Effects of extended struts on Hydros .

[Tom Foley]

Last few years there has been an amazing shift to long extended struts on many outriggers . Aside from moving the prop back from the rudder does anyone have some back to back handling testimony to add ? Better handling , worse , pulls more prop , less prop . Interested to hear some feedback as I have never tried one before . It would seem that it would lengthen " wheelbase " so to speak and make it handle smoother but that has not been my observation watching others . Pic for attention . Thanks for all replies !

 

[jack dyer]

I know you said on riggers but I found this past summer running one on my p hydro I was blowing over a lot switched to a standard strut and the boat was more stable.

 

[Brad Christy]

I know you said on riggers but I found this past summer running one on my p hydro I was blowing over a lot switched to a standard strut and the boat was more stable.

Jack,

I have found the exact opposite effect on outriggers. Blowing off is is all about attitude, and the extended strut seems to provide additional leverage, preventing the attitude from increasing to a point where sufficient lift is present to cause the boat to blow off.

Tom,

I have NOT done back to back tests to sufficiently prove the above mentioned theory. I build my boats with extended struts and the seem reluctant to blow off once they are dialed in. It's just that: My theory.

Just my thoughts.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

 

[dr gary turner]

The longer strut increased the after plane thus making the boat more stable and less likely to blow off.

It also can result in turning less prop due to increased tail weight

Again as always it depends on the boat set up. A tight running boat will not like an extended strut. A loose but more importantly a free running boat will do well with the extended strut

 

[dr gary turner]

I have long struts on all of my hydros and mono

 

[ALLAN YUEN]

Depend on character rigger issues rear shoes bit of different extended strut “ flat” or “ round” I like extended strut really fast and more prop

 

[John Beardslee]

I found on full sized outboards that an extended strut/ lower unit put the prop in cleaner water, many times we would run less pitch but ran faster and more consistent. I found the same in RC boats. You may find that you no longer can pull the same props but with a few changes you’ll run faster and quicker through the turns.
Thanks John

 

[Buckshot]

Also heard of them being called anti-walk struts.........

 

[Tom Foley]

I have long struts on all of my hydros and mono

Well , what's your take ?

 

[Terry Keeley]

On a hydro I don't think it matters if the prop is placed 3" behind the transom or if the tub is 3" longer, where the rears and the rudder are in relation to the prop is more important.

I've seen mono's want to "stuff" more with long struts...

 

[dwilfong]

longer strut puts the crutch farther from the prop in the turns.
The closer crutch is to the prop and rudder the more control it will have on the rear of the boat to keep the prop from being driven into the water deeper.
Now lift in a prop will make up for this . But more lift is wasting power that can be used for thrust.
If you move the strut back you also need to move the rudder to keep it tracking strait.
Closer translates in to a smaller crutch less drag in the corners.
Crutch is what ever you use on the back as a planning surface.
If you want a longer boat get a longer boat.

 

[DON MAHER]

David,
What do you think the effects would be on all of these problems with no “crutch” ?
l am pretty sure l know but would very much value your opinion!

 

[dwilfong]

Don I still have my SGX with nothing on the rear but two of the last style wings Andy made.
I did lots of testing with this boat.
It was a great rough water boat and the props where supper efficient with this set up. The back of the boat was rock solid with just the prop to control it.
The biggest problem and the reason I gave up on it was it was hard to launch with any kind of prop that would have good speed and lift to it.
The recurve in the back with the lift in the prop balance them self out then the wing hold it true.
The problem was the recurve acted like a suction cup and the back would not pop out of the water on launch.

 

[Bob Blazer]

I'll give you my down home take on this. If say you exaggerated the length of the strut, say a foot. What would be the result? It would put more weight on the front because you moved the effective cg back. Now think of the distance between the prop and the CG. It would be like using a longer wrench to unloosen a nut. Therefore the farther back the easier it would be to have prop walk. "With a long enough fulcrum I could move the world" someone important said that.

 

[Jeff Lutz]

Buckshot is the only one that mentioned the anti walk strut. That’s what it was all about. When coming on pipe hard they don’t allow prop walk as bad. So they say. I like them for the prop placement versus rudder and they do get your props in cleaner water. Andy started producing the anti walk extended strut about 1998.

 

[Brad Christy]

I'll give you my down home take on this. If say you exaggerated the length of the strut, say a foot. What would be the result? It would put more weight on the front because you moved the effective cg back. Now think of the distance between the prop and the CG. It would be like using a longer wrench to unloosen a nut. Therefore the farther back the easier it would be to have prop walk. "With a long enough fulcrum I could move the world" someone important said that.

Bob,

Yup. That.

Unless you are considering the strut itself to act somewhat as a rudder, the longer the aft plane, the more lateral influence the prop will have on the boat.

The extended strut is all about leverage against lift and reducing the need for lift in the prop.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

 

[DON MAHER]

Don I still have my SGX with nothing on the rear but two of the last style wings Andy made.
I did lots of testing with this boat.
It was a great rough water boat and the props where supper efficient with this set up. The back of the boat was rock solid with just the prop to control it.
The biggest problem and the reason I gave up on it was it was hard to launch with any kind of prop that would have good speed and lift to it.
The recurve in the back with the lift in the prop balance them self out then the wing hold it true.
The problem was the recurve acted like a suction cup and the back would not pop out of the water on launch.

David,
Get rid of the recurve and you will see a whole new boat! You are correct about the efficiency of the prop without the rear “training wheels “ lol . When the c/g is correct you will need very little lift in the prop and launching is not a problem! I have been running true 3 point hydros for a very long time and in my opinion there is nothing faster in the corners period.....

 

[Steve White]

Bob,

Yup. That.

Unless you are considering the strut itself to act somewhat as a rudder, the longer the aft plane, the more lateral influence the prop will have on the boat.

The extended strut is all about leverage against lift and reducing the need for lift in the prop.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

Interesting. I would have thought just the opposite. Moving prop back, all things equal will lengthen after-plane, which will move CG forward with respect to that - which would lighten the load on the prop to carry the transom - that should lessen the tendency to prop walk on paper. I see your point as well with the length and relative position of the prop which makes sense. Probably many other factors at play. I know when the engine is rich or down on power they tend to prop walk more - at least the boats I have ran in the past did.

I've had some boats that were tough to get to run in a straight line and ended up with a wider rudder blade on them. Building up an outrigger so I can experiment some more.

 

[Brad Christy]

Interesting. I would have thought just the opposite. Moving prop back, all things equal will lengthen after-plane, which will move CG forward with respect to that - which would lighten the load on the prop to carry the transom - that should lessen the tendency to prop walk on paper. I see your point as well with the length and relative position of the prop which makes sense. Probably many other factors at play. I know when the engine is rich or down on power they tend to prop walk more - at least the boats I have ran in the past did.

I've had some boats that were tough to get to run in a straight line and ended up with a wider rudder blade on them. Building up an outrigger so I can experiment some more.

Steve,

Have you ever used a "cheater bar" on a wrench?

Same, same.

Essentially, the CG of the boat is really not a factor as far as prop walk is concerned. It only comes into play, at least laterally, in the turns. So extending the strut doesn't change the CG of the boat, relative to the string between the turn fin and the rudder. The CG DOES, however, come in to play, in regards to a tendency for the boat to blow off. In the relation of CG and the string between the turn fin and the prop, extending the strut does move the CG forward, which increases the props leverage against the attitude of the boat.

At the end of the day, extending the strut is a trade off of vertical leverage for lateral leverage. It's a trade off of a force that you can't easily counter without additional trade-offs, for one that you can.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

 

[Tom Foley]

longer strut puts the crutch farther from the prop in the turns.
The closer crutch is to the prop and rudder the more control it will have on the rear of the boat to keep the prop from being driven into the water deeper.
Now lift in a prop will make up for this . But more lift is wasting power that can be used for thrust.
If you move the strut back you also need to move the rudder to keep it tracking strait.
Closer translates in to a smaller crutch less drag in the corners.
Crutch is what ever you use on the back as a planning surface.
If you want a longer boat get a longer boat.

I am going to set up my other Twin with a set of short struts and shafts and run it , then put the existing long struts and shafts back

longer strut puts the crutch farther from the prop in the turns.
The closer crutch is to the prop and rudder the more control it will have on the rear of the boat to keep the prop from being driven into the water deeper.
Now lift in a prop will make up for this . But more lift is wasting power that can be used for thrust.
If you move the strut back you also need to move the rudder to keep it tracking strait.
Closer translates in to a smaller crutch less drag in the corners.
Crutch is what ever you use on the back as a planning surface.
If you want a longer boat get a longer boat.

in and try it . I could do this at the lake in 30 minutes and see the difference .