Update on props for 1977 Californian w/Perkins

Hi all,

I just wanted to post an update. Sorry it is slow in coming. I just got the boat back. It was at the yard for 2 months. It ended up needing props, struts, and a shaft, as well as the previously anticipated bottom prep and paint and usual through-hull and packing gland maintenance. I took it to Gambol Industries in Long Beach. Jeff there was really helpful and patient with a new boat owner. The delays were mostly because I authorized the work one step at a time, which stacked the part delays. The props came via Gary at Wilmington Propeller, who was also great to chat with. (And, usual thanks to S&W Diesel for their help with engines, e.g. new thermostats, tach sender, stop solenoid, etc).

At any rate, recall that I have 2x Perkins 6.354 MGT turbo 185HP "breadbox" engines and was told WOT RPM under load should be about 2450. The props on the boat when I got it were 23x21x1-3/8" (and very corroded). I was seeing about 2050-2100RPM and 14kn/h WOT and it started to let loose some grey smoke at about 2000RPM. The RPM was verified with an optical counter from Amazon, as was suggested here.

I replaced the props with 23x19x1-3/8, losing 2" of pitch, to try to increase the WOT RPM by 400 (200RPM per 1" of pitch).

I got the boat back and gave it a brief test run. It looks like it worked perfectly. I saw 2450RPM WOT and the grey smoke kicked in at about 2400, maybe 2350. The wind wasn't stead and I didn't run back and forth enough to get a good measure, but my GPS was reading 14.5kn/h - 15kn/h, so I don't think the pitch change cost me much, if anything, in speed.

I checked in with Bob at S&W Diesel and he told me that was perfect, because I was just beginning to over-fuel at the very top of the RPM range. He said that I could adjust the prop by a hair to get rid of it totally -- or just do the wiser thing and run the engines nowhere near that hard. He suggested a cruise of 2000-2100RPM. I was mostly going slower, e.g. 1800RPM last weekend, so I'll see how 2000 feels next weekend.

I get some white smoke (not steam) before I leave the slip. I've been told it is to be expected with the Perkins engines of that era, but I'm probably going to have the injectors rebuilt on one of them and see it it cleans it up any. I'll post again in a few weeks or couple of months to update about how that works.

At any rate, I just wanted to let anyone interested know how the prop change affected things.

Cheers!

-Greg

Good to hear, Greg. Sounds like you nailed it on the first time!

Your engines are naturals, right? Mine are natural 4.236 Perkins...your engines with 2 cylinders lopped off. They seem to like lugging along at 1800 RPM. I used to run at 2000 RPM for 8 Kts but the noise and fuel flow seem much better at 1800 (7.5 Kts). I saw a drop from 2.0 GPH per engine to 1.6 GPH per engine.

Alright, glad to hear you got it straightened out.

My 6.354s are the same, a little smoke at start up. They're on the low end of the compression range for a diesel anyway and with wear and time that doesn't help. Had my injectors rebuilt and it didn't go away.

They will also produce visible white exhaust vapor from time to time at cruise, but seems to be more of an atmospheric condition, temperature/humidity level, than anything going on with the engines. Usually it's early in the morning or just before sundown.

Thanks for the update.

Hi FlyWright, Hi Edelweiss,

FlyWright: With what it cost me for a turbo rebuild a a new turbo, I wish mine were NAs. But, they are turbos. I hearsay that also contributes a bit toward the unburned fuel at idle.

Your experience with the injector rebuilds saddens me. The guy at the injector shop had me convinced that there are new nozzles that get a better pattern and that I'd see less smoke, even if there is nothing wrong with the old ones. Like I said, I'm going to hedge my bets and do one engine first and see how it goes. The Perkins specialist mechanic who did all of the initial work (Martin Ball) told me the injectors are fine and it is just characteristic of the older engines and nothing to think twice about. He recommended against doing the injectors. Guess we'll see! I feel like I should try.

Edelweiss: Thanks for the report. My engines start up instantly, so I feel like their compression is okay? If it doesn't turn out to be the injectors, I'm probably going to bet on the 10 year old fuel that is still in the mix (added a ton of cleaner) and/or just characteristic of the engines. I feel like the boat is flying at 14+ kn/hr and starting right away, so I just don't feel like they are losing much power. It just gives me the idea that it is just a hair too much fuel rather than too little compression?

THANKS FOR EVERYTHING!

-Greg

Boats usually have a sweet spot for cruising where vibration, speed and efficiency come together. I run at 80% power with good results.

Greetings,
Mr. gk. Ask the "...guy at the injector shop" for a money back guarantee and see what he says.

Hi all,

MVDarvin: That 80% puts me right where the mechanic did at about 2000rpm. I guess I've been told most diesels like 80-85%, and not more than 90%. Had too much wind and too little time to measure, but 2000 does sound and seem solid

RT Firefly: Wouldn't money back guarantees be nice?