Princess 32 - Engine soundproofing

[boatone]

P32 with twin Volvo AQD32's currentlay has what I believe to be original 'eggbox' type foam insulation in engine compartment and under hatch. Anyone experience of using newer sound barrier materials? What improvement should I expect?

boatone@boatsonthethames.co.uk

 

[jfm]

Haven't done this myself but there were some big threads on it maybe 6 mths ago, you could check archives if they go back that far

JFM

 

[ArthurWood]

I've done it to my Sea Ray and I believe MattS did his sometime back. My 7.4l Mercruisers are pretty noisy, so people tell me. Anyway, the new, sandwich-type sound proofing seems to have cut down the higher frequency noise on my boat, but it's still noisy. Depending upon your engine compartment config, it's a pretty easy job, the most difficult and messy part being the removal of the old stuff and its adhesive. Good luck.

 

[eddieperkins]

Did it on a Project 31, no improvement that I could see (or should that be hear!), I would stay with shat you have got
Regards,
Eddie

 

[Guest]

Be careful of the egg box type foam insulation, it's not fireproof. One of my friends recently bought a Birchwood 26 (I think) and on the delivery trip back along the river smoke started pouring out of the engine compartment. Closer examination revealed that the foam insulation had come away from the engine hatch and dropped onto the exhaust manifold and it was smouldering and smoking like a steam train. No actual flames, but enough choking smoke to make his eyes water (and for his bum to pucker up too!!).

He replaced it all with the lead sandwich foil finished stuff and is well pleased with the result though whether its quietened it down is hard to tell since he didn't have it long enough "pre fire" to gauge noise levels.

 

[Guest]

Yes, I did engine soundprofing on a targa48.

1) the flameproof issue, mentioned by others, obviously vital in selecting the correct stuff, as the boat-advertised sandwich stuff all is. I checked it witha blowtorch, nasty heavy fumes, but no bursting into flames.

2) The "falling off" issue. test this first. You need a method of attaching the stuff that is strong. Glues are good enough to hold it temporarily, but it needs a positive mechanical method of attachment: aluminium straps for example, screws with colossal washers, and so on. The stuff is very heavy, so it need to be striong enough so that you can't rip it off by hand - and glues can't do this long-term.

3 ) The thickness issue. Apparently the sound insulation improves up to SIX inches of the stuff. I did a double thickness (four inches) under the engine hatch.

4) The airtight hatch issue. The insulation is useless unless the hatch itself is very tightly shut- the direct noise from the engine travels through air, even tiny gaps. To demonstrate this, get a battery powered radio, switch it on loud, and plop it in the fridge. Quiet huh? Now try with a tiny gap - much louder. You could do other tests involving foam, radios and fridge but wife will go potty. Make it, if possible, so no air can sneak out from around the hatch. Extra hatch catches, dense foam strips that will mould to the shape all help. Have an overlap around hatches if possible, so that the engine hatch foam mates with foam on the engine hatch roof.

The boat manufacturers have to have the stuff metal-shing side out, for flameproofing. But I think that it must be less effective with shiny side out, losing some noise-wave deadening prperties and that I'd be on a liferaft by the time that the flame-ratardent form (which it all is) became anything of an issue. I used black foam 2inches thick , heavy plastic interlayer (you've obviously seen it) foam on one side, metal? whatever (woven) on the other.

Anyway, after a grovelling around with drills, screw, washers, foam, stanley knife I managed to get six sheets of praps 1m square on the upper inside of the engine compartment. Dramatic improvement. It wasn't silent, but you could hear the waves sploshing outside the hull and have normal-level conversation in the cockpit. Eventually some of the heat-gun glued-on bits fell off, so had to screw them down. Later t48's have two catches instead of one, and are better I expect.

Oh, and while you are fitting the stuff, make sure that there's some means of communicating with outside, in case of accidents- during fitting, you will find yourself inside the engine room and can't easily be heard unless wife reading paper immediatley above with you shouting - which is what your after. She may have been ignoring me on purpose tho..

Small areas insulated, like on production boats, incidentally, is nearly useless (f'line are you listening?) : that just deadens the panel a bit. You need a wall of the stuff with no gaps at all. You may find that you become a fanatic, and realise that the main difference between posh silent cars and loud cheap cars is down to a few sheets of sound-deadening under the bonnet and in the passenger footwells -otherwise all that is separating you from the engine is the tin of the bonnet and the windscreen. Can't fit this yourself out of sheets, but definitely worth a thought down at the scrapyard - will an extra thickness make a difference? Oh yes.