Ducknutt Build 500 Caddy

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kwanjangnihm
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Re: Ducknutt Build 500 Caddy

Post by kwanjangnihm » Mon Jul 31, 2017 9:04 am

Ducknutt what is the current length/measurement?

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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Mon Jul 31, 2017 10:43 am

I'm at work now, I'll have to check this evening.

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pontoon outlaw
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Re: Ducknutt Build 500 Caddy

Post by pontoon outlaw » Mon Jul 31, 2017 1:54 pm

Mine is 5 inches from my prop on my cad 507 with a box spinning a ,76 inch ,2 blade stump puller

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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Mon Jul 31, 2017 2:30 pm

Yeah, with the fab as it is now I can never get that tight. Without being there to measure I believe I'm closer to 16-17 range. I can drop four off that by placing mounting brackets in front of support rather than behind (which is easy). As long as I'm not fighting handling I'm ok, but if it is a problem I will definitely adjust.

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Re: Ducknutt Build 500 Caddy

Post by pontoon outlaw » Mon Jul 31, 2017 4:11 pm

I would think turning that beast would be difficult being that far back

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Re: Ducknutt Build 500 Caddy

Post by Deano » Tue Aug 01, 2017 11:03 am

DuckNutt wrote:Yeah . . . As long as I'm not fighting handling I'm ok, but if it is a problem I will definitely adjust.
I know it is not what you were hoping to hear, but if no one else is going to, I will be the bad guy and say it.
You will be ahead of the game and be much happier later, if you stop, regroup and make the correction at this point.

While it would be natural to 'hope for the best', the quality of the rig you are building easily justifies having it 'right' and maintaining your likelihood and expectation of ending up with the big grin you'll deserve when you float him the first time. To float it the first time and not have that grin, is a real kick in the balls; not to mention having to redo it later and having it looking scabbed up.

There are multiple ways to remedy what you have there. Mostly a little more time consuming, not so much difficult.
To over simplify the scenario, you really just need to move the two horizontal rudder supports (with the tabs) toward the transom about a foot (?) .

While impeding the flow of progress may not seem desirable at this point, in the long run, you will forever be glad you did. Image
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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Wed Aug 02, 2017 8:57 am

Thanx Deano, totally agree. We'll makecorrection before we move forward.

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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Wed Aug 02, 2017 9:18 am

Just searched old posts and I see opinions on rudder setback from 5-14 inches and everything in between. There does seem to be concensus that the wider your prop and the higher the torque the further the distance from the prop, but you'll eventually get to the point that you'll be putting undue stress on the rudders and frame the further back you go.

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BluByU2
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Re: Ducknutt Build 500 Caddy

Post by BluByU2 » Thu Aug 03, 2017 11:17 am

I've got mine set at 9.5", and it works great for my application.

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Re: Ducknutt Build 500 Caddy

Post by kwanjangnihm » Thu Aug 03, 2017 2:13 pm

Ducknutt did you have time to measure?
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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Thu Aug 03, 2017 3:17 pm

No, I'm off tomorrow so I'll get a measurement and some more pictures. By the research I did I could be good further out by my prop and torque range. I'm thinking I'm going to put another mounting bracket in front that would give me 3.5 - 4 inches closer and try both for tuning. If neither works good then re-do it. I'm not wanting to pull it out on an assumption just yet.At any rate I'll post pic and measurement tomorrow.

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Re: Ducknutt Build 500 Caddy

Post by kwanjangnihm » Thu Aug 03, 2017 4:26 pm

DuckNutt wrote: I'm not wanting to pull it out on an assumption just yet.At any rate I'll post pic and measurement tomorrow.
Ha yea I know bro!
I hated to bring it up like Deano stated because the build looks really good thus far and it sucks to redo the setup!! :cheers:

Mine is at 4.5" and these guys can tell you, I can stroke a set of rudders with the best of them!! LMAO :rebel:
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Re: Ducknutt Build 500 Caddy

Post by Deano » Thu Aug 03, 2017 11:00 pm

DuckNutt wrote: . . . By the research I did I could be good further out by my prop and torque range. . .

I believe you've mistaken rudder spacing (laterally) for rudder distance from prop. :wink:
DuckNutt wrote: . . . I'm not wanting to pull it out on an assumption just yet . . .
Not sure why you would do all that ? :scratch: No need to, as far as I can tell.
Were it me, I would simply remove from the rear hoop, back. Then, straighten the horz supports just enough to close up the gap fore and aft, trim them, put them back, and re-brace them. By the time you paint it, no one could tell by looking that there was ever a hick-up in the game plan.

Naturally, this has no scale since there are no measurements and it's not possible to discern angles from the supplied pictures.
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Re: Ducknutt Build 500 Caddy

Post by SWAMPHUNTER45 » Sat Aug 05, 2017 9:34 am

Duck in a few days I should be back together and I will post my set back measurement.

I have been on Blu's boat which is a gear drive Cadillac and his steering is very responsive with no stick fight. He runs a 3 blade Whirlwind and his boat is a sporty ride.

On my boat with the 4 Sensenich S blades I have a smooth effortless stick with no fight either. At cruise I can let the stick go (test only) and the rudders stay true and don't force a turn. Just tossing my opinion at this but it appears that using the old "beer can" rule albeit maybe a tall one for some boats is a fair specification for spacing of the prop trailing edge to the rudders leading edge.

I could not imagine a better steering dynamic for a big power application than my current set up geometry that Blu fabricated. Will get you the measurements as soon as it's together.

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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Sat Aug 05, 2017 5:12 pm

Appreciate it. Just stopped working on removable front singles from the darn heat. The setback is 15"

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Re: Ducknutt Build 500 Caddy

Post by Junker » Mon Aug 07, 2017 8:46 pm

Deano wrote:
DuckNutt wrote: . . . By the research I did I could be good further out by my prop and torque range. . .

I believe you've mistaken rudder spacing (laterally) for rudder distance from prop. :wink:
DuckNutt wrote: . . . I'm not wanting to pull it out on an assumption just yet . . .
Not sure why you would do all that ? :scratch: No need to, as far as I can tell.
Were it me, I would simply remove from the rear hoop, back. Then, straighten the horz supports just enough to close up the gap fore and aft, trim them, put them back, and re-brace them. By the time you paint it, no one could tell by looking that there was ever a hick-up in the game plan.

Naturally, this has no scale since there are no measurements and it's not possible to discern angles from the supplied pictures.
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In the pics it looks to be just tack welded for the most part ............. Now would be the time.
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Deano
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Re: Ducknutt Build 500 Caddy

Post by Deano » Tue Aug 08, 2017 2:28 pm

Perhaps there is another, better way to describe or look at what is typically done to attain the end you are after.

Let's forget/ignore prop to rudder setback for a moment and consider boat (top of transom) to rudder setback. If the front of the rudders where even with the top of the transom, when you go full travel with the stick, it will have no choice but to immediately push the stern sideways, and steer much like a fork lift. Setup like this, it is possible at idle, to just about turn around in a boat length by blipping the throttle. With the push point (sideways) at the transom, the would be pivot point is just about amidships. In my opinion, and others, this makes docking and maneuvering around other boats (and especially people) more controllable and consequently, a safer and less stressful endeavor.

Now picture for example, the same boat with the rudders mounted two feet behind the transom. First, with the rudders mounted that much further aft, not only does the would be pivot point move aft, but instead of the stern moving immediately sideways, the boat moves forward and then turns in a measurably larger radius when it does turn. This setup is simply not capable of turning around (or even turning) in the same space as the first one.

While a docking scenario at idle may be the most dramatically obvious example, the same physics will mandate that the further back the rudders are, the less responsive the steering will be. Hence, Chuck's statement in that first quote about diminishing returns on rudder effectiveness at a distance. Naturally, the more power involved and the bigger the prop, the further the acceptable distance is if running at speed. However, those parameters do not change the physics involved with the docking/low speed scenario whatsoever. They do have a bearing on your spacing though, which I believe to be spot on and outside this the scope of this rambling.

The rudders on my bigger boat are 8 inches from my prop, but their leading edge is just inside the top of the transom. My steering is as described in the first scenario above. Blu has stated that his are 9 1/2 and his steers the way he expects it should. If he shares where his rudders are in relation to the transom, I'm willing to bet the distance is small. Since he built Swamp's I will bet that it's similar and since he says his steers like it should, I would also bet his transom to rudder distance is small as well. The pictures that Swamp Thang posted also appear to both show a short distance.

I guess what I'm trying to convey is that while there have been many discussions about prop to rudder distance, that is not actually the only and/or deciding thing that needs to be considered. Those discussions have typically not included other relevant info pertaining to prop or rudder placement in relation to the transom. I am of the opinion after reading and re-reading many of those threads that it is simply presumed that the prop is at some kind of standard distance (the proverbial beer can) from the transom as it is most often not even mentioned. If true, that would in fact, very loosely place the front of the rudders near the top of the transom (or possibly even forward of). I think this is not a co-incidence.

On that note, I have to give a big :thumbleft: to my heretofore, unmet friend, MyDixieWrecked, who is the only one I recall that addressed the transom as part of the prop to rudder distance scenario. He is due another level of respect for his astuteness for this subject matter. :salute:

If you were to look through the gallery at a hundred good side views of boats on the hill or otherwise, I don't think you will find a handful with rudders that far back from the transom. (Counter-Rotators and Geared, Supercharged A/C don't count, they have complications to deal with unto themselves where this subject matter is concerned.)

I hope it doesn't seem to you, like it does to me, that I've overpowered your build thread. My only intent was to help you avoid a result that you didn't see coming, and for sure do not want. We already had a cage/steering problem that went on for eleven pages and nearly a year. None of us wants to see that happen to you.

You're build is looking great ! Don't take any suggestions made, to be an implication of anything else.
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but it is not the path to knowledge; it has no place in the endeavor of science."
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pontoon outlaw
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Re: Ducknutt Build 500 Caddy

Post by pontoon outlaw » Tue Aug 08, 2017 7:08 pm


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Re: Ducknutt Build 500 Caddy

Post by pontoon outlaw » Tue Aug 08, 2017 7:08 pm

Mine are ,6 inches from prop on my ,12 hull

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Re: Ducknutt Build 500 Caddy

Post by DuckNutt » Wed Aug 09, 2017 5:43 am

Deano, I really appreciate your inputs and everything you're saying makes perfect sense and I am taking the input/recommendations to heart. My intent is to first mount additional brackets to the front of my rudder supports and test both positions before I remove supports and move entire setup closer. The bracket move will put me right at 12" from prop. It will also give me a comparison when I run both to validate to myself that I'm moving in the right direction. Should that improve steering (which I bet you're correct it will) then I can move supports forward to put both brackets at 12" for outer and 8" for inner. So basically I plan on using the two brackets to "tune" the rudder/steering so to speak. That way as long as I'm seeing improvement I can keep moving it forward until it no longer improves. As soon as I get to the sweet spot for the rig, thats the spot.

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