What is this?

[Thor]

To the outside of each jet is a hole in the fiberglass, with a plastic ring around it. Inside the hole I found a sealant that had come loose on each side. What is the purpose of this? Terrible picture as it difficult place to take a photo.

 

[Murf'n'surf]

It's extra sealant that gets squeezed out when the exhaust thru-hull is tightened. Just pull it out and toss it.... Totally normal.

 

[itsdgm]

X2 on what Murf said. It's just excess sealant.

 

[Thor]

It's extra sealant that gets squeezed out when the exhaust thru-hull is tightened. Just pull it out and toss it.... Totally normal.

That hole is where the engine exhausts?

 

[Scottintexas]

x3, check out this video from the FAQ to see how the cooling water and exhaust work,

 

[Murf'n'surf]

That hole is where the engine exhausts?

Yes sir!

 

[scot71]

That hole is where the engine exhausts?

Yep!

 

[Thor]

Yes sir!

I feel like I should put chrome tips back there!

 

[Cobra Jet Steering LLC]

Funny you said that chrome tip comment, actually on the P W C s they put rubber flaps over the opening where the pump sits, these rubber flaps cut down the exhaust noises when the hull is on plane , some of the people here trying to quite down their boats may want to take a look at the brackets and flaps used on the skies and try it on their boats . I have no doubt it would be simple to fabricate. If you look at 35 and 36 plus the related brackets you can see the parts that I am referencing http://www.yamahapart.com/oemparts/a/yam/5547798987a8660fa85af569/jet-unit-4

 

[itsdgm]

Great tip @Cobra Jet Steering LLC I never knew those existed.

 

[swatski]

Funny you said that chrome tip comment, actually on the P W C s they put rubber flaps over the opening where the pump sits, these rubber flaps cut down the exhaust noises when the hull is on plane , some of the people here trying to quite down their boats may want to take a look at the brackets and flaps used on the skies and try it on their boats . I have no doubt it would be simple to fabricate. If you look at 35 and 36 plus the related brackets you can see the parts that I am referencing http://www.yamahapart.com/oemparts/a/yam/5547798987a8660fa85af569/jet-unit-4

@Cobra Jet Steering LLC That is a great tip. If these (35, 36) parts were available or could be fabricated for our boat pumps - I want them bad.

I have no experience in fabrication of such parts, but would appreciate any suggestions very much. Now that I think of it, this could be huge in the overall noise reduction scheme.

 

[Cobra Jet Steering LLC]

I know my 2010 S H O had them and my 2014 F X H O cruisers have them so I guess they have been doing it for a while now as for fabricating them I think checking patents would be in order first I have no idea if they are patented and if you ever read what is printed right on the front of a patent it prohibits you from importing offering for sale or even "USING" a patented item.
I do not recall seeing these baffels on other p w c s

 

[swatski]

No intention to infringe on any patents. I thought you meant fabricating some kind of gasket/seal to insulate the pump from the hull to reduce vibration.

 

[Cobra Jet Steering LLC]

no this is a rubber baffle that traps in the exhaust sound when it exits the hull near the pump it's like an extra muffler. I was just thinking it may be patented and it may not. I don't really know, just being thorough .

 

[swatski]

Ohh, my bad!
From the parts schematic these rubber brackets (35 and 36) looked to me like a gasket/seal type of material that would fit between the pump's transom plate and the transom...
The boat pumps don't seem to have these parts...
I still think that insulating the pump from the hull with a rubber seal of some kind would potentially dampen vibrations a great deal. I'm just not sure how it would affect the clearances of all the moving parts etc.

 

[Big Shasta]

The picture is from my pump removal fiasco on my 05 AR230 but you can see my exhaust exit on the right. Yamaha stopped putting the flange on the outside and just covers it in sealant?

 

[Cobra Jet Steering LLC]

Yes and on the p w c's they enclose that pump area with rubber to quiet it down more since an operator is sitting so close to the exhaust exit area, however I do not see why that would not also quiet down a boat exhaust also.

 

[swatski]

@Cobra Jet Steering LLC Soooo.... Do you think that rubber part could be adapted/manufactured/installed in a boat pump?

Sorry guys, I'm a bit obsessed with noise reduction and running out of practical ideas...

 

[Cobra Jet Steering LLC]

Perhaps you can go to a dealer and look at the p w c and the boat pump areas and see for yourself I really never looked that close if the pump housings are the same then the brackets should also be the same.

 

[swatski]

Perhaps you can go to a dealer and look at the p w c and the boat pump areas and see for yourself I really never looked that close if the pump housings are the same then the brackets should also be the same.

Okay, now I understand! Hard to get a good shot, but it is exactly how you described it - a baffle. Or, a very thick rubber curtain of sorts. Not what I imagined at all. Had to go and look at some waverunners at St. Charles Boat and Motor.