The Marinervideo
Rough Antifoul vs Smooth. Which is Better?
26 June 2025 · 20 min · 3K views · Portland, Victoria
What this video covers
Chris applies four coats of Interprotect (two on bare metal, filler, then two more) and two coats of antifoul to the keel blade of his boat in Portland, then argues at length that a rough antifoul surface outperforms a smooth one at high speeds.▶ 8:15 The keel developed paint bubbles and rust pitting in a roughly 45-centimetre triangular patch because Chris missed that area during acetone prep, trapping moisture under the paint; hot weather (35°C) then forced the contamination through.▶ 3:06 He decides not to re-fill and repaint the area before launch, planning instead to media-blast the keel when the boat comes out in approximately 100 days.▶ 3:46 The keel bulb and rudder are painted red — no extra cost over standard antifoul — to improve visibility in a capsize scenario.▶ 7:21 Chris's hydrodynamic argument: a turbulent boundary layer, like the dimples on a golf ball or the rough skin of a shark, reduces induced drag by allowing flow to reattach faster behind the hull, making a deliberately rough antifoul surface beneficial on a fast, heavily loaded hull.▶ 13:03 He also notes that a slowly rotating propeller is hydrodynamically more efficient than a fixed prop, and that 10 knots is the practical upwind speed ceiling.▶ 17:20 Deck stripes are dropped from the schedule; white single-pot paint will go on the deck instead.▶ 6:58
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