RAFNAR Hull –A New Kind of Hull For Reduced Slamming

gCaptain had a report on this new hull form, which a University of Iceland study found reduced slamming as much as 95% compared to a deep-v hull. It explains the development of the hull, I needed more information to understand how it worked.

The company website has many much clearer photographs as well as the video above.

Claimed advantages are:

  • Exceptionally smooth and comfortable due to limited slam on waves.
  • Significantly reduced slamming results in less mechanical and equipment fatigue, extending the lifetime of expensive electronic equipment on board.
  • Greater on-board safety from significantly reduced slamming means reduced risk of injury, lower crew & passenger fatigue and related costs
  • Precision performance without compromising cruising or top speed.
  • Immediate handling response with no sliding
  • No wake created behind vessel, resulting in less water disturbance
  • Exceptional stability and balance when idle and at speed
  • High payload capacity without compromising cruising or top speed

Could this concept be scaled up for a Motor Surf Boat? Apparently the Icelandic Association for Search and Rescue is already looking into the possibility of a 15 meter (49 foot) MLB.

Thanks to Lee for bringing this to my attention

 

14 thoughts on “RAFNAR Hull –A New Kind of Hull For Reduced Slamming

  1. The video makes me wonder if the price to pay was increased roll, but the shape looks as if it should rather decrease roll.

    • Upon reviewing the company website, I believe the concept is a combination of shape and weight, creating sort-of a hybrid of a planing and displacement hull form. It’s like the planing hull pushes up, but the deeper keel, centered fore-and-aft, provides a displacement-hull still in the water. Another important aspect is that the displacement part of the hull is carefully located at the center of gravity of the craft, rather than all the way at the stern, as with common planing hulls.

      A pure guess on my part is that the keel may be weighted as well. If my guess is correct, how much weight and where it is distributed might make this ideal for MLB (self-righting), or horrible… I’m guessing since Iceland’s CG and SAR services both use these, it’s more likely to be “ideal.”

    • @lastdingo – The more I watch that video, the more I feel like the rolling movement is the “normal” rolling motion, but it looks more accentuated because the fore-and-aft bouncing has been removed.

  2. This may have been too obvious to even mention, but in addition to applying this to MLBs, the stability would make Response Boats much better gun platforms.

    • The most important aspect of all, in my opinion, is the mitigating of shock, protecting passengers’ spines, increasing endurance, and mitigating the need for expensive shock-absorbing seats (which also would free up cabin space).

  3. I wrote RAFNAR and asked about the current state of the 15 meter design. This was their response.

    “Regarding the 15m, named Nökkvi 1500, design work on that vessel is ongoing and is foreseen to be completed in late 2019 to early 2020. We are working very closely with the Icelandic Association for Search and Rescue (ICE-SAR) in the design for that craft and have regular meetings with ICE-SAR to align on requirements and specifications. The ICE-SAR recently decided on three tiers of SAR boats, where the 15m meets the requirements of the third, or largest class, tier. The hull of the vessel will be based somewhat on its smaller sibling, the Leiftur 1100, but scaled up to meet the requirements of a 15m SAR ship. While the design will primarily be for SAR work, the craft will be designed to be modifiable to other applications, both commercial and recreational. The 15m will come to be our largest vessel, but in the past we did design and construct prototypes for vessels larger than the Leiftur 1100, including a 12m prototype that we trialed in 2015 with the Icelandic Coast Guard (ICG). See the video for a boarding exercise with the ICG.

    “Along with the 15m, we are also designing a new 12m vessel, Leiftur 1200, that will serve the needs of ICE-SAR’s middle tier. Developments for this vessel are not as far along as those for the 15m, but we aim to have solid concepts ready by late 2019. It will be an enclosed vessel, but current designs are only available for an open concept.”

    Notes below the YouTube video, “Boarding exercise with the Icelandic Coast Guard on a 12m prototype built on the Rafnar Hull. It is worth mentioning that this was the operator’s first time of using this boat.”

  4. Wow. Having come along many vessels underway in everything from the 41′ UTB to small RHI’s, that looked way too easy! I think a real challenge would be to come alongside and depart a buoy tender’s buoy deck safely.

  5. I have ridden in the leiftur 1100. We had rigged up accels on 3 locations on the hull. Unfortunately, our data logger broke soon after the trial started so we weren’t able to collect any objective seakeeping data. The boat has virtually no bow rise and experiences no hump, unlike a traditional monohull planing craft. The shaping of the hull keeps the stagnation line in one spot throughout the speed range from 20 to 55 kts. I believe the shaping of the hull controls the location of the center of pressure when planing and is what reduces the dynamic pitching of the hull in a sea state as well as maintaining a relatively constant trim. We ran this boat full tilt in two different displacements with a significant wave height of 3’+ head on, quartering, and downwind comfortably and were able to maintain max throttle. It was quite impressive.

  6. Boat has entered service with the Icelandic Coast Guard. https://www.bairdmaritime.com/work-boat-world/small-craft-world/5132-vessel-review-loki-icelandic-coast-guard-sar-rib-for-some-of-the-world-s-toughest-conditions

    “With a platform that has been shown to reduce the number of wave slamming impacts by 82 to 95 per cent, Loki delivers considerably more usable deck space at the bow as a result, as well as much enhanced directional maneuverability, and safety and comfort for the crew.”

  7. Pingback: 19 meter (62 foot) Motor Surf Boat, Maybe a Small Port WPB Alternative | Chuck Hill's CG Blog

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