@mtudb24 — seeing your AR220 maiden post today reminded me that I never replied back to this thread.
In short — the 1'' DynaCore made a
huge difference.
Honestly, I wasn't expecting much from the DynaCore — it's just a sandwich of low-density foam and thin, ripstop fibrous fabric after all. If I had all the time in the world, I would've installed Rockwool SeaRox with mechanical fasteners to insulate the engine bay. But... I had neither the time nor the desire to spend a whole day on this project. So, DynaCore was my one-hour solution.
I used heavy-duty scissors (with an alcohol-soaked rag to remove the adhesive buildup on the scissor blades between cuts) to shape a single sheet of DynaCore into two large pieces to fit the undersurface of the engine hatch. I cut up a second sheet of DynaCore to fit the underside of the two hatches to the left and right of the engine bay, as well as the firewall between the engine bay and the cockpit. Precutting the DynaCore was a mistake, as I'll explain shortly.
I covered the open engine bay with masking paper and scraped the leftover foam off of the engine hatch, but otherwise did no other cleanup or prep.
I sprayed 3M 90 onto the boat's surfaces, let it dry to tackiness while I peeled off the DynaCore's paper backing, then applied the DynaCore using a roller. DynaCore's self-adhesive layer is on a "backside" of a grid-like webbing that tries to maintain the shape of the mat. Unfortunately, when the paper backing is peeled off, DynaCore shrinks by roughly 5–10%! Therefore, I had to stretch each piece as I slowly peeled and rolled it — which was very difficult to do upside-down, when I was trying to align the edges of those big pieces to the somewhat articulated shape of the engine hatch. And I only had one shot. Uggh!
If I ever have to do this job again, I'm definitely removing the engine hatch first, so I can work on it right-side-up. And I'm also cutting down the mat into smaller pieces — one at a time — so I can carefully align each piece, and then cut the next piece a little bit bigger, knowing it'll shrink a little, vs. trying to stretch big-ass sheets while rolling them. Once I had the engine hatch completed, I cut down the firewall sheets into half a dozen manageable pieces before applying those.
Despite the installation difficulties — I finished in an hour, and I was very surprised at DynaCore's effectiveness. I can now have a conversation with the person next to me —
without yelling — when we're both at the helm while running the boat on plane. When the engine hatch had just the stock foam underneath it, we had to yell to be heard over the sound of the engines.
It's been almost 2 months since I installed the DynaCore, and so far, it's held in place fine, even with the extreme heat of the engine bay — not only when I'm running, but also with the boat sitting uncovered on my backyard lift in the baking FL sun. With that said, the lightweight foam that makes up the core of the DynaCore is very delicate, and I can see it shredding/shedding over time. One of these days, I'll spend a half hour applying DynaTape to the exposed edges of the DynaCore.
