Propeller size for the 100 hp engines.

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dstrecker1
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Propeller size for the 100 hp engines.

Post by dstrecker1 » Tue May 21, 2019 9:24 am

I am interested in what other have found to be best pitch for 100hp 3 and 4 blade engine props.

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AMCarter3
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Re: Propeller size for the 100 hp engines.

Post by AMCarter3 » Tue May 21, 2019 12:08 pm

Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

Gusto
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Re: Propeller size for the 100 hp engines.

Post by Gusto » Thu May 23, 2019 12:30 pm

My boat is a 2006 with 100 hp engines. It had 17" x 14" props. WOT rpm was about 3400. According to Mastry Marine, a Yanmar distributer, Yanmar wants the WOT rpm for those engines to be 3800 rpm. I had the props repitched to 17" x 12" and got real close to 3800 rpm at WOT. I now run the engines about 200 rpm higher to get the same speed, but according to the Mastry guys, my engines are a lot happier.

Cheers,

Bob MacNeill
Gusto

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AMCarter3
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Re: Propeller size for the 100 hp engines.

Post by AMCarter3 » Thu May 23, 2019 1:05 pm

The combination of: 1) new injectors; 2) adjusting all valves: 3) have both shafts balanced; and 4) having both props pitched to 17"x13" resulted in massive improvements:
• WOT of 4000 rpm (up from 3400)
• Speed increase to over 18 knots (flat water, no wind)
• Significant decrease in engine noise and vibration -- can now carry on normal conversation on flybridge.
• I suspect, but cannot verify we get better fuel consumption too.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

kjoverbeck
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Re: Propeller size for the 100 hp engines.

Post by kjoverbeck » Sun May 26, 2019 10:49 am

We hit rocks damaging starboard shaft and prop. Actually, it killed them both. New shaft and both props ( 3 blade) set to 15.5"pitch. Wide open throttle at 3800 and 17 MPH at 3200. Rebuilt turbos, injectors and valves adjusted. Runs very smooth and quiet. I have since sold Rising Tide but the new owner confirms same performance levels.

Kent Overbeck Formally of Rising Tide 2005, 100 HP

Nick
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Re: Propeller size for the 100 hp engines.

Post by Nick » Sun May 26, 2019 4:53 pm

Haha! Yes, we are the new owners of “Rising Tide” (now Catsaway) and can confirm the boat will go 17mph comfortably at 3,200 and above 20mph at 3,80O fully loaded and with full fuel. No vibration, no complaint. It’s not a ski boat, but really goes when throttling up. This leads to a question...what is the “happy place” for these 100hp Yanmars? Fuel economy aside, the motors really feel solid at 3,000 to 3,200. Steady temps and steady oil pressure, but does it hurt them to run at this level hour after hour? If running that range, should I still run them wide open for ten minutes to blow out turbos?

I’ve read All Heart’s charter manual (which is a super good reference document) describing top end as 9-11 knots at 2,400 to 2,800, but mid-2,000’s is not a happy place for our boat. Wants more or less, but not that range. Still learning as we go!
Nick & Barb
Catsaway
2005 PDQ34 #66

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AMCarter3
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Re: Propeller size for the 100 hp engines.

Post by AMCarter3 » Sun May 26, 2019 6:13 pm

We ask our charter guests to not exceed 2800 RPM... which is approximately 75% of 3800 RPM. This is based on what our local Yanmar diesel experts advise. These guys deal with diesel engines on a lot of commercial fishing boats as well as recreational boat like ours in Puget Sound. They said these engines REALLY run well and last longer when are well maintained and run fairly consistently at about 75% of full throttle. So, that's the guideline we follow.

They also said it is a good policy to occasionally run them above 75% -- like up to 80-90% of full throttle for about 15 minutes. This is to allow the engines to heat up a bit more than normal in order to blow off some of the normal carbon buildup in the exhaust system. So we follow that advice too.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

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Re: Propeller size for the 100 hp engines.

Post by deising » Mon May 27, 2019 5:31 am

Nick,

From everything I have come to understand, if you are running your engines 3,000-3,200 RPM, you should not need to go higher to "blow out the turbos." An occasional excursion to WOT will be good simply to tell you if you can still achieve the rated RPM (about 3,800) and to monitor the coolant temp to see if the system is still capable of holding the temp in an acceptable range. I believe you should not be surprised to see the temp rise above normal (about 175F), but hopefully will stabilize below 190F. Running in 85F vs. 50F sea water will make a difference, too.

You should clean the turbos periodically, as instructed in the manual. It is very simple.

Congrats on purchasing an outstanding boat. Kent took good care, and improved her, over the years. Enjoy her!
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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Re: Propeller size for the 100 hp engines.

Post by AMCarter3 » Mon May 27, 2019 11:35 am

Duane,

Could you comment a bit more about how you handle the task of cleaning out the turbos on the 100 HP Yanmars? I've never done that and the diesel guys here implied it is not so simple to take it apart. And, I don't see a section in the 4JH3-HTE service manual I have about maintaining the turbos.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

duetto
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Re: Propeller size for the 100 hp engines.

Post by duetto » Mon May 27, 2019 11:47 am

i think duane's referring to cleaning the intake side turbo fan. i've done it on our 75s. on the 75s you remove the aircleaner and then get a small paint brush and a bowl of lacquer thinner or your favorite solvent. you use the brush to bathe the fan with solvent and eliminate any oil and dirt build up. given the small size of the fan any extra weight or resistance will hurt performance.
john & diane cummings
duetto mv34 #23

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Re: Propeller size for the 100 hp engines.

Post by deising » Mon May 27, 2019 12:40 pm

I found it in the Operations Manual. I have been told to use a dish detergent diluted down, say 10 drops of detergent in 1/4 cup of water. Putting that in a spray bottle for introduction to the intake works well. Others might know better and will advise here.

Here is the relevant snippet:
turbo wash.png
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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