# Why aren't there many ships with transom bows?

Transom basically is a flat aft, usually vertical. It reinforces the structure, adds deck area, and because that the flat part is above the waterline, no fluid dynamic is hurt.

The extra deck area is of course utilized for profit in container ship designs: Image courtesy of International Labour Organization, under Attribution-NonCommercial-NoDerivs 2.0 Generic license.

In navies, there are aircraft carriers/amphibious assault ships/whatever ship equipped with a through flight deck, with the bow flared to support rectangular deck outboard.

There are also prototypes of yachts with almost vertical transom bows.

My question is: Why don't other ships have a transom bow? With both directions' transoms, the whole main deck shall become a rectangle, so that more containers can be loaded.

• Why do you think it reinforces the structure? If anything the every transom aft or bow makes it weaker than it could be. Rectangles collapse real easily. Commented Mar 9, 2022 at 14:30

The problem is known as slamming.

From Ship Design And Construction - Lamb (2003):

The problem of slamming, that is when the forward bottom of ships strikes the sea when sailing with low forward draft in rough head seas, causing severe bottom damage, is more of a problem for tankers and bulk carriers due to their fullness forward (large block coefficients).

Damage by wave impact can also happen in the aftbody if formed in an extreme way, for example, flat, horizontal areas above propeller and rudder, and large flat transom sterns.

As a ship heads directly into waves, it rides up and then slams down into the sea. It is an existing problem for ships with a high block coefficient, $$C_B$$, like bulk carriers if they are unloaded and floating high. Unloaded they travel with full ballast for stability and minimize slamming. Slamming can be mitigated by not travelling directly into waves.

Basic Ship Theory - Rawson et al (2001):

The block coefficient, $$C_B$$, is the ratio of the volume of displacement to the volume of a rectangular block whose sides are equal to the breadth extreme, the mean draught and the length between perpendiculars.

The closer it is to 1 the more rectangular the hull.

Above the waterline, you are proposing a transom or flat bow, with a conventional bow below the waterline. An overall wide ship with a high $$C_B$$. Works on a flat ocean, but heading into any waves the wider area above the waterline will experience slamming sending vibration throughout the ship compromizing every joint. Ships are made of steel, but not over engineered.

Even aircraft carriers, which are wide at the flight deck have a flared bow to cut through the waves.

The cargo ships are desinged for high-seas with possibilty of storms with waves of 80-100 feet high.

As they are their simple geometry means more strength and resilience. Any additional corners or breaks in the streamlined design will weaken the structure.

Besides any surface not aligned with the track of the ship in the water can attract explosive wave crashes and imminent structural failure.

• Structure wise, why doesn't a boxy aft hurt as well? Commented Mar 8, 2022 at 17:42
• corners, suddenl changes in geometry, are stress traps leading to potential structural damage. In a stormy sea the waves engulf the ship like a submarine. and for a submarine the most efficient shape is the long streamlined one. Commented Mar 8, 2022 at 17:52
• @CrystallizedRefresher It does hurt it, but at least with just a transom aft you have something vaguely triangular or arch-like. Rectangles collapse real easily, Commented Mar 9, 2022 at 14:32

### Ships dont have transom bows because marine designers generally know what they are doing.

Ships cut through waves. High waves can break even over the bow. Waves hitting againt a flat surface would be a disaster.

Most smaller boats/yachts/ships don't even have flat aft sections due to the risks of following seas.

Aircraft carriers are built without cost as an object and have unique design considerations, so don't draw conclusions from them.

Try pushing a knife through water edge first, then flat face first or even a plate. What do you notice?

Boats, planes even cars have pointy ends because pushing fluid out of the way means work.

Then if you need to add a few more containers, it is easier to add to the length and keep the pointy end. Look at the length of those cargo ships and, of course, how long they take to stop.

• Well, I think the OP's unstated assumption was that the transom bow would be above any waterline. The problem, of course, is waves. Commented Mar 7, 2022 at 16:25