The proper prop?

I have a 1990 E28 with a Universal M3-20 engine with only 835 hours on it. The engine runs great and I burn only about a quart of diesel fuel per hour. I'm getting some soot on my transom and I wonder if I'm running her to hard or is the pitch on my prop to great? My prop is a 12" fixed 2 blade Michigan Sailor with a 12" pitch. I run her at 2800 rpm's and get on average a speed of 5 3/4 knots. My horsepower rating is 18 at 3600 rpm's max but if I run full throttle I can get her up to only 3400 rpm's.

Any comments from any one in the know?

Thank you in advance for your response.

Sincerely,

Sam

What is High Idle RPM in neutral? Probably ~ 3750 or so? Even tho you are over-propped some, you are better than most. You are most likely getting most of your soot during maneuvering and acceleration and not at steady state speeds. This is a characteristic of non-turbocharged diesels. Try to maneuver more slowly and gently and use your glow-plugs longer during starting.
Hope this helps.

Prop response question from Sam

Dear Gary,

Thank you very much for your response.

I was wondering what you meant by suggesting I should use my glow-plugs longer during starting?

Do you mean I should hold the glow-plug button in longer before I hit the start button or should I continue to hold the glow plug button in a little longer even after the engine has started?

Thanks again,

Sam

On achieving "smoke and fire"

Do not continue to energize the glow plug circuit after engine starts. Our '88 Universal diesel takes about 10 sec. of preheating with the glow plugs and then starts easily. If the ambient temp is under 40 degrees, I give it 12 to 14 seconds.

Start drill: 1) trans in neutral, 2) set throttle to half way, 3) hold in the glow plug button for ten seconds, 4) Hit the start button for a second or three.
If too cold and engine will not catch and run, glow plug it again for 15 seconds and hit start button.
Soon as it fires up, reduce revs to 1000.

Warm it for a bit and put it gently into forward and then into reverse while at "idle" throttle setting... if it's gonna stall you might as well find out before you untie from the dock.

No problems with ours for 14 years. We do try to be proactive on engine maintenance...


Loren

ps: title is from an old friend and diesel repair guy. A little bit tongue in cheek...

Actual Prop Performance

I have test results of 2 adjustable pitch props on my Olson 34 with a Universal 25XP diesel rated at 23 hp at 3200 max RPM.
The original pitch recommendation from PYI, Seattle was 12.5 in pitch and 24 deg angle. I do not have a performance curve, but the max performance obtainable was 2700 RPM and 6.93 Knots. At next haulout I changed the pitch to 11.4 in or 22 degree angle. Resulting performance curves are shown.

I am happy with the performance even though the pitch chosen will not reach the 3200 rpm maximum rpm recommendation, I think it is a good compromise for fuel economy and speed. It seems we are always in a hurry to get there.

I changed from the Max prop to the Kiwi because of a driveline vibration problem that I could not get solved, even after a new shaft when I installed the dripless packing ane had engine alignment checked several times as well as having PYI check the prop for balance.

Since this boat is primarily used for racing, a 3 bladed feathering prop is not usually recommended, but the Kiwi feathers corresponding to the water flow. So even though the shaft angles to the water flow, there is minimum drag.

A note on Max Prop is the excellent reverse power. It can bury a Danforth anchor in mud-clay like in Bud Bay, Olympia, deep enough to require a lot of effort to free it. The 2 blade Max prop had noticably more punch out of the hole than the Kiwi Prop probably because of the slight flex capability of the plastic blades of Zytel or Delrin.

Just for a point of reference, I have a 1986 E28 with the Universal M12, with ~1,000 hrs on it. It is rated at 10hp. I actually get very little soot on the transom. Though the manual shows max rpm at 3600, I can only get it to rev to 3000. I typically run it at 2600 rpm, and in flat water it will run at about 5.9 knots. At 2800, it will run at 6.1 knots.

I know that it has a 2 blade fixed prop, but I am not sure of the size or pitch, and won't be there to see it for a few weeks.

Andy

Sam,
If glow plugs are only activated for a few seconds then the engine is started there will be unburned fuel and possible bluish-white smoke after start up. This can put a sheen on the water which is not good. This is why I asked how long you use the glow plugs. I use mine about 12-14 seconds during the summer and in the spring when it is cold I will extend that time some. Yeah - don't keep the glow plugs activated during starting.
Excessive starter motor cranking is not good for the starter and can lead to too much water in the exhaust system before the engine does start.

The operators manual for my Universal diesel 5416 M20 16 hp engine says to operate the glow plugs for 30 seconds in warm temperatures and 30 to 60 seconds in colder weather. It goes on to say that if it is very cold, depress the glow plug and starter buttons simultaneously to start the engine.

We sail in British Columbia, where summer temps are 60 - 80 degrees fahrenheit, water temp about 60 degrees; current air temps are about 40 degrees and water is about 38 degrees. My experience with our engine which has about 735 hours and runs well is that it starts best in summer with about 35 seconds glow plugs, and in winter about 65 seconds; anything less and the engine won't cooperate, but with that glow plug use it starts almost right away.

I wish I only had to use the glow plugs for 14 seconds like Loren, but that's not my experience. I mention this just so you don't get the idea that if you use your glow plug for longer than that, it's abnormal.

Frank

M25xp

I had a universal 25 xp that put soot on the transom; i added Power Service diesel additive (from Advance Auto Parts); cleared up 90% or more of the soot and added 4 to the cetane rating.

I agree with this statement.

Frank Langer said:

The operators manual for my Universal diesel 5416 M20 16 hp engine says to operate the glow plugs for 30 seconds in warm temperatures and 30 to 60 seconds in colder weather. It goes on to say that if it is very cold, depress the glow plug and starter buttons simultaneously to start the engine.

We sail in British Columbia, where summer temps are 60 - 80 degrees fahrenheit, water temp about 60 degrees; current air temps are about 40 degrees and water is about 38 degrees. My experience with our engine which has about 735 hours and runs well is that it starts best in summer with about 35 seconds glow plugs, and in winter about 65 seconds; anything less and the engine won't cooperate, but with that glow plug use it starts almost right away.

I wish I only had to use the glow plugs for 14 seconds like Loren, but that's not my experience. I mention this just so you don't get the idea that if you use your glow plug for longer than that, it's abnormal.

Frank

Click to expand...

My 1985 Universal M23xp also requires at least 30 seconds of glow plug before starting in most conditions. In cooler weather - considerably more. The only time it needs less (or none) is if the engine is already warmed. I have never needed to apply simultaneous glow and start.

the proper prop

we just got our 1986 28 and she had soot on th etransum. After some investigation we fould that she is way over proped. But the prop is what was issued at the factory. According to our survey it is a RH 12 X 10. My mechanic says she is getting no morethan 2100 rpms. We are installing a tack since it has none. I have seen one item on the internet that says a owner thought the prop should be 11X7. We have a universal Deasel 12 rated at 10 HP with a 3/4" shaft.

Does anyone know the proper pitch ratios for this engine and shaft?

thanks

tgardnersail said:

we just got our 1986 28 and she had soot on th etransum. After some investigation we fould that she is way over proped. But the prop is what was issued at the factory. According to our survey it is a RH 12 X 10. My mechanic says she is getting no morethan 2100 rpms. We are installing a tack since it has none. I have seen one item on the internet that says a owner thought the prop should be 11X7. We have a universal Deasel 12 rated at 10 HP with a 3/4" shaft.

Does anyone know the proper pitch ratios for this engine and shaft?

thanks

Click to expand...

I have the same boat...an '86 E28 with the M12 Univeral and a 3/4" shaft. The prop that I have is a 2-bladed RH 12 X 8, just like you, and I have no problems. I am surprised that you don't have a tach, as my boat does have one. We get almost no soot on the transom. I get max RPM of ~3,000, but typically run it at 2600 rpm, and in flat water it will run at about 5.9 knots. At 2800, it will run at 6.1 knots.

Andy

Good Info

One small comment on the underlying assumptions, if I may....
Be sure that the tach is reading correctly. Besides visually observing the smoke in the exhaust, and being sure of your boat speed through the water, the accuracy of the engine rpm's is the third clue in your mystery.
(How's your boat's speedometer? Calibrated?)

There are several threads here on tachs that were not accurate, and measures to check on their readouts.
This example is not the definitive thread, but just one that came up with a quick search -- note that there are references to using optical tachs to read the crank pulley.
http://www.ericsonyachts.org/infoexchange/showthread.php?t=2807&referrerid=28

Good luck.

Regards,
Loren

tgardnersail said:

we just got our 1986 28 and she had soot on th etransum. After some investigation we fould that she is way over proped. But the prop is what was issued at the factory. According to our survey it is a RH 12 X 10. My mechanic says she is getting no morethan 2100 rpms. We are installing a tack since it has none. I have seen one item on the internet that says a owner thought the prop should be 11X7. We have a universal Deasel 12 rated at 10 HP with a 3/4" shaft.

Does anyone know the proper pitch ratios for this engine and shaft?

thanks

Click to expand...

I think the best thing you can do is e.mail a prop mfg. and they will work out the details for you.
I did so this winter and had the prop on my E-28 reduced in pitch by 1". The prop was a 12diam. x 12 pitch 2 blade fixed Martec. It now is pitched at 11". My WOT tach reading is 3700 rpm's in neutral and I can now hit 3600 rpm's when motoring if I have to. Before I could only get 3200 rpm's out of the motor. Keep in mind that the motor in my boat is a 3 cylinder Universal M3-20 diesel with 18 hp.
I think Michigan Wheel told me to go to 11" on the pitch and several others gave me 10 to 10-1/2" on the pitch. The motor not runs smoother and the bow of my boat does not raise up as high as it use to when I have to kick it hard.
I chose to go to the lesser pitch 1st thinking that I could always go a little more later and didn't want my prop bent back and forth any more than necessary.
That's my experience, talk to the pro's. Hope it helps.
Good luck,
Sam of "Nauti Jo"

Proper prop pitch.

Sam, I've had three pitches on the same prop since owning our boat with the last two dialing it in to a Tee. I used as my target, the top RPM allowed by the manufacturer of my 3GMF Yanmar engine. You too should have a maximum and cruising RPM outlined in your owners' manual. Armed with this (and a tachometer in your boat) and after determining the present maximum RPM, you can then intelligently approach a prop shop asking that the pitch be changed to deliver the makers maximum RPM. That said, it's the case that my engine can't sustain top RPM, otherwise in about an hour of running it'll overheat. My engine should be capable of 3,700 RPM under way on flat water for a short period but needs to run no more than 3,500 RPM sustained, to prevent overheating. Your numbers may well be different (lower I think) but the same principles still apply. Best of luck and keep us posted, Glyn Judson, E31 hull #55, Marina del Rey CA

Proper Prop

Thanks everyone,
my diver is pulling the prop and based on my mechanic's data and with the help of a quality prop shop we are getting it repitched. I will let you know the results.

Hard to find props

does any one have 3/4 12 X 8 or 12 x 9 two blADE PROP. RH.

I have tried to find one and can't. The 3/4 are not made aftermarket anymore. I found a LH but that is no good. If some one has one please let me know. thanks

If you are dealing with a 3/4" shaft that you need to fit a prop on, you can get bushing/adapters to make a 1" bore (or whatever size) prop fit on the 3/4" shaft.

3/4" prop availability

I shopped for a prop this past winter and was able to get quotes for my E-28. My shaft is 3/4".

I spoke with Michigan Wheel, Martec and Deep Blue Yacht Supply.

Deep Blue had the best price but didn't have one in stock. They said it would take 6 or 7 weeks and the price was $278.00. That blew the others away price wise.

In the end I just took mine to a prop shop and they cleaned it and repitched it.

My WOT at idle is 3700 rpm's and using the advise I was given I can now run my engine in gear up to 3500 rpm's for a short burst. Before I could only get about 3200 rpm's. I had a 2 blade 12" prop with a 12" pitch and reduced the pitch to 11" and it worked out great for me.

Good luck,

Sam