Hi there. I'm in the process of installing a Bimini on my 1981 O'day 22. I'd like your opinion on the screw length for the hardware. The instructions don't specify the length of the screws for securing the deck mounts and padeyes (for webbing straps). They do specify the sizes. It is 1/4" or M6 for the two deck mounts and 5/32" or M4 for the two padeyes. What length would you recommend? Another manufacturer's instructions, Carver, spec a 1" long screw for both fasteners. Naturally, the deckmount is thicker and there is less screw going into the deck. However the padeye is thinner, and would be installed on the cabin top, so more screw would penetrate. I'm concerned about the screw popping through the cabin top or punching through the deck.
O'day Bimini Installation
- Thread starter Capri
- Start date
Are you concerned about the Bimini lifting off the boat pulling screws out in a strong gust of wind?
Our boats are unlike our homes. There is a thin skin of fiberglass separated by foam, on end balsa, or in some cases plywood, and a second thin skin of fiberglass on the inside. They are not designed to take the loads of a screw and hold it in place while you attach a piece of cloth that will act like a sail.
That is why you install these attachments with thru bolts and backing plates. Better yet you oversize the hole, fill with thickened epoxy, then drill through the thickened epoxy to place your bolt. The bolts, if visible, can be capped on the inside with cap nuts. They will save you from scrapes when moving about inside the boat.
Here is a link Sealing Deck Penetrations To Prevent Core Rot - Marine How To
All this is to reduce the opportunity for water to get into the inner wood or foam core and destroy the deck of your boat. Screws into the deck are a primary suspect for leaks inside a boat.
Good luck. A Bimini is a great shade. Just don't let the install be the beginning of the end for your boat.
