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Engine Box Insulation

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quitchabitchin
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Engine Box Insulation

Post by quitchabitchin » Sat Aug 09, 2014 3:37 pm

I see that the older models all seemed to have a Homasote type board insulation on the inside of the engine box, but I can't seem to find anything like what my boat has. It looks like fiberglass insulation wrapped in a fiberglass mat material. I can't seem to find anything like this anywhere online, so is this something I might have to remake or should I use a newer type of product like a fiberglass/lead mat?
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FLASH1969 Chris Craft Cavalier Ski-230 HP 327Q

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Chad Durren
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Re: Engine Box Insulation

Post by Chad Durren » Sun Aug 10, 2014 6:38 am

Looks like something they came up with at the factory - with the staples holding it all together.

If you're going after originality, it should be pretty easy to replicate. If not, just go with the modern, thermal acoustic lining stuff designed for the same purpose.
1952 CC 18' Sportsman
1969 CC 19' Commander Super Sport

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Paul P
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Re: Engine Box Insulation

Post by Paul P » Fri Aug 15, 2014 10:14 am

Okay guys I have an opinion on the motor box thing and I am "compelled" to share it with you, lol.

My advice..........LOSE THE INSULATION. I have designed some of the largest and best equipped recording studios in the Nashville area (one complex had 8-million in equipment alone) and have hired the best acousticians in the country, and I can tell you insulation on a motor box is a waste of time, plus the fact, the old style homasoat would flake off and get into everything, what a mess, what a disaster. The best and only thing a motor box can do for sound is to be tight and without holes to the seating area, and reflect sound down under the floor where it will be diffused. The old style boxes with holes still had the insulation, and that is laughable. The stuff can get wet too if your flywheel scoops some water or have a hose leak. It makes the box heavy too. While in a lab it might actually show a difference on a db meter, but in practice, there are too many other competing sounds for an ear (or meter) to tell the difference. Now if you are running a Casale old style v-drivce unit, good luck with that..........you're going to have your work cut out for you. In a normal inboard, just the box will do fine, especially with a nice cushion on top.

Here is my light weight and brutally strong box for the 1966 20-foot Sea Skiff. removable cushion top gives easy and immediate access. The box is made of white oak and 1/4" marine plywood, intentionally light for handling, but very strong too, and is painted with bilge paint on the inside.

Here are the videos of the box in operation, you hear NOTHING coming through the box, but you do hear wind, splashing, and exhaust note. :-)

My advice, .............. "Lose the insulation, go boating, be happy, worry about something else".
If you are going for originality then I understand, but this post did not indicate that intent.

Eh.........what are friends for anyway?

Here we are at speed......................
http://www.youtube.com/embed/aBM8B0feNLc?rel=0

Here we are at idle.........................
http://www.youtube.com/embed/YTueLeIOmF8?rel=0

best,

Paul
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1956 17' CC Sportsman, 300-hp
1957 17' CC Sportsman, 95-hp
1966 20' CC fiberglass Sea Skiff, 210-hp+
1973 23' CC Lancer inboard project, 427/375-hp.
1966 38' CC Commander Express, 427/300-hp(2)

So many boats.........so little time.....but what a way to go!!

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quitchabitchin
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Re: Engine Box Insulation

Post by quitchabitchin » Mon Sep 01, 2014 10:07 pm

As for now, it is just painted. I'm working my tail off trying to get it finished by the end of September for the Bluegrass Rendezvous. If i do address it, it will more than likely have to wait.
FLASH1969 Chris Craft Cavalier Ski-230 HP 327Q

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bflaherty
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Re: Engine Box Insulation

Post by bflaherty » Thu Sep 11, 2014 11:38 am

When we redid our upholstery we rebuilt our engine box (or at least about 60% of it, as the lower corners where rotten or broken off completely) in our 1969 Cavalier Ski Boat. We had the same strange fiberglass insulation (must have been something Chris-Craft did at the factory) and like yours it was torn, and flaking all over everything. So I removed it all, painted the entire box, inside and out, with bright white oil based urethane paint. Then I lined the sides and back with the modern black vinyl lined foam insulation. I didn't really do it for sound protection, but rather for heat protection... When we are out running all day there is a lot of heat coming from the motor and I wanted to prevent the box from getting so hot that the vinyl glue starts to melt (seen it happen). We also often have our toddler holding onto the ski pole while leaning against the back of the box so I didn't want excessive heat anywhere near him.

In hindsight, I would have used a thinner version of the foam but I got just enough scrap pieces, for free, to cover all the areas I was worried about. I used 3/4" thick stuff and it is just enough that it sticks to the exhaust risers when they get warm (not bad, but just enough that it has lifted a bit of the blue engine paint)

I can post some pictures when I get back to the garage.
Brian Flaherty
1969 Chris-Craft Cavalier 17 Ski Boat "TUPPERWARE"

"You'll never discover great lands, with your feet planted in the sand"

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Re: Engine Box Insulation

Post by boat_art » Thu Sep 11, 2014 9:16 pm

I am with Paul on this one....lose the insulation. Get an electric boat if you want quiet.
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1956 CC Connie 47'
1959 Caulkins bartender
1965 Cheoy Lee Frisco Flyer
1953 Chris Craft Holiday
1941 Chris Craft Deluxe
Plus 8-12 customer boats at any time
God don't count the days spent messing around in wood boats.

bflaherty
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Re: Engine Box Insulation

Post by bflaherty » Fri Sep 12, 2014 9:59 am

Here are a couple photos of my "restored" engine box.
photo.PNG
photo1.PNG
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Brian Flaherty
1969 Chris-Craft Cavalier 17 Ski Boat "TUPPERWARE"

"You'll never discover great lands, with your feet planted in the sand"

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