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Anchors of the Great Lakes: Types, Usage, and Best Practices

Introduction

Anchoring has been an essential part of maritime navigation on the Great Lakes for centuries. Whether securing large cargo ships in deep waters or mooring smaller fishing vessels along the shoreline, anchors play a crucial role in ensuring vessel stability and safety. Anchors on the Great Lakes operate based on weight, embedding, or a combination of both, depending on the lakebed composition and the type of vessel being secured.

Types of Anchors Used on the Great Lakes

Permanent Moorings (Weight-Based Anchors) These anchors rely primarily on their sheer mass to provide holding power. Commonly used for navigational buoys, docks, and mooring fields. Example: Concrete blocks or slabs, sometimes with embedded steel loops for attachment. Used in locations where vessels need long-term mooring and embedding in the lakebed is impractical.
Mushroom Anchors (Semi-Permanent Anchors) Shaped like an inverted mushroom cap, this anchor is designed to embed into soft lake bottoms. Frequently used for semi-permanent moorings in areas with mud or silt. Can develop significant holding power over time as sediment accumulates around them. Used by fishing boats, smaller commercial vessels, and fixed mooring locations.
Ship’s Anchors (Large Vessel Anchors) Used on Great Lakes freighters and bulk carriers, these anchors depend on both weight and fluke engagement with the lakebed. Typically made of high-strength steel and weigh thousands of pounds. Common designs include:
Stockless Anchors – Large flukes pivot to grip the bottom, commonly used on freighters and tankers.
Admiralty Pattern Anchors – Feature long shanks and two fixed flukes, used less frequently but effective in rocky bottoms.
Danforth and Plow Anchors – Known for their ability to dig into sand and mud, often used on smaller commercial or recreational boats.
Modern Anchors for Small Vessels Designed for recreational boats, fishing vessels, and small commercial boats. Feature lightweight metal flukes that hook onto rocky surfaces or bury into sand/mud.
Danforth Anchors (lightweight with strong holding power in sand or mud).
Claw/Bruce Anchors (effective in rocky or mixed seabeds).
Grapnel Anchors (used for temporary anchoring, often for fishing or small craft).

Anchor Rode and Holding Power

An anchor rode (also called a warp or cable) is the connection between the vessel and the anchor. It can be made of rope, chain, or a combination of both. The holding power of an anchor depends not only on its weight and shape but also on the type of bottom it rests on and the ratio of rode length to water depth (known as scope).

Best holding grounds: Hard-packed sand and mud (anchors can dig in and develop strong resistance).
Poor holding grounds: Shell, loose gravel, or soft clay (anchors may not set properly or can shift).
Obstructions: The lakebed may have rocks, wreckage, or submerged debris that could foul an anchor.

Anchoring Techniques on the Great Lakes

Proper anchoring is critical to prevent vessels from drifting, grounding, or capsizing in high winds and currents. Here’s how it’s done:

Selecting an Anchorage Location Choose an area that is sheltered from strong winds and waves. Ensure the lakebed has good holding material (sand, mud, or clay). Check for adequate depth at low water levels to prevent grounding.
Dropping the Anchor Approach the chosen site from downwind or down current. Slow or stop the vessel before releasing the anchor. Lower the anchor quickly but in a controlled manner until it reaches the bottom.
Laying Out the Rode (Scope Ratio) As the vessel drifts backward, the anchor line should be veered out slowly. A proper scope ratio is generally 5:1 or greater (e.g., in 20 feet of water, at least 100 feet of rode should be used). For storm conditions, a 7:1 or higher scope may be required for better holding.
Setting the Anchor Once enough rode is laid out, the vessel should be gently reversed (astern) to apply pressure on the anchor.A hand on the anchor rode can detect vibrations (indicating dragging) or steady tension (indicating a set anchor). If the anchor drags, it should be retrieved and reset.
Monitoring & Adjustments The vessel should be checked for drift using shore references, GPS, or depth readings. If the vessel swings too much, additional scope or a second anchor may be necessary. In high winds or changing currents, additional chain weight can improve holding.
Challenges of Anchoring on the Great Lakes Unpredictable Weather: Sudden storms and shifting winds can cause anchors to drag. Strong Currents: Areas like the Straits of Mackinac and the St. Marys River have currents that make anchoring more difficult. Rocky or Hard Bottoms: In places like Lake Superior and northern Lake Huron, setting an anchor can be challenging due to rocky terrain.
Ice Formation: During winter, vessels must be secured differently, as anchors may not hold in ice-covered waters.

Historical Importance of Anchors in the Great Lakes

Throughout history, anchors have played a vital role in the Great Lakes maritime industry:

19th-Century Sailing Ships: Schooners and brigs relied on heavy Admiralty-pattern anchors to secure in unpredictable conditions.
Freighters & Steamers: As steam power took over, larger stockless anchors became the standard for bulk carriers and passenger vessels.

Shipwrecks & Anchors Lost: Many lost vessels still rest on the lakebeds with their anchors intact, providing clues for shipwreck hunters and historians.

Portsmouth Harbour Anchor

Krupp Steel & Anchor Manufacturing Krupp Steel (Friedrich Krupp AG) was a major German steel manufacturer known for producing ship anchors, naval artillery, and heavy industry products. The backward (left-facing) swastika was a trademark of certain steel products before the 1920s.