Exhaust Cover or Extension to decrease noise

[KenK]

Hello all, I am new to this so I hope I am posting this in the correct way.
I own a 2004 Islandia and love it. One thing I would like to do is decrease the amount of noise that comes from the exhaust. I read in the manual that there are optional exhaust covers that can be purchased to quiet the noise.
I have searched for the covers but have been unable to locate them. My other idea is welding a 90 degree elbow on the exhaust and putting it 5 inches into the water. If anyone knows where I can purchase the exhaust covers that would be great. Or any other ideas on how to quiet the exhaust down would also be great.
Thanks.

 

[Dr Honda]

Welcome.

I moved your thread to the Merc section, since the Rotax powered boats are totally different.

Anyway... I'm not sure what covers you are asking about, but maybe some of the other members know about them. But I would also be interested in them. I don't find my Islandia very loud... but anything to clip the noise it makes would be good. Most of the noise at speed is wind noise.

Do you have a picture of the cover you are thinking about? (or the part number since you found it in the manual)


As far as pushing it deeper into the water... that may work... but it will cut your HP, and it won't let the system drain, if you are leaving it in the water.

 

[KenK]

Thanks for helping me out Dr Honda and for the quick reply.
I found mention of the cover in the 200/210/240 HP Jet Drive Installation Manual.
It looks like with the cover that the exhaust would still have the ability to drain if left in the water.
Please see the following link for the manual, you can see the cover on pages 41 and 42.
http://www.mdmotors.ru/netcat_files...etDrive_Instruktsiya_po_ustanovke_motorov.pdf
On the Exhaust Aft View (page 41) it is labeled as "h" and on the Exhaust side view (page 42) it is labeled as "d".
Does anyone know where I can purchase these?

 

[Dr Honda]

OK.... I see what you are talking about. Unfortunately, that design is already incorporated into your boat. The covers shown in the install manual are to help with noise at idle, on a generic install, with a flat transom. They only go below the water surface when at rest. (or at no wake speed) Once you get moving... they are well out of the water.

On our Islandia's... our exhausts point down, into the water at idle, from under the swim platform. And... they should be just below the water surface. This is effectivally the same design.

 

[KenK]

For some reason the above link doesn't work so I attached the two pages as screen shots.
That is interesting, because I don't have the covers on my Islandia.
My exhausts point straight out and not down into the water from under the swim platform, so when at idle or non-wake speeds it is pretty loud.
I also see on the attached images that it say's they are optional which makes me think the original owner never purchased them or had them installed.
Do you have any ideas on where I could purchase the exhaust covers to install on my Islandia?

Thanks Again for taking the time to answer my questions and helping me out.

 

[Dr Honda]

Ummmmm.... Not to sound like a jerk... but did you read my response above?

Our exhaust incorporates that cover "design". It comes out at an angle, and should be just below the water surface.

The manual shows a "Generic" install, and those covers are for a flat transom hull (like if you put this power system into a regular bass boat) and does not refer to an OEM install, with an under tail exhaust. Those covers aren't meant for an Islandia.

 

[KenK]

You're not, I re-read it and now I understand. This is my first boat and I am still learning all the terminology and how everything works.
I got a little confused on your response. Thanks for the explanation it makes sense.
It sounds like the configuration on your boat keeps your exhaust down in the water a lot more then mine, so I get a lot more noise. I will probably look into a 45 or 90 degree extension to keep it in the water during idle or non-wake times.

 

[Dr Honda]

OK... good. Since we aren't face to face... things can be taken out of context.

I guess you could just extend the exhaust where it's at... but there may be draining problems. And... along with that... there could be starting issues from back pressure.

If you are going to try the extensions... make them removable just in case. If it works out... you can weld them in place.

 

[KenK]

I posted this thread last year and wanted to update it with my latest modification that worked awesome.
I installed a exhaust extension called Fresh Air Exhaust from http://www.freshairexhaust.com/
This was a great buy, not only did it reduce the noise on my Islandia by 80% but it also makes sure all exhaust is pushed out in the jet of the Islandia.
If you go to their website you will notice that Sea-Doo Islandia is not an option. I worked directly with FAE to get a custom fit on my Islandia and they now have all the dimensions and measurements to put this on other Islandia's.
Working with them was great and they were very helpful. In the end it is a perfect fit and looks really good.
I have pictures of the final fit and will try to get them uploaded soon.
For now if you are interested check out the site and tell them Ken referred you for the Sea-Doo Islandia and you will get setup with a custom FAE.
Also, I have had this on all summer now with no exhaust issues and no power or performance issues.

 

[Dr Honda]

Yes....


Please post up the pics when you can. I would be interested in this, since the smoke at idle can get a little ugly.

 

[KenK]

Here are some images when we were getting everything fitted.
So this is the exhaust before having its final black finish, which makes it look really nice.
I will try to get some pictures of it with the black finish on it.

 

[buckeye_paul]

Interesting.

How much did it cost? Does it cause more spray behind the nozzle?

 

[KenK]

I got a big discount since I helped him fit it for the Islandia. I am not sure what it runs, but I don't think it is too expensive.
It doesn't cause more spray behind the nozzle, I did a before and after test on spray and there was no difference.
I will say the Islandia already puts up a large amount of spray due to the jet.
There is a Mastercraft on our lake that has the FAE installed and they wake and surf behind the boat and there is no difference in spray.

 

[Murph_13]

I'm sure Doc meant to post and thank you for the pics...but I'm sure he's probably busy putting the final welds on his own FAE...LOL!

So on Doc's behalf and the rest of us...Thanks!

Looks like a nice setup...interesting that the outlet is directly inline with the jet nozzle...no issues with that? Also looks like two vertical supports were added?

 

[Seadoobuddy]

Question:
I don't have a twin engine boat but I had a 350 Camaro with a single exhaust which I converted to dual exhaust to help it breathe better. Aren't you turning an exhaust from 2 motors into one???

Why not just put a 45 elbow on each as suggest above in another post.....or a small "glasspak"

 

[KenK]

Ha! Yeah, Doc helped me out a lot when I first got my Islandia.

With it being directly inline with the nozzle it pushes all the exhaust away from the boat, no issues.
I actually did an experiment with the FAE installed and then with it off. I watched for performance, power, spray, how it handled on turns.
The FAE didn't affect anything except for the noise was dramatically reduced and I hardly ever smell exhaust now.
I have pulled tubes on the boat with it on and it hasn't budged a bit with all the sharp turns and accelerations.

Yes, two vertical supports were added, it was a little scary drilling 2 small holes in my boat for the first time but it worked out really good.

 

[Dr Honda]

Yes... thanks for the pics.


I may go out and buy some stainless pipe, and try to make something... but, it seems VERY bulky.

My exhaust is different than yours. But, there is enough room, inside the hull, that it could have been all internal. Sure, you would have needed to cut a new hole for a single, center outlet... but it would be less "bulk" outside the hull.

 

[buckeye_paul]

I looked over their web site. This product would not work for me. As a recreational boater I kill enough fish as it is.

Just my .02

 

[don't sink]

Interesting! To be honest- it looks kind of ugly but if it's under the water it does not matter right? I do like that the noise and smoke is now reduced greatly but wasn't your exhaust already under the water to begin with? Guess I'm not fully understanding how this is different.

But as Seadoo Buddy asked, can't this be done with Stainless Steel pipe with bends? Keep them as dual exhaust and just have each pipe go into the water?

 

[Dr Honda]

Interesting! To be honest- it looks kind of ugly but if it's under the water it does not matter right? I do like that the noise and smoke is now reduced greatly but wasn't your exhaust already under the water to begin with? Guess I'm not fully understanding how this is different.

But as Seadoo Buddy asked, can't this be done with Stainless Steel pipe with bends? Keep them as dual exhaust and just have each pipe go into the water?

For the most part... yes... the tail of the islandia is under the water. (Swim deck is nice and low)

As far as the exhaust.... his is a little different than mine. But yes... at idle... his exhust is WELL under the water. Mine comes out the angled section, and is just skimming the surface of the water. on step... it's out of the water.

I think the point of this was it puts the exhaust fumes away from the boat since it's injecting it, into the jet stream. And in turn... that water pushes it away from the passengers. I know my boat is a little stinky at idle.... but I'm not sold on the way this system is doing it.


Here's my thoughts.


1) When it was designed... it was meat to be behind a prop. (like in a ski boat) A prop is more like a tire on a car. At cruise, there is a limited mount of "Slip". So... in realistic terms... the velocity of the trust, on a prop, is very near the velocity of the boat. (assuming minimal drag. SO no tubes, boards, or being over weight) So... for the most part... that new exhaust tube, only has to fight 40 MPH worth of water pressure.

2) On a "Jet Boat"... our water velocity is CRAZY high compered to a prop. I've never measured it.... but I can assume it's several magnitudes higher. It's a simple "Equal but opposite" thing. SO... the down tube may have to withstand 200 mph water??

3) When a Jet Boat is on step... the pump is completely out of the water. So, at that point... the system isn't even working. (My exhaust would still be going behind me) In the prop boat... the down tube would be below the water, and the prop thrust would move it back. BUT... the important thing here is... IT'S STILL BELOW THE WATER ON THE PROP BOAT.

4) My final thought on why it's quieter at idle, and low speeds is.... since you are choking the exhaust down to a single outlet.... you are simply choking it off. (put a rag over your lawn mower exhaust, and you will see what I mean)



OK.... don't take what I'm saying the wrong way. I'm sure... at idle, or low speeds... it's quieter, and it's pushing the exhaust away. And, I love ingenuity, and helping to keep the general public happy with some of the hobbies I do... but I'm not sold on it's function with a jet boat.



But... with all that said... I would love to hear a report on it at the end of next year, with the following:

1) how as it held up?
2) Hove you noticed a reduction in top speed? (since it's partly blocking the thrust)
3) Any issues wit running hot?
4) Any reduction in cruise fuel usage?

 

[SeptemberC]

Resurrecting an old thread. My exhaust is waay loud too. It kinda makes my ears ring. My exhaust tips are not underwater like my Challengers were.
Other than maybe just some clamped on turn downs do you have any other suggestions?