I need advice please

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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BR5491972
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I need advice please

Post by BR5491972 »

]Ok for starters I had never been on an airboat until I put mine on the river a week ago (5/8/20). Both times in the water were successful. I didn't die and didn't sink the boat. However I did spend 3 hours digging sand out of the way stuck on a sandbar in the middle of the Arkansas river about 30 miles north of the Kansas/Oklahoma border. I live a half mile from the boat ramp on the Kansas side. My airboat is a homemade 12' long× 74" wide fiberglass over plywood hull, dd 60" prop that is powered by a 1965ish dodge 318poly motor.
Problems... The rudders don't turn equally to the right as they do turning left. I think I've got that issue figured out. The rudders are 36"×22". How far away from the prop leading edge do the front of the rudders need to be? How far apart? And how high off of the transom? I'm going to redo part of the cage so that's the start of my steering issues. I'll try to post a couple of pictures of the boat for reference. It has a steering wheel not a stick. It might be kinda sketchy looking but it gets on plane and it feels like your strapped onto a rocket with really sketchy steering. Thanks in advance. All the forums I've read so far you all have already started answering more questions if mine than you will ever know

Gladesman06
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Re: I need advice please

Post by Gladesman06 »

My best advice for you is to get rid of the steering wheel and make it a steering stick. You have more steering one way then the other because your linkage of what ever you are using to connect the steering wheel to the rudders is not set evenly.

BR5491972
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Re: I need advice please

Post by BR5491972 »

I tried to get pics of the boat to load. Because a picture is worth a thousand words. How do you set up the stick steering? My boat was set up like it is now when I bought it. I thank you for responding btw.

Gary S
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Re: I need advice please

Post by Gary S »

Will need pictures

BR5491972
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Re: I need advice please

Post by BR5491972 »

Thanks for your response. I'm not able to add attachments yet but I've tried to contact admins to firgure out what I'm doing wrong. Thanks for your patience.

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rick
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Re: I need advice please

Post by rick »

I can't find a reason you shouldn't be able to attach files.

Do you see an "Attachments" tab below the area where you type your post? If so, click it and there will be button that says "Add files". From there you should be able to browse to a picture on your computer and attach it.

If you can do all of that and it still won't post the attachment, email the file to me and I'll see what I can do: webmaster@southernairboat.com

Rick

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rick
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Re: I need advice please

Post by rick »

Here's those pics. Not sure what the problem was. I just opened them with a graphics program and saved them as a different file.

IMG_20200517_152402562-2.jpg
IMG_20190512_193518930-2.jpg
IMG_20200510_195932635-2.jpg
IMG_20200517_152338190_HDR-2.jpg
IMG_20190512_193448484-2.jpg

Rick

BR5491972
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Re: I need advice please

Post by BR5491972 »

Thanks

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Slidin Gator
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Re: I need advice please

Post by Slidin Gator »

That is a really cool looking boat, it's a classic Utah style setup :thumbleft:

Your issues getting off the sandbar will take some work and may not be practical. The steering is addressable.

Cable steering like you have is hard to tune tight to keep the rudders from wandering. Stick steering with a Teleflex cable will clean that up. The rudders don't look to be parallel, you need a rigid tie bar between the two rudders so they work together and remain parallel.

That giant trim tab across the whole transom can also cause handling issues. I see it is adjustable, I would adjust it up a good bit and then test and adjust it back down until she handles good. Ultimately, moving the engine and rudders forward might let you get rid of the tab.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Deano
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Re: I need advice please

Post by Deano »

BR, please note: I am posting a saved draft from yesterday that I didn't have time to proof read. Sliding Gator's previous post was not here then, so realize what follows should be considered in addition to, and NOT in lieu of, his comments. I don't believe we are in disagreement about anything but maybe using different verbiage to describe similar thoughts. In other words, I didn't edit this post on account of his; it is ALL good information for you to consider, imho.

BR5491972 wrote: . . . My airboat is a homemade 12' long× 74" wide fiberglass over plywood hull, dd 60" prop that is powered by a 65ish dodge 318 motor
Looks like a VERY COOL little project to me. :salute: I trust that it is all strong & solid. Of course, the existing superstructure under the deck and supporting your engine and torque loading of the hull are of paramount concern. Even a small block can wreak BIG havoc.

Problems... The rudders don't turn equally to the right as they do turning left. I think I've got that issue figured out. The rudders are 36"×22".
The method for centering your steering is to unhook one end to attain some slack, then turn the wheel so that were the cable is centered on the drum is displaced either CW or CCW and then reattach and recheck. Hard to tell much by the pics, but there should be springs at the terminating ends if there currently is not. Cable routing likely could be improved, but preferred rudder placement should be accomplished first in any case.

How far away from the prop leading edge do the front of the rudders need to be? How far apart? And how high off of the transom? I'm going to redo part of the cage so that's the start of my steering issues.
These are all good thoughtful questions, but more applicable to the design of a new build than the preexisting circumstances that you currently have to deal with. Specifically, where height of the rudders above the transom goes, there would generally be an intrinsic assumption that the prop shaft is not nearly as high compared to the rudders, as yours appears to be. Note that your rudders are currently mounted in a more vertically traditional position. Then note where your prop shaft is in relation to the vertical center line of your rudders. Therein lies the bulk of the steering issue you need deal with.

It has a steering wheel not a stick. It might be kinda sketchy looking but it gets on plane and it feels like your strapped onto a rocket with really sketchy steering. . .
IMO, nothing wrong with the wheel (provided it is ALL strong and solid), and given the configuration/setup or the hull it may be the better option. Where it me, I would use all of what is there to see if I could correct it enough to be usable. AFTER that, I would start tweaking and making changes to improve what I started with.
Realize that the outermost perimeter of the prop provides little forward thrust, as the air moves down the blades toward center before actually moving aft. Consequently, the current position of your rudders renders the lower half of them ineffective at best (ie. below the prop wash thrust column).

To a large extent, the majority of your steering issues are that your rudders are mounted so low as to be largely below the thrust column of air that you are generating. I would expect that 36" rudders should work with a 60" prop, however they need to be centered vertically in thrust column of air in order to maximize their effectiveness. This will most likely be the one change that you can make that will provide the biggest single improvement in your steering.

With all that having been said, be aware that ANY and EVERY thing you change, has a bearing on everything else.
Sometimes a small change here can make a big change there. Moving your rudders up to where they will work as intended could potentially create or compound other issues that we may be unaware of. Not to beat a dead horse, but strong and solid are also applicable to your cage and rudder mounting. Be aware that the higher the rudders are mounted, the more torque loading there will be on the cage and mounts.
In this particular case, leverage will not be working in your favor.
Kept in mind, that is not a big deal to address. It is important though, to NOT overlook.
Such suggested change could make the overall feel of the steering more 'top heavy', so go easy at first, and be careful. :idea:
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

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Slidin Gator
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Re: I need advice please

Post by Slidin Gator »

Inherently I agree with Deano, the quote below in particular. I would never mount a rudder that is not centered vertically on the prop hub so my steering stays balanced and I get maximum authority from the rudder. I would expect the Utah style rudder setup to pull bad at hard throttle, like wrestling a mud motor all day.
Deano wrote:
Tue May 26, 2020 9:34 am
To a large extent, the majority of your steering issues are that your rudders are mounted so low as to be largely below the thrust column of air that you are generating. I would expect that 36" rudders should work with a 60" prop, however they need to be centered vertically in thrust column of air in order to maximize their effectiveness. This will most likely be the one change that you can make that will provide the biggest single improvement in your steering.
But that said, the Utah crowd keeps building them that way. So obviously it works for a purpose.

Image



This is "Southern Airboat" so all of our input is going to be colored by the boats we build and run, which are different from this particular rig. I hesitate to recommend a whole hog change of a key aspect of a classic rig with a classic look, I don't know much more than that, other than speculating it might be an earlier prototype. Cage/rudder changes will definitely change the look and handling. For better or worse :dontknow:

On this board, one of your best resources may be GeeLeDouche, I suggest you PM him or quote him from one of his past posts. I would search this board using "Utah" as a search term and finally I would start a new thread using "Utah Style" in the title.

memberlist.php?mode=viewprofile&u=13108

Also go to the Utah Airboat site for sure:
https://www.utahairboat.com/

Finally, let us know what you come up with, we can talk engine and prop later, I want to see how this one turns out for sure. :thumbleft:
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

BR5491972
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Re: I need advice please

Post by BR5491972 »

Thank you for all the help. You guys are awesome. I will definitely follow the advice given. I will post updated pictures when it's done.

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Slidin Gator
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Re: I need advice please

Post by Slidin Gator »

Best case the Utah guys tell you their daddy's rudders pulled so that's how it must be... :stirpot:

Then you can take our advice with confidence :cheers:
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Slidin Gator
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Re: I need advice please

Post by Slidin Gator »

I decided to take my own advice and check out the Utah forum. In short order I found this.

Image

At first I tired to figure out the camo scheme, then I noticed the rudders are cut all the way down to prop center. I said Hmmm?

Them Utah boys are crazy, with the rudder and cage cut down they roll over easy for duck blinds. :slap: :slap:

The paint job only makes sense if you are laying under the boat looking up on a partly cloudy day. Us Florida folk prefer not to talk about them days.

Image


So the big question is: how do ya'll Utah folks keep the camo job from wearing off the bottom? :stirpot: :stirpot:
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Re: I need advice please

Post by Scotty1 »

:rebel: Slidin Gator it seems you are feeling your oats these days have you got in to the private stash. :dontknow: :rebel:

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