Trojan Boat Forum

When we did the original restoration on our F-26, we added sound insulation to the bottom side of our cockpit floor and hatches to help reduce engine noise. Since the floors and gunnels are fiberglass they don't suppress sound very well on their own. The insulation under the floors helped a little however recently I realized that a large part of the engine noise was coming from the sound resonating between the outside hull of the boat and the cockpit wall (gunnel). This area is open to the engine bay.

I decided to try a little experiment. I took some 1 1/2" thick insulation and cut strips wide enough to fit between the inner cockpit wall and the outer hull at the floor level only in the cockpit. I cut them large so that they would hold themselves in place. I did this across the transom and up both sides from the transom to the first set of bulkheads. This was as far as I could reach. I did leave a couple small areas open to still provide ventilation.

The result is less sound resonating in the gunnels and a 20 db noise reduction in the cockpit. The job took just over an hour.

If you're looking for effective sound suppression in the cockpit, this works great. Be sure to allow some ventilation though.

Then I would have to listen to my wife, I mean I would be able to hear my wife.

You're right. Oh my, what have I done???

Paul, you're right, what have you done???!!!

I've convinced my wife that "there's nothing like the sweet sound of an inboard engine at 3200 rpm". The boat underway is the only place where she gives up talking.....

Actually, your idea is very "sound" indeed!

Thanks

The 10 Meter has factory sound insulation in the cockpit floor and inside all the gunnels, even those aft.

Doesn't kill all the sound, just takes off the "edge"

RWS

Humm,

A pair of 12-valve Cummins is so load you can't begin to hera anything.

RWS

Do you know what material was used for sound insulation on your boat?

This is what I did on my F32... at 3200 rpm it is comfortable to be in the salon while underway!
From Wilrep on Matheson Blvd, Mississauga
Behind engine bulkhead under aft deck from side to side I used:
F200
http://www.wilrep.com/WilrepDataSheets/ ... orbF/F.htm

Under the salon floor I used this foil side out, again side to side:
FTMM 200
http://www.wilrep.com/WilrepDataSheets/ ... M/FTMM.htm

Easy to put in you just cut to manageable strips to allow it to be glued to underside of deck/floor and spray on the glue and push in place.

Michael, I'm not familiar with that flammability rating. Is it rated for engine spaces?

Did you cut it to fit between the ribs under the cockpit floor, or apply as one sheet over the ribs?

Paul wrote:RWS

Do you know what material was used for sound insulation on your boat?

======================================

The factory insulation is a foam style with a foil type exterior backing.

I left the factory insulation alone and went over top of it with Soundown brand insulation that contains a thick layer of composite underlayment.

It is specifically designed for marine engine rooms.

The product is so heavy it had to be supported with fasteners and oversized fender washers.

End result:

The diesels and diesel genset are quieter than the 454's and the Onan.

Good results.

The only negative is the added weight,m, however we really don't consider tyhat an issue.

RWS

Thanks RWS

I guess I'm on the right track.

Big D wrote:Michael, I'm not familiar with that flammability rating. Is it rated for engine spaces?

From their website: Use for engine compartments.
3150 0.88 0.85 1.05 Flammability: MVSS 302 – Passes, UL94 HF-1 – Passes


That rating (302) is federally mandated for passing in the automobile applications. So I suspect that their rating, Marine Vessel Safety Standard 302 (MVSS 302) is their standard as well.

Standard No. 302 - Flammability of Interior Materials - Passenger Cars, Multipurpose Passenger Vehicles, Trucks, and Buses
(Effective 9-1-72)
This standard specifies burn resistance requirements for materials used in the occupant compartments of motor vehicles. Its purpose is to reduce deaths and injuries to motor vehicle occupants caused by vehicle fires, especially those originating in the interior of the vehicle from sources such as matches or cigarettes.

Thanks Jamie. Good to know.

obeejr wrote:Did you cut it to fit between the ribs under the cockpit floor, or apply as one sheet over the ribs?

Over the ribs.. sorry for late reply been away looking at boats in Middle River, Annapolis and Kent Island. Lake Guntersville, Alabama this weekend... don't ask not Trojan's.