Hull Vane hydrofoil solution integrated on a Holland-class OPV model (Credit: Dutch Ministry of Defense)

Naval News reports that,

Today, June 8th, the first Hull Vane for the Royal Netherlands Navy has been delivered in Den Helder. This Dutch invention consists of a submerged transom wing which renders ships more efficient and quieter, while improving their seakeeping.

This Hull Vane will be installed in early 2023 on the aft ship of the HNLMS Groningen, an ocean-going patrol vessel of 108 meter, pertaining to the Holland Class.

This decision is a strong endorsement for an innovation that appears directly applicable to US Coast Guard cutters. The Holland class Offshore Patrol Vessels are similar in size, power, speed, and hull form to the Bertholf class NSCs and particularly to the Argus class Offshore Patrol Cutters.

The hull vane reportedly recovers some of the energy that would normally be lost in creation of the wake. Fuel savings of 10% or more are reported. It also is reported to reduce pitch make for improved boat and helicopter operations.

Besides energy saving, which automatically leads to a reduction of CO₂ emissions, the Hull Vane^® also offers many tactical advantages for the ship. Due to the suppressed stern wave, the vessel leaves much less visible wake, making her less visible to satellites, drones and even certain types of torpedoes. Helicopter landings will be safer in rough weather, and it is expected that the slipway in the stern can be used more frequently to launch and recover the FRISC, a fast daughter craft. The ship will have a higher top speed, and will be able to cross a long distance faster, e.g. when being deployed for calamities. But above anything else, the goal is to reduce the dependency on diesel fuel. That is valuable in peace time, but even more so during war.

“Wake behind transom on patrol boat at 11 kn without Hull Vane® (left) and with Hull Vane® (right), leading to 25% lower fuel consumption”

We have been following this promising innovation for the last seven years. Previous posts on this topic were:

• Hull Vane on an OPV, Sept. 2015
• Hull Vane Claims Improved Performance, June 2017
• Hull Vane Experiment on 52 Meter OPV, July 2018
• “Dutch Navy To Test Hull Vane Hydrofoil On HNLMS Zeeland OPV” –Naval News, Nov. 2020

French OPV Themis fitted with Hullvane. Source: https://www.hellenicshippingnews.com/mv-themis-hull-vane-retrofit-improves-opvs-performance/

Results of a 2018 test on the 172 foot, 409 ton French patrol vessel Themis, a vessel similar to the Webber class FRCs, included a “comparison with the benchmark sea trials – conducted in January in exactly the same conditions – by CMN’s sea trial team showed a reduction in fuel consumption of 18% at 12 knots, 27% at 15 knots and 22% at 20 knots. The top speed increased from 19.7 knots to 21 knots.”

PBCF installed on a propeller

Marine Log reports,

Mitsui O.S.K. Lines, Ltd. (MOL) reports that the propeller boss cap fin (PBCF) sold by its group company MOL Techno-Trade, Ltd. has been certified as the “Best-selling Energy-Saving Ship Appendage Brand (Cumulative)” by Guinness World Records and received an official certificate on December 23, 2021.

On sale since 1987, the PBCF was the first device in the world to be commercialized to recover the energy wasted in the vortex that forms behind a rotating propeller and increase the thrust by breaking up this vortex. Analysis has shown that equipping a vessel with PBCF results in energy savings of 3% to 5%.

Such a device would not have much effect on speed, but it might improve range and fuel economy.