Description

Name: Collision Mat
Brand: Collision
SKU: SCMAT

This triangular Collision Mat is patterned after, design by well-known cruising expert John Neal. Intended for power or sail boats, it temporarily puts, ''patch'' over, hole in your hull if you collide with an object. Using its three securing lines, the Collision Mat is passed under your hull until it covers up the hole. Water pressure, and tightly secured lines, hold the mat against your hull and reduce water flow so you can attempt repairs or call for help. Made from heavy, orange, vinyl-coated fabric with 2''-wide nylon webbing around the perimeter which also reinforces the heavy grommets in each corner. For securing, we include 20' of three-strand nylon lines at each corner. Measures 4' on each edge.

Specifications

Fothering refers in nautical contexts to covering a leak in a ship with a sail containing rope fibres to prevent it from sinking after being damaged. This was the technique used to help to refloat HMS Endeavour after she went aground on the Great Barrier Reef on 11 June 1770.

Boat Flooding Rates in Gallons per Minute
Depth of Hole Below Waterline	Diameter of Opening or Hole
Depth of Hole Below Waterline	1 in	1.5 in	2 in	2.5 in	3 in	3.5 in	4 in
1 ft	19.4	43.8	77.9	121.7	175.3	238.6	311.6
2 ft	27.8	62.5	111.1	173.6	250.0	340.2	444.4
3 ft	33.9	76.3	135.7	212.0	305.3	415.6	542.8
4 ft	39.3	88.4	157.1	245.3	353.5	481.2	628.4

The volume of water that enters a boat is proportional to the square root of the depth of the hole and proportional to the square of the hole’s radius. That is, a hole twice as deep allows in 1.4 times more water, and a hole twice as large lets in four times more water. A deep but small hole is safer than a shallow large one!

A two-inch hole that is one foot below waterline can fill a 55-gallon drum in 42.4 seconds!

Remember that each gallon of salt water weighs 8.6 pounds. A one-inch hole that is two feet below the water line is forcing your boat’s weight to increase at 240 pounds per minute or four pounds per second. Remember, too, that as your boat fills with water, the effective hole depth increases, forcing faster water ingress!