aftermarket Exhaust riser for 1988 34

[obie]

Is there a good reason to not use an aftermarket riser on my m-25xp. It would go on just after the flange on the back of the manifold, it has around a 10 inch hump and the water gets ejected in to it, then you would use a pice of flex to the lift box. I would think it would be the correct way to do this. Cook Engine in Portland (which is a very respectable Marine engine outfit), said it is a great way to go. That is what they would do on a re-power??
Obie

{corrected spelling of exhaust in topic title - Stu}

[Stu Jackson]

Obie, sure you could do that.  Many folks have changed out the old water lift box for a Vetus "muffler" and redone the piping from the manifold flange to the water lift box.

I'd be careful in the selection of the "flex" from where the water is injected, however, since the vibration at the water lift flange may harm the flange on the box itself, which is why we recommend using "hump hose" between the existing nipple point and the box. 

Ron will most likely chime in here, too.  Also be aware, if you haven't already, of this old discussion from the "old" FAQ page (which has morphed into the wiki but I can find it on the old FAQ page more quickly --- http://www.c34.org/faq-pages/faq.html):

http://www.c34.org/faq-pages/faq-exhaust-pipe.html

I bought mine from Catalina in 2003, I recall, back before they insisted on sending in the old one.  I think I posted some pictures under "Exhaust Riser Replacement" -- I'll go look for it and post it up here if you'd like.

[Stu Jackson]

Try this:

http://c34.org/bbs/index.php/topic,1070.0.html

The whole story is in the online Tech Notes since I wrote it for Mainsheet in the Tech Notes.  Check the "Knowledgebase."

[obie]

Thank you for your reply Stu, and I new I spelled it wrong, but i could not come up with it (dyslexic) . I am new here, but am finding this site to have a great wealth. I see your boat is i Alameda. I sailed my other boat (Choat 41 name Wizard) there a couple years ago. I thought I was going to go do the Ba Ha, but ultamently decided that 7 months at See by my self was long enough and I was not going to go to Mexico alone, so I turned around one night a couple of days out side the gate. I have my boat in Marina Village.
Obie

[Stu Jackson]

We're right down the street at Grand Marina.

Are you coming to the Catalina Rendezvous in mid-July?  It's at Marina Bay Harbor in Richmond.

[Ron Hill]

Obie : I'm sure that that engine company knows what they are doing with a flex hose.  I'd much rather go for a stainless sold pipe myself and the "flexes" could have a weak point and eventually leak.

I stick with the Catalina muffler because of its interior volume.  The Vetus and other guys mufflers may be OK, but where does the water in 17ft of exhaust hose drain in to when the engine stops??  A few thoughts to consider

[obie]

I am planning on using the Catalina lift box. and as far as the flex leaking we are all using many feet of it now, I am only adding 18 inches. I think the vibration will be a lot less at the box with 18 inches of flex as there is now only a few inches between the lift box and the riser.
    Stu, My Choat 41 is there. I actually sold it on a contract. My new to me Catalina is in the puget sound. but I truly miss the bay. I loved sailing the gate, and there was always wind in the bay. It is hard to beat anchoring in Ghirardelli Square, and walking. when I showed up there and made that turn to head in under the gate it was magical. It was foggy, and the huge fog horns were going, then slowly the gate appeared, as if it were put there just for me. And then to see Alcatraz for the first time, and all the swimmers in the fringed waters.
Obie

[obie]

can I use silicon bronze on the hot side of the exhaust. I know I should not use galvanized pipe, but I have some silicon bronze.
Obie

[Ron Hill]

Obie : I'd say not to use bronze as I know of NO boat/engine manufactures that have used it in the exhaust system. 
Not too sure what the acid exhaust gases mixed with salt water would do to bronze - don't think it would be good.