[C38] Prop size and repowerd

[Steve Smolinske]

Make sure to consult with the prop manufacturer and engine manufacturer to size your engine correctly,  Diesels like to run hot, somewhere in the 75-80% max rpm range.   Anything less and you actually are harming the engine by allowing the cylinders to glaze.   Beta, Westerbeke Im sure have the people to work with you on hull speed, displacement, horse power and prop issues.   

Steve

-----Original Message-----
From: Listserve [mailto:listserve-bounces at catalina38.org] On Behalf Of Max Soto
Sent: Thursday, May 12, 2016 2:23 PM
To: Catalina 38 Listserve
Subject: Re: [C38] Prop size and repowerd

Hi Ken,
 A year ago I installed a 40hp Yanmar 3JH4E. The maximum prop size that will fit is a 16, but I know that there is somebody with a 17" two blade prop. 
The more diameter on the prop, the more efficient it will be, so I installed a three blade 16" Maxprop Easy. 
It is very expensive but very efficient. 
There were a few, but easy modifications to the engine bed that have to be made despite which engine I  installed, because no modern engine has the three mount design as our 5424 / M30..
But everything is pretty straight forward.  My 40hp engine is smaller and 40lbs lighter than the old 24hp engine. Go figure!!
With a beta 35hp (that uses the same engine as the universal M35B (four cylinder)  you'll have more engine room, despite that they are four cylinder, they are very small and obviously, vibrate less.   They are the engines that came with the last models of the C38. 
I went with the 40hp because I wanted really good punch trough the waves when the wind is on the bow.  
BTW, the original the two blade prop should be 15x30, and the three blade, if I'm not mistaken, a 15x12. 

Every 38' boat comes now with this engine.  Apparently, the rule now is a hp per foot....
That engine is now installed in two C38's that I'm aware of.  
The newer model is the Yanmar 3JH5E. 
If you get a Yanmar engine, despite the model, make sure that you get a 2.1:1 transmission ratio.  
With the 2.6:1, the prop turns slower and on the big engine, the prop must have more pitch that diameter. 

I did all the job myself, and I have to say that it was not hard.  
Let me know if you need more info and pics!
Hope this helps!


Regards,
Max Soto 
C38 Estancia
+506-8312-1367
Alajuela, Costa Rica 

> On 11 may 2016, at 09:50, Kenneth St. John <kennethstjohn at gmail.com> wrote:
> 
> Hey listers,
> Long time lurker here. Ken St. John of Tacoma, owner of Naughty By Nature, hull 147.
> This weekend on they way to Seattle opening day, ugly Betty, out Universal 5424 did too many bad things and it's time to repower or leave it in Seattle forever. 
> Two questions:
> 1)   How big a prop can I swing? Currently I believe it is 13 x 12, three bladed fixed (we're cruisers)
> 2)  I'm looking at a Yanmar and a Beta, 30 hp. Anyone have thoughts on that?
> Thanks in advance
> Ken
> _______________________________________________
> Listserve mailing list
> Listserve at catalina38.org
> http://catalina38.org/mailman/listinfo/listserve_catalina38.org

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