Anything on a river boat will eventually get wet, so cover the cargo with lashed waterproof tarps, put goods that must stay dry in sealed barrels or containers, raise the cargo platform 15-20 cm above the bilge, and double-bag small items in a waterproof bag. A raised floor protects against nuisance seepage and spray, not against a real leak: 15 cm of water over the floor of a 6 m by 2.4 m scow is 14.4 m² × 0.15 m = 2.16 m³, a weight of 2,160 kg, so water must be bailed long before it reaches the cargo.
Part of River Navigation & Ferry Systems
Cargo waterproofing is the combination of covers, sealed containers and raised stowage that keeps goods dry on the water.
Four Layers, Each Defeating A Different Source Of Water
The carrier lists four measures. Tarpaulins: cover all cargo with waterproof tarps secured with ropes; they shed rain and spray. Barrels and sealed containers: best for goods that must stay dry (grain, gunpowder, documents); they survive a swamped boat. Raised floor: a cargo platform 15-20 cm above the bilge keeps goods above any water that enters the boat. Double-bag: put items in a bag, then that bag in a waterproof bag such as a trash bag, dry bag or waxed sack.
Each measure answers a different source: rain and spray from above, splashing and wash over the side, bilge water from below, and a total swamping. No single layer covers all four.
What You Need
- Tarps of the heavy woven type, with eyelets or lashing points (see Waterproof Fabric)
- Barrels or drums with sealing lids, that have never held fuel, solvent or pesticide (see Container Selection: Choosing Safe Vessels)
- Planks or pallets for the raised floor
- Waterproof bags and rope for lashing
- A bailer, tied to the boat
Method: Layer The Protection
Step 1: Raise the floor. Lay dunnage (planks on crosspieces) 15-20 cm above the bilge, with gaps for water to flow under.
Step 2: Pack sensitive goods in sealed barrels or double bags, packed tight so contents cannot shift.
Step 3: Cover the load with tarps, lashed so wind cannot lift them; a tarp that flaps can pull the cargo or catch a gust like a sail.
Step 4: Test the seals by closing a barrel and submerging it for an hour with a dry cloth inside.
Step 5: Bail early and often, and check the bilge at every stop.
Worked Example: What A Raised Floor Does And Does Not Do
Bilge water at depth h over a floor of area A has a volume of A × h cubic metres and weighs 1,000 × A × h kg: 14.4 × 0.15 = 2.16 m³ for the scow below. For the 6 × 2.4 m scow, A = 14.4 m² and h = 0.15 m gives 1,000 × 14.4 × 0.15 = 2,160 kg. Adding it to a boat with a payload of 3,720 kg raises the draft by 2,160 ÷ 14,400 = 0.15 m, which takes the freeboard from 30 cm to 15 cm. A 4.5 m canoe with a 0.6 m floor has A = 2.7 m², and 15 cm of water weighs 1,000 × 2.7 × 0.15 = 405 kg, a heavy load for a small boat. So the floor height is no excuse to delay bailing: by the time the cargo is wet the boat is badly overloaded.
A sealed 200 L barrel of grain at 750 kg/m³ (from Logistics & Load Planning) holds up to 0.2 × 750 = 150 kg of grain; with a 20 kg barrel (an assumed mass) the barrel and content weigh 170 kg and displace 200 kg when submerged, so it floats with 30 kg to spare. A sealed barrel of grain therefore adds buoyancy if the boat swamps, while a barrel of stone or iron would not.
Common Mistakes
- Trusting a barrel lid without testing — a bad seal wets everything and a slowly filling barrel sinks.
- A tarp tied at the corners only — wind lifts it.
- Packing wet grain — it swells, ferments and can burst the barrel.
- Using a fuel or chemical drum — residues contaminate the cargo and may be explosive.
Safety
Never cut or weld a drum that held fuel
Sealed drums can hold flammable vapour even when empty; do not cut, drill, or heat them, and do not use them for food or drinking water. See Approved vs. Improvised Containers for the container rules, and keep heavy cargo lashed so it cannot shift when the boat heels.
What’s Next
- Learn next: Loading for Stability — where to put the weight once it is packed
- Combine with: Barrel & Drum Raft — using sealed drums as flotation