underwater exhaust system help

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   Well, we are finally putting together my workboat, it's a 21,5'' cabin boat, much like a CC San Juan but with a soft rounded V hull, I got a Commander 351W engine and a Borgwarner 1.5:1 Velvet drive just rebuilt.

Engine/tranny instalation is the next big step as stringers are finished and floor will be layed on next week. This boat is being converted from a Diesel sterndrive to a straight line inboard engine.

As I'm planning on taking passengers, I wanted this boat to be low on noise, I've been considering doing some underwater exhaust like this one:

http://www.centekindustries.com/underwater_horiz.html

Does anyone have any experience with a system of this sort? I think they are a really good idea and wonder why no company is installing them OEM, on ski boats maybe they wash the wake??

What about water displaced pressuring the exhaust enough to not allow the gases to evacuate? 

Would that be the reason for the bypass line? is it really needed?

I believe the outlets should be placed between the propeller and rudder, any idea what shape would help create vacuum for the gases to flow out better?

And mostly, is it worth doing this installation vs the typical transom wet exhausts?

thanks in advance, will be posting pics as soon as I get some.

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Luchog Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135	Post Options Post Reply Quote Luchog Report Post Thanks(0) Quote Reply Topic: underwater exhaust system help Posted: June-13-2009 at 11:48pm
	Well, we are finally putting together my workboat, it's a 21,5'' cabin boat, much like a CC San Juan but with a soft rounded V hull, I got a Commander 351W engine and a Borgwarner 1.5:1 Velvet drive just rebuilt. Engine/tranny instalation is the next big step as stringers are finished and floor will be layed on next week. This boat is being converted from a Diesel sterndrive to a straight line inboard engine. As I'm planning on taking passengers, I wanted this boat to be low on noise, I've been considering doing some underwater exhaust like this one: http://www.centekindustries.com/underwater_horiz.html Does anyone have any experience with a system of this sort? I think they are a really good idea and wonder why no company is installing them OEM, on ski boats maybe they wash the wake?? What about water displaced pressuring the exhaust enough to not allow the gases to evacuate? Would that be the reason for the bypass line? is it really needed? I believe the outlets should be placed between the propeller and rudder, any idea what shape would help create vacuum for the gases to flow out better? And mostly, is it worth doing this installation vs the typical transom wet exhausts? thanks in advance, will be posting pics as soon as I get some.
	1980 Ski Nautique Commander 351W

SNobsessed Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102	Post Options Post Reply Quote SNobsessed Report Post Thanks(0) Quote Reply Posted: June-14-2009 at 1:18am
	Luchog - I have a 'fresh air' exhaust, which does this same thing but it is an add on. It does slow down the boat on the top end, but other than that has not had any adverse effect on performance. Here is a picture. I know this device is not popular with the majority of this site population, but it cured my daughter's CO headaches when we surf & cruise slow. (She likes to lie on the back seat) You can still hear the engine purr though! FAE
	“Beer is proof that God loves us and wants us to be happy.” Ben Franklin

Luchog Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135	Post Options Post Reply Quote Luchog Report Post Thanks(0) Quote Reply Posted: June-14-2009 at 11:13pm
	Hey Chris, I have seen that system and it's an option in case I decide to do the wet exhaust install. Since I'm going from scratch here I can choose how to do the whole install.
	1980 Ski Nautique Commander 351W

eric lavine Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Grand Poobah Joined: August-13-2006 Location: United States Status: Offline Points: 13413	Post Options Post Reply Quote eric lavine Report Post Thanks(0) Quote Reply Posted: June-19-2009 at 9:46am
	I just did a boat with Silent Choice, with the flick of a switch, a solenoid would move a valve and would exhaust out of the side of the boat instead of down through the outdrive. maybe you could incorporate this when taking on passengers and go below the water line behind the boat. i have really never seen a boat that exhausts underneath the boat because i think it would rumble. the best bet would be a couple good mufflers out the back under the waterline, and like above in the pic
	"the things you own will start to own you"

Luchog Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135	Post Options Post Reply Quote Luchog Report Post Thanks(0) Quote Reply Posted: June-19-2009 at 1:57pm
	Eric are the fourwinns comming with that silent choice? I think I've seen one here. Yes, someone also stated they could feel the underwater exhaust rumble in their feet on a 23' wake boat. Maybe in a much heavier boat you wont.
	1980 Ski Nautique Commander 351W

eric lavine Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Grand Poobah Joined: August-13-2006 Location: United States Status: Offline Points: 13413	Post Options Post Reply Quote eric lavine Report Post Thanks(0) Quote Reply Posted: June-19-2009 at 4:58pm
	Silent Choice was a must when i would sneak back from Put in Bay, alot of boats use them, this one was a rinker and the exhaust came out the sides with a nice oval outlet
	"the things you own will start to own you"

kapla Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148	Post Options Post Reply Quote kapla Report Post Thanks(0) Quote Reply Posted: June-23-2009 at 2:26am
	lucho your link wet exhaust
	<a href="">1992 ski nautique

underwater exhaust system help

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