Propellors yet again..

[Paul D.]

Good luck Amit and please return here and let us know how it turns out. Be curious to here your observations on the difference.

[amit]

Hi Paul,
I will certainly post an update on this thread in a couple of weeks.

Regards
Amit

[John Stone]

I think Jim Walsh hit the nail on the head. Make no mistake about increased drag going from two blade to three blade fixed prop. I have done it both ways. The change from three blade to a two blade (that we could lock vertically behind the deadwood)regarding light to medium air sailing performance was astonishing. If you are inclined to motor when the conditions are light then it doesn't matter. But if you enjoy light air sailing you'll do better with a two plade of a feathering/folding three blade.

[Sea Hunt Video]

A few posts mentioned "backing up" in a Cape Dory. I thought I would share a recent experience.

Last week I motored S/V Bali Ha'i to the sailing club's dock to begin prep work on the deck. As I approached I was advised to stand off for a few minutes so the dock staff could rearrange a few sailboats already tied to the main dock.

I decided to take advantage of the time and practice "going in reverse" and trying to keep a straight path in reverse. There was no wind, no current and I was stone cold sober. The effort was a dismal failure. No matter what I did S/V Bali Ha'i went in whatever direction she wanted; it seemed to be helter skelter with no reason for what was happening.

I assumed that because I have a clockwise rotating prop in forward that, in reverse, prop walk would "pull" the stern to port. I tried countering this prop walk with a slight amount of tiller to starboard. I started going in a reverse circle OK, try the tiller to port. Result - zig zag (big zigs and big zags) and then in a circle The rpms were very low (1100) because I did not want any "accidents" with the dock.

After trying everything I could think of I finally surrendered and sheepishly motored in forward away from the dock and lined up for a forward approach.

I was later reminded of a "demonstration" by a experienced sailor on an O'Day 32 (fin keel) at the sailing club several months ago. He managed to use the prop to literally carve tiny circles in forward or reverse; move the bow away from the dock while keeping the stern glued to the dock; and a lot more. I asked him about full keel sailboats like ours. He smiled and said "they are beautiful sailboats". From that I gathered that I will NEVER be able to go in reverse in S/V Bali Ha'i and have any hope of maintaining a straight course.

[Jim Walsh]

A few posts mentioned "backing up" in a Cape Dory. I thought I would share a recent experience.

Last week I motored S/V Bali Ha'i to the sailing club's dock to begin prep work on the deck. As I approached I was advised to stand off for a few minutes so the dock staff could rearrange a few sailboats already tied to the main dock.

I decided to take advantage of the time and practice "going in reverse" and trying to keep a straight path in reverse. There was no wind, no current and I was stone cold sober. The effort was a dismal failure. No matter what I did S/V Bali Ha'i went in whatever direction she wanted; it seemed to be helter skelter with no reason for what was happening.

I assumed that because I have a clockwise rotating prop in forward that, in reverse, prop walk would "pull" the stern to port. I tried countering this prop walk with a slight amount of tiller to starboard. I started going in a reverse circle OK, try the tiller to port. Result - zig zag (big zigs and big zags) and then in a circle The rpms were very low (1100) because I did not want any "accidents" with the dock.

After trying everything I could think of I finally surrendered and sheepishly motored in forward away from the dock and lined up for a forward approach.

I was later reminded of a "demonstration" by a experienced sailor on an O'Day 32 (fin keel) at the sailing club several months ago. He managed to use the prop to literally carve tiny circles in forward or reverse; move the bow away from the dock while keeping the stern glued to the dock; and a lot more. I asked him about full keel sailboats like ours. He smiled and said "they are beautiful sailboats". From that I gathered that I will NEVER be able to go in reverse in S/V Bali Ha'i and have any hope of maintaining a straight course.

Full keels essentially don't like to go astern, but, you can get them to almost behave if you turn the wheel (or till the tiller ) and goose the engine more than you think is prudent. That gets the prop wash working on the rudder and gets some momentum in play to overcome the desire of the vessel to do as it pleases
Once you feel yourself moving immediately reduce speed to what is needed. If you practice away from all fixed objects and those who hang around just waiting to be amused you'll find it's not impossible, just a pain in the stern.
I use prop walk to kick my stern into place in my slip every time I return. If you know how your boat reacts (practice, practice, practice ) you can make it look simple. Since I'm always alone I can't afford to guess how ORION will react in tight quarters. If I get into trouble with current or an errant breeze I back off and try again. I try never to get myself into a box canyon with the cavalry on my tail
Fin keel boats can maneuver astern as well as they go forward. I was always amazed at how maneuverable my Erickson 29 was when going astern. I used to do it just to show off since most people just avoid going astern and never become proficient at it. I used to turn around with my back to the wheel and facing the stern and I could go anywhere I wanted in complete control.

[Neil Gordon]

... I was stone cold sober... The rpms were very low ...

I think I see the problem.

[Ben Thomas]

On my CD 30 ( Beta 20 2.19:1 gear ratio) I switched over from a 3 blade (13x9) to the Variprop blue water feathering 4 blade. 13x10 in forward 13x9 in reverse. In reverse the blades swivel into a forward pitched position. I had to relearn how to back out of my slip, very little prop walk, stops on a dime. Excellent thrust in forward and reverse. Under sail shift into reverse and blades feather.
Variprops hub is not as long as the max props and is engineered to fit in smaller apertures, pitch changes are done without taking prop off or apart and in very small increments, (not an inch at a time)
I was going to get the 3 blade variprop, but the engineers at variprop stated the 4 blade was a better match.
I have no affiliation with Variprop folks other than a very satisfied customer.
The caveat is $, many many boat units went into it, but well worth every penny.
Here is the link to their site:
http://www.spw-gmbh.de/en/variprop.html

Cheers

[Astronomertoo]

I assumed that because I have a clockwise rotating prop in forward that, in reverse, prop walk would "pull" the stern to port. I tried countering this prop walk with a slight amount of tiller to starboard. I started going in a reverse circle OK, try the tiller to port. Result - zig zag (big zigs and big zags) and then in a circle The rpms were very low (1100) because I did not want any "accidents" with the dock.
---------
Yes our old fin keel spade rudder could be driven in tight figure eights while standing in front of the wheel, facing aft, but the ride at sea was sure different.
If you think about what happens when you put a prop in reverse, it is logical the boat will walk to one side due to static prop wash. Think about where you want the wash to go for reverse, like forward over both sides of your full keel. How to get it there? certainly not at idle.
Try this: when you are free from the dock, rev up the engine enough to get the prop wash flowing over the keel, THEN turn your rudder enough to steer in reverse, and idle down as needed as you start moving. It will always work, as soon as, and IF you get some motion of the boat in reverse, the steering will work good enough to pick a direction you want to back up to. That is how the big guys do it, and it works for us little guys too.
In addition, if you have a fixed outboard on a 25 like mine, BEHIND the rudder, it also works similar. You must get some way on before turning the rudder at which time the engine wash in reverse will push on the rudder to help the steering motion in reverse, IF you are moving fast enough to make it happen. But you must throttle up in both cases to get the boat moving prior to using the rudder. And like the big boats, you can use the side wash to your advantage at times to move your stern in close maneuvering.
BTW, a 2 bladed prop is always lower drag when sailing. A 3 bladed is always more powerful in motoring and handling. Folding blades can most all get crapped up and not fold up, or not totally fold down. Catch 22. Chose as you prefer.
Practice makes perfect.
Bob C

[Dick Villamil]

Looks like you have it all wrong! Clockwise prop rotation devices were developed in Australia (south of the equator) and you should be using a counterclockwise prop drive while north of the equator to achieve the proper prop-wash directional stability when in reverse!

[Jim Walsh]

Looks like you have it all wrong! Clockwise prop rotation devices were developed in Australia (south of the equator) and you should be using a counterclockwise prop drive while north of the equator to achieve the proper prop-wash directional stability when in reverse!

The often misunderstood anti-Coriolis effect.

[Neil Gordon]

Looks like you have it all wrong! Clockwise prop rotation devices were developed in Australia (south of the equator) and you should be using a counterclockwise prop drive while north of the equator to achieve the proper prop-wash directional stability when in reverse!

Not to mention winches... I'm told they change rotation direction when you cross over the line.