I just used our 'small' box anchor for our 26' Formula. I used it on Lake Michigan in a sandy area. The box anchor worked great with little scope and no chain. The anchor grabbed immediately and did not slip once over a 4-hour period (there was about 10-15mph wind, but little chop).
Love it!!!
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2006 Formula 260BR, BIII, Merc 496 MAG, Prestige Trailer