bertram31.com

I have replacemet decks and at any speed above 5 kts the rattle to the point that we go around and put pieces of paper / business cards from insurance salesmen in the joints. Not much works. What has been done to quiet the decks?

John,

First, the deck must be securely screwed down. If you've got the 3 section Glastech style aftermarket deck. there are 3 sections, port, starboard and center. The center section has flanges on both sides and spans the center deck joists. There should be three to four #10 flat head screws running fore to aft on each flange. The joists have to be solid wood and in good shape, (no rot).

The port and starboard sections rest on the flanges of the center section. I lock these down to the center section from under the deck, through the hatch openings with 2 #10 per hatch. The screws run up from the side section and into the center section flanges at about a 30 degree angle.

The only screws that are visible from the top side of the deck are 3 #10 along the outboard side of the side sections, down into the outboard joists. These are hidden by the side panels if used. I use pan head screws for these with EPDM rubber washer to prevent water intrusion.

Properly locked down, the deck sections themselves will not rattle.

The hatch covers must be cushioned with thin rubber strips glued to the under sides of the covers. Very little rattle will come from them with the rubber strips.

Thanks Capt. I have the 3 section Glastech deck and when I put in he new fuel tank I rebuilt the sub structure with FRP "C" channel. The deck is screwed down as you describe. The hatch covers have some rubber strips on them but they must not be thick enough. Is there any way to positively lock the hatches? I have seen some twist handles at West Marine, but at about $50 each that's a lot plus the re routing and repair work to get them recessed.

John,

Without installing hatch plate latches there is only one possible solution...

The hatch plates are relatively light, maybe 2 lb each for the 4 medium sized and 5 - 6 lbs for the large one. The small fuel fill inspection plate probably doesn't make much rattle sound.

By adding weight to the under side of the hatch plate you'll reduce the bouncing effect. Start by working from the top, setting on a known weight that won't slide around. I wouldn't go above 15 lbs. If that works, look for a low profile weight that can be semi-permanently mounted to the under side of the plate. Could be lead, concrete, etc screwed and glued with polyurethane adhesive. Think outside of the box!

Signs of deck rattle could also be vibration from the running gear or questionable alignment or engine mounts transferring and making anything loose vibrate. Might be worth an inspection.

To verify it is the hatches rattling...have you tried running with them off for a bit?
Lay them on a towel or something, run a bit...rattle stops then attack hatches and/or source of your rattle.