets could be retrieved without the risk of damage along projections or mountain woods. In addition, edges bend inwards, which makes work on and with the nets easier. We also can observe a transom, attached rudder and a shallow keel for sailing, which extends the entire length of the ship. Due to its displacement, this sailboat needs wind, which in this area is frequent. From wind force 5 to 6 a reef goes into mainsail. The max speed is 6.5 knots.

The word Zuidersee meaning “southern sea” is located between Holland and Friesland, as seen on the below map.

Below a drawing of this type of sailboat.


The Sailboat is powered with a Yanmar 3GM30 with a keel cooling system.

Setup of the engine.

The sailboat already had some marine engine mounts installed of the engine. Although the engine mounts where periodically cleaned and well maintained, these engine mounts were showing too much deflection (Gap below 5mm as indicated on the right image below). This fact made that the engine was moving excessively, specially at low revs. This fact motivated the replacement of the old marine engine mounts to a brand-new set of Ellebogen marine engine mounts.

A Yanmar 3GM30 marine engine is a 3-cylinder engine.  These types of engines tend to generate more vibration than 4-cylinder engines due to their uneven masses in movement that generate more eccentricity and therefore vibration. Also, the fact that 3-cylinder engines have a lower disturbing frequency than 4-cylinder engine. The main disturbing frequency of a 3-cylinder engine is normally the order 1.5 whilst on a 4-cylinder engine the predominant frequency is the order 2.

Lifting the engine for flexible engine mount replacement

The system for lifting the engine was simple as the sailboat has a phenomenal access to the engine. The use of a transversal wooden bar and several pulleys allowed a clean lift of the engine.

The below image shows the engine with the new flexible engine mounts from Ellebogen. The bilge was already clean but after the replacement of the marine mounts received another session of cleaning.

The Alignment was done 48h after putting the new mounts. The careful process of alignment was done step by step following the rules indicated on this link https://www.ellebogen.com/en/engine-bed-flatness-and-correct-process-for-alignment/

Lifting the engine for flexible engine mount replacement

Here is a video of the new flexible engine mounts once they have been installed and received the correct alignment.

It is always pleasing to receive a message like this:

Keel cooling system.

The Yanmar 3GM30eu (2002) has keel cooling and a dry exhaust. Keel cooling is also called “closed” cooling. The coolant flows through the cooling water spaces of the engine, and then flows through a tube or a bundle of pipes under the ship through the keel, where is cooled by contact with the outboard water.

On this sailboat, on flatbottom and keel runs on sb and bb a 3-meter-long steel strip that is filled with coolant. The impeller pump sucks in the coolant and pumps it through the engine/exhaust manifold and then it runs back into the strip and cools. This goes on constantly.

Advantage: always cooling, protection against corrosion and frost up to -36 degrees, and no contamination of the cooling ports.

Rebuild process report.

Robert van Heyst has published a very comprehensive report on all the steps of the rebuild of the sailboat. Full information can be seen on the link below:

https://www.ssrp.nl/stamboek/schepen/zuiderzee-hl38-2044

The report follows the steps of the build from the hull construction, through internal furniture creation until the  result. Real ly interesting reading.


For those who are interested on this topic I also leave a couple of links related on this matter.

Staversee Jol Foundation: https://www.staversejol.com/over-stichting-de-staverse-jol/

Sailing rental company in this area: https://www.heechbydemar.nl/

We wanted to express our thanks to Mr Robert