What Size Lag Bolts do I Need to Swap Out Bunk Boards on 20 Foot Bass Boat?
Updated 02/09/2026 | Published 02/02/2026
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Question:
what size of lag bolt do i need to attach bunk board to trailer i have 20ft bass boat trailer and replaceing new bunk boards
asked by: Randy C
Expert Reply:
Hello Randy,
Great question. For replacing bunk boards on a 20 ft bass boat trailer (like # CE27845), you’ll want 3/8 inch diameter lag bolts that are 1-1/2 to 2 inches long, depending on the thickness of your bunk brackets. Go with hot-dipped galvanized or stainless steel, use flat washers, and drill a small pilot hole (1/4" bit will do the trick) so the wood doesn’t split. Lightly countersink the heads so they don’t rub through the carpet, snug them down without overtightening, and you’ll be good to go. Simple, solid, and trailer-ready.
We don’t currently carry that size, but you should be able to find them easily at a local hardware store.
Where do you mainly fish? I dabble in some local bass tournaments at Lake of the Ozarks and Mark Twain Lake here in Missouri. It’s been a little cold this season, but the ramps won’t be frozen this weekend, so I’m excited to get out there and hopefully catch some fatties.
Brian
2/9/2026
I replaced the bunk bolts on my 2000 TRAILMASTERVANGUARD 18 feet boat trailer using the Stainless Steel Hex Lag Screw bolt .Works perfectly
Product Page this Question was Asked From
Stainless Steel Hex Lag Screw - 3/8"
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Mark F.
2/6/2026
I replaced the bunk bolts on my 18ft pontoon trailer and a jet ski trailer using this size bolt. Haven’t had any issues since.