[C320-list] Low speed under Load

Tue Jul 14 14:45:29 PDT 2015

All
Thanks for all the info.
Changed  all filters, (Oil, fuel & air) within last 2 weeks.  No change.
Pulled mixing elbow. Looks good, no blockage. Inside of exhaust riser looks good. No black stuff. Good water in exhaust. 

MaxProp serviced last haulout in 2014 (Lubriplate grease thru a zerc fitting). Lubriplate is spec'd by PYI. It is a 3 Blade MaxProp  15'' dia. set to 11.4" pitch.  The yard originally set the pitch at 12.5" but backed it off after sea trials, according to the data given to me by the first owner. I believe the boat came with a fixed 3 blade 15R12 from the factory.  Some may have come with 2 blade 15R9?  Worked great from San Diego to Ventura 3 times at 6-7knots  and numerous trips to Santa Cruz Isl/San Nicholas Isl.  Hard for me to believe it now works great up to 2000rpm then fails .  It is not a variable pitch prop. Local Boat Yard says if MaxProp is good at 2000 rpm then should be good at 3000rpm. Can a MaxProp change its pitch if it Fails some way?

I can get 3600 rpm in neutral. No smoke of any kind except some water vapor when temp gets to 180 or so. 

Heat exchanger core in mine was upgraded under warranty before I bought it. 
The thermostat in the 3YM30 is spec'd to be fully open at 185 F. Expect some variation between actual and gauge?  I expect the gauge is not  accurate.  I am going to get a temp gun at Harbor Freight
   and verify actual vs gauge temps one of these days. Same with tachometer, one of these days.

I also have Kanzaki trans with 2.62:1 gear ratio. Local Boat doctor indicated that he has rebuilt a couple of Trans of this make and model due to clutch slipping. Also calling the MaxProp folks for their input.
I will keep everyone posted.
Don
"Mandolin Wind" 

On Jul 14, 2015, at 9:51 AM, Jeff Hare wrote:

> Sounds like you're set up perfectly!  I'm jealous!  180-190 is perfectly fine (in fact, a good thing).  You really do want it to run in this temp range.  200+ is starting to get a bit hot for my taste, but ours runs all day at 180-185 so don't sweat it up to ~190.  When we run 3200 rpm for more than 20 min or so we hit 190.
> 
> -Jeff 
> 
> -----Original Message-----
> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Marek Fluder
> Sent: Tuesday, July 14, 2015 11:11 AM
> To: C320-List at Catalina320.com
> Subject: Re: [C320-list] Low speed under Load
> 
> Jeff,
> 
> Your input is always greatly appreciated.
> I max out at 3600 rpm with 7.3 knots of speed (flat, no wind).
> For longer runs my 3YM30 tends to run a bit hot - temp climbs to 180-190 with rpms closer to 3000.
> I suspect I still have one of the original undersized heat exchanger cores which were upgraded in later engines.
> 
> Kind regards,
> 
> Marek
> #1028
> 
> 
> 
> On Tue, Jul 14, 2015 at 10:29 AM, Jeff Hare <Catalina at thehares.com> wrote:
> 
>> Marek,
>> Interesting.  You also have the 3YM engine.  It has a bit more power 
>> than the 3GM.  In forward with normal to flat seas, if you can't get 
>> your engine up to at least ~3400 RPM *I think* it's most likely over 
>> pitched.  Yanmar would probably not approve the pitch if your engine 
>> cannot get up to RPM under load.
>> 
>> If you get these speeds at those RPM and CAN rev the engine under load 
>> up to 3400 or so, then that's great and I think you're all set!
>> 
>> Others who know the Yanmar diesels better could probably comment, but 
>> the engine doesn't have a throttle in the automotive sense, it has a 
>> speed governor.  So, you set the RPM lever for the engine speed you 
>> want, and the governor adjusts the fuel flow to try to hold the 
>> specific RPM the lever is set to.  That's why the engine speed stays 
>> constant and doesn't speed up when you surf down a wave and slow down 
>> when climbing up another one.  If you find that the engine won't reach 
>> the rated continuous RPM of around
>> 3000+, it's over loaded and may not be burning quite all the fuel the
>> governor is feeding it.
>> 
>> The other aspect of reaching the proper RPM is that you need the 
>> engine to be reaching the proper exhaust and oil temps. The exhaust 
>> temp is important to control carbon buildup.  The oil temp is required 
>> to burn off the water that condenses in the oil which if isn't burned 
>> off becomes sulfuric acid because of the sulfur in the fuel.  We all 
>> know what sulfuric acid does to engine parts over the long haul.
>> 
>> But, I'm no diesel mechanic.  This is just what I (think I) learned in 
>> my Mac Boering diesel engine class a few years back.
>> 
>> Always interested in knowing what the "real" answer to this is!
>> 
>> -Jeff
>> #809
>> -----Original Message-----
>> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On 
>> Behalf Of Marek Fluder
>> Sent: Tuesday, July 14, 2015 9:25 AM
>> To: C320-List at Catalina320.com
>> Subject: Re: [C320-list] Low speed under Load
>> 
>> Jeff,
>> 
>> I have also Yanmar 3YM30 with fixed 3 blade 15R12 prop and found that 
>> my speeds are similar to Don's:
>> 1500 - 4 knots
>> 2000 - 5 knots
>> 2500 - 6 knots
>> Kanzaki transmission with 2.62 gear ratio.
>> Am I over-pitched as well ?
>> 
>> Marek
>> #1028
>> 
>> 
>> 
>> On Mon, Jul 13, 2015 at 3:26 PM, Jeff Hare <Catalina at thehares.com> wrote:
>> 
>>> Well...
>>> 
>>> First, to be getting 5kts at 2000 rpm means you're well over pitched 
>>> regardless of which prop you have.  So, you'll be building up carbon 
>>> in the elbow like crazy this way.  Even if it seems ok it isn't.  So 
>>> I'm guessing your exhaust elbow is probably clogged unless you can 
>>> rev to 3800 RPM easily in neutral.  Since your diver says your prop 
>>> is clean, there are really only a few things I can think of that can 
>>> keep you from getting over 2800 rpm under way.
>>> 
>>> 1:  Over pitched prop
>>> 2:  Clogged elbow
>>> 3:  Dirty prop  (ruled this one out)
>>> 4:  Dirty Primary or Secondary fuel filter
>>> 
>>> I think #1 caused #2.
>>> 
>>> -Jeff Hare
>>> #809
>>> 
>>> -----Original Message-----
>>> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On 
>>> Behalf Of Donald Lawson
>>> Sent: Monday, July 13, 2015 2:33 PM
>>> To: C320-List at Catalina320.com
>>> Subject: [C320-list] Low speed under Load
>>> 
>>> All
>>> I have 2004 320 with a Yanmar 3YM30 fitted with a 15x9 MaxProp by PO.
>>> Everything has worked well for 3 years. At last spring haulout I had 
>>> the prop serviced and bottom painted. Boat worked great. Recently I 
>>> get 5 knots at 2000 rpm, which is normal.  However there is no 
>>> increase in boat speed past 5 knots up to 2800rpm.  Cant' get above
>>> 2800 rpm. Rpm to 3000+ easily in neutral.  No visible exhaust  at
>> 2000rpm.
>>> Skipper says some minor black smoke at 2800 rpm. Seemed like a mist 
>>> to
>> me.
>>> Recently serviced.  Got fuel and air OK. Had diver check MaxProp.
>>> Seems OK.
>>> Diver cleans bottom and prop once a month.
>>> Anyone had a transmission trouble with a Yanmar? Starting to grasp 
>>> at straws.
>>> 
>>> Don Lawson
>>> "Mandolin Wind"
>>> Ventura, CA
>>> 
>>> 
>> 
>> 
> 