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propeller size and type, add nauseam

Saullincer

Member I
Hi Anyone and Everyone,
This is my first post. I have an '83 Ericson 30+ with a 16 horse Universal diesel motor. I recently purchased the boat and would like to fix two symptoms I think are related to the propeller being replace by a previous owner. First, at cruising speed the boat has a significant "pull" to starboard. Second, at idle it does not go as slow as I would like or expect. There is currently a 15 inch 2 blade prop, and the shaft seems to be extended so the prop is very close to the rudder. I have read most, if not all, of the propeller discussions on the website. I've checked one of those propeller calculators with my boat specs and it recommended the 15 inch prop. I would like to find out what size the original propeller was for the boat if any of you can still remember. I think this would be a good starting point. It seems like this propeller issue is one of the "great debates!"
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Options and Considerations

While waiting for a more nuanced answer, there are some bits to consider.
1) You want the prop to be fairly close to the cutlass bearing, about 1.5 diameters of the shaft size IIRC.
2) You want the tip clearance where it passes close to the hull to be under about 2 inches or so.
3) You want as much prop diameter as allows it to fit within these desirable constraints.

4) Maximizing the prop diameter is a good thing if you can do so, up to a point (see 1, 2, and 3).

For our boat the prop that fits best is a 15 inch size. I have been told that more blades are better for smoothness under power, albeit with more drag under sail. I can confirm that when we went from a feathering two blade prop to a narrow-blade three blade fixed configuration our motoring speed increased by around 1/3 of the knot or a bit more. The drag under sail does rob us of a half knot and some pointing ability too.

Prop selection is not quite a 'black art' but there are several variables that have to be considered. I am not sure of the relative values of some of the choices, either.
i.e. the more I know the less I am sure of. :rolleyes:

If you search threads here -- use google -- put in prop selection and my name, several threads will emerge.

ps: where in PDX do you moor?
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
We have a 1984 E30+ with the 16 hp diesel engine on which the previous owner installed a 13" x 9" two blade folding propeller. When we got the boat I phoned the propeller manufacturer (Brunton/Varifold) and they suggested that for our boat the 15" x 9" would be the correct propeller. Unfortunately, our prop shaft is a bit too long and the 15 inch propeller would be too close to the rudder for my comfort, so we still have the 13 x 9 prop.

With that propeller, I can motor comfortably (at about 80% of max rpm as they recommend) at about 6.2 knots in flat seas with no current. My more common motoring speed is about 5.8 knots without stressing the engine. I have no noticeable pull to starboard when cruising at that speed. I do have fairly significant port prop walk in reverse until the boat gains some "way" and allows proper steering, and then I can steer her fairly accurately in reverse (though I still don't like to dock in reverse). I'm wondering if your larger prop contributes to the pull to starboard, which my smaller prop minimizes (though probably at the expense of some extra power through waves).

My engine will idle at low/almost stalling speed in neutral, but I don't do that much as I understand it's better for the valves/tappets to idle at slightly higher speed. There are adjustments that can be made to the idle speed where the throttle cable connects to the engine (a couple of nuts that can be loosened or tightened at that cable connection to allow more "play" where the cable connects to the engine. Also, ensure that your cables (throttle and gear shift) are in good condition and not sticking as a sticking throttle cable could be a source of idle problems.

Hopefully another E30+ owner will reply with the answer to your original question about what prop the factory installed on these boats. I'll be interested in that as well.

Frank
 

mjsouleman

Sustaining Member
Moderator
Discovery is also an 83 Ericson 30+ with 16 hp engine.

I replace the 16 with a 21 hp engine.

Note: I think Discovery also has a 2 blade 15" prop but I will have to check that when I pull her in December.
There are a few of us with 83/84 Ericson 30+s so someone may have a better solution

Mark Soule (MJS)




Hi Anyone and Everyone,
This is my first post. I have an '83 Ericson 30+ with a 16 horse Universal diesel motor. I recently purchased the boat and would like to fix two symptoms I think are related to the propeller being replace by a previous owner. First, at cruising speed the boat has a significant "pull" to starboard. Second, at idle it does not go as slow as I would like or expect. There is currently a 15 inch 2 blade prop, and the shaft seems to be extended so the prop is very close to the rudder. I have read most, if not all, of the propeller discussions on the website. I've checked one of those propeller calculators with my boat specs and it recommended the 15 inch prop. I would like to find out what size the original propeller was for the boat if any of you can still remember. I think this would be a good starting point. It seems like this propeller issue is one of the "great debates!"
 

bigd14

Contributing Partner
Blogs Author
I have a 13 inch 3 blade Campbell Sailor that came with the boat when I got it. I have not calibrated the knot meter so I am not sure what speed I am getting, but I feel like its a bit slow. I do not notice significant pull in forward. Idling speed in forward doesn't seem excessive but I have noticed that the boat does not slow down very quickly (efficient hull form!). I have to shift between forward and neutral a lot to maintain a slow enough docking speed. Prop walk in reverse is not bad, in fact I wish I had a little more to spin around in the marina. I did not do my research when I went to replace the prop shaft but I should have gone with one about 3 inches shorter to fix the problem Loren noted with the exposed shaft aft of the strut.
 

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Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
First, at cruising speed the boat has a significant "pull" to starboard.

We had a quite recent thread in which several members reported such a pull on their models--I think it was considered "normal."

I couldn't find the thread. Anybody else?
 

HerbertFriedman

Member III
The PO changed the prop to a three blade fixed prop on y 87 E34 for cruising, will have to measure the diameter when I haul out next month. But I significant pull to starboard in forward and no noticeable prop walk in reverse. Dont understand that.
 

markvone

Sustaining Member
First, at cruising speed the boat has a significant "pull" to starboard.

We had a quite recent thread in which several members reported such a pull on their models--I think it was considered "normal."

I couldn't find the thread. Anybody else?

It was for the early E28+ model (80 - 85) which has the engine mounted to port of the centerline and the shaft exits the hull port of the centerline. I remember my dealer saying that the side pull was particularly noticeable on the tiller model. This model had a double quarterberth which extended over the centerline and pushed the engine to port. All changed on the 1986 E28-2.

https://sailboatdata.com/sailboat/ericson-28

https://sailboatdata.com/sailboat/ericson-28-2

Mark
 
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Saullincer

Member I
Thank You

Thanks to everyone for the great information. If I extrapolate the 1.5 inch space from the cutlass bearing and 2 inches from the hull I might get close to the correct size prop. right now I think the shaft is about 5 inches from the cutlass bearing, probably adding to the "pull", and also too far from the support. I'll post results after winter haul out.
 

lschill

Member I
I have a 13 inch 3 blade Campbell Sailor that came with the boat when I got it. I have not calibrated the knot meter so I am not sure what speed I am getting, but I feel like its a bit slow. I do not notice significant pull in forward. Idling speed in forward doesn't seem excessive but I have noticed that the boat does not slow down very quickly (efficient hull form!). I have to shift between forward and neutral a lot to maintain a slow enough docking speed. Prop walk in reverse is not bad, in fact I wish I had a little more to spin around in the marina. I did not do my research when I went to replace the prop shaft but I should have gone with one about 3 inches shorter to fix the problem Loren noted with the exposed shaft aft of the strut.

I have hull 664 1984 30+. I have a standard two blade prop. I could sure use a little more power to windward or even a little more speed. Would changing to a three blade help me? Size? Suggestions?
 
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