BOAT-COMPARATOR Guide
Plow, Delta, SPADE: the main anchor types you'll find on a rental boat
Plow, Delta or SPADE anchor: how to tell the main anchor types fitted to a rental boat apart, and what that shape actually changes for holding power at anchor.
Not all anchors look alike, and the one hanging off your rental boat's bow roller is no small detail: its shape directly shapes how well it bites into the seabed and stays put.
Plow and Delta, the most common on rental fleets
On most rental RIBs and sailboats, the standard-fit anchor is a plow (CQR-type, hinged share) or a Delta (fixed share, no hinge): recognisable by its plough-like shape, it sets well in sand and mud, stows easily in a bow roller, and suits standard coastal cruising.
SPADE and the new-generation anchors
Over the past twenty years or so, "new-generation" anchors such as the SPADE, unhinged and tip-weighted, have become common on newer or larger boats: their geometry favours faster penetration and better holding at a shallower pull angle, particularly on trickier seabeds.
What the anchor's shape genuinely changes
A study published in the journal Geotechnics, which modelled the holding capacity and efficiency of different drag embedment anchors according to their geometry and the seabed involved, confirms that fluke shape and the fluke-shank angle directly affect the holding capacity obtained for a given anchor weight (Olyasani, M., Azimi, H. & Shiri, H., Predicting Efficiency and Capacity of Drag Embedment Anchors in Sand Seabed Using Tree Machine Learning Algorithms, 2025, see the study on Google Scholar) — anchor geometry, then, is not just cosmetic.
What a renter can actually do with this
In practice, you do not choose your anchor on a rental boat: it comes with the boat. The real lever stays the amount of chain paid out, covered in our guide on the right scope ratio, and the way you anchor itself, covered in our anchoring right guide.
If the anchor won't hold
Whatever its shape, any anchor can drag over seagrass, rock or soft mud. Check the bottom before you drop anchor, let it dig in firmly in reverse, and see our guide on a dragging anchor if it will not bite on the first try. A quick look at the boat's inventory sheet before departure, or a question to the operator, tells you which type is fitted — useful context before your first night at anchor.
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