FAQ

What kind of maintenance does the Hull Vane® require?

The Hull Vane® is a fixed appendage without moving parts. It requires no other maintenance than the ship’s hull and other appendages, such as the bilge keels. Fouling (marine growth) can deteriorate the performance, hence a good anti-fouling coating and/or regular cleaning is recommended.

Are there any subsidies to soften the investment cost?

The fuel savings caused by the Hull Vane® lead to a reduction in emissions of similar proportions. The ship’s Energy Efficiency Design Index (EEDI) is improved. The subsidies granted are country-specific and can be investigated on a case-by-case basis. Even without subsidies the savings of the Hull Vane® are of such proportions for many ships that it makes business sense to look into it.

Will there be a conflict with the free-fall lifeboat?

We are investigating whether there can be an issue with free-fall lifeboats.  Launching from the stern is not a problem, but hoisting has to be considered. Please contact us for the latest information.

Does the Hull Vane increase the length-over-all of the ship?

In most applications, the Hull Vane is situated aft of the stern and does indeed increase the length-over-all. In cases where it is important to protect the Hull Vane from tugs or other vessels, a tubular frame can be built above the waterline. In some cases, the Hull Vane is situated entirely within the ship’s length, so please consult us if this is an issue.

How much does it cost?

We do not publish a price list, as the cost of the Hull Vane® depends of a number of factors, such as the amount of CFD work needed, the production costs and the material costs. For each individual hull shape, a detailed CFD analysis is needed to produce an effective design. Building a Hull Vane® without a proper study to determine its optimal shape and location can lead to an extra source of resistance for the ship instead of a fuel saving device.

The installation of a Hull Vane® is an investment which pays itself back over a period of time, much like solar panels, real estate, etc. The investment risk is extremely low: as long as the ship is sailing, and oil prices aren’t decimated, the Hull Vane® will pay dividend. As there are no moving parts on the Hull Vane, there are no unforeseen costs to be expected in the future.

For new vessels in the design stage, the application of the Hull Vane® can lead to a reduction in size of the main engines and their exhaust systems, leading to a more compact engine room. Furthermore, the savings in installed engine power will offset most of the investment cost of the Hull Vane®.

Is the Hull Vane® patented?

The Hull Vane® is protected by patents in all major shipbuilding countries. The development of the Hull Vane® took over 10 years and required a significant investment. If you wish to become a licensed manufacturer of the Hull Vane, please contact us.

What about the weight of the Hull Vane® and my LCG?

The Hull Vane® is usually built of steel and has a significant weight, which is partly offset by its own buoyancy. If relevant, the impact on trim and loading of the vessel can be investigated. In some cases, the Hull Vane® can be built of aluminium or composite materials.

What about sailing vessels?

One of the first applications of the Hull Vane® was built for an America’s Cup sailing yacht. It was proven effective but outlawed in the America’s Cup regulations as an appendage which would give an unfair advantage. It’s definitely worthwhile to study the effectiveness for sailing yachts, but on smaller yachts (below 30 m), we fear the cost may be prohibitive. For the time being, we are focused on commercial ships, as there is an urgent need to  reduce fuel costs and emissions.

What are the disadvantages?

Care has to be taken when sailing astern to avoid contact with the dock. Tugs providing assistance cannot push on the stern, unless a protective structure above the waterline is provided.  In future drydockings, there will be a bit more surface to clean and paint. Marine growth should be avoided as much as possible, as is the case for propellers and rudders.

Can the Hull Vane® be mounted on ships with Ice-Class notations?

Model testing has been done with the Hull Vane® at the Aker Arctic ice model basin in Helsinki. During navigation in ice, the speed is too low to provide an advantage. When sailing astern ice can collect against the Hull Vane®, but no other issues were found.

Can the Hull Vane® be retrofitted to an existing ship?

Yes, the Hull Vane® is equally suitable for newbuildings and refits. While it may be convenient to schedule the mounting of the Hull Vane® during a drydocking, this is not required. In one case, a Hull Vane® has been mounted with the vessel in the water. This is only possible when the ship can be trimmed to get the complete stern above the waterline.

Which modifications are needed to the ship’s structure?

The Hull Vane® is usually mounted to the stern of the vessel, but sometimes on the bottom. As the distance between the vertical struts can be varied to a certain extent, it is possible to align them with the ship’s primary structure (bottom girders). Some additional stiffening structure inside the ship may be needed.

Can you give a ballpark figure for the fuel savings on my vessel?

We can’t give a ballpark figure, as the performance depends a lot on the hull shape of the ship, the operating profile and the loading conditions. We need to do an exact study with CFD software to give an exact number. Such a study also provides useful information for the correct placement of other appendages, such  as the rudders and bilge keels.

Is CFD reliable enough or should we model test the Hull Vane® in a towing tank before ordering?

Hull Vane B.V. works exclusively with Van Oossanen Fluid Dynamics, the Dutch sister company with ample experience in both CFD work and model testing. In recent years, the technology in CFD has evolved to such a point that it is now more reliable than tanktesting, as there is no problem with the scaling of viscous effects. Nevertheless, a large number of tank tests have been carried out with the Hull Vane® to verify its effects.

On request, model testing in a towing tank can be carried out to validate the CFD calculations.