Inboard engine questions

shemandr · Monday at 3:39 PM

At some point you may lower the idle RPM but not necessary for your trip - forward neutral pulsing works. Remember sailboats are maneuverable at low speed because the rudder is so big. So you should have steerage at as little as .5 kt or even less with a clean bottom.
As for cruising speed I would run my diesel at about 80% full speed. Diesels do like to work at that point on the power curve and they are efficient in that area. As a general rule you are not helping your diesel by babying it. It likes to run.
I would have spare fuel filters, water pump impeller, belts and enough oil to replace the engine oil. A multimeter, box and socket wrench set, screwdrivers, tools for tightening or loosening the stuffing box, plugs for thru hulls, and an auxiliary rudder of some sort.

kappykaplan · Monday at 3:43 PM

john6206 said:
In forward gear, the slowest I can go (in calm winds) is 3 kts. Throttle all the way down. That seems crazy fast. I find myself in neutral in marina, bumping in and out of forward gear to maintain steering without speeding up much.

What is the RPM? Is the bottom clean? Prop & shaft?

john6206 said:
Also, best practice for cruising a relative distance (50 nm is the longest leg I have planned).

If your speed over the ground is 5 kts, that's a 10-hr day - very long day when you add set up time at the beginning of the day and tear down/stowage at the end of the day. 35 nm is the sweet spot.

john6206 said:
A friend of mine says “diesel engines like to work hard” so when he is cruising he runs the engine at higher rpm for 20 minutes, then backs it off to cruising speed, then right at the end he cranks it up a bit again, does that make sense? He said he got that advice from multiple diesel mechanics, but his boat is VERY different from mine.

Diesels do like to be pushed, 85-90% of max rpm is good. I run mine wide open from the slip to the river, usually about 20 minutes. You'll also find that higher rpms are better for the mixing elbow (where relatively cool water from the heat exchanger is mixed with the exhaust gases).

None of us became experts overnight, so keep asking questions. :beer:

Don S/V ILLusion · Monday at 4:33 PM

john6206 said:
.

What else should we do before we pull out? Seems like they did pretty food maintenance a year ago and then never used it, raw water strainer looks perfectly clean.

the “other” stuff can be more important than idle speed.

Check all hoses and double clamps. Check all thruhulls to ensure they work freely. Check all bilge pumps. Check to verify integrity of anchor, chain and rode. Fire extinguishers, battery capacity and charge system efficacy, etc… the list of safety concerns on a new old boat is large so don’t forget to check the stuff that can bite you.

Steve_Catalina · Monday at 5:56 PM

Check out your c320 international site, catalina320.com the usually suggestion for the universal engines is 80% max rpms for normal top speed cruising. The site probably has the manuals for your boat.Good luck

Davidasailor26 · Monday at 6:32 PM

john6206 said:
o I just go full throttle and watch the rpm?

Yep, that will tell you the maximum output the engine can give. Then cruising at 80% of that should be fine.

Tally Ho · Monday at 7:36 PM

An engine should have a max RPM. My Yanmar 2GM20F is rated at 3600 rpms max and 3400 rpms continuous. So I like to run mine about 2800 rpms.

Greg

Tally Ho · Monday at 7:49 PM

john6206 said:
Ok, next dumb question….
Top off the 19 gallon diesel tank in Manitowoc.
It‘s 26 miles to Keewaunee - no diesel available, 52 miles to Frankfort.
78 miles on 19 gallons.

Any reason to worry about fuel? Even a little?

Even if we have to motor the whole way? even if the wind is in our face?

Right now the forecast says wind will be with us the whole time,
but wind forecasts change pretty quickly.

Do you have a fuel gauge?

Even if not, you can get an idea of fuel usage based on engine run time.
I am going to guess your 27HP engine burns around 3/4 gallons an hour. Someone may correct or refine that…

So 19 gallons should let you run the engine at least 20 hours. Closer to 25 hours, but who knows how much crud is in the bottom of the tank. If you are going 5 knots an hour, that is about 6 miles an hour (1.2 miles per knot).

So 20 hours of run time x 6 miles an hour…you can probably go 120 miles. Maybe closer to 150…but I would not want to run the tank that low.

If someone corrects the fuel usage (say 1 gallon an hour), you can recalculate and get a revised estimate.

I would get fuel at your next available stop and maybe carry a 5-gallon Jerry can with an extra 5.

I forget how far you are going….is the 78 miles the full trip? If so, you should be fine.

Greg

jssailem · Monday at 8:53 PM

Your Westerbeke engine performance chart is identified here at 3600 rpm

https://www.westerbeke.com/advanced%20specs/30b%20three.pdf

I recommend you calculate the engine fuel consumption. I suspect it will be between.5 and .75 gallons per hour.

Tally Ho · Monday at 8:55 PM

john6206 said:
@Tally Ho

75 miles is the distance between two ports that have diesel.
total trip is about 400nm.

i think you can do 75 miles easily. My 2cyl Yanmar burns about 1/2 gallons an hour. Someone may have the spec on your westerbeke. But I think 19 gallons gets you easily 120 miles… and potentially up to 150 if the burn rate is 3/4 gallons an hour. If it turns out it burns a gallon an hour, then you are down to about 114 miles at best….and I wouldn’t plan on more that 85 or so.

Foswick · Monday at 11:13 PM

john6206 said:
Catalina 320, Westerbeke 30B (27 hp If i remember) I have several questions about my 30 year old diesel.

In forward gear, the slowest I can go (in calm winds) is 3 kts. Throttle all the way down. That seems crazy fast. I find myself in neutral in marina, bumping in and out of forward gear to maintain steering without speeding up much.

Is that “normal?” Is something badly out of whack?

That sounds like you are idling high. Assuming this is your engine:

https://www.westerbeke.com/operator's%20manual/20b%20two-30b-30c%20three%20operators%20manual%2036906%20rev%205.pdf

... then idle should be between 1000-1200 RPM. Since the boat is new to you, do not trust the tachometer, yet. If you don't have one, get an inexpensive handheld digital tachometer and verify. This is very easily done by putting a piece of reflective tape on crankshaft pulley, pointing the tachometer at it, and looking at the number (with the engine running, of course).

If your engine is idling high, you might also find that it is slow to go into gear.

Of course, there is another variable - your prop. It is possible your engine is idling correctly but the prop is not appropriate for your boat. Someone who is more knowledgeable about props than me would have to comment on that.

But, it is also possible that everything is working fine. It is normal, on most boats, that you do not need to remain in gear around the marina - periodically taking it out of gear to avoid moving faster than you prefer. 3 kts seems pretty quick, if that is your true speed through the water with no wind in your favor.

john6206 said:
Also, best practice for cruising a relative distance (50 nm is the longest leg I have planned).

At 2000 rpm I’m doing about 5 kts (again - pretty calm wind). Does that seem like “cruising speed?

A friend of mine says “diesel engines like to work hard” so when he is cruising he runs the engine at higher rpm for 20 minutes, then backs it off to cruising speed, then right at the end he cranks it up a bit again,

does that make sense? He said he got that advice from multiple diesel mechanics, but his boat is VERY different from mine.

Others have answered this, but I'll just reinforce that. If I showed you the correct operator's manual for your engine, then you should be cruising at 2500-3000 RPM. The engine does not care about speed. It cares about RPMs. It is true that a diesel engine should be run at about 80% of max load. At lower RPMs, combustion can be incomplete, which is bad for your engine over time if you don't run it under higher load sometimes. You are not doing your engine any favors by running it below that load. So, you might as well. You should not cruise for extended periods at 2000 RPM. That is too low for long-term health.

At that speed, you should be able to achieve hull speed pretty readily under most conditions. For your boat, that's about 8 kts.

There is a rub here. It is possible that your engine/prop/boat combination is such that, by the time you reach a cruising RPM, the boat is already going at hull speed. So, at that point, you are just pushing water without going any faster. I do not think that is the case here. If you are seeing 5 kts at 2000 RPM, that is about what you would expect if the boat reaches hull speed at somewhere approaching 3000 RPM.

john6206 said:
Ok - last one. In the last four days I’ve changed the oil, oil filter, impeller, filled the coolant.

What else should we do before we pull out? Seems like they did pretty food maintenance a year ago and then never used it, raw water strainer looks perfectly clean.

Also, we have a decent bag of parts in a Westerbeke bag, looks like PO bought the spare parts kit.

What spare parts would you not leave port without?????

I'm the wrong person to answer this because I like to have everything I might ever possibly need. But, the contents of the Westerbeke spare parts kit pretty well covers what I wouldn't want to go far without - all belts, all filters, impeller kit, etc. But, a better way to think about this is to assess what you have the skills to fix. No point in carrying a spare injector assembly if you don't know how to replace it and/or diagnose that you might need to.

john6206 said:
I feel like I’m overthinking, never going to be perfect, just trying to maximize odds of not breaking down.

That's all anyone ever does. I think the key is to understand that you can prevent some problems and others are outside of your control. You can fix some yourself, and some you cannot. With experience, this hopefully gets better, but the most important thing you gain from experience is knowing what you don't know.

sailme88 · Tuesday at 4:05 AM

Sounds like you have done most of the basic PM activities. How about inspecting and or changing out the engine zinc in the heat exchanger?
The engine RPMs are tied to your wheel ( prop) size and pitch. You "COULD" swap out props and notice different hull speed at different RPM's. The usual difference is more speed vs more torque.

Sailboats coast. you received some good advice regarding pulsing the transmission. Give it some time. 5 days experience is very short..Learn, really learn what the prop walk that your boat has. Learn to use the prop walk to your advantage. Starting from zero speed, you'll always have more command over your boat in forward. But once you have water over your rudder in reverse, the available command can be impressive.

kappykaplan · Tuesday at 4:46 AM

john6206 said:
My mantra has become, “I’m not trying to sail 400 miles, I’m trying to sail 25 miles today.”

Congratulations! :beer:

LakeOntario270 · Tuesday at 4:59 AM

In the 13 years I have owned a Westerbeke 20B Two I have had 3 problems
Overheated after a coolant fluid change and didn't get all the air out.
Started the engine and no water came out in the exhaust. Obviously and engine problem. It was a fish stuck in the seacock.
Starter motor would not turn over. It was a loose screw on the engine terminal strip, the one that connects the engine to the boat.

I have a friend who bought a used 320 with the Westerbeke and it left him stranded. It was a stuck piston ring, serious problem most likely caused by lack of oil changes (I have read as to possible causes).

I cruise at 1800 rpm because I get a lot of hull vibration over 2000 rpm where as at 1800 only a little vibration.

dmax · Tuesday at 8:33 AM

"I cruise at 1800 rpm because I get a lot of hull vibration over 2000 rpm where as at 1800 only a little vibration. "

It would be wise to fix that situation as you're running your engine too slow and will shorten its life - most likely the engine just needs to be re-aligned.

Inboard engine questions

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SBO Weather and Forecasting Forum Jim & John

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