• Untitled Document

    Join us on March 29rd, 7pm EST

    for the CBEC Virtual Meeting

    All EYO members and followers are welcome to join the fun and get to know the guest speaker!

    See the link below for login credentials and join us!

    March Meeting Info

    (dismiss this notice by hitting 'X', upper right)

An Over Powered e32 or wrong prop?

Ensenada Crab

Member I
So my e32-2 has a universal 5416 (16hp at 2,800 rpm) and a two bladed prop. but at just 1,000 rpm the boat moves along quite nicely at about 5 knots. it seems silly to run the engine at 80 percent of max rpm given the the boat is already moving right along. i understand that diesels like to run at 80 percent of max rpm to keep warm. and i can understand that, since at 1,000 rpm the engine is only running at about 150 degrees. the recommended operating temp is 175 to 190.

so i wonder if i have the wrong propeller, or maybe the wrong thermostat to get the temp up and move along at a reasonable clip?

a leaking packing gland has kept me from going beyond 1,500 rpm. but the questions remains. is it reasonable to push an e32-2 along at 8-10 knots?
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
It's probably just your tachometer. And who knows if your temp gauge works.

Under 80 percent power you should get about 6 knots or so GPS speed, more or less.

You can exceed hull speed sailing down waves, but not motoring in flat water.

Tach testers and temperature guns are cheap if curiosity continues.
 

Alan Gomes

Sustaining Partner
So my e32-2 has a universal 5416 (16hp at 2,800 rpm) and a two bladed prop. but at just 1,000 rpm the boat moves along quite nicely at about 5 knots. it seems silly to run the engine at 80 percent of max rpm given the the boat is already moving right along. i understand that diesels like to run at 80 percent of max rpm to keep warm. and i can understand that, since at 1,000 rpm the engine is only running at about 150 degrees. the recommended operating temp is 175 to 190.

so i wonder if i have the wrong propeller, or maybe the wrong thermostat to get the temp up and move along at a reasonable clip?

a leaking packing gland has kept me from going beyond 1,500 rpm. but the questions remains. is it reasonable to push an e32-2 along at 8-10 knots?
As covered in some recent threads, you first want to determine that your tach is reading correctly, or at least close to it. Getting one of these will help: https://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html Then, there is also the question of whether your speed readings are right. You need accurate readings that also take into account whether you are being helped along (or hindered) by any current.

So, for the sake of argument let's assume your tach is at least in the ballpark....

I'm not sure why a *leaking* packing gland would keep you from hitting your top RPM. (One that is severely too tight could possibly cause problems like that, but that packing gland would be running really, really hot. But you are talking about one that is apparently loose, not too tight.) Rather, your installation shows at least some of the telltale signs of being over propped. Significantly over propping your engine is one of the worst things you can do to it. Diesels like to run at 80% of max because that puts them in an advantageous part of the torque curve. If you are severely over propped you will shorten the life of your engine.

Here's a rough way of knowing if your prop (and/or engine functioning) is close to right. You should be able to hit the top rpm that your engine is designed to hit, give or take maybe 150 rpm or so. If the engine hits top rpm too easily, i.e., when you open up the throttle it just sort of zooms right up to peak rpm, close to the way it does when you are in neutral, then you are probably under propped. If you are truly only able to hit 1,500 rpm, then either you are WAY over propped, or something is keeping your engine from producing its rated horse power, or the prop is severely fouled, or maybe some combination of all of those. If the prop and engine are performing as designed, you should be hitting close to max rpm with the engine having to work to squeeze out those last couple of hundred rpm.

Don't mess with the thermostat; figure out what is going on with the prop. Do you know what the specs are for the prop--specifically, the diameter and pitch? If you had a survey done when you bought the boat it is common for the surveyor to note that in his or her report. You can then contact a prop shop and they will tell you whether what you have sounds right. They will need not only the specs for the prop but certain specs from your engine, such as your transmission's gear ratio. But they will tell you what they need, assuming they don't already have the info for your particular engine on file.

Hope you get this sorted out. If you truly cannot hit more than what is actually only 1500 rpm with that engine then something is seriously wrong. However, assuming the engine itself is fine, getting your prop re-pitched is no big deal and you'll be happy with the performance improvement if you do.

Good luck and report back.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
This might be an opportune time....

This might be an opportune time for a few of you Ericson experts (and I know there are many on this site :egrin:) to give us a few tips on engine etiquette, related to this thread.

Most of us know that diesels do not like to idle for long due to carbon build-up and should be run at fairly high speed. We also know that we should not run them for just short distances as they need to run at operating temps for a while--but for how long? Is a 20 minute run long enough? 30 minutes? 60 minutes?

We also know that most manuals recommend running them at about 80% of max rpm. But is it best to run at a constant speed or to vary that a bit from time to time?

A fellow sailor has suggested that one should rev the engine quite hard before final docking to blow out the carbon. I can't imagine that being good for the engine to rev it hard, but what do you think?

Finally, is it good to occasionally run at max speed/wide open throttle for a few minutes, or is that bad for the engine to be under that load for any time? I never run my car at max rpms or red line on the tach, so I'm thinking that can't be very good for the boat's engine either, right?

Any other similar tips or advice would probably be much appreciated by many of us.

Thanks,

Frank
 
Last edited:

supersailor

Contributing Partner
A diesel is basically an air pump. The more air in and out, the more the power output. That's why you see so many diesel trucks with gigantic exhausts. The diesel uses oil (diesel fuel) as fuel. Diesels use cylinder heat to fire the mixture. This is why the compression ratios are 20-1 or more. The glow plugs provide the initial heat needed. The harder a diesel is run, the hotter the mixture burns and the more efficient it is. Most diesels are optimized at about 80% load. This makes them ideal for stationary units and boats where you push up the throttle and leave it there. At low loads, the cylinders run cooler causing inefficient burning and soot.

A gasoline engine uses a volatile solvent (gas) as fuel. The gas engine needs a spark to fire because the compression ratio must be kept below the spontaneous heat that would ignite the fuel. The gas flashpoint is sometimes a little unpredictable and causes detonation which can destroy the engine. Because of this, gas engines usually have a compression ratio of 7.5 to 1 with a max of about 11 to 1. This limits torque (twisting force) that the engine can produce. Gas engines like to run at about 23% load and they like variations in RPM. This makes them ideal for automotive use where you only use max power every now and again and your speed constantly varies.

Another plus of the diesel is that the diesel mixture constantly lubes the upper cylinders greatly increasing the life of the engine. The downside has been engine noise. That has been greatly improved in the new models of the engines.
 
Last edited:

Ensenada Crab

Member I
wobbly packing gland. . . urges caution

Bit of info missing: What's the tach show under way at wide open throttle?
i have not taken the engine past 1,500 rpm on the tack as the packing gland was not dripping; water was whipping off the spinning drive shaft in something of a cascade. and could have been my imagination but i thought i smelled friction.

sitting in port with everything off i am getting probably getting 30 drops to the minute. there seems more than enough green on those brass fitting to justify replacing the whole caboodle.

so thinking forward, i need to repack the gland at a minimum, and am wondering, if the shaft is scored, can the packing gland be moved in or out by an inch (by a longer or shorter rubber section) to engage a smooth part of the drive shaft?
 

Ensenada Crab

Member I
the prop. . . .

according to the last survey the vessel has a: 12” LH 2 blade bronze propeller (pitch not marked)

capture-20181207-171311.png

i have to believe that the hull, engine and prop were designed to move the boat along at optimum speed at optimum rpm for that engine.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Crab,

Too many factors in play. Let's deal with the gland first. Or the tach. Before thinking about changing props.

A traditional packing gland is very simple. If the big nut won't tighten any more, maybe there's no packing left at all. They're easy to repack (usually, sometimes, maybe). At random, here's (maybe, probably) what yours requires.

https://www.pbo.co.uk/expert-advice/expert-answers/how-to-repack-a-stern-gland-step-by-step-1031

http://www.pbase.com/mainecruising/stuffing_box

Cant have all that water spewing out. Isn't your bilge filling up when you leave the boat?

To repack the gland in the water would be good to have an experienced hand there so you can watch him panic, but it is quite possible to do in the water.
 
Last edited:

Ensenada Crab

Member I
Bilge is an annoyance, and recording speed

thanks so much for the article on repacking, realistically, that's all the boat requires (right now) though the first step would be to see if i can tighten that nut. so much for running off into the future.

at this point, after 24 hours there is less than an inch of water in the main bilge. i would say less than a gallon of water.

i have a velocitek s-10 (a gps sailing tool) which records gps data every two seconds. that's what i use for a recording speed. it even allows for playing back sails which is pretty cool. my top speed sailing (on a beach, in a home built sail cart) is just shy 40 mph. so the pic below is from my last sail; powering out into the bay.
capture-20181207-174854.png
 

Alan Gomes

Sustaining Partner
i have not taken the engine past 1,500 rpm on the tack as the packing gland was not dripping; water was whipping off the spinning drive shaft in something of a cascade. and could have been my imagination but i thought i smelled friction.

sitting in port with everything off i am getting probably getting 30 drops to the minute. there seems more than enough green on those brass fitting to justify replacing the whole caboodle.

so thinking forward, i need to repack the gland at a minimum, and am wondering, if the shaft is scored, can the packing gland be moved in or out by an inch (by a longer or shorter rubber section) to engage a smooth part of the drive shaft?
Oh, *NOW* I understand what you meant when you said, "A leaking packing gland has kept me from going beyond 1,500 rpm." The packing gland did not literally preclude you from hitting higher than 1500 rpm, but because of the leaking you CHOSE NOT TO run it higher than 1500 rpm. Big difference. When I first bought my boat, the packing gland was so tight (because the PO had installed the wrong sized packing) that the packing gland literally kept the engine from getting up revs and in fact would even kill the little Yanmar 1GM! But that was a case of too tight vs. too lose--hence, my confusion.

Anyway, Christian is correct; there are too many variables in play to give you any kind of answer. You really don't know whether your tach is correct. You really don't know what your max rpm is at WOT when under way because you have chosen not to run it at WOT due to the packing gland leak. Your packing gland is leaking far more than it should, which typically would not make it run HOT, but which does sling a lot of water around your engine compartment (as you've observed).

First things first. Fix the packing gland. Repack it with the proper sized packing. It typically will take three rings. The site to which Christian pointed you is quite good on how to do this: https://marinehowto.com/re-packing-a-traditional-stuffing-box/ Don't screw around with trying to reposition the stuffing box hose.

Next, check the calibration of your tach. You've already received good advice on where to get a great deal on an optical tach.

Then, once you know your actual engine rpm, take it out and run it at WOT to see what the engine will hit. What I wrote in my previous post will then apply.
 
Last edited:

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
So my e32-2 has a universal 5416 (16hp at 2,800 rpm) and a two bladed prop. but at just 1,000 rpm the boat moves along quite nicely at about 5 knots. it seems silly to run the engine at 80 percent of max rpm given the the boat is already moving right along. i understand that diesels like to run at 80 percent of max rpm to keep warm. and i can understand that, since at 1,000 rpm the engine is only running at about 150 degrees. the recommended operating temp is 175 to 190.

so i wonder if i have the wrong propeller, or maybe the wrong thermostat to get the temp up and move along at a reasonable clip?

a leaking packing gland has kept me from going beyond 1,500 rpm. but the questions remains. is it reasonable to push an e32-2 along at 8-10 knots?

Under power, you will obtain about 6.5 knots with a smooth bottom and efficient prop. Might be a little more possible but not much... That model has enough 'tuck up' in the stern sections to cause it to squat when additional power is applied; i.e. it cannot climb up out of its 'hole in the water'. Stated another way, it cannot get onto a plane.

By comparison, our boat has a longer DWL and a much flatter run aft, and we can only motor at about 7. 2 kts or so, pedal to the proverbial metal.

Our hull shape does permit faster sailing off the wind, however. "Everything's a compromise" as the saying goes. Your hull form likely goes to weather with less fuss.

Another note: if you run the engine at 1000 rpm, you are probably only using about 7 or 8 hp. That's OK in flat water and going 5 kts, but you cannot use the rest of the HP curve for making progress into waves or adverse winds. What does the manual advise for steady cruising rpm? I might guess about 2400, give or take. You might be over propped by a significant amount.

As pointed out, several parts to the problem and you'll have to check 'em off one by one.

Regards,
Loren
 

markvone

Sustaining Member
Crab,

Prop shaft scoring typically occurs when the gland is too TIGHT and doesn't drip water used for seal lubrication and cooling. You get heat, friction and wearing between the seal parts and the shaft causing the scoring. Note: you can't change the gland seal nuts or hose without removing the shaft, but you can change the packing if you have fore-aft room.

The 5416 is a RH turning engine (per the manual), check that you really have a LH prop! It looks like a LH in the pic.

I have the same optical tach Alan linked to. I had to adjust my new tach by 800 rpm when I installed it. After tach calibration, I would check that you get 2800 rpm in neutral. This will verify that engine is revving to max with no load. I just checked my 5424 at 3000 rpm (max) in neutral before motoring 12 nm to a marina for haul out. I could only get 1500 rpm and 4.8 knots per GPS during the trip (no wind, fighting slight Bay tide). My hull was dirty (slime growth) and I had ~ 20 barnacles on my folding prop. Normally, I get 7 knots max at 2800 rpm. I've had barnacles on the prop before and they have a significant effect.

Calculated hull speed (in knots) for a displacement hull is 1.34 x sq. root of the LWL (in feet). This can vary some but is a good guide. Generally, added weight, dirty bottom, etc. will slow the boat down slightly. Not often will a hull be faster, super light and/or very low drag hull shape. For the E32-2 LWL = 24', sq root = 4.9 x 1.34 = 6.56 knots.

Mark
 

Alan Gomes

Sustaining Partner
according to the last survey the vessel has a: 12” LH 2 blade bronze propeller (pitch not marked)

View attachment 25716

i have to believe that the hull, engine and prop were designed to move the boat along at optimum speed at optimum rpm for that engine.
Don't assume that you have the correct prop. For one thing, manufacturers certainly did not always get this right, even from the factory. Second, unless you bought the boat new, you have no idea whether someone may have changed out the prop at some point.

The pitch should be stamped somewhere on the hub of the prop; perhaps it was inadvertently left off. Regardless, without knowing it you are flying blind. Of course, until you get all your other issues resolved, you don't yet know whether you can hit top rpm at WOT. Once you take care of the packing gland and tach calibration, you should get a reasonable idea as to whether the prop is close to right--assuming, of course, that your engine is operating at something near its rated HP. If you are over pitched based on the symptoms and decide to have it repitched (vs. replacing it), a prop shop will be able to figure it out and set it right.
 

supersailor

Contributing Partner
If you are thinking about a new shaft log, consider replacing it with a PSS shaft seal. I did this on my 34 because of the difficulty getting to the log to service it twice a year. With the shaft seal, I have a totally dry bilge and I only need to service it once every 7-10 years. The seal is more expensive but the lack of maintenance and dry bilge make it more than worthwhile. Many boats on this site have the shaft seals.
 

nquigley

Sustaining Member
I used this handheld tachometer to confirm my tach gauge readings.

For $13 it's not hard to justify.

Right after reading your post, I ordered that tachometer.
I got surprising data this last weekend (M25 engine in E32-3) taking measurements while just sitting in the slip (after engine had warmed up for ~5 min at just above idle speed).
RPM by gauge in cockpit RPM by tachometer
1000 1758
1500 2690
2000 3690

There's something clearly wrong.
For reference, while underway (2-blade prop), the gauge maxes out at about 3200 RPM, and we're at hull speed (can't recall exactly - about 6.5 kt?)
 

supersailor

Contributing Partner
On the back of the Tach there are adjustable settings. It sounds like the one for number of pulses is misset. Adjust it until the two tacs are close to the same. The other adjustment os for fine adjustment.
 
Top