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Mino

Decreasing Boat Noise

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Mino

I have a 2005 RLXI. The boat has the downturn exhaust and the standard muffler system. I am looking to make the boat quiter from the outside. I want to start skiing earlier in the morning, but do not want to get my neighbors mad. Looking for advice on what can be done to make the boat more quite, including how difficult it was to make the modification.

Thanks

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VinRLX

Swap out to Quiet Rider mufflers

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davemac

If your boat does not already have it, the insulated motorbox mod will help a little bit (from the outside, lots from the inside). Several thread here w/ all the details. I just did it to a buddy's boat last weekend ($140 materials & it will take you 2 or 3 hours the first time you do it).

Another option is inline silencers. I bought some from Peter (aka smoothwaterman) last spring and installed them. There is a photo of the install in progress in my gallery (first picture...second is the insulated motorbox). I can't remember the cost....I think just under $300. Install not too technical, but wrestling and cutting the exhaust hose is a biyotch due to the steel cord that spirals through it.

Edited by davemac

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WakeGirl

Swap out to Quiet Rider mufflers

Dude, where have you been?

If your boat does not already have it, the insulated motorbox mod will help a little bit (from the outside, lots from the inside). Several thread here w/ all the details. I just did it to a buddy's boat last weekend ($140 materials & it will take you 2 or 3 hours the first time you do it).

Another option is inline silencers. I bought some from Peter (aka smoothwaterman) last spring and installed them. There is a photo of the install in progress in my gallery (first picture...second is the insulated motorbox). I can't remember the cost....I think $200. Install not too technical, but wrestling and cutting the exhaust hose is a biyotch due to the steel cord that spirals through it.

Insulated motor box DIY article

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areamike

If your boat does not already have it, the insulated motorbox mod will help a little bit (from the outside, lots from the inside). Several thread here w/ all the details. I just did it to a buddy's boat last weekend ($140 materials & it will take you 2 or 3 hours the first time you do it).

Another option is inline silencers. I bought some from Peter (aka smoothwaterman) last spring and installed them. There is a photo of the install in progress in my gallery (first picture...second is the insulated motorbox). I can't remember the cost....I think $200. Install not too technical, but wrestling and cutting the exhaust hose is a biyotch due to the steel cord that spirals through it.

How much "real life" engine noise difference could you tell in the cabin of the boat after you did these two mods, Dave?

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Woodski

Insulating the motor box will not make a noticible difference to someone on shore, good for inside the boat. The silent rider exhaust is the quietest on the market, in fact it is quiet enough to make the engine mechanical and water noise on the hull actually be audible. That is the ideal set up for early ski sets and low noise.

Short of that, make sure the existing silencers are good, the rubber baffles offering good spring back to the exhaust tips and your impeller in good shape. A good portion of the silencing is from the water mixing with the exhaust.

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davemac

How much "real life" engine noise difference could you tell in the cabin of the boat after you did these two mods, Dave?

Whatup Mike,

I wish I could give you a quantified answer. I insulated the motorbox and installed the inline silencer before the start of last season...thus I didn't have any recent outings to compare it to, and couldn't accurately separate the benefit of each mod. At slow and cruising speed, I immediately noticed w/in the cabin that I no longer needed to raise my voice to talk to peeps in the spotters seat, and could hear my (lame system) tunes much clearer.

I can also tell you that last fall, my buddy briefly borrowed my boat (to take his 80 yr old mother for a quick ski). He returned to the dock completely amazed at how much quieter my boat is compared to his (05 Response Barefoot pkg w/ HH). He has no motorbox insulation, but has the upgraded exhaust (not sure if silent riders- I did notice a rubber hose connecting the two mufflers?).

Thus, last weekend I did the insulation install to his boat...in exchange for BF lessons. He later emailed me that he was very pleased and actually thought the cabin was noticeably quieter at all speeds. I think he may be heading out to that BF tourney in either Michigan or Milwaukee in a couple weeks. If you are heading out there, you could seek him out for specifics since I'm assuming your boats are similar.

Dave

Edited by davemac

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WakeGirl

Dave,

Just curious, did you do the STE tips or did you do the actual Silent Ride mufflers?

My experience with the motorbox insulation was very similar. We did ours & lived with it for a while & got used to it, then got in a friend's Response whose box was not insulated. I couldn't believe the difference that it made, going straight from our boat to his.

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davemac

Dave,

Just curious, did you do the STE tips or did you do the actual Silent Ride mufflers?

My experience with the motorbox insulation was very similar. We did ours & lived with it for a while & got used to it, then got in a friend's Response whose box was not insulated. I couldn't believe the difference that it made, going straight from our boat to his.

Hey Trace,

I did neither...since the retrofitting the tips is such a PITA w/ a direct drive...requiring gas tank removal, etc. Honestly, I'm not sure what mufflers are in my boat.. I assume the standard ones (they don't have the rubber hose connecting the two of them that I noticed in my buddy's Response).

I installed Stainless Steel silencers (mfg by KB Performance) that install midway in the exhaust hose (the first pic in my gallery shows them...look like aluminum cans between exhaust manifold and muffler). Some expressed concern over them causing a reduction in horsepower. I did not notice this. Holeshot is unchanged...and (if anything) dropped no more than 1 mph off top end.

Agree w/ you on the motorbox install. They pass my "acid test"...that being...money well spent and I would absolutely do it again (or order it as an option on any future boats). Aside from the quiet while cruising, its especially nice when you have a skier/rider in the water behind you and can easily hear their "start" commands.

Edited by davemac

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WakeGirl

I haven't been keeping up, I didn't realize that that type of mod was available. That seems like a really good solution for those that don't want to tear their boats completely apart.

The STE tips aren't a complete downturn the way that the first downturns were. The part that's different is that (as I understand it) the STE's have actual baffles & silencing properties to them, whereas the first downturns were just hollow tips that really did nothing more than dress up the boat's rear end. I had those on the last boat & wouldn't bother with them again quite honestly. The STE's are a different matter though, I would give those a shot based on what I've read.

I'll see if I can dig up some pics of both, that way everyone reading the thread can see what I'm talking about.

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WakeGirl

Okay, found some good links.

Here's a link to the STE's on Bake's: LINK

Here's a picture of what the first turndowns looked like:

post-1-127438342072_thumb.jpg

Additionally, this is a really good topic on this specific issue: LINK

I like Peter's comment from that thread:

....

My opinion is that the inline silencer (which mounts between exhaust manifold and exhaust hose) does a better job reducing the sound level before the muffler, and it's easier to install.

Lots of good info in that thread.

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Bobby Light

I have a 2005 RLXI. The boat has the downturn exhaust and the standard muffler system. I am looking to make the boat quiter from the outside. I want to start skiing earlier in the morning, but do not want to get my neighbors mad. Looking for advice on what can be done to make the boat more quite, including how difficult it was to make the modification.

Thanks

STE exhaust tips definitely work good.

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Mino

Thanks everyone for the info. My boat does already have the insulated motor box, so that is already covered. Has anyone actually installed the silent rider mufflers as a modification? If so, where did you get them and how difficult was it to do?

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WakeGirl

If anyone here would know, it would be Peter. Personally in 7 years between this site & the old one, I can count the number of people that have actually done a Silent Rider on a direct drive on 1 hand. It's a really rare mod, & from what I can remember from those that actually did it is that it didn't always seem to be very effective.

Give Peter a shout, he'll know: [email protected]

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Malibudude

STE exhaust tips definitely work good.

Plus1.gif

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CedarLakeSkier

If anyone here would know, it would be Peter. Personally in 7 years between this site & the old one, I can count the number of people that have actually done a Silent Rider on a direct drive on 1 hand. It's a really rare mod, & from what I can remember from those that actually did it is that it didn't always seem to be very effective.

Give Peter a shout, he'll know: [email protected]

I did the inline Silent "tip" exhaust in my iRide. As explained earlier, this goes on the muffler tubing between the engine and exhaust. I insulated the engine cover at the same time so I don't know how effective they were individually. However together they definitely made a big difference. The inlines aren't all that expensive and other than cutting through the reinforcing wire in the exhaust tubes the install wasn't that bad either.

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Woodski

A silent rider install is not that difficult. It is a large diameter plenum that mounts crosswise just over the distributor or behind the intake or over the bellhousing/transmission area. The only limitation would be any hardware currently mounted in that area. They are very quiet units.

I have noticed that the 05 RLXi seems to be a bit louder than other ski boats, not exactly sure why, but an '05 just landed on our lake and is louder than I would have expected.

Edited by Woodski

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Deke

For the motor box I used a very thick 1 3/8" composite called Quiet Barrier from MarineFoam.com. This stuff has a decoupler, barrier, and absorber. If you call them they'll point you to the right product. Mine was actually slightly damaged, surplus stock sold at a discount. I can tell you that my head feels a lot better after this mod and in comparison to friends boats it is considerably more quiet in the driver seat. As someone else mentioned, you can actually talk in a normal volume to someone in the observer seat and most importantly, hear the person in the water without shouting. For all day outings this is a must!

My boat also has some kind of mufflers on it called Primex. They are fiberglass on the outside and who knows what inside. I don't think they are as quiet as they could be so I am considering inline silencers like DaveMac mentioned in addition. Hopefully they don't reduce power as our lake is at 7000' and we need all we can get. Does anyone know if they are the reflective type?

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davemac

Deke,

Can you clarify what you mean by "reflective"? The inlines I installed were a pretty simple design w/ no moving parts. Entire thing is stainless steel. Outer diameter of the canister is about 3 1/2 or 4". In the center of the silencer, there is a smaller diameter pipe (from memory.. I'm guessing 2" diameter, and only an inch or two long) welded to a "restrictor plate" that has a couple holes in it.

While not an engineer, I'm speculating that... when the outward flow of exhaust/water hits the inner plate/tube, it is redirected in a "re-circulatory" manner generating the desired result.

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SmoothWaterMan

Hey guys.

Here's some additional info -

First off, KB performance that used to make the STE tips has gone out of business..again. After Malibu got another supplier to make the exhaust tips when KB went out the first time, there was not enough sales market left for KB to maintain market share for ski boat tips. Thus, the inline silencers are no longer available, which is really too bad.

The STE tips and STE inline silencers were designed and worked on the principle of sound wave cancellation. I am not a sound engineer what-so-ever, but the idea of the perforated plate and inward stand tube is to cancel some sound waves without restricting exhaust flow or decrease performance. And, in my experience and a few owner tests of their own, it worked quite well. My belief in the few inlines I've used personally was the inline prior to the silent rider muffler actually worked the best, as then the muffler had less sound to mix with the water and absorb prior to leaving the boat. The tips add some eye candy as well as working for all boats, were-as the inlines only fit the direct drive models.

That all said, while you can add STE tips still currently from Malibu dealers, my first option would be to install the silent rider mufflers on the direct drives. The silent rider muffler is a larger diameter tube in the aft bilge area, and it has a cross-over tube (hose) at the front, which crosses over the propshaft area. If you have a cross-over tube, you have silent rider mufflers. If you have silent riders and insulated motor box (on a direct drive), the only option left is the STE tips, or add a second raw water pump and dump more water into the exhaust. More water (to a point) will produce less sound.

V-drives benefit from using the largest diameter silent rider muffler available, as a standard oem equipment. This muffler will not fit in any current generation direct drive, meaning 95-up. The older Echelon motor boxes had more space above the transmission for a v-drive style muffler, but those days are gone in box design to create more room in the boat.

Note : the 90 degree stainless turn-downs that were available for a few years from Malibu are actually louder than the standard flapper-style exhaust ports, and the fiberglass platforms are louder than teak. Particularly at low speeds, the sound is directed towards the water surface at 90 degrees. The sound then bounces off of the water and hits the platform at 90 degrees, and bounces back to the water. A few hundred times later it may leave the confines of the space between water surface, wave behind platform, the bottom of the platform, and the transom. Those tips are no longer available.

Hope that helps,

Peter

Edited by SmoothWaterMan

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CedarLakeSkier

... The silent rider muffler is a larger diameter tube in the aft bilge area, and it has a cross-over tube (hose) at the front, which crosses over the propshaft area. If you have a cross-over tube, you have silent rider mufflers.

Peter,

Question for you.

I have the inlines (lucky me since they are no longer available), but NOT the silent rider mufflers. Are the Silent Riders available seperately? Any idea on the cost for ones that fit an iRide?

I thought I read in a previous thread it wasn't worth replacing the regular mufflers for silent riders, but from what you say it may be.

Thanks

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VinRLX

Thus, the inline silencers are no longer available, which is really too bad.

I think Jerry got his inline silencers from Rex Marine, IIRC. Here is a link to take a look at.

Happy summer Peter! Let me know when you're gonna be out my way. :)

Hi Tracie!

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Deke

Peter, thanks for posting that information. What I hear you saying is that the only inlines available are whatever is left on dealer's shelves?

Here's another question... If I already have the stock Primex mufflers in my '99 RLX, would there be a worthwhile gain by replacing them with Silent Riders? Or, would installing inlines on the existing setup get me into the same ballpark?

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BuFootin

If your boat does not already have it, the insulated motorbox mod will help a little bit (from the outside, lots from the inside). Several thread here w/ all the details. I just did it to a buddy's boat last weekend ($140 materials & it will take you 2 or 3 hours the first time you do it).

Another option is inline silencers. I bought some from Peter (aka smoothwaterman) last spring and installed them. There is a photo of the install in progress in my gallery (first picture...second is the insulated motorbox). I can't remember the cost....I think just under $300. Install not too technical, but wrestling and cutting the exhaust hose is a biyotch due to the steel cord that spirals through it.

I did the inline silencers as well on my RLXi. Really helped reduce exhaust noise.

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SmoothWaterMan

Peter,

I have the inlines (lucky me since they are no longer available), but NOT the silent rider mufflers. Are the Silent Riders available seperately? Any idea on the cost for ones that fit an iRide?

Thanks

The SR mufflers are about $280 each.

Peter

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