[C320-list] Normal Performance Limits?

[Dennis Harris]

Jack,

    If I'm not badly mistaken, the Raymarine knotmeter still has a 
calibration routine ..consult the hand book. Take the boat out where there 
are two navigation day markers.  Determine from the navigation chart the 
distance between the two.  Motor directly from one (get a running start and 
be at a given speed for the entire distance)....time the run and determine 
by calculation what your actual speed at the given throttle setting is.  At 
the same setting, make a turn and return back in the opposite direction for 
a second run between the day markers .... time this second run and determine 
by calculation what your actual speed is.  Average the two runs, and at the 
same throttle setting, adjust the Raymarine knotmeter to show that speed. 
To prevent fouling of the paddle wheel of the knotmeter, remove it when you 
are not sailing and insert the plug in the opening.   Actually, assuming you 
have a GPS, an absolutely accurate knotmeter is not that important anyway. 
You can use an inaccurate knotmeter to determine whether sail adjustments 
have increased or decreased speed.  If you are traveling from one port to 
another, it seems that speed over ground as determined by the GPS is more 
important than absolute boat speed.  Because the knotmeter gets fouled with 
marine growth rapidly in our area, I don't even use mine most of the time.

    As for the leak, I haven't experienced that one, so I can't help. 
Finally, boats and most other things don't always work perfectly.  Unless, 
it's horribly bad, as in the darn thing is sinking or about to sink, just 
use it and enjoy it.  Not sure whether the inaccurate tachometer thread is 
yours, but again, it's not too important.  If the manual says it should run 
at 3600 max and yours runs at 3200 max at hull speed, then run at that rpm. 
If your engine is smoking while running at approximately hull speed 6-7 
knots regardless of tachometer reading, then there is a problem that needs 
attention.  Some people say that a diesel needs to be run at full load at 
top speed for best results...I personally don't believe that.  Running for 
long times at low speeds can sometimes lead to carbon deposit problems, but 
running anywhere in the upper half of the speed range, but some where less 
than absolute top speed will likely do just fine and be the best for the 
engine.

    Just my two cents worth.

    Dennis Harris C320 #694


----- Original Message ----- 
From: "Jack McDonough" <mcdonough5 at verizon.net>
To: <C320-List at Catalina320.com>
Sent: Sunday, October 05, 2008 1:28 PM
Subject: Re: [C320-list] Normal Performance Limits?


> Bob & Bruce:
>
> I may have been unclear, Bruce, on the knotmeter situation. In fact, the 
> knometer speed reading differs from SOG at ALL times, both under sail or 
> under power.
>
> Bob, my fresh water leaking problem is, as you surmised, at the point 
> where the fresh water tubing connects to the pullout faucet/sprayhead. The 
> tubing (hose) is joined to the stem of the faucet beneath the sink by a 
> hard plastic connector. This connector, which is probably four inches 
> long, is the thing that leaks from time to time. I have done plumbing work 
> in my time but this baby is different. There is a plastic hex nut at the 
> top and a sort of wing nut at the bottom. When it starts leaking, usually 
> from the top, I try alternately turning the hex nut with a wrench or the 
> wing nut with my hand. I have managed to stop the leak eventually but 
> never know exactly what brought about success because I never know which 
> way to turn the hex or the wingnut. Since it's a boat problem, it is 
> naturally difficult to reach and work on. I have to remove the door 
> beneath the sink, lie on my back (with the head threshold digging in to my 
> ribs) and reach up with one hand (it's not possible to get two hands up 
> there) to work on the problem.
>
> Amazingly, it seems that no other 320 owner has had this problem. I have 
> thought of possibly cutting out the connector and replacing it with 
> another piece of hose with hose clamps. The challenge is that the fresh 
> water hose is larger than the faucet stem, so I'd have to devise a 
> solution to that problem. I also would need better access to the connector 
> site, probably by removing the two drawers in the quarter berth.
>
> My ratio of problems to enjoyment the last few years has not been 
> favorable.
>
> jack
> sure bet  #947
>
>
> ----- Original Message ----- 
> From: "Robert Seastream" <robert.seastream at comcast.net>
> To: <C320-List at Catalina320.com>
> Sent: Saturday, October 04, 2008 6:17 PM
> Subject: Re: [C320-list] Normal Performance Limits?
>
>
>>I cut all the leading addresses (for brevity), but left the authors 
>>signatures.
>>
>> Brian (797), I have a 2002 with the 3GM30F Yanmar with a fixed three 
>> blade prop.  I typically run it at 2500-3000 RPM, easily making hull 
>> speed within that range.  Yanmar specifies 3200 as the continuous 
>> rating, 3600 as the max/one hour rating.  I've heard 2400 is best fuel 
>> economy (half gallon per hour) rating.
>>
>> My knotmeter always reads lower than my GPS whether under sail or  power, 
>> even around slack water times.  I've put it down to seaweed,  barnacles, 
>> whatever restricting the paddlewheel assembly.  I've  cleaned it at 
>> spring launch, to no avail and have gone with GPS  readings since.  I'm 
>> not usually in such a hurry that speed knowledge  matters.
>>
>> Jack (947), is it the flex hose leading up to your pullout faucet/ 
>> sprayhead in the head sink that's leaking, or something further  upstream 
>> from it?  Where are you located?
>>
>> Our haulout is 10-13-08.  I love NH in particular, New England in 
>> general, but the sailing season is way too short.  With 11 years to 
>> retirement, I often (around fall, how odd) consider transferring as  far 
>> south as would permit year round sailing, probably the Virginias  or 
>> Carolinas.  I'd like to cruise the Bahamas on our own bottom  someday. 
>> Sigh.
>>
>> Bob Seastream
>> Intuition # 906
>>
>>>
>>
>>> Sounds like the knot meter has a problem. If it was current, then at 
>>> some point in your travels you would have contrary current and your 
>>> knot meter would read higher than your SOG.
>>> You can calibrate the knot meter on a measured course or use the GPS 
>>> reading at slack tide conditions to get it reading more accurately.
>>> I can't comment on your water problem.
>>> Kirk
>>> #124
>>>>
>>
>>>> Bert:
>>>>
>>>> I understand the analogy. But it seems to me that my knotmeter must  be 
>>>> registering unrealistically low speeds when it always, and I  mean 
>>>> always, shows one or two knots less than SOG.  And this also  happens 
>>>> when running under power only. It seems doubtful to me that  the 
>>>> difference is always current. Anyway, I consider this to be  more a 
>>>> situation than a problem to be solved.
>>>>
>>>> The leaking fresh water connector under the head sink, on the other 
>>>> hand, is a problem.  I'm not getting any takers on that one. 
>>>> Apparently no one else has had the same experience.
>>>> jack
>>>> sure bet #947
>>>>>
>>
>>>>> Jack,
>>>>>
>>>>> Using speed over ground is fine for determining when you'll get  some 
>>>>> where.
>>>>> However, it tells you nothing about  how your engine is  running  as 
>>>>> far as
>>>>> speed is concerned.  If an airplane is flying at 200  knots, but   has 
>>>>> a 50 knot
>>>>> headwind, it's only going 150 knots over the  ground...same with a 
>>>>> boat only
>>>>> the variables are wind, current, tide, etc.
>>>>> Bert
>>>>> At Ease
>>>>> #442
>>>>
>>
>>>>> Monte  & Bert:
>>>>>
>>>>> My 320 is now on jackstands for the winter after another  short  New 
>>>>> England
>>>>> season. Now I'm eager to get in the water in the spring  to see  how 
>>>>> the
>>>>> engine sounds at 3000 to 3600. It has always seemed to me  that it 
>>>>> "sounds"
>>>>> like it is content at the lower  rpms.
>>>>>
>>>>> Additionally, I have always thought that the knotmeter reading   was 
>>>>> lower
>>>>> than the actual speed of the boat through the water. It  regularly 
>>>>> records
>>>>> speeds  in the 3, 4 and 5 knot range when I'm  certain I'm going 
>>>>> faster than
>>>>> that by any visual estimate. That's why I  pay more attention now  to 
>>>>> the SOG
>>>>> when I'm intent on getting where I'm  going.
>>>>>
>>>>> And, while I have your attention, has anyone read my earlier  e- mail 
>>>>> about
>>>>> the leaking fresh water connector under the head  sink?
>>>>> Jack
>>>>> #947
>>>>>>
>>
>>>>>> I  have owned mine since new in 1999 and have accumulated about  750 
>>>>>> engine
>>>>>> hours. For most of those hours I ran it very conservatively at   2500 
>>>>>> RPM's
>>>>>> and not quite 6 knots. After reading the posts about  exhaust  elbow 
>>>>>> coking,
>>>>>> I pulled my ex. mixing elbow and found  it to be quite coked but 
>>>>>> nowhere near
>>>>>> plugged as some have reported. I  now run it at 3000 and it is 
>>>>>> actually
>>>>>> smoother at that RPM and  obviously faster at the expense of a 
>>>>>> higher fuel
>>>>>> burn. I think Yanmar  calls for max RPM of 3600 and max  continuous 
>>>>>> of 3400.
>>>>>> I have  come to believe that diesel's like to work near their  design 
>>>>>> load
>>>>>> limit and at lower RPM and load tend to run rich and the lower 
>>>>>> exhaust  gas
>>>>>> temperatures cause exhaust component coking. I don't know how  they 
>>>>>> avoid
>>>>>> this with automobile diesel engines but they are not designed to   be
>>>>>> continuous duty cycle as these small industrial and marine  engines 
>>>>>> are.
>>>>>> Monte
>>>>>> Laima #620
>>>>
>>
>>>>>> I've had my 320 since it was new in 2003 and I have  never run my 
>>>>>> Yanmar 27
>>>>>> much more than 2600 or, rarely, 2800 rpm. With  a three-blade  prop, 
>>>>>> I'm
>>>>>> probably doing about 6 knots over the ground.  My recollection is 
>>>>>> that
>>>>>> those rpms are about what the engine  mounting plate and the 
>>>>>> Catalina manual
>>>>>> suggest. Am I right or  wrong?
>>>>>> Jack
>>>>>> #947
>>>>>>>
>>
>>>>>>> I didn't disagree with Rod. I reiterate,  these instrument  systems 
>>>>>>> (tachs)
>>>>>>> are poorly calibrated and if you  normally run your engine at a
>>>>>>> conservative RPM and  then firewall it you may expect to see  smoke 
>>>>>>> just from the higher
>>>>>>> exhaust gas temp burning combustion deposits out of the exhaust 
>>>>>>> system.
>>>>>>> That having been said I would agree that prop  pitch controls  max. 
>>>>>>> RPM.
>>>>>>> Monte
>>>>>>> Laima  #620
>>>>
>>
>>>>>>> I agree with  Rod, low RPM and black smoke with clean bottom &  Prop 
>>>>>>> means
>>>>>>> it is overpitched. Should run at 3600 RPM at Max  throttle.
>>>>>>> Joe Barrett
>>>>
>>
>>>>>>> These boats  also have notoriously inaccurate tach,s, something 
>>>>>>> else to check.
>>>>>>> Monte Laima #620
>>
>>>>>>>  It sounds to me that you are over propped. You should be able  to 
>>>>>>> get up to 3400 RPM.
>>>>>>> Can you adjust  the pitch on the Kiwi? If so, just reduce the  pitch 
>>>>>>> and you should be able to get
>>>>>>> up to the full RPM
>>>>>>> Rod  Boer Odyssey, #688
>>
>>>>>>> I had my boat on the water  yesterday afternoon for likely the  last 
>>>>>>> sail of
>>>>>>> the season. Although the wind was 15-20 knots on departure it  had 
>>>>>>> dropped to
>>>>>>> near nil by the time the crew decided to head for home. To   ensure 
>>>>>>> we
>>>>>>> arrived at the dock before dark I slowly  pushed the throttle to 
>>>>>>> maximum. On still
>>>>>>> water this gave me revs  at 2900, knots at 6.75 and plenty of  black 
>>>>>>> smoke.
>>>>>>> On easing the throttle back to 2500 revs I was able to maintain  6 
>>>>>>> knots and
>>>>>>> eliminate the smoke. I have a Yanmar 3GM30, a clean bottom and   a 
>>>>>>> Kiwi
>>>>>>> prop.  Is this approximately normal?
>>>>>>> Brian  Amirault #797 Waltzing Bear, too
>
>