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Old 09-13-2017, 03:37 PM   #1
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2003 30' Pilot with 315 Yanmar

Our new to us 2003 30' Pilot with a 315 Yanmar (1200 hrs) has a top RPM of 3400. I believe I am a little over propped as Yanmar specs call for 3800 to 3900. I would be grateful if anyone with a 2003 or new 30 Pilot with the same power would let me know what their top rpm's are and possibly their prop specs. I am having a heck of a time trying to find this info. Some dock mates claim boat manufacturers intentionally over prop. The PO installed a line cutter which I am told will steal 50 rpm's? Thanks for any help.

regards Holty
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Old 09-13-2017, 05:25 PM   #2
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Mainship is pretty good about propping as my last two Mainships were 50-100 over rated at wot.

Check your rpms with a phototach. Dash tachs can be off a couple of hundred rpm.

David
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Old 09-13-2017, 06:45 PM   #3
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I have used a photo tach and showed I was only off 50 rpms.

regards Holty
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Old 09-14-2017, 12:28 AM   #4
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Originally Posted by holty View Post
Our new to us 2003 30' Pilot with a 315 Yanmar (1200 hrs) has a top RPM of 3400. I believe I am a little over propped as Yanmar specs call for 3800 to 3900. I would be grateful if anyone with a 2003 or new 30 Pilot with the same power would let me know what their top rpm's are and possibly their prop specs. I am having a heck of a time trying to find this info. Some dock mates claim boat manufacturers intentionally over prop. The PO installed a line cutter which I am told will steal 50 rpm's? Thanks for any help.

regards Holty
Holty,

You dont say which way the tach reading was off (high or low) as if you take the rated RPM which is 3800 RPM (If yours is a 6LPA-STP2) and your prop cutter you may be getting closer ?
How ever a couple of points:

Does the engine get full (3800) at free revs (out of gear)

1) Is the hull bottom and prop absolutely clean as it only takes but a few barnacles to quickly drop the top RPM
2) Checking/changing fuel filters can make top end RPM improvements
3) Try removing or replacing your air filter
4) Check the cable adjustment is getting full RPM
5) Is there any sign of Black Smoke
6) Depending on age a possibility of partially blocked exhaust riser/or system and @1200 hrs should be OK - BUT depends on usage in time terms
7) Is the engine room getting enough COOL air

If all those above items check out OK, then yes perhaps your are marginally over pitched or over diameter

Cheers Steve
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Old 09-14-2017, 01:48 PM   #5
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Should get 4000 WO out of gear, and propped correctly 3900 in gear running, you are WAY over propped or something else is causing it, good news is you checked it.
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Old 09-14-2017, 11:14 PM   #6
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Originally Posted by Marlinmike View Post
Should get 4000 WO out of gear, and propped correctly 3900 in gear running, you are WAY over propped or something else is causing it, good news is you checked it.
Copied from my Yanmar Service Manual (All 6LPA Engine Series)

All the 6LPA series are designed to be operated at maximum throttle (3800-1 Rpm) for less than 5% of total engine time(30 minutes out of ten hours)and cruising speed (2800-1 Rpm or less ) for less than 90% of total engine time( 9 hours out of 10)


Cheers Steve
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Old 09-15-2017, 06:28 AM   #7
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Thanks for the comments. Exhaust flow is good, no black smoke ( little white), bottom clean, both fuel filters new, linkage fine. What troubles me is PO said prop is stock. She runs like a top doing about 17-18kts at 2800 burning 8 gph. I will pull prop when hauled and give spec I have and spec needed to my prop guy. I am really curious to hear numbers from other 30 Pilots 2003 or newer with same power. I know I am over propped but WAY over propped? I will be pulling injectors this off season for reconditioning. Waiting to meet with Yanmar mech to pick his brain regarding serviced injectors possibly give me more rpms.

regards Holty

are we serious about running full throttle out of gear?
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Old 09-15-2017, 07:34 AM   #8
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"are we serious about running full throttle out of gear?"

Yes, won't hurt anything and the governor won't let it over rev. You want to be sure that the governor is set to allow W.O.T. RPM's. Not sure why you are pulling the injectors? Injectors should be fine unless you have introduced them to dirty fuel.
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Old 09-15-2017, 07:42 AM   #9
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I would think that @1200 hrs your injectors will be fine(under normal conditions), injectors for Yanmars and most other motors with fuel pumps are set at a pre designed opening pressure and time only allowing that amount of fuel into the combustion chamber, (it's not some thing that can be played with,

Older and some new engines you can change the nozzles regarding the amount of fuel but these are in engines where the injector is the fuel pump as well,



Good luck with your prop dimensions

Cheers Steve
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Old 09-15-2017, 07:49 AM   #10
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Second that, your engine should happily run up to 3800 and if free reeving even slightly higher, you dont need to hold there for long -just enough time to check the RPM,

Its done routinely to check the free RPM and set up engines

Cheers Steve
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Old 09-15-2017, 08:05 AM   #11
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Just for further info here's a couple of reviews and info regarding your ship which you might find interesting:

1) In its first year of production the Pilot™ 30 encountered noise and vibration problems particularly on boats equipped with larger Yanmar engines. The cause seemed to be insufficient propeller tip clearance and was addressed and repaired under warranty by Mainship.

2)Our test boat was powered by a single Yanmar 315 SE Diesel, rated at 315 hp. With a half tank of fuel and two people on board, we hit a top speed of 26 knots. Although the Pilot 30 rides with a slight bow-high attitude, in part because of its up swept forward lines, a little bit of trim tab improved visibility at cruising speed. Off the line, the boat reached 20 knots in six seconds. Midrange acceleration was also very good.

3)In 2003, the updated Series II Pilot featured a new cherry interior and a revised cabin layout with a V-berth that folds in half when not in use. (Note that the Series II also incorporates a shortened keel, propeller tunnel, and a five-blade prop.

4) Early models with a single 170hp Yanmar diesel will cruise at 14 knots (16–17 knots top), and those with a 230hp Yanmar cruise at 16 knots (19–20 knots top). Series II models with a 315hp Yanmar cruise at a steady 18 knots and reach a top speed in the low 20s.

Cheers Steve
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Old 09-15-2017, 10:06 AM   #12
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Thanks again for the come backs. I would like to pull the injectors hoping a cleaning by my local injector shop will eliminate the white smoke I have at idle. They charge $25 for each injector and I think that will be money well spent. I am cruising 17 to 18 kts now with a top end in the low 20's. A photo tach shows my console tach is off by 10 rpms running at 1000. Next trip out I will us photo tach at full throttle to get a better read.

regards Holty
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Old 09-15-2017, 10:25 AM   #13
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Yep: white smoke is an issue with many of the engines today that are in perfect mechanical condition. but below are some common issues:

1. Poor fuel quality (low cetane rating).
2. Low inlet air temperature.
3. Low coolant temperature.
4. Low compression ratio.
5. Retarded (incorrect) ignition timing.
6. Incorrect/failed fuel injection components.

You’ve got air feeding the engine that’s being cooled by seawater (after-cooler-if fitted), you’ve got cold engine oil being sprayed at high volumes to the underside of the piston crown slowing it’s heating process, and you’ve got a mechanical fuel delivery system that is designed to be at optimum efficiency at WOT or close to it. Other than the fuel system, it’s the temperature again that is the common denominator.

After every thing else fails,it can be fixed by, increasing start-up temperature by adding block/pan heaters to engines and still offer's many benefits. You’ll still get improved start-up and oil circulation, less moisture build up in the engine room spaces, and a much nicer environment for the engine to live in (warm and cozy) if in colder climates.

Cheers Steve
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Old 09-17-2017, 06:16 PM   #14
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Today after she got up to temp I briefly throttled her all the way up in neutral. She made 4K easy. The 5 blade wheel will be pulled after November haul for a tune up.

regards Holty
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