Manecraft Deep Sea Seals

Manecraft Deep Sea Shaft Seals: Proven Reliability, Built on Marine Engineering Heritage

The Manecraft Deep Sea Shaft Seal is not just a modern upgrade for traditional stuffing boxes — it’s a continuation of British marine engineering expertise. Originally designed by Deep Sea Seals Ltd. (DSS) in the 1970s, these face-type shaft seals were widely used in naval and commercial vessels. Following DSS’s acquisition by Wärtsilä in 2002, the product family became part of a global propulsion solutions group.

Today, Industrial Rubber Ltd., based in the UK, is the trusted manufacturer of Manecraft shaft seals. With over 15 years of continued production, they ensure every unit meets high marine standards. The result is a reliable, water-lubricated shaft seal trusted by both commercial operators and leisure users alike.

If you're seeking a clean, low-maintenance, and high-performance sealing system — Manecraft delivers.

Cutaway view showing internal components of the Manecraft shaft seal

Why Choose Manecraft?

Choosing the right shaft seal is critical for long-term reliability and vessel performance. Manecraft seals stand apart by combining decades of marine sealing heritage with modern materials and manufacturing. Whether you’re fitting out a new build or upgrading from a worn-out packed gland, Manecraft offers a proven, low-maintenance solution that’s trusted by commercial fleets, leisure craft, and professional installers alike.

 
1. No Shaft Wear: Bronze face seals against a rotating collar — zero metal-on-metal damage.
2. Emergency Clip: Factory-fitted red compression clip can seal water ingress instantly.
3. UK Manufacturing: Made and tested by Industrial Rubber Ltd.
4. Simple Installation: Fits directly to sterntube and shaft — no custom machining needed.
5. Seawater Cooled: Water injection port cools the seal during operation.

Watch the Seal in Action

CAD Simulation highlighting the construction of the Manecraft shaft seal

What’s Included in Your Kit

Every Manecraft seal kit is shipped complete and ready to install — no hidden extras or custom parts required. From the pre-fitted emergency clip to the vent and water injection fittings, each component is designed for straightforward installation and long-term reliability. Whether you’re working in a workshop or afloat, the included compression gauge and printed instructions ensure correct alignment and seal pressure every time.

1. Pre-assembled seal housing with emergency clip
2. Rotating collar (EM or EY series)
3. Vent line and clamps
4. Water injection fittings
5. Compression gauge for setup
6. Printed instructions

Vent and Water Injection Setup

The seal is water-lubricated and includes a vent line to prevent air locks. The vent must be routed vertically above the waterline. A seawater flush line must be connected from the engine cooling system to the injection port on the seal body.

Water flow layout for the EY Manecraft Deep Sea Seal

Choosing the Right Series: EM vs EY

When selecting the right Manecraft shaft seal for your vessel, the choice typically comes down to two series: EM and EY. Both share the same core sealing technology and high-quality materials but are optimised for different vessel types and operational demands.

The EM Series is best suited to leisure craft, sailing yachts, and light-duty motorboats. These units are more compact, easier to install in tight engine bays, and provide quiet, vibration-free operation. They're engineered for shaft diameters up to 100 mm and perform reliably at cruising speeds up to 25 knots — perfect for recreational use or smaller commercial vessels with moderate propulsion loads.

The EY Series, on the other hand, is designed for demanding environments including high-speed planing vessels, offshore workboats, fishing boats, and heavy-duty commercial applications. These seals feature a larger, more robust housing and a thicker seal face (13 mm) for increased durability, better handling of engine misalignment, and superior performance under prolonged high-load conditions. If your vessel operates in rough seas, runs long duty cycles, or needs extra tolerance for shaft vibration, the EY series is likely the better choice.

Both EM and EY models include a built-in emergency sealing clip, are water-lubricated, and require no grease or frequent adjustment. If you're unsure which is best, our technical team can help assess your vessel's shaft diameter, sterntube size, and operating conditions to guide your selection.

EM Series Sizing Guide

Model	Shaft Dia IN	Shaft Dia mm	Sterntube OD IN	Sterntube OD mm
EM SET 2	1.0 to 1-1/4	25 - 30	1-3/8 to 1-5/8	35 - 43
EM SET 3	1.0 to 1-1/4	25 - 30	1-5/8 to 2.0	43 - 51
EM SET 4	1-1/4 to 1-3/8	30 - 35	1-5/8 to 2.0	43 - 51
EM SET 5	1-1/4 to 1-3/8	30 - 35	2 to 2-3/8	51 - 60
EM SET 6	1-3/8  to 1-5/8	35 - 40	2 to 2-3/8	51 - 60
EM SET 7	1-3/8  to 1-5/8	35 - 40	2-3/8 to 2-3/4	60 - 70
EM SET 8	1-3/4 to 1-7/8	43 - 46	2-3/4 to 3-1/8	70 - 80
EM SET 9	1-7/8 to 2.0	46 - 51	2-3/4 to 3-1/8	70 - 80

EY Series Sizing Guide - Large Imperial

Model	Shaft Dia IN	Shaft Dia mm	Sterntube OD IN	Sterntube OD mm
EY SET 11	2-1/4	58	3-1/8 to 3-1/2	80 - 90
EY SET 12	2-1/2	64	3- 1/8 to 3-1/2	80 - 90
EY SET 13	2-3/4	70	3-1/2 to 4.0	90 - 100

EY Series Sizing Guide - Large Metric

Model	Shaft Dia IN	Shaft Dia mm	Sterntube OD IN	Sterntube OD mm
EY SET 14	2.165	55	2-3/4 to 3-1/8	70 - 80
EY SET 15	2.362	60	3-1/8 to 3-1/2	80 - 90
EY SET 16	2.559	65	3-1/2 to 4.0	90 - 100

Download Fitting Guides

• EM Series Fitting Instructions (PDF)
• EY Series Fitting Instructions (PDF)

Compatible Installation Types 

Manecraft Deep Sea Seals are designed to retrofit a wide variety of stern gland types, whether the vessel originally used a flexible, rigid, or threaded stern tube arrangement. The seal body and bellows are adaptable to different shaft configurations, but correct interface with the stern tube is critical to ensure durability and watertight integrity.

1. Flexible Stern Gland – Common on smaller craft, typically hose-clamped to a GRP or bronze tailpipe. The standard Manecraft seal fits directly with minimal modification.
2. Rigid Stern Gland – Often flanged to the hull or secured with a rigid stuffing box. These typically require a short adapter or alignment correction during retrofit.
3. Threaded Stern Gland – Found on some European production vessels. A threaded adapter bush or flange plate may be needed to achieve correct axial seal face pressure and shaft centring.

 

Illustration of Flexible, Rigid, and Threaded Stern Gland Configurations

Key Compatibility Considerations

1. Shaft Diameter and Stern Tube ID must match the Manecraft seal specifications. Tolerance mismatches can lead to premature wear or misalignment.
2. Mounting Length must accommodate the compression range of the seal bellows — too short, and seal compression will be excessive.
3. Water Injection Point should be verified. If not already present on the boat, a pickup from the engine raw water circuit must be plumbed in.
4. Ventilation Height must always be above the waterline to avoid trapped air and poor sealing performance.
5. Rigid Stern Tubes may require alignment verification or minor lapping to ensure the mating face is true.

Special Note for Retrofitting

When replacing traditional stuffing boxes, bear in mind that older shaft logs may have lip seal grooves or corrosion that should be cleaned and remeasured. Fitting a Manecraft unit over an uneven surface can reduce sealing face life. Always clean, measure, and if necessary, sleeve or bush the area.

Common Fitting Oversights

Manecraft shaft seals are engineered to be straightforward to install, even without specialist tools — but like any precision component, successful performance depends on correct setup. Over the years, a few recurring issues have been observed during onboard installations, particularly when upgrading from traditional packed glands or retrofitting in tight spaces.

These oversights are easy to avoid and often come down to routing or alignment. The following tips help ensure the seal performs exactly as intended, preventing early wear or reduced sealing efficiency. Following the included fitting instructions and using the supplied compression gauge are the most reliable ways to guarantee a professional result.

1. Vent line not routed above waterline — air lock will occur
2. No water injection fitted — seal will overheat at speed
3. Seal overtightened — must match factory-set compression
4. Oil or grease contamination on seal face

Ready to Order or Need Help?

Our technical team can help you choose the right unit. Provide shaft diameter and sterntube OD, and we’ll quote and confirm availability within 1 working day.

Email: data@lancingmarine.com
Phone: 01273 410025