Onan Generator Exhaust thru hull


Richie Whyte
 

Hi All
I am in the middle of a mini refit and I’d like to check something with those of you that know better. My Onan generator exhaust seems to flow into a reinforced rubber hose and from that it eventually goes out through the hole in the side of the boat. This hose is siliconed in place. The silicone is perished and the whole setup feels like a forgotten running repair to me - there is no proper thruhull as can be seen from the pic. Is this as it should be and if not do you know what should be here instead?
Many thanks

Richie

Richie Whyte
Why Knot (formerly GUMA)
SM2K#261
On the hard, Kos Marina
Kos, Greece


Bill Kinney
 

Ritchie,

When Amel designed their boats they had a number of criteria.  First (second and third!) it had to be robust and safe.  Fourth, it had to be easy to build.  Somewhere further down the list was the ease of long term maintenance.  One of the examples of this is the glueing in exhaust hoses. Of course all rubber hoses have a finite life, and need to be replaced--eventually.  The Amel design is a great system, right up until it is time to replace the hose...

I don't have the specifics of the design of the generator exhaust hose attachment to the hull, I suspect a search through the archives will find some information, although I think most discussions have centered more on the engine exhaust which is more complex. Like here: #19663  

If you end up adding a thru-hull fitting because rebuilding the original system is too complex, use a bronze fitting, be sure it is attached to the bonding system, and use a flush mounted fitting so nothing protrudes from the hull.  

Bill Kinney
SM160, Harmonie
Brunswick, GA


Richie Whyte
 

Hi Bill
Thank you for your reply and for allaying my fears. Your Amel criteria point is well taken. I went through the engine exhaust posts and unless I’m mistaken the preferred solution is to replace like with like..excavate the silicone out, replace the hose if needs be and reconstruct the silicone bung that the hose passes through.
Your suggestion would be the direction I would naturally lean towards however and inclined as I am to keep the boat as Amel as possible I suspect my marine contractor will agree…but we’ll see next week.

Many thanks for your help


Richie

Richie Whyte
Why Knot (formerly GUMA)
SM2K#261
On the hard, Kos Marina
Kos, Greece


Ruslan Osmonov
 
Edited

Hi Richie, 
I think Amel did it on purpose. Hot salt water will corrode metal pretty fast and if you go with metal it will become constant maintenance/replacement issue. 
after all it served you for more than 20 years 🙂 without much maintenance on your side. 
I would look into either doing the same, or look at what Amel did later with 54s as they added a flap to prevent back flow (per my understanding). 
Another option to look into things like marelon or other non corrosive seacocks, that can deal with heat.

Regards, 
Ruslan. 
(in search of one)


Ron Hynes
 

For what it’s worth, I have a 1976 Amel Meltem and the generator and engine exhaust are combined into a fiberglass “Y” that is fiberglassed into the hull and exits on the port side just above the waterline. I am in the process of re-powering and the new turbo charged Diesel requires a 3 inch exhaust. Since I no longer have a generator, I plan to cut out the “Y” and glass in a new 3 inch tube. I like the idea of a flap on the exhaust to prevent backflushing sea water into the engine and may employ this. The former owner destroyed  two engines when sea water entered the engine from following seas, once across the Pacific and then again across the Indian Ocean before putting in a ball valve. I never liked the ball valve since it reduced a minimally sized exhaust by about 30%. Probably explains why I am on my third lift muffler due to excessive pressure caused by the restriction of the undersized exhaust.

Ron Hynes
954.319.0944

On Jul 30, 2021, at 11:57 AM, Ruslan Osmonov <rosmonov@...> wrote:

Hi Richie, 
I think Amel did it on purpose. Hot salt water will corrode metal pretty fast and if you go with metal you it will become constant maintenance/replacement issue. 
after all it served you for more than 20 years 🙂 without much maintenance on your side. 
I would look into either doing the same, or look at what Amel did later with 54s as they added a flap to prevent back flow (per my understanding). 
Another option to look into things like marelon or other non corrosive seacocks, that can deal with heat.

Regards, 
Ruslan. 
(in search of one)


Eric Freedman
 

Amel recommended 4200 and not silicone for this job.

Fair Winds’

ERIC

Kimberlite Amel SM 376

 

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Richie Whyte
Sent: Friday, July 30, 2021 8:28 AM
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] Onan Generator Exhaust thru hull

 

Hi Bill
Thank you for your reply and for allaying my fears. Your Amel criteria point is well taken. I went through the engine exhaust posts and unless I’m mistaken the preferred solution is to replace like with like..excavate the silicone out, replace the hose if needs be and reconstruct the silicone bung that the hose passes through.
Your suggestion would be the direction I would naturally lean towards however and inclined as I am to keep the boat as Amel as possible I suspect my marine contractor will agree…but we’ll see next week.

Many thanks for your help


Richie

Richie Whyte
Why Knot (formerly GUMA)
SM2K#261
On the hard, Kos Marina
Kos, Greece


Eric Freedman
 

HI,

Amel suggested removing all the old sealant and replacing it with 4200. So far 6 years no problems.

Fair Winds

Eric

Kimberlite Amel Super Maramu #376

 

 

From: main@AmelYachtOwners.groups.io On Behalf Of Richie Whyte
Sent: Thursday, July 29, 2021 8:44 AM
To: main@AmelYachtOwners.groups.io
Subject: [AmelYachtOwners] Onan Generator Exhaust thru hull

 

Hi All
I am in the middle of a mini refit and I’d like to check something with those of you that know better. My Onan generator exhaust seems to flow into a reinforced rubber hose and from that it eventually goes out through the hole in the side of the boat. This hose is siliconed in place. The silicone is perished and the whole setup feels like a forgotten running repair to me - there is no proper thruhull as can be seen from the pic. Is this as it should be and if not do you know what should be here instead?
Many thanks

Richie

Richie Whyte
Why Knot (formerly GUMA)
SM2K#261
On the hard, Kos Marina
Kos, Greece


Richie Whyte
 

Hi All
Monsieur Amel must have visited me in my dreams as I have decided to go the 4200 sealant route at the next hail out. Thank you all for your advice. 


Richie

Richie Whyte

Why Knot (formerly GUMA)

SM2K#261

On the hard, Kos Marina

Kos, Greece


Randall Walker
 

Richie,
Take photos of your task and post them, Fur all the Amel present and future owners.

Randall
A54#56

On Tue, Aug 3, 2021 at 04:39 Richie Whyte <richiewhyte@...> wrote:

Hi All
Monsieur Amel must have visited me in my dreams as I have decided to go the 4200 sealant route at the next hail out. Thank you all for your advice. 


Richie

Richie Whyte

Why Knot (formerly GUMA)

SM2K#261

On the hard, Kos Marina

Kos, Greece


Richie Whyte
 

Hi Randall,
It will take a year or so before our next haul out but I will document the job when I do it then.

Richie


Richie Whyte

Why Knot (formerly GUMA)

SM2K#261

On the hard, Kos Marina

Kos, Greece