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Motor Crusing speed E35 74'-76'

Captain Crunch

Member II
Can anyone tell me the expected motor crusing speed for a '74 to 76' Ericson 35 w/ newish 24 hp Yanmar. Or maybe the best prop I cuold use for the best crusing speed. Thanks!
 
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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Without crunching your numbers of WL length, static and moving, and calculating the amount of surface slime, and the number of cans of Dinty Moore stored below... :p

I would expect about 6.3 to 6.6 kts at "full honk" under power, and some black smoke coming from the exhaust and a nice following wave built up behind the transom...

It might do almost 7 with a really slick bottom, right out of the yard. My 34 footer will do these numbers, but I may have a little more WL than you. OTOH I have 23 "well-seasoned" HP in an engine that was new in 1988.
Hull shape of your boat is different enough that my figures may be "all wet" when attempting to make comparisons.
As they say.... YMMV.
:)
I bet you could cruise easily on a windless day at just under 6 kt, and only burn around a half gallon per hour.

"Best" Prop? -- most of my friends that power a lot seem to have three blade props, and just shrug off the loss of speed sailing in light air.

Loren
 
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Gord Bell

Member II
I have a 1970 35-2 and at cruise speed under power I am doing about 6 - 6.25 knots. At full throtle I can get the boat up to just over 7. This is done with a 27hp diesel turning a 3 blade Max Prop. At cruise I am burning about 1/2 gallon per hour and at full throtle it is close to 1 gallon per hour.
cheers Gord
sv Huckleberry
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Without having a tach on our Ericson 30+, how can one tell what the best/most appropriate speed is? I have been told that running too slow leads to carbon in the diesel (and doesn't get us to the destination), but too high RPMs could place too much stress on the engine. Any advice for the Universal 18 h.p.? At this point I let it warm up 10 minutes, then bring to full throttle and back off about 10% or so as the cruising speed at about 6.0 - 6.2 knots. I did end up with a bit of black soot on the transom.
Thanks,
Frank.
 

Seth

Sustaining Partner
"Smoke on the Water"

Fire in the sky?:nerd:

But seriously, a good rule for those without tach's is to make sure you have clean exhaust-if you see black particles, black water, or black smoke, back off on the throttle at least until you have (visible) particle free exhaust and clear water coming out..Your engine will love you for it!

S
 

CaptnNero

Accelerant
Frank, there is a clear cut procedure for evaluating the prop size and engine performance. The soot could be indicative of a problem, one of which is an over sized prop. Constant generation of soot can lead to coking of the exhaust, which in turn increases back pressure and other problems. If you can't borrow a handheld tach, you might want to hire a marine diesel mechanic for the task. Also, you can get a handheld laser tach off of Ebay for $25 plus shipping.

As it has been explained to me by my mechanic, you need to establish the no load max rpm by briefly revving to max rpm in neutral and putting a tach on it. After reducing to idle, run the vessel at full throttle in gear until the boat speed maximizes. If the loaded max rpm is within 10% of the unloaded max rpm, the prop is properly sized. Then your cruisng rpms should be 80% of the loaded max rpms. The max unloaded rpm can also be taken from the engine manual. Having established the cruising rpms is much less helpful without installing a tach for reference when you are cruising.

In case you didn't know, the standard tach for the Universal diesel is about $145. Installing a tach is relatively uncomplicated except for calibration where once again a handheld tach is needed. Operating without a tach its hard to determine proper cruising speed since it will vary with conditions (waves, wind) that you will have to interpret with your throttle setting. Using boat speed to set cruising rpms, you will need to somewhat discount the expected boat speed such as when going into a strong wind or seas, but how much ?

Our first boat had a smoking problem which a mechanic determined was from an oversized prop. When we checked, it indeed had an oversized Martec folding prop. The previous owner came up with the original Michigan sail prop and all was well.

I've never heard that running too slow is a problem. On the other hand, running the diesel to fast will wear it out faster. For our M25XP I think the manual recommends 2400 or 2600 for cruising with a max unloaded rpm of 3200. We cruise at 2400 at 6 knots.

Frank Langer said:
Without having a tach on our Ericson 30+, how can one tell what the best/most appropriate speed is? I have been told that running too slow leads to carbon in the diesel (and doesn't get us to the destination), but too high RPMs could place too much stress on the engine. Any advice for the Universal 18 h.p.? At this point I let it warm up 10 minutes, then bring to full throttle and back off about 10% or so as the cruising speed at about 6.0 - 6.2 knots. I did end up with a bit of black soot on the transom.
Thanks,
Frank.
 
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Mike.Gritten

Member III
Our 35-2 has the old Westerbeke 4-92 (or W30) spinning a 12" 3-blade Max Prop feathering propellor through a 1:1 Paragon Gear transmission. With a nice clean bottom and immaculately polished prop, we motor all day at just under 6 knots reading 1900 rpm on our tach (surveryor says the tach reads low). When we "put the hammer down" we can get almost 7 knots, but by then the wave is trying to get aboard via the transom (i.e. stern seems to be sucked down into the water). Last year we were experiencing a relatively minor overheating problem that turned out to be a combination of a very tired coolant pressure cap and a nearly plugged up heat exchanger, so we couldn't run at near full throttle for long. We do get prop cavitation if we try and accelerate too quickly from a standstill or when the bottom becomes fouled with growth. We have come to the conclusion that this is because of a combination of the 1:1 gearing and the relatively small diameter prop. I don't think we can go any larger, prop-wise due to clearance issues between prop and hull.
 
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