TRI CABIN UNDERWATER EXHAUST SYSTEM

aaronbocknek · Post by **aaronbocknek** » Fri Nov 18, 2011 8:47 am

some of you have wanted to know what the tri cabin underwater exhaust system looks like. here are two pics, a third will be added to show the 'idle hull side bypass'.

this is the exhaust collector system and through hull (5") bellows. the small muffler to the left of the round collector system is the hull side bypass.

this is the underwater 'clam shell' assembly. facing forward is to the right of the pic, the 'jet holes' that face aft, are to the left.

i'm curious to know if other tri cabin owners, those with the engines under the salon, have the same set up.

Commissionpoint · Post by **Commissionpoint** » Fri Nov 18, 2011 10:12 am

Cool. I've never really seen that setup before. I knew it was out there, just never saw a close up of it. I would imagine its relatively quiet compared to the traditional arrangement. Is there some kind of safety check valve or flapper in there or is it like a Merc outdrive, torn bellows = sink?

Tri-Guy · Post by **Tri-Guy** » Fri Nov 18, 2011 3:50 pm

I have most of the same system. I do not have the muffler or diverter, I only have the 5 inch exhaust under the boat. The system is very quiet, also scary hole in bottom of the boat. My boat never seemed to have the other half of your system.

k9th · Post by **k9th** » Fri Nov 18, 2011 5:13 pm

Mine is identical to yous Aaron.

alexander38 · Post by **alexander38** » Sat Nov 19, 2011 5:09 am

that's a very cool system, where the gen-set exhaust exit ?

aaronbocknek · Post by **aaronbocknek** » Sat Nov 19, 2011 6:11 am

alexander38 wrote:that's a very cool system, where the gen-set exhaust exit ?

the genset exhaust is just forward and up from the idle over flow through hull fitting. i'll take pics of this today if i remember my camera. follow the hose from the 'lift' muffler, that's for the genset. personally, the system scares the crap out of me. i check the neoprene bellows on a bi-monthly basis. one split and it's good by tri cabin. there is no way to shut that massive 5'' hole off. to top it off, if you need to change out exhaust hoses and/or 90 degree elbows, the boat has to be hauled. water is always in the system. from what i understand, trojan's mind set was two fold.
1. save money and space for the traditional exhaust run and muffler system, and 2. the exhaust that 'jets' out the clamshell, actually lifts the boat for faster and easier plane. it also, from what my mechanic tells me, sucks the exhaust out of the engines keeping back pressure lower. it's still an odd set up.

aaronbocknek · Post by **aaronbocknek** » Sat Nov 19, 2011 6:16 am

Tri-Guy wrote:I have most of the same system. I do not have the muffler or diverter, I only have the 5 inch exhaust under the boat. The system is very quiet, also scary hole in bottom of the boat. My boat never seemed to have the other half of your system.

TRI GUY, what year, make and model is your tri cabin? i'd (we) would love to see pics of your system. and believe me, that 5'' hole with no way to shut it off scares the crap out of me. i'm always checking those neoprene bellows for signs of cracking etc...... is your collector the same? i actually have a spare collector that the PO left onboard. why i have no idea. but, if i remember, i will take some detailed pics of it and post it here on this thread. again, i'm curious to know about other underwater exhaust systems my fellow troganers have......

alexander38 · Post by **alexander38** » Sat Nov 19, 2011 8:58 am

Id be worried to about it...but it does seem to be a sound system, there's times we wished ours was underwater due to the station wagan effect, but underwater exhaust for the Gen set would be great ...

rbcool · Post by **rbcool** » Sat Nov 19, 2011 9:11 am

Mine is the same, except my "Pan Flute" is slightly different.

Ron

Commissionpoint · Post by **Commissionpoint** » Sat Nov 19, 2011 10:06 am

alexander38 wrote:Id be worried to about it...but it does seem to be a sound system, there's times we wished ours was underwater due to the station wagan effect, but underwater exhaust for the Gen set would be great ...

As would I worry, but its really no different than an outdrive I suppose. I have had lots of those, in fact there are two complete 1.51:1 units in my garage right now. I think that like an outdrive, you make sure the bellows are in good shape and you change them immediately if there is the slightest question in your mind as to thier integrity. I wonder if a 4" CPVC ball valve (CPVC is rated at 180F at 100PSI) would be a good addition to this system. Like an intake seacock but on the exhaust side. Trick woul be how to integrate it to the exhaust thru hull I would imagine. Maybe have a 4 inch gate valve braised to the damn thing? Custom casting? I dunno. Bilge water alarm at the very least. Won't help if you are away, but might if you are sleeping on board and something goes very wrong with it. I'm willing to bet that system has put more than one boat on the bottom. I know that torn bellows on outdrives certainly has.

rcamaine · Post by **rcamaine** » Sat Nov 19, 2011 10:23 am

Mine is the same setup as Aaron's. Having only got the boat back in August I only looked at the bellows once.

Where can one expect to find replacement bellows?

Thanks.

aaronbocknek · Post by **aaronbocknek** » Sun Nov 20, 2011 7:49 pm

here are some more pics of the underwater exhaust system. i'm curious to see/know about other versions of this system. the bellows, from what i understand, might be replaced with a bellows system from trident marine systems. i've put in an email to them, but have not heard anything.

here is the top view of the spare collector the PO left onboard.

underside view of collector

exterior view, starboard side, idle/low speed bypass port, genset exhaust is in the right hand corner. the small thru hull in between is the salon a/c condensate overboard drip port. no dripping into the bildge.

ultra closeup of starboard bellows/collector/small rubber muffler for low speed/idle exhaust.

now, this is the setup that will be removed over the winter. for some reason, the PO installed a second holding tank for the aft head. this setup limits access to the shaft log and extends OVER the port exhaust system with only 1/4" clearance! when the engine starts, the exhaust bellows needs to flex up and down and with this current set up, it hits the holding tank assembly causing the boat to shudder. i can't wait to get this POS out of there.

Allen Sr · Post by **Allen Sr** » Mon Nov 21, 2011 5:26 am

All that green on the side axhaust fitting would also give me some concern as well, but thats me.

alexander38 · Post by **alexander38** » Mon Nov 21, 2011 6:20 pm

is all that bonded ? Aaron ...

JGedridge · Post by **JGedridge** » Sat Nov 26, 2011 10:25 pm

Mine is EXACTLY the same. I do like it because it is semi quiet and it rumbles sometimes. I do miss the straight through exhaust systems like on my old boat and the Sea Rays.

Joe

btw: the Sea Rays have a different underwater exhaust system. I like theirs better however, but what can ya do?