Stinger or strut.

[Ian Inverarity]

John,

Okay, a few pics of the transom:

https://www.intlwaters.com/gallery/displayimage...=241&pos=86

https://www.intlwaters.com/gallery/displayimage...=241&pos=83

https://www.intlwaters.com/gallery/displayimage...=241&pos=85

https://www.intlwaters.com/gallery/displayimage...=241&pos=82

https://www.intlwaters.com/gallery/displayimage...=241&pos=84

The last couple of pics show the strut deceptively, it looks like the strut is kicked down at the back, when it is actually flat with the keel. I just checked and it is still flat, despite what it looks like. If you click on the pics, higher res pics come up.

Also the rudder kicks back on the play in the shear screw. The pivot axis stays where it should be while the blade kicks back, what affect would this have in turns? This is not a new issue tho, and with many props like the one shown it isnt an issue.

When you say trip you mean create a moment to push the bow down?

Ian.

 

[John Finch]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.

Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

 

[El Zorro]

Wow, sounds like some of the many conversations John and I had many years ago traveling to the races in the van. What an education I got from those trips! Those of you that saw any of those yellow Twincraft monos run back in the day now know why they ran so well..............I'm pretty good at listening!

Thanks again John, for sharing your wealth of knowledge with all of us here who love this hobby almost as much as you do. It doesn't get any better than this..............

Dick Tyndall ( that's TWO L's, John......... )

 

[Andy Greene]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

Very nice explanation John.

I learned the darty turns and spinouts from jumping too many bouys and kicking the blade back being greedy in the corners - lol

That said, if in theory one was running a boat in heat trim and was on the edge of loose but fast, then the winds pick up between rounds and now we are too loose. Could one not go SLIGHTLY toward the transom with the leading edge of the rudder and tighten the boat up slighty ??(if in fact it was set at the same angle as the transom to begin with) without having to make the strut adjustment. Thinking about one of Jerrys boats in particular.

 

[John Finch]

Wow, sounds like some of the many conversations John and I had many years ago traveling to the races in the van. What an education I got from those trips! Those of you that saw any of those yellow Twincraft monos run back in the day now know why they ran so well..............I'm pretty good at listening!Thanks again John, for sharing your wealth of knowledge with all of us here who love this hobby almost as much as you do. It doesn't get any better than this..............

Dick Tyndall ( that's TWO L's, John......... )

oops. I found the other L It was on my keyboard. It was your surface drive setup that everyone eventually went to. You were a bit ahead of the game there. Your hardware and setup plans are excellent. Sort of the benchmark for what we all run today.

 

[John Finch]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

Very nice explanation John.

I learned the darty turns and spinouts from jumping too many bouys and kicking the blade back being greedy in the corners - lol

That said, if in theory one was running a boat in heat trim and was on the edge of loose but fast, then the winds pick up between rounds and now we are too loose. Could one not go SLIGHTLY toward the transom with the leading edge of the rudder and tighten the boat up slighty ??(if in fact it was set at the same angle as the transom to begin with) without having to make the strut adjustment. Thinking about one of Jerrys boats in particular.

When you get the right position for the rudder on any boat. It stays there. Jerry uses a strip of tape on the bottom of the rudder to trip the bow down. We need to also realize some boats have trim tabs that can be adjusted for water conditions. Ones that don't have tabs can sometimes benefit from weight added to the cg on rough days. I would use a little CA on the bottom of the boat to trip the bow instead. Thing is.............The hook or rocker at the rear of the boat is probably the most effective manner to control the ride. The prop is a quick and easy change for different water conditions too. On my 67 sgx I have three different props and they are labelled as to what lake they work best on. There are a thousnd ways to skin a cat.

 

[Ian Inverarity]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

John,

I think I get what you are saying!

I was hoping to keep the discussion generalised rather than focus on a specific hull. I am trying to understand what happens on a mono in a turn as opposed to on the straights, getting back to my earlier question relating to the effect of strut depth being different in the straights and corners.

Ian.

 

[John Finch]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

John,

I think I get what you are saying!

I was hoping to keep the discussion generalised rather than focus on a specific hull. I am trying to understand what happens on a mono in a turn as opposed to on the straights, getting back to my earlier question relating to the effect of strut depth being different in the straights and corners.

Ian.

Ian,

The thing is............the boat design has a lot to do with how well a boat turns. The keel is actually a big player in turning the boat as it has more affect in holding the boat in the turns than the turn fin. The chine angle, vee angle, and bottom hull design dictate what you have to work with. There are some hulls out there that are designed in a maner that it is not possible to make the boat turn linear turns no matter what you do on the hardware setup. Here are a few known facts that can help.

1. When the boat turns and leans over on it's side, the boat will slide to the outside while turning. Thats just centrifugal force. The keel keeps the boat from sliding into never never land. If the keel bites hard in the forward section of the hull and the rear of the hull lifts because of a deep strut or strut that is too long (has too much leverage), the boat will spin out or dart. That's where a boat with a forward cg can dart more than one that has a 30 to 31 percent cg. If the hull is a warped plane bottom it is easier to control the pressure points to control the pressure at different parts of the keel. When you have a non warped plane bottom every little non conformity has an equal and opposite reaction to water under the hull. Like a hook for instance can be good for trimming the boat for the straightaway but be devastating for control in the corners.

2. Trim tabs affect cornering and can be adjusted to make the boat turn tighter or with less sensitivity on warped plane hulls, but not on most non warped plane boats.

3. If the strut puts the prop too far back the boat will hop in the corners. Mostly nitro boats because the extra weight of the gas boats keep the transom planted.

4. Sometimes we forget about the servo power. if the boat tends to stay turning after you let up on the steering wheel, the servo is too weak to center. If the boat fades or gets less responsive halfway thru the turn the servo is too weak.

5. If the prop is too large it may walk the boat around at the transom. Try a smaller diameter prop with more pitch.

That's it for now, got to get to work.

 

[mtruex]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

John,

i see why my little mono hops in the turns now..great info as always..MT

I think I get what you are saying!

I was hoping to keep the discussion generalised rather than focus on a specific hull. I am trying to understand what happens on a mono in a turn as opposed to on the straights, getting back to my earlier question relating to the effect of strut depth being different in the straights and corners.

Ian.

Ian,

The thing is............the boat design has a lot to do with how well a boat turns. The keel is actually a big player in turning the boat as it has more affect in holding the boat in the turns than the turn fin. The chine angle, vee angle, and bottom hull design dictate what you have to work with. There are some hulls out there that are designed in a maner that it is not possible to make the boat turn linear turns no matter what you do on the hardware setup. Here are a few known facts that can help.

1. When the boat turns and leans over on it's side, the boat will slide to the outside while turning. Thats just centrifugal force. The keel keeps the boat from sliding into never never land. If the keel bites hard in the forward section of the hull and the rear of the hull lifts because of a deep strut or strut that is too long (has too much leverage), the boat will spin out or dart. That's where a boat with a forward cg can dart more than one that has a 30 to 31 percent cg. If the hull is a warped plane bottom it is easier to control the pressure points to control the pressure at different parts of the keel. When you have a non warped plane bottom every little non conformity has an equal and opposite reaction to water under the hull. Like a hook for instance can be good for trimming the boat for the straightaway but be devastating for control in the corners.

2. Trim tabs affect cornering and can be adjusted to make the boat turn tighter or with less sensitivity on warped plane hulls, but not on most non warped plane boats.

3. If the strut puts the prop too far back the boat will hop in the corners. Mostly nitro boats because the extra weight of the gas boats keep the transom planted.

4. Sometimes we forget about the servo power. if the boat tends to stay turning after you let up on the steering wheel, the servo is too weak to center. If the boat fades or gets less responsive halfway thru the turn the servo is too weak.

5. If the prop is too large it may walk the boat around at the transom. Try a smaller diameter prop with more pitch.

That's it for now, got to get to work.

i see why my little mono hops in the turns now..great info as always..thanks john MT

 

[Ian Inverarity]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

John,

I think I get what you are saying!

I was hoping to keep the discussion generalised rather than focus on a specific hull. I am trying to understand what happens on a mono in a turn as opposed to on the straights, getting back to my earlier question relating to the effect of strut depth being different in the straights and corners.

Ian.

Ian,

The thing is............the boat design has a lot to do with how well a boat turns. The keel is actually a big player in turning the boat as it has more affect in holding the boat in the turns than the turn fin. The chine angle, vee angle, and bottom hull design dictate what you have to work with. There are some hulls out there that are designed in a maner that it is not possible to make the boat turn linear turns no matter what you do on the hardware setup. Here are a few known facts that can help.

1. When the boat turns and leans over on it's side, the boat will slide to the outside while turning. Thats just centrifugal force. The keel keeps the boat from sliding into never never land. If the keel bites hard in the forward section of the hull and the rear of the hull lifts because of a deep strut or strut that is too long (has too much leverage), the boat will spin out or dart. That's where a boat with a forward cg can dart more than one that has a 30 to 31 percent cg. If the hull is a warped plane bottom it is easier to control the pressure points to control the pressure at different parts of the keel. When you have a non warped plane bottom every little non conformity has an equal and opposite reaction to water under the hull. Like a hook for instance can be good for trimming the boat for the straightaway but be devastating for control in the corners.

2. Trim tabs affect cornering and can be adjusted to make the boat turn tighter or with less sensitivity on warped plane hulls, but not on most non warped plane boats.

3. If the strut puts the prop too far back the boat will hop in the corners. Mostly nitro boats because the extra weight of the gas boats keep the transom planted.

4. Sometimes we forget about the servo power. if the boat tends to stay turning after you let up on the steering wheel, the servo is too weak to center. If the boat fades or gets less responsive halfway thru the turn the servo is too weak.

5. If the prop is too large it may walk the boat around at the transom. Try a smaller diameter prop with more pitch.

That's it for now, got to get to work.

John,

Thanks, food for thought!

Ian.

 

[Joe Warren]

Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.

Very nice explanation John.

I learned the darty turns and spinouts from jumping too many bouys and kicking the blade back being greedy in the corners - lol

That said, if in theory one was running a boat in heat trim and was on the edge of loose but fast, then the winds pick up between rounds and now we are too loose. Could one not go SLIGHTLY toward the transom with the leading edge of the rudder and tighten the boat up slighty ??(if in fact it was set at the same angle as the transom to begin with) without having to make the strut adjustment. Thinking about one of Jerrys boats in particular.

Drew you will do best adjusting the seaducer by the strut ride height. Not angle. I run 1/8 off the bottom Normally. unless the water is rough Then I push the drive line to the bottom of the boat. But always keep it perfectly straight in relationship to the bottom of the boat. The boat should appear tight during early mill time. Or on water by itself. if you have to rasise the strut higher than 1/8 inch spec to get the SAW speed it will not turn well.