[C38] Exhaust Riser and Flange. thanks

[Don Strong]

Steve: Thanks a lot. This is very interesting. My Yanmar 3G has a 
similar riser that is fine except for the tendency to shear the bolts at 
the manifold. This has happened twice, with lots of subsequent drama. My 
jobber says that it needs a support at the apex to prevent vibration.
Regards, Don

On 1/7/11 8:35 PM, Steve Smolinske wrote:
> I actually had the riser and flange fabricated at work, this being the second time "repairing" the dang thing I couldnt bring myself to reduplicating what I did the last time.  Especially since the 18 month old galvanized riser looked like it had been at the bottom of the ocean for that amount of time.   It worked itself loose at the flange and the elbow so I really didnt want to have to address it again, thus the welding.
>
> The stainless block that the flange was machined from cost $193.00  it took about 15 hours of machine time on the CNC and the pipe pieces in total cost about $40.   Once the flange was machined, I dry fit everything at the boat by taping the pieces together and then once aligned marking them with a sharpie so the guys at work could then scribe them before welding.   We also used the old riser for comparison to make sure that the dry fit pieces and the old riser matched.
>
> Tom T forwarded me a nice suggestion about including a water jacket on the hose end at the water inlet, If I were to do it again I would add that feature.   I did take the boat to the yard tonight and monitored the temp of the riser off the flange and at the water inlet with an IR thermometer the two values were 250 and never more than 180 degrees respectively,   the blue silicone hose should more than handle the 180.  I think I will carry a spare just in case.  I have to say that the difference in performance with the engine was noticable on the 2 hour trip to the yard,  the engine was so smooth and I actually cruised at 2500 rpm at 6.8-7.1 knots depending on water and wind conditions.  Also a first I was able to get the engine to easily hit top rpms of 2800 prior to this I could never get it over 2500   (protected Lake and canals),  normally I would cruise at about 22-2400 and do 6.5 tops.
>
> Doing this project I noticed that my water muffler leaks and Ive already repaired it once,  I'll write up an article for Mainsheet that covers the exhaust system from the flange to the stern and throw in our ongoing topic of heat exchangers too.
>
> If anyone is interested in doing this for their boat, Ill put together a bill of materials, and some notes that can go on the website for future reference,  Ill also throw out the offer to machine the flange, since we already have the program written, if your interested contact me off line and we can talk about cost, there would be a minor charge for the machining, Im not going to charge 15 hours of machine time, but something to pay for the set up to let it run over night.    Catalina Direct does now offer a stainless exhaust riser for our boats I am not sure if it is welded or threaded it does use the existing cast iron flange so it would IMHO have the weak link of threads.   The cost for their riser is $425, honestly I believe you could get threaded stainless fittings at granger for a fraction of that and do it yourself.
>
> Steve
> #312 Peregrine
> Seattle
>
>
> ________________________________
>
> From: listserve-bounces at catalina38.org on behalf of Don Strong
> Sent: Fri 1/7/2011 2:03 PM
> To: Catalina 38 Listserve
> Subject: Re: [C38] Exhaust Riser and Flange. Please write up for Mainsheet
>
>
> Dear Steve S. Yes to Steve O's post. Please tell us more. Don
>
> On 1/7/11 12:02 PM, S Orton wrote:
>
> 	Steve S,  A very nicely fabricated part, with no mitered bends.  Is this a Catalina Direct part?  If not where and how much did it cost?  This is a good tech article for the MAINSHEET.
> 	
> 	Cheers, Steve O
> 	
> 	
> 	
> 	Date: Wed, 5 Jan 2011 14:01:58 -0800
> 	From: SSmolinske at rainierrubber.com
> 	To: listserve at catalina38.org
> 	Subject: [C38] Exhaust Riser and Flange
> 	
> 	
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> 	This should take care of the problem, cant wait to get it installed.   Schedule 40 SS pipe welded to a machined SS flange,
> 	
> 	Steve
> 	
> 	
> 	
> 	From: Steve Smolinske
> 	Sent: Wednesday, January 05, 2011 2:00 PM
> 	To: Steve Smolinske
> 	Subject:
> 	
> 	
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> 	
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-- 
Donald R. Strong
Professor
Dept. of Evolution and Ecology
University of California, Davis 95616

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