E 38-200 3 Blade Prop Size

[dfharris02]

Hi:

I just purchased a Michigan 16x12 three blade prop from Tacoma Propellers. The technician recommended that I keep the standard size so that I got more thrust out of it. Well, the prop arrived and it seems really quite large to me. I'm not worried about drag because I sail in San Francisco and we have high winds; however, I am concerned that the little MD 40 might not have the power to turn the propeller. Any thoughts or experiences with a three blade 16x12 prop?

David
Ericson 38-254
Vuja De
Alameda CA

 

[joerun26]

3 Blade Prop Size

Dave -

I'm prop shopping as well and was quoted a 16x12 Michigan for my 35-III. I have aYanmar 3GM30F rated at 27 HP @ 3600 rpm. I've been reading the threads to determine whether a fixed 2 or 3 blade would meet my needs best. I know a 3 blade feathering would be ideal, but with 2 in college - it'll have to wait. I'm replacing an older 2 blade folding Martec that has no interest in reverse and has worn to the point of excessive vibration under way.

Let me know how the 3 blade works for you if you install it.
joe

"Tenacious"

 

[u079721]

Large?

When you say you think the prop is really quite "large", just what is your concern - the diameter, or the pitch?

IIRC the original prop is a 16" diameter 13" two blade prop. The PO of our 1989 E-38 had a three blade feathering Max prop installed, 16" diameter, and the shop just went ahead and pitched it at the same 13", which of course WAY over propped the engine and led to all kinds of smoke. I don't have my log book with me here, but in our case we finally settled on a pitch of (I think...) 9.8" for the Max, after trying and being over propped at 11" and 12" pitch.

So my experience would suggest that yes, you are probably overdoing it with that pitch, though of course the diameter is OK. Lots of great threads on this board (use the search funtion) about prop pitch. The rule of thumb is that if you can not get the max rpm up to the suggested in the manual, then you have too much prop. In your case the M-40 has (IIRC) a max rpm of about 2800 to 2900, and a cruising level of 2450 rpm. If your wide open throttle is much below 2800, then again you have too much prop.

The good news is that a prop shop can repitch the prop should you wish to keep it. (Not sure about the cost.)

 

[Trucker Doug]

I'm new here and the last poster seems knowledgable so I'm tossing this in. I've an E38 with a 3 blade prop that pushes the boat nicely at not too much above idle. (Tach doesn't work and a bit speedy docking but in and out of neautral works) So what's wrong with an overkill prop? Seems like it would save fuel. Uh, other than being aware that the stern is going to leap to port when hitting reverse is a good thing to know ahead of time.

 

[Chris Miller]

Hey Joe,
Martec will rebuild that for you for a couple hundred $, might be something to look at before you sell it- or mention to it's new owner. I'm looking at having mine rebuilt by them this winter. Just thinking it might help your sale price.

 

[u079721]

So what's wrong with an overkill prop? Seems like it would save fuel.

Diesels are designed to run at a certain rpm to achieve their rated horsepower. If you have too much prop and the engine can't reach the desired rpm, then you won't get the full rated power of the engine. You will overload the engine, actually burn more fuel, foul the valves, and shorten the engine's life. None of which is perhaps that big a deal if you don't use your engine except to leave and enter the marina. But do any serious amount of cruising, and you will want to have the prop match the engine.

 

[joerun26]

Hey Joe,
Martec will rebuild that for you for a couple hundred $, might be something to look at before you sell it- or mention to it's new owner. I'm looking at having mine rebuilt by them this winter. Just thinking it might help your sale price.

Thanks Chris.. Its an older style (non-geared) and not very effective in reverse. I'm thinking I'd be happier with the performance improvements of a fixed at this point (given the cost difference to a feathering). I'm coming to realize that the additional drag I may experience could be overcome with better attention to sail trim. Still learning ......

 

[mark reed]

Our boat came with a 2-blade MaxProp, which gave us a good turn of speed and plenty of power in reverse. However, we were unhappy with the amount of vibration we were experiencing, and after aligning the engine (many times), and replacing motor mounts, driveshaft, cutless bearing, etc. we finally bit the bullet and traded in the 2-blade for a reconditioned 3-blade MaxProp. The guy at the yard said we could accommodate a 17" diameter prop, so that is what we have, even though every other 38 seems to have a 16". After a full season of use, we are very happy with this prop. It has reduced our vibration (though not eliminated it) and has increased our top speed by close to 1/2kt. Not sure what the pitch is, as it was calculated and preset by PYI.

 

[Geoff Nelson]

Three blade prop

My '381 came with a 2 blade Martec folding prop that was almost useless in reverse and I could not get over 2200rpm (at about 6.7kts bs). 5 months ago I bought a Campbell Sailer three blade (15X9) that is quite nice. I actually have two gears now and a lot of vibration went away and it's faster. And if I come in hot, I can slow down even!!! I am a big fan. Cost was very reasonable (~$550) compared to a feathering or folding prop. I don't really notice the drag but being in SD we motor/motor sail a lot.

http://www.westbynorth.com/CampbellSailer.aspx

I think it is slightly over propped as I can't get it above 2200rpm and I should hit 2800 but there is no smoke or fibration and the previous 2-blade martec prop (don't know the pitch off-hand) had the same problem.... 2200 rpm max. I only can get to full rpm in reverse or neutral.

Hope this helps.

Cheers,

G-

 

[ligolaiva38]

Three blade prop

My Ericson 1984 381 had a 16 x13 two blade which was the original prop. I now have a 3 blade sailing prop (Michigan Wheel Prop---not as wide blades as normal wide blades) which is 16 x 12. The engine runs full speed at 2800 rmp and 7.1 knots in flat water with clean botom. I cruise the engine between 2200rpm and 2400rpm at aprox. 6.5 knts.
JOhn
E-381 LAIVA

 

[dfharris02]

Nice Conclusion to the 3 blade Prop

Hi:

I had Vuja De hauled last weekend (painted the bottom and buffed the hull) and had the three blade 16x12 Michigan Prop put on. We took her out last night and what a huge difference. The ride is much smoother and at 2k rpm our SOG was 7kts..which is a 1kt improvement. I'm sure that the freshly painted bottom helped to. The engine also runs up to full RPM. At three quarters throttle I can create quite a stern wave!!

It will be interesting to see how she sails with a 3 blade prop.

David

VuJa De
Ecricson 38-254

 

[Kerry Kukucha]

E38-200 Matching Prop & engine

Hello All:

Very informative thread - we have just been advised that our existing prop installed by the previous owner was not only the wrong size (14/11) but also designed for a motor boat. This in part has probably contributed to a series of problems including diesel fuel diluting the engines oil & overheating, smoking, etc (mechanic just advised that we were topping out at 2100 rpm's rather than 2800).

We are now looking at installing a new a Campbell Sailor 15/9 or 16/8 as reccomended by westbynorth, who have serviced other E-38's.

Nakesa is a 1988, 38-200 with a Universal 5432 & Hirth transmission. As we don't have the original 1988 manual/spec's, was wondering if anyone with the same model/year might be able to confirm if the gear ratio is 2:1 or 2.14:1 (would .04 make much of a difference?).

many thnx,

Kerry
Nakesa E38-200

 

[Tom Metzger]

Confusion

My records indicate that the 5432 was built until 1982 and the M-40 was built from then on.

You can find both of the operator's manuals on this site under "Specs & Documents", "Engines".

There would be no meaningful difference between 2.1:1 and 2.14:1. I suspect that the difference might be in rounding numbers rather a mechanical difference. The difference is much less percentage-wise than the 1" difference in prop pitches or diameters.

 

[hathanger]

three bladed prop

Dave -

I'm prop shopping as well and was quoted a 16x12 Michigan for my 35-III. I have aYanmar 3GM30F rated at 27 HP @ 3600 rpm. I've been reading the threads to determine whether a fixed 2 or 3 blade would meet my needs best. I know a 3 blade feathering would be ideal, but with 2 in college - it'll have to wait. I'm replacing an older 2 blade folding Martec that has no interest in reverse and has worn to the point of excessive vibration under way.

Let me know how the 3 blade works for you if you install it.
joe

"Tenacious"

I also have a mk35 and thinking of going to a 3 bladed prop, have you installed the prop yet and if so, has there been a change in speed??? Thanks, Chip " Hat Hanger "

 

[joerun26]

I also have a mk35 and thinking of going to a 3 bladed prop, have you installed the prop yet and if so, has there been a change in speed??? Thanks, Chip " Hat Hanger "

Haven't changed yet.. I'm going to be pulled for the winter next week. I'm still undecided on whether to have the 2 blade Martec folder refurbished as recommend by Chris (cost approx 200), or replace with a fixed 3 blade. I'm leaning toward the Campbell Sailor if I go with a 3 blade fixed (cost approx 600).

joe

 

[u079721]

Hi:

I had Vuja De hauled last weekend (painted the bottom and buffed the hull) and had the three blade 16x12 Michigan Prop put on. We took her out last night and what a huge difference. The ride is much smoother and at 2k rpm our SOG was 7kts..which is a 1kt improvement. I'm sure that the freshly painted bottom helped to. The engine also runs up to full RPM. At three quarters throttle I can create quite a stern wave!!

It will be interesting to see how she sails with a 3 blade prop.

David

VuJa De
Ecricson 38-254

I can't argue with success, but I am sure surprised that the three blade 16 x 12 prop wasn't overdoing it, given that our experience with our three blade Max Prop at 16 x 12 was way too much pitch. (We finally settled at 16 x 9.8").

All of which sort of makes me wonder just how universally useful these numbers are? Do calculations that suggest a certain pitch for a certain number of blades for a particular engine/boat setup only apply to one design of prop? What a mess.