Splitting Waves and Hairs: Comparing X-bow, Axe Bow, and More

We currently enjoy an explosion of variety in bow shapes, each suited to a different task. Nearly the same bow shape, used on a different hull, may work for entirely different reasons. This time we distinguish between four prevalent bow shapes: conventional hull, X-Bow, Axe Bow, and wave piercing.

REFERENCES
[5] U. Kvamsvag, "The Foreship Arrangement for a Vessel of the Displacement Type," PCT, vol. No. 000073, 2006.
[6] D. E. Nordas, "Optimization of Bow Shape of Large, Slow Ships," in Master Thesis in Marine Technology, Trondheim, Norway, NTNU- Trondheim: Norwegian University of Science and Technology, June 2012.
[7] M. A. Mosaad, M. M. Gafaary, W. Yehia and H. M. Hassan, "On the Design of X-bow for Ship Energy Efficiency," in Influence of EEDI on Ship Design & Operation, London, U.K., 22 September 2017.
[10] J. Gelling, "The Axe Bow: The Shape of Ships to Come," in 19th International HISWA Symposium on Yacht Design and Yacht Construction, Amsterdam, The Netherlands, 13 and 14 November 2006.

[TheTiacat]

I can’t believe this held my limited attention span for 20 min. Really neat. I actually learned something watching YouTube.

[maddun]

Thanks Nick. Another excellent video, I learned a lot. As usual you deliver the right amount of infomation for a layman like myself to understand without being too technical or too simplistic.

[swimspud]

I’ve been curious about why we see different bow types for a while. Thanks for the awesome and in-depth discussion

[andreasrajagoklassitorus]

this channel is great. your explanation is technical enough but not too difficult to understand. perfect for a naval architecture student like me. good job nick!

[RyanRWHoldings]

Very interesting video with lots of information - I had been wondering how an X-Bow design would work and handle at sea. Thank you for sharing a designers insight, I loved it!

[paulmcmullan]

I would be intrigued to know about the often backward racked bow of a dreadnought class battleship and zumwalt class destroyer.

[skyak]

Nick, this is the best video I have seen on the subject. As they say "a picture is worth a thousand words" this video is worth 10X the thousands of blog posts I have seen bouncing this topic around and never achieving any resolution. I think your insights on attributes are all true, but you stop short of putting numbers and dimensions on these concepts. Wave height capacity and frequency response would make deciding on a bow design clear and simple. I know that as a professional you can't give away all your secrets, but I have seen so many NAs insisting that this is a mystical process I think you could clean up as the guy who makes this a clear and simple optimization. All these bows have a wave height capacity with varying negative consequences from exceeding that capacity. Wave height from the ships perspective is wave height apparent, which is a function of incident frequency which is a function of ship speed, wave incidence, and ship heave natural frequency. You don't even have to be a genius to know what the expensive CFD studies are going to find.

[darrellbedford]

The axe bow reminds me of what was called "Destroyer Bow" as used on military destroyers of old.

[jshrawder]

That was a great great video thank you for going through this information in a very simple way in English!!! Keep up the great videos!!!

[mikewalrus]

From my small experience at sea - deck hand to master over 37 years, sadly I find that Marine Architects and the ships crew are at different ends of the spectrum - rarely do the two meet (a bit like shore side architects and builders) on the one side the architect designs grandiose shapes on the other side both crews and builders put themselves at risk to either operate or build these designs. despite that I would like to congratulate the presenter for at least looking at both sides of the coin. Very well done sir, we are finally getting somewhere, let us hope others will move that way too (I do of course include ships crews who often complain as a matter of course despite the efforts of the architect)

[budsbustbi]

slight broaching?? the one i worked on would broach just thinking about a following sea!!

[predator]

I want to know which X-BOW is suitable for a small cruising sailing yacht about 20 meters long? The priority is to reduce the comfort of the pitch movement and the efficiency of the drive.
thx！

[nauticalwolf]

I like your energy and how you explain things in a way a layman can grasp. Keep it up!

[D-dd-rpve]

17:16 Could you put an image of every bow ship with every bow type? Thanks!

[geraldhoag]

I have seen videos on youtube that show an x-bow next to a conventional bow of oilfield service ships in the north sea and notices that the x-bow had less pitching. This seems to me to cause the thrust from the props to remain more horizontal. This will make the thrust more efficient, improving effective thrust, improving fuel economy, or reducing thrust requirement to maintain a given speed.

[yoghik]

What a great man! As a yacht designer I found out a tonn of usefull information here!!! Grand thanks!

[nicolasruiz]

Very interesting video, thanks! Now, I can't avoid thinking of the bows in canadian canoes which I guess are suitable for rivers and lakes (small and short waves). I would love to hear some comments on that.

[augenmaugen]

Kudos, oddly fascinating material and unexplainably engaging style. I’m in a land locked state, may never own a boat, but still fascinated.

[besearchingforwisdom]

At 4:30 into your description, you said "...initial shock of entry", not 'shock of initial entry', which I mistakenly thought I heard and then I formed a new concept of that "point of lift" at the point of entry to "cushion" against the shock of entry you described as ride quality. A video of this is from waverider boats in Australia, and would love to hear your views on that design he used on a trihull hydrofoil. Though my thought is to make the bow of a "V" hull affecting greater lift at the point of entry and causing an improvement in ride quality and handling, especially during a following sea.

[christopherpardell]

I think the long bow is simply moving the personnel spaces toward the center of pitch rotation. That is, the tip of the bow experiences the same high accelerations, because it is moving up and down a significant distance... but the crew spaces are at or near the center of that rotation and simply move a shorter distance in the same period.