How replace the foam insulation in your cowling (outboard cover)

Last fall I purchased a 1990 90-hp Force that hadn't been run in almost 2 years and I have spent this season getting it up and running. After finally getting the mechanical issues sorted out, I decided to redo the foam insulation in the cowling/outboard cover in order to quiet her down. There was pretty much no insulation left when I purchased it, except for some small patches attached to old glue, which made her very noisy. I did some research on the hull truth and decided to fix this myself.

Here is my cowling


Next I used isopropyl alcohol and a razor/scrapper to clean out the remaining foam, glue, and residue. It actually took me a good hour or two to fully clean it out and this was the end result.


Next I gathered my materials including 3M-90 aerosol spray glue and silver tape.


....and I couldn't forget about the foam! I used a product from Sound Down that was 1/2-inch thick and had a mylar face to protect the foam from gas and heat. Sound Down has two layers of foam sandwiched together that is separated by a vinyl barrier. This product is pricey and cost me about $70 for a 32inx54in piece.


Next I started to create stenzels inside the cowling out of paper. Then I careful cut each section piece by piece, and then fit it into place and trimming where necessary before moving onto the next piece. Once the piece fit I sprayed both the cowling and foam contact surfaces with the 3M-90 and pressed them into place. I did have to make some shim pieces out of scrap to fill small gaps.


Lastly, once all the pieces were glued into place I covered up all the edges with silver tape to keep water/gas from getting into the foam and keep the edges in place.
https://lh5.googleusercontent.com/-...epaU/w865-h646-no/2013-07-21_13-14-02_889.jpg

I tested the new insulation out this morning on the water and it did make a big a difference. Note that this foam is pretty heavy and added significant weight to the cowling....it may have actually doubled in weight!

Re: How replace the foam insulation in your cowling (outboard cover)

Looks like you did an excellent job of replacing the foam. I've been thinking about doing the same, but I was looking for something a little cheaper. Good job though! Thanks for sharing.

Re: How replace the foam insulation in your cowling (outboard cover)

Nice job. I did mine using dynaliner and ice and water shield for the joints about 3 years ago. It made a big difference and has held up pretty well.

Re: How replace the foam insulation in your cowling (outboard cover)

Thanks guys. Could only attach 5 photos per thread so here is the final finished product:
View attachment 204797

Re: How replace the foam insulation in your cowling (outboard cover)

Great job. This is one of my next projects on my list.

Re: How replace the foam insulation in your cowling (outboard cover)

pnwboat said:

Looks like you did an excellent job of replacing the foam. I've been thinking about doing the same, but I was looking for something a little cheaper. Good job though! Thanks for sharing.

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I second all of that!

Re: How replace the foam insulation in your cowling (outboard cover)

Good job! A cheaper alternative is 1/4" closed cell foam, used under car vinyl tops. It shapes and glues easily, won't disintegrate and can be found at most upholstery shops. You can find it in 1/2" with some extra searching.

Re: How replace the foam insulation in your cowling (outboard cover)

Anyone who has worked on alot of Force/Chryslers will tell you about bits of foam in the puddle drains.Once the cowlings have been removed dozens of times the flywheel teeth chew into the foam.If you start having ignition problems your cowling may be too well insulated and holding heat in.Sometimes ya just can't win.

Re: How replace the foam insulation in your cowling (outboard cover)

Good job,
I used rubberized undercarriage spray. I personal think the motor is much quieter with the spray than the foam. But that's just my two cents.

Tom

Re: How replace the foam insulation in your cowling (outboard cover)

SweeperForce said:

Good job,
I used rubberized undercarriage spray. I personal think the motor is much quieter with the spray than the foam. But that's just my two cents.

Tom

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I've been thinking about using the same thing. Since I have a spare motor which also has no foam left, maybe I should do one cowl with foam and one with undercoating, and see which is quieter...

Re: How replace the foam insulation in your cowling (outboard cover)

Let us know if you do and the results. I'd be interested if in fact the spray is more effective. I'd probably end up redoing mine with the spray if it is.

Pulling this thread from the distant past......because my boat was born in the distant past. 1985 VRO 140. Does anyone have an update on different approaches? After reading the thread, my thoughts are: 1) Clean it up great like Mitch, 2) Spray it with rubberized undercarriage spray like Sweeper, 3) Replace the cowling seal, 4) If necessary, apply the 1/4 closed cell foam red suggests.