Fire proofing and Sound Deadening

[Tony B]

I recently finished my new floor boards which is actually the cabin sole directly over 2 Crusader 270 engines. There are 8 boards are approx. 2' X 3' each.
Sound deadening is not too much of a concern, however, some sort of fire retardant or fire proofing should be in stalled.
What is recommended for the sound and fire proofing insulation?

 

[Brooksie]

If soundproofing is not a great concern (as with your gas engines) I'd use a layer or two of fiberglass ceiling tiles, the kind used in dropped ceilings 2' X 3' X 1". They meet commercial building & fire codes and have an easy to clean textured layer on one side. You could put a layer of sheet lead between 2 layers for the ultimate in soundproofing.
I have used them with great success on both gas & diesel boats, they are cheap and available at Lowes or HD. If white is not your color of choice, they can be painted with Krylon Fusion paint.

 

[Tony B]

Thanks.
Other than in 'dropped ceilings', I have never used these.
1). What would u suggest for the best way to install these to the undersides on the plywood?
2). Would these panels tend to crumble from vibration?

 

[CPseudonym]

I've seen non marine installations use really large washers over both screws and small diameter nails. Sometimes combined with liquid nails in splotches.

Vibration was never a factor in the installations I've seen.



.

 

[Brooksie]

Thanks.
Other than in 'dropped ceilings', I have never used these.
1). What would u suggest for the best way to install these to the undersides on the plywood?
2). Would these panels tend to crumble from vibration?

1) I installed mine with a few rust resistant deck screws and plated fender washers.
2) The tiles are quite durable, the fiberglass is "compressed" and has sizing in it to hold it together.

What about the edges where the fiberglass is exposed? Do your floorboards have trim around the edges of the underside? If not you could add it of 3/4X1 or 3/4X2 screwed on edge. Or maybe aluminum duct tape would be good enough.

 

[Tony B]

1)...........What about the edges where the fiberglass is exposed? Do your floorboards have trim around the edges of the underside?......

Thanks to all for the great ideas.

Brooksie: I have 2X3's around the trim area that is screwed to the bottom of the plywood decking. This sets below the surface and stiffens the plywood and limits movement between the floor beams. I believe these may be original because I salvaged them from the old floor boards.

Question to all: I was also thinking of getting that aluminum foil looking stuff - very thin (about 1/4") with sound deadening qualities. Thought it would make the installation look very neat also. maybe I'm too paranoid about the panels flaking off.

 

[Cyclone]

Tony B: I too have gas engines, 454 and genny, and am about to do some major upgrade of sound and fire protection. First off sound: You must create a means where by the sound cannot travel up. How to do that? I suggest that you place the aluminum foil on the underside of the deck, then use ROXUL SAFE AND SOUND batts. They come in 16 or 24 widths for either wood or steel studding. These are fire, water proof and sound deadening. Then place peg board against the batt secured to the floor joist. No need to paint the peg board unless you wish and the board will not flake or break as do the ceiling tiles. The sound will travel through the peg board be absorbed by the batt and refelected back into the engine room by the foil. All products available from your local big box building supply and easy to install. Bill

 

[rwidman]

Anything you use must obvuously be fire proof and oil resistant.

It's impostant to not rely on glue or mastic to hold anything in place over the engine because if the glue or mastic eventually fails your material will fal onto a hot engine with moving parts.

Mechanical fastening such as screws and washers is required.

 

[funangler]

I have had good luck with rock wool and thin metal sheeting on top it to keep it clean looking.

 

[Tony B]

Here is what I did today.

I spent most of the day working on a new settee, so I only did one just to see what I would be up against. it went easy and everything fit snug.
The first pic was with the ceiling tiles in place.
I used really large washers to hold everything in place and secured with Stainless Steel screws. Forgot to take pics of the finished product.
Tomorrow i will finish the rest of them.