I watched a terminal work a feeder with 3 cranes. Two hours into operations, Crane 1 finished. Cranes 2 and 3 still had 90 minutes of work ahead.
One crane idle. Two cranes working. The vessel paid for 3 cranes but got the productivity of 2.
The problem wasn’t the terminal. It was the stowage plan. Specifically, where the 20-foot containers were placed.
The Myth: “20’ Go Where They Fit”
On most feeders, 20-foot containers are treated as filler cargo. The planner places the 40’ first, because they’re bigger and more constrained. Then the 20’ go wherever there’s space left.
Bay 10 has gaps? Put 20’ there.
Bay 46 needs weight? Put 20’ there.
The hold has odd slots? 20’ will fit.
This approach is wrong. It treats 20’ containers as leftovers when they should be treated as strategic assets.
Every container type has a role. 20’ containers have several.
Role 1: Crane Split Balancing
A container vessel’s bays are not equal. The forward bays are smaller. The midship bays are larger. The aft bays vary.
When you assign cranes to sections of the vessel, this creates imbalance:
| Section | Typical bays | Container capacity | Crane work |
|---|---|---|---|
| Forward | Bays 02-14 | Smaller bays | Less moves |
| Midship | Bays 18-34 | Largest bays | Most moves |
| Aft | Bays 38-50 | Medium bays | Medium moves |
If you distribute cargo evenly by weight and TEU, the midship crane will always have more work. The forward crane finishes early and sits idle.
The solution: Use 20’ containers to balance crane splits.
20’ containers create more moves per TEU than 40’ containers. Two 20’ = 2 moves. One 40’ = 1 move. Same TEU, double the crane work.
By placing more 20’ in the forward bays, you increase the move count where the crane would otherwise finish early.
The result:
| Without 20’ strategy | With 20’ strategy |
|---|---|
| Crane 1: 180 moves | Crane 1: 240 moves |
| Crane 2: 320 moves | Crane 2: 280 moves |
| Crane 3: 260 moves | Crane 3: 250 moves |
| Total port time: 4.5 hours | Total port time: 3.8 hours |
Same cargo. Same cranes. 45 minutes saved. Because 20’ went to the right bays, not the convenient bays.
Role 2: Trim Optimization
Heavy 20’ containers are gold for trim management. Here’s why.
A heavy 20’ (24-28 tons) concentrates weight in a small footprint. Placed strategically, it shifts the vessel’s center of gravity precisely where you need it.
The rule: Heavy 20’ go forward. Never aft.
Why never aft? Because feeders naturally trim by the stern when loaded. Adding heavy containers aft increases stern trim further, pushing you away from optimal.
Heavy 20’ at the bow:
- Counteracts natural stern trim
- Allows you to reach optimal trim (0.5-0.8m) without excessive ballast
- Reduces ballast water needed, saving fuel and time
Empty 20’ are acceptable aft for crane split purposes. They add moves without adding weight. But heavy 20’ belong forward.
Role 3: The Standard Container Advantage
Here’s something most people don’t know: standard height containers (8’6”) can give you an extra tier compared to high cubes (9’6”).
The math:
High cube: 9’6” = 2.90m Standard: 8’6” = 2.59m Difference: 0.31m per tier
Over 6-7 tiers on deck, that 0.31m adds up. With high cubes, you might max out at tier 8. With standards, you can reach tier 9.
Where this matters most: Forward bays.
Forward bays often have air draft restrictions (height from waterline to highest point). Bridges, cranes, and port infrastructure limit how high you can stack.
By placing standard containers (not high cubes) in forward deck positions, you gain one extra tier. On a feeder with 6 forward bays, that’s potentially 30-40 extra slots per rotation.
Annual impact:
40 extra slots × 50 rotations × $300 average freight = $600,000 additional revenue capacity.
From choosing standard over high cube in forward bays.
Role 4: The 40’ + 40’HC Pattern
In the holds and midship deck areas, there’s another optimization most planners miss.
The pattern: Alternate 40’ standard and 40’ high cube in deck tiers.
Why? Because lashing bridges have fixed heights. The gap between tiers matters for lashing rod angles and securing forces.
When you stack 40’HC on 40’HC on 40’HC, you maximize height quickly. You might hit lashing limits at tier 6.
When you mix 40’ standard and 40’HC:
- Tier 1: 40’HC (2.90m)
- Tier 2: 40’ standard (2.59m)
- Tier 3: 40’HC (2.90m)
- Tier 4: 40’ standard (2.59m)
The average height per tier drops. You stay within lashing limits longer. You might reach tier 7 instead of tier 6.
One extra tier in midship bays: 60-80 TEU additional capacity.
This requires having the right cargo mix. You need both 40’ standard and 40’HC available. Which brings us back to load list coordination.
Putting It All Together
Every container type has a strategic role:
| Container type | Strategic placement | Purpose |
|---|---|---|
| 20’ standard (light/empty) | Forward bays, can go aft | Crane split balancing |
| 20’ standard (heavy) | Forward bays only | Trim optimization |
| 40’ standard | Mixed with HC in holds/midship | Extra tier capacity |
| 40’ high cube | Mixed pattern, not concentrated | Flexibility |
| Standard height (any) | Forward deck | Air draft optimization, +1 tier |
The planner who understands this creates 5-10% more capacity from the same vessel.
The planner who puts containers “where they fit” leaves money on the table every rotation.
The Cascade Effect
Good cargo placement creates positive cascades:
Every placement decision ripples through the entire rotation.
Why This Doesn’t Happen on Feeders
These optimizations require three things:
Time. Analyzing crane splits, calculating tier heights, planning 20’ distribution takes hours. The Chief Officer doesn’t have hours.
Data. You need to know exact container dimensions, weights, and terminal crane assignments. This information often arrives late or incomplete.
Expertise. Understanding how cargo types interact with trim, stability, crane operations, and tier limits takes years to develop.
On mainliners, shore planning teams have all three. They spend full days optimizing a single port call.
On feeders, the Chief Officer has 3-4 hours and a dozen other responsibilities. They place cargo where it fits. They verify stability. They move on.
The optimization never happens. Not because they’re incompetent, but because they’re overwhelmed.
The Numbers
Let me quantify what strategic cargo mix delivers:
| Optimization | Impact per rotation | Annual (50 rotations) |
|---|---|---|
| Crane split balancing | 30-60 minutes saved | $15,000-30,000 |
| Trim optimization (heavy 20’ forward) | 0.3-0.5% fuel | $8,000-15,000 |
| Standard containers forward (+1 tier) | 20-40 TEU | $300,000-600,000 revenue |
| 40’/40’HC pattern (+1 tier midship) | 30-50 TEU | $450,000-750,000 revenue |
Not all of this is pure profit. Revenue capacity doesn’t mean you’ll fill every slot. But even capturing 20% of the potential adds $150,000-300,000 annually.
From placing containers strategically instead of conveniently.
What Changes With Shore Planning
Before (reactive placement):
20’ go where they fit. 40’HC stack on 40’HC. Heavy cargo spreads randomly. Crane splits are whatever they are.
After (strategic placement):
20’ heavy forward for trim. 20’ light balanced for crane splits. Standards forward for extra tier. 40’/40’HC mixed for lashing optimization.
The cargo is the same. The capacity is higher. The operations are faster. The fuel consumption is lower.
Same vessel. Same cargo. Better results.
The Question
When your Chief Officer builds a stowage plan, are they asking:
- Where should heavy 20’ go for optimal trim?
- How do I balance crane splits across bays?
- Can I gain a tier by using standards instead of high cubes forward?
- What’s the best 40’/40’HC pattern for maximum deck tiers?
Or are they asking:
- Does it fit?
- Is it stable?
- Can we sail?
The first set of questions creates optimized operations. The second set creates legal operations.
Both are necessary. Only the first creates profit.
Who’s asking the optimization questions for your vessels?
Nothing should go where it “fits.” Everything should go where it performs.