Frequently Asked Questions

Ocean Seals® are stern tube seals engineered by RM Propulsion for reliable marine propulsion performance. They are:

• DNV type-approved
• Manufactured in Europe
• Compatible with major OEM systems
• Suitable for both EAL and mineral oils

Yes. Ocean Seals® are DNV type-approved and comply with international marine standards.

RM Propulsion uses high-quality elastomers, including:

• FKM (Viton®)
• HNBR (Perbunan S®)

Yes. The FKM seals are specifically designed for both EAL oils and mineral oils.

HNBR material is compatible with mineral oils.

The seals are compatible with systems from manufacturers such as:

• Wärtsilä
• Simplex / SKF
• Blohm+Voss
• Kobelco / Kemel
• Lagersmit

Types:

• SKF Simplex® AirSpace, Compact SC-1, Compact 2000, SC-2
• Kobelco® C, CX, DX, AX
• Kemel® C, CX, DX
• Wärtsilä® Airguard, MK-2, OLS2, OLS3, OLS4
• Lagersmit® Supreme Seaguard Ventus
• Lagersmit® Supreme
• Lips® MK-2
• John Crane® MK-2
• Waukesha® MK-2
• Chuetsu® MK-2
• Dover Japan® MK-2
• JMT (Japan Marine Technology®) MK-2
• Deep-Sea Seals® MK-2

We offer a global service. Anywhere our service engineers can reach you without a visa, or if we can organise a visa with customer help, we can offer our service.

Our engineers are based in:

• The Netherlands
• Tallinn, Estonia
• Shanghai, China
• Turkey

Not necessarily.

We usually work in the dry-dock for practical reasons. However, when circumstances require us to work afloat or help with an underwater repair, we will,  if it is possible for your vessel and safe for our staff.

In order to perform afloat repairs of the aft seals, the stern tube has to be trimmed at least 0,5 metres out of the water. This means trimming down the forward side and lifting the aft side out of the water.

However, this puts extra strain on the vessel’s structure. It is therefore crucial that afloat repairs can be carried out in calm water, preferably without swell or waves from passing boats.

Forward seals can be replaced with minimal or no trim, but you must be certain the aft seals are not leaking.

The crew of a vessel and its technical department will be able to calculate whether the vessel can trim far enough to perform the repair. In some cases, pumps are required for cooling if the sea chests are trimmed out of the water.

Many tankers and bulk carriers will be able to trim enough for an afloat repair, but this is less common for container vessels.

When problems arise, you may not have time to check the manufacturer’s manual for answers. (Although your crew should always be able to refer to it.)

We know almost all manuals off by heart, so reach out to us with any questions via our contact details above.

Whether or not we have worked on your system, we are happy to help. In many cases, we will be able to guide your crew through the best way to manage the situation.

If not, we can give you transparent recommendations on what your next steps should be, based on our many years of experience.

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Absolutely! Our stern tube seal services and parts come with a one-year warranty. Our propulsion services and parts come with a six-month warranty.

In an ideal situation with proper preparation, organization, and planning, an overhaul of aft and forward stern tube seals using the bonding method can typically be completed within 3–4 days. This is the basis of our standard quotation.

However, the actual duration and final costs depend heavily on the condition of the equipment and the working circumstances on site.

The most important factors for an efficient project are:

• Proper preparation
• Clear communication of the scope of work
• Good drydock planning
• Availability of manpower, tools, and yard support

During the project, unforeseen circumstances may occur that can prevent our service engineers from working continuously, such as:

• Stern tube oil not drained prior to arrival
• Weather conditions
• Lack of scaffolding or staging
• Sandblasting activities in the working area
• Liners requiring machining due to grooving or pitting
• Replacement liners or other spare parts that need to be ordered
• Additional damaged parts discovered during dismantling
• Lack of suitable tools or machinery
• Insufficient manpower or support from crew, yard, or subcontractors
• Delays caused by other contractors or drydock activities

Due to the above-mentioned circumstances, the final invoice may be higher than originally quoted.

Recommendations to help the project run smoothly

• Review the vessel’s previous service reports before drydock and check for recommendations
• Inform RM Propulsion in advance about any leakage, vibration, or operational issues
• Ensure stern tube oil is drained before mobilization when required
• Confirm the availability of cranes, scaffolding, and support personnel
• Read the preparation document provided by RM Propulsion before the project starts

Proper preparation and planning help minimize delays and ensure the work can be carried out as efficiently as possible.

Please note that our quotation is based on estimated work under normal and well-prepared conditions. The final invoice will be recalculated based on the actual travelling, working, standby days, spare parts used, additional repairs, and related expenses, according to the signed timesheets.

RM Propulsion supports many major thruster brands, including:

• Rolls-Royce
• Kongsberg
• Brunvoll
• Berg
• Kawasaki
• Schottel
• Wärtsilä
• Kamewa
• Ulstein
• Nakashima
• etc.

RM Propulsion services a wide range of marine and offshore thruster systems, including:

• Tunnel Thrusters
• Bow Thrusters
• Stern Thrusters
• Azimuth Thrusters
• Retractable Thrusters
• etc

RM Propulsion works with a wide range of vessels, including:

• Cruise vessels
• Tankers
• Container vessels
• Cargo ships
• Tugs
• DP2 vessels
• Offshore Support Vessel
• Anchor handling vessels

Most classification societies require overhauls every:

• 5 years
• 10 years (major overhaul)

The duration of a thruster service depends on several factors, including the brand and type of thruster, whether it is a 5-year or 10-year overhaul, the number of thrusters being serviced, and the overall scope of work.

Turnaround time is also influenced by drydock planning, the number of propulsion engineers involved, shipyard support capacity, available tooling and lifting equipment, and spare part availability.

Minor maintenance can be completed within a few days, while major thruster overhauls during drydock may take several weeks.

The clearer the customer defines the scope of work, the more accurate and realistic RM Propulsion can make the quotation and planning.

However, due to the condition of components and findings during dismantling and inspection, the exact scope and turnaround time can never be predicted with complete certainty.

All in all, the duration depends on many different factors. However, thanks to RM Propulsion’s extensive experience with thruster services and overhauls, we are able to provide reliable estimates and efficient project planning.