H4 Marine Limited innovation in technology

The above system is a self contained unit that transfers power from the engine to the prop more efficiently and with less turbulence than a traditional open shaft, whilst also reducing noise and vibration dramatically. It is a shaft within a tube containing a bulkhead through hull mounting and thrust assembly.

How is it more efficient?

Running the shaft in oil and on needle roller bearings in one shaft results in reduced losses when compared to drives that change the direction of the drive such as V drives, pods and stern drives or when shafts are run in rubber bearings and through stern glands. A more efficient system is also cooler and quieter.

Isolated drive loads.

Taking thrust directly to the hull structure rather than the engine and its mounts has long been a source of reduced noise and less vibration Seatorque includes this feature and is either bolted to the through hull moulding or to an internal bulkhead. By isolating the engine from thrust loads the engine floats freely, softer mounts can be used less noise is transmitted.

The Seatorque unit is coupled to the engine using current automotive technology with a cardan shaft, this coupling allows free movement of the engine, to the point that vessels with Seatorque systems have returned to port not knowing that the engine had come off its mounts following a severe grounding.

The additional support when compared to a conventional shaft also resists the tendency of the shaft to deform under torque and thrust loads. The Seatorque shaft is supported every 30" with journal bearings inside the tube.

Hydrodynamics, what happens at the prop.

Under the water the Seatorque system improves the water flow to the prop. This is something that is not often appreciated in an open shaft system. The technical explanation as simply as it can be put is that an object such as a cylinder with liquid or gas flowing past it can impart a spinning motion to only a very thin layer next to the surface. The motion imparted to this layer affects the manner in which the flow separates from the surface in the rear. Boundary layer separation is delayed on the side of the spinning object that is moving in the same direction as the free stream flow, while the separation occurs prematurely on the side moving against the free stream flow. The wake then shifts toward the side moving against the free stream flow. The result is that at the P bracket support the water flow is not fore and aft in relation to the vessels motion but angled meaning that the strut/P bracket leg displays a much wider surface area to water flow.

I the boat there are no water feeds and a dry bilge, there is a small oil reservoir and an internal pump that circulates the oil which is cooled.

Maintenance and running costs are also reduced with an oil chenge and service only required after 3000hours. Seatorque units have been in use on a variety of vessels in the US for over ten years so they are proven.

The whole system is supplied from adaptor to prop nut and is covered by a two year or 500 hour warranty. Full details of warranty can be downloaded from the www.seatorque.com site.

Seatorque systems can be retro fitted, if you are considering a thrust bearing assembly to reduce noise and vibration for a similar price you may be able to have a completely new drive train.

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