Material Choice for Engine Enclosure

[Briarpatch]

I have checked the forums for prior advice of materials/thickness for building an engine enclosure but have found nothing so far.

So, I am planning to build a wooden engine enclosure around my newly installed Beta 35 (this is a "new" build). See photo attached.

What type of plywood and what thickness are recommended for the construction?

[psk125]

Our engine box is half-inch plywood with an ash exterior veneer. It has rabbeted solid wood corner posts, and framing, to give it added strength without adding too much weight, since it hinges up for access. Leaded-foam soundproofing on the inside.

[Hesti]

Half inch where you put your weight on.

[a64pilot]

How much room do you have, and how weight sensitive are you?
The heavier and denser and thicker it is, the more vibration and noise it will attenuate as opposed to pass on.
I’d want one from dual layers of 3/4 ply myself, actually particle board would be better from a sound / vibration perspective, but unless you can get it with a 100% waterproof adhesive I wouldn’t use it, and even then probably only the inner layer.

However you make it, try to make as much of it removable as is possible, they Joy’s of an easily accessible engine is a gift that never stops giving.

[kenbo]

You didn't say what your anticipated end goal of the enclosure was. I'm assuming noise reduction primarily. if so, you need to decouple the enclosure from the hull and the sides and top of the enclosure should be decoupled as well if you want a good result. For the enclosure i'd use two layers of 3/8" glued together with Green Glue (greengluecompany.com) and use a good acoustic panel on the inside like the product Sailor's Solutions sell.

How you build the base that the enclosure rests on is very important as well. That base needs to be decoupled from the hull. The low frequency vibrations are difficult to attenuate.

Also give some thought to ventilation, control cables and wiring openings. If done improperly your noise attenuation efforts are greatly diminished.

[sailingchiro]

I recently built my box for a genset. 3/4" marine plywood, layer of 1/16" lead sheeting adhered to plywood with roofing adhesive tape and short stainless screws (extremely sticky-like 5200 as tape), then a layer of sound killer used on automobiles. The sound difference is amazing. The lead did the best at reducing sound. It weighed about 40 lbs. The sound killer made it look nice. Bought both on ebay for less than $100 each.

[oleman]

Line with Lead sheet for the best sound and vibration suppression.

[Djarraluda]

As others have said, density is needed.
The weak point in many installations is the bilge, ideally you should use the lead/foam to line the hull as well and seal the sides to this. It tends to deteriorate more though, so may only last a few years before needing replacement.

[rmlarson1098]

Originally Posted by Briarpatch

I have checked the forums for prior advice of materials/thickness for building an engine enclosure but have found nothing so far.

So, I am planning to build a wooden engine enclosure around my newly installed Beta 35 (this is a "new" build). See photo attached.

What type of plywood and what thickness are recommended for the construction?

Of interest might be fire-resistant lumber? Nuclear facilities/power plants required it going back 25 years and maybe more. And while we used 'fire-proof' scaffold planks, etc. (probably fire-resistant in realty) you might find fire-resistant plywood. Not sure how water-resistant it would be, or how available it is.
Just a thought. I do worry about fires in the engine room. If we needed a new engine enclosure, I'd probably use aluminum ckecker-plate, or even light steel plate, rather than wood. If I had to use wood it would be 1/2" (as previously mentioned) exterior or marine plywood if space allowed.