River cargo work is three jobs done together: load by weight so the boat keeps its freeboard (the water-to-gunwale distance should never be under 15 cm, and more in rough water), keep the cargo dry, and schedule trips by season and direction. In the worked example a flat-bottomed scow 6 m by 2.4 m carries 5,880 kg of cargo at 15 cm of freeboard but only 3,720 kg at 30 cm, and a 30 km trip takes about 6.7 hours drifting downstream at 4.5 km/h but 10 to 15 hours tracked upstream at 2-3 km/h.
Part of River Navigation & Ferry Systems
River cargo operations are the loading, waterproofing and scheduling of goods carried on a river boat.
Weight, Water And The Calendar Decide The Trip
Rivers carry heavy loads downstream for free, and a boat of modest size moves several tonnes. The three constraints are how much weight the hull can carry and still ride high, how to keep the load dry, and when the river lets you go. They are separate subjects, covered in Loading for Stability, Cargo Waterproofing and the seasons in Reading the River.
The carrier’s seasonal pattern is: spring has the highest water and the fastest current, best for downstream freight but dangerous with floating debris; summer has low water, easiest for upstream poling and tracking, and shallow-draft boats only; fall brings sudden rises after rain, so move high-priority cargo before freeze-up; winter, in cold climates, closes navigation.
What You Need
- A weight list of every item, in kilograms (see Logistics & Load Planning for densities)
- The boat’s displacement figures: length, beam, depth and empty weight
- Waterproofing: tarps, barrels, bags
- A trip plan: distance, direction, the river’s season and the places to land
Method: Plan A Trip
Step 1: Weigh or estimate the load item by item.
Step 2: Compute the payload at the freeboard you choose (see the example).
Step 3: Stow heavy items low and centred, equal weight on each side (see Loading for Stability).
Step 4: Waterproof with tarps and sealed containers.
Step 5: Time the trip from distance and speed, and pick a season in which the river will carry you.
Worked Example: Payload And Trip Time
Scow 6 m by 2.4 m, depth 0.60 m, empty weight 600 kg (an assumed hull mass). Waterplane area 6.0 × 2.4 = 14.4 m², so each metre of draft is 14,400 kg.
- Freeboard 15 cm: draft 0.60 − 0.15 = 0.45 m, displacement 14,400 × 0.45 = 6,480 kg, payload 6,480 − 600 = 5,880 kg.
- Freeboard 30 cm: draft 0.30 m, displacement 4,320 kg, payload 3,720 kg.
The ratio is 5,880 ÷ 3,720 = 1.58: the extra 15 cm of freeboard costs 37% of the payload (2,160 ÷ 5,880), and buys a margin against waves. The carrier’s 15 cm is the floor for cargo boats; the 30 cm of the carrier’s ferry is the figure it uses where people and animals are aboard.
Trip time for 30 km. Downstream, drifting with a current of 1.25 m/s = 4.5 km/h (the float example in Reading the River): 30 ÷ 4.5 = 6.7 hours. Upstream by tracking at 2-3 km/h: 30 ÷ 3 = 10 hours to 30 ÷ 2 = 15 hours. A round trip is therefore 6.7 + 10 = 16.7 to 6.7 + 15 = 21.7 hours of travel, about 17 to 22.
Common Mistakes
- Loading to the minimum freeboard in rough water — the carrier says more in rough water.
- Counting only the cargo, not the crew and gear — they are part of the load.
- Planning upstream and downstream at the same speed — the trip is one-way fast.
- Leaving high-priority cargo for the last trip before ice — see the calendar.
Safety
An overloaded boat has no margin
A scow loaded to its minimum freeboard ships water in any wave or wake, and a swamped, heavily loaded boat in a current is hard to recover. Keep the margin, stay with the hull if you capsize (see Safety & Capsizing Recovery), and do not load in flood.
What’s Next
- Learn next: Loading for Stability — keeping the load upright
- Combine with: Cargo Waterproofing — keeping it dry