Reducing engine noise in Sportster

[ausgezeichnet7]

Although I like the performance of the boat, the noise is a little bit much for the passengers. I know my 2-stroke (947 I think?) will be noisier than a 4-stroke... but it seems like I could do something...

I've been thinking of jamming some foam of some kind in all of the open hull areas between the engine compartment and the rest of the boat. There is some stuff there from the factory but it seems loose. I also considered putting thicker foam on the engine compartment shelf. Has anyone else messed with this? Looking for ideas/suggestions on material types.

[jclairday]

I have an 02 sportster LT. ( Twin 717's ), and engine noise is not loud at all with only a thin sheet of foam glued to the under side of the removable pannel. Have you checked your exhaust connections for any leaks?

[Steve762us]

I've got a 1996 Challenger, which I've seen described as "the loudest boat that Seadoo ever made." Pilotsmith and I have exchanged notes and found the biggest gain in quieting our boats was stuffing/blocking the LARGE spaces leading from the engine compartment foward (along the sides of the cockpit, not the breathing holes).

Use whatever will stay put and not shift and cause you problems...I used a combination of expanding foam and styrofoam blocks. I like the foam and styro blocks, since they're light and add buoyancy, not a bad thing to have.

Now when I'm running over 30 MPH, the main "noise" is from the wind..not the engine!

Keep in mind drainage from forward to rear, and operating cables/linkages. I also shot expanding foam between the fuel tank and (underside of the )rear "bench" seat.

Once you've done this stuff, you'll notice the noise is islolated to the engine compartment, instead of reverberating thru the hull, all around you.

[ausgezeichnet7]

Thanks for the input... You're exactly right about the wind noise too, and I decidely don't go 45mph everywhere specifically becaue of the wind noise fatigue, but I'm thinking primarily about the 5-10mph range. We like to take leisurely rides around the lake to check out what the other lake residents are up to and gawk at the absurdly large houses. In an old stern-drive it was easy to cruise around and be able to chat. With the Sportster it seems like I have to run at about 4000rpm to keep up 5-7mph.

I considered expanding foam but was worried that someday I might need to get it out. Not sure why I cared about that, but I could certainly use it above the gas tank like you mentioned!

[ausgezeichnet7]

I have an 02 sportster LT. ( Twin 717's ), and engine noise is not loud at all with only a thin sheet of foam glued to the under side of the removable pannel. Have you checked your exhaust connections for any leaks?

I'm not even sure where/how to go about checking... do I idle the engine and dribble soapy water on the various exhaust parts? There is no visible discoloration that I can see.

[jclairday]

If you did have an exhaust leak, you would see some black carbon build up / residue at the leak. Steve762us has a good point, with nothing to dampin the sound between the engine compartment and the remaining hull sections, you are basically surounded by the noise coming from the engine compartment.
By the way, thanks for the reply about the stereo install.