Ducted Propeller vs Prop Walk

[Ensenada Crab]

I recently bought a e32-2 and was amazed by the prop walk in reverse. ain't never seen that on an outboard. . .

so my question is has anyone tried using a ducted propeller to minimize prop walk and optimize the output from that tiny propeller.

i must also say that the westerbeke 2 cyl diesel makes about 5 knots at 1,000 rpm through a two bladed prop, so the engine seems pretty efficient as is but the prop walk in reverse is a real handicap in close quarters.

 

[kapnkd]

I recently bought a e32-2 and was amazed by the prop walk in reverse. ain't never seen that on an outboard. . .

so my question is has anyone tried using a ducted propeller to minimize prop walk and optimize the output from that tiny propeller.

i must also say that the westerbeke 2 cyl diesel makes about 5 knots at 1,000 rpm through a two bladed prop, so the engine seems pretty efficient as is but the prop walk in reverse is a real handicap in close quarters.

I too have an E32-II that now has the Westerbeke engine. LOTS of torque with a diesel for sure, but the Westerbeke is indeed a great and perfect engine in the 32.

Prop walk was always an issue even when she had the A-4 engine. It was something one learned to compensate for and actually use to your advantage when maneuvering around with some practice. ALWAYS OPT FOR A DOCK ON YOUR PORT SIDE when you come in. When leaving the dock and starting to back, a good hand shove on the stern area dock post offsets the torque till momentum overtakes the torque steer.

When turning to port, you can turn the boat on her own length if need be using forward, reverse and playing the helm. Same with docking if to your port side. You can come in and walk the stern gently up to the dock and slip the stern line over the post. I’ve had people comment on how she handles like a powerboat with twin screws (but it’s simply using the torque steer to one’s advantage.)

 

[ThatJeffGuy]

Yeah torque steer is great, but...

I have a ship mate with a habit of pushing off on the bow when I back out of the dock, which with the torque steer makes the boat do a 90 degree turn in about six feet, unfortunately the neighbors boat is 5'11" away...

He doesn't mind and he admits that he has hit my boat plenty in the past (mostly before I owned it), (the boats are an E32-2 and a similar vintage C&C ~31', they take their bumps well).

I was thinking of a three bladed prop and I have seen a lot of conversations on here about props but not sure if any were specific to the 32-2.

On a side note, I also heard a wonderful story of when my previous owner T-boned a 30' Catalina with the boat, turns out the Catalinas are not built as heavy. I think the terminology used was "That F'n Ericson put a hole the size of a basketball right in the side of the boat!"

 

[Christian Williams]

I do the pushing, pile-walking and all manhandling of the boat. Just me. "Nah, that's OK, I've got it, no problem."

Nobody else knows the subtleties of prop walk, and anybody who tries to help screws it all up.

Impossible to explain except here.

 

[toddster]

ALWAYS OPT FOR A DOCK ON YOUR PORT SIDE when you come in.

I'd agree except when you have to dock on the windward side. (E.g. our fuel and guest docks.) A nice burst of prop-walk in reverse peels the boat right off the dock with no rubbing or scratching. Especially if you've got plenty of room. I may have overdone it once this summer, or there was a lull in the wind just then, so we did a 270° reverse turn. Fortunately I was wearing dark glasses so it all looked pretty cool as the bow came up on the desired heading and we smoothly powered away.

 

[supersailor]

All boats with fixed shafts prop walk unless you have twin engines with counter-rotating shafts. Ericson's are one of the best at backing of all the boats out there. If you want to get frustrated, try backing a full keel boat in a crowded marina. When backing, the prop does not throw water against the rudder so the boat needs to be moving before the boat will respond. An outboard is different as the prop can be rotated to cancel the walk and turn the boat.

Most mariners are too afraid to use power in a marina. A short burst with the rudder hard over does not add speed. It quickens the turn. Remember also that the boat has to be moving if you want to steer it.

When teaching someone to dock, I like to take them out to a plastic buoy and practice approaching it in forward and reverse at various wind angles until the student can put the buoy along side on either side before attempting the dock. This saves a lot of gelcoat vs. bouncing off docks and other boats. It also gives he student confidence in the most difficult maneuver on the boat.

 

[Alan Gomes]

I recently bought a e32-2 and was amazed by the prop walk in reverse. ain't never seen that on an outboard. . .

so my question is has anyone tried using a ducted propeller to minimize prop walk and optimize the output from that tiny propeller.

i must also say that the westerbeke 2 cyl diesel makes about 5 knots at 1,000 rpm through a two bladed prop, so the engine seems pretty efficient as is but the prop walk in reverse is a real handicap in close quarters.

Others are commenting on the prop walk so I'll not say anything about that. But I will point out that getting high motoring speeds at low rpm is not necessarily a sign of efficiency from your engine or your prop but may in fact be an indication that you are overpropped and need to have your prop modified. Can you hit top or close to top rpm for that engine when you open up the throttle under way? If not, you may be running it at a less than optimum rpm for the engine's torque curve and this is not going to be good for the health of your engine. Overpropping the engine is one of the worst things you can do to it.

I don't know anything about your particular Westerbeke but I am speaking generally. I'd have to think, though, that if you are making 5 knots at 1,000 rpm then something is wrong. I assume, of course, flat water with no or little current pushing you.

 

[supersailor]

Also, your tach may not be accurate, It can be checked with a test tach that reads crank shaft rpm's. They are inexpensive at an auto supply store or maby a friend has one you can borrow. The adjustment is in the back of the tach.

 

[Alan Gomes]

Also, your tach may not be accurate, It can be checked with a test tach that reads crank shaft rpm's. They are inexpensive at an auto supply store or maby a friend has one you can borrow. The adjustment is in the back of the tach.

Excellent point. Here's a fairly inexpensive one: https://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html

Not sure about his engine but on the Yanmar there really is no way to adjust it. So the thing to do in that case is to use the digital tach to make up a deviation table.

 

[Loren Beach]

Also, your tach may not be accurate, It can be checked with a test tach that reads crank shaft rpm's. They are inexpensive at an auto supply store or maby a friend has one you can borrow. The adjustment is in the back of the tach.

After our new diesel engine was installed and running, a mechanic friend advised me to check the indicated RPM's. Our drive train was ordered with the optional 70 amp alternator, and he had seen (albeit rarely) one delivered with a tach that needed to be calibrated. He said that the re-calibration was easy, but it is best to check it on a new engine package.

I bought one and put the little piece of while tape on the drank pully ... and the factory tach is spot on -- well, at least it's as accurate as eyeing the needle movement on the analog tach will permit.

 

[footrope]

I recently bought a e32-2 and was amazed by the prop walk in reverse. ain't never seen that on an outboard. . .

so my question is has anyone tried using a ducted propeller to minimize prop walk and optimize the output from that tiny propeller.

snip ...

Sorry, but I don't think anyone, including me, has any idea if a ring around your inboard engine prop would make a difference in the amount of prop walk in reverse. Have you looked at what it would take to retrofit your boat with a temporary test duct? It would be an incredibly fun design project.

 

[Alan Gomes]

Just my opinion, but I think you'd be better off just embracing the fact of prop walk, which is characteristic of virtually any inboard engine installation, and actually trying to use it to your advantage. Take a look on some of the sailing forums (e.g., sailboatowners.com) and do a search on the key words "prop walk back fill" for information on the technique known as "back and fill."

That said, it is true that different props can produce different degrees of prop walk on the same boat. For example, on my previous Catalina 30 I had a 3-blade fixed prop that had prop walk from hell. I switched to a 2-blade folding prop (Martec) to reduce drag under sail and noticed that it had considerably less (though still some) prop walk. It also had much less thrust in reverse, though good enough. All that to say, you are probably not going to be able to eliminate it entirely but it will vary with the specific prop. With that 3 blade, using a back and fill technique, I could spin the boat in a really tight space.

From your initial post, I think there is a rebuttable presumption that you are overpropped. If so--and I strongly suspect that it is so, if you are hitting 5 kts. at what is truly 1,000 rpm--then you need to either replace the prop or get it re-pitched. If you have some pitch taken out of it that will surely affect the prop walk. Since you may need to take care of the prop anyway, why not do that first and see what effect it has on your prop walk?

Frankly, I'd bag the idea of messing with ducting the prop. It represents unnecessary complication, drag, and it is dubious that it would do any good. Learning to manage the prop walk through proper technique won't cost you anything and will be worth the effort. But again, make sure you get the right prop on that boat before doing anything else. Contact a good prop shop and they will tell you what pieces of information they need to know in order to set things right.

 

[Parrothead]

I'll second Alan's opinion that your prop has excessive pitch for your engine and less pitch will result in less prop walk. Also, if you're struggling with the boat in reverse, try taking her out of gear when she starts moving backwards and coast. Your steering control will magically return.

 

[Kevin A Wright]

Don't know what I'd do without the prop walk. Using it is so ingrained into my reflexes now I'd crash and burn without it. And using it I've actually gotten a standing ovation from the 'dock rats' by using it to 'parallel park" during a storm.

That and the fin keel let's you spin 360 without any forward movement so as long as the fairway is about 6" wider than your boat you don't have to worry about backing anyway. But yes go for a bow in port tie up when you can.

Although a shroud would be helpful keeping crab pot lines out of the prop.

Kevin Wright