New Builder/First Air Boat
03-26-2017, 03:13 PM
#126
Ok. Sorry to hijack this thread for a moment, but I have a question regarding your post below, or above (wherever the forum puts it). Anyways, since we are talking about this airboat, and the rudders, could I just clarify something. From my reading your post, I am led to believe that it would be better to make my rudders longer (further away from the boat), rather than taller? I am just asking to clarify as I was just about to make a new set the original depth, but double the height, as I have turning issues myself. But now, I am thinking I would be best to build them the same height, but 2" longer? Thank you.
The only problem you could run into is whether the paint is chemically compatible with epoxy. Generally speaking, 2-component finishes are compatible with other 2-component paints. 2-component means the material uses a catalyst/crosslinker/hardener. There are limits to this however - polyester resin is 2-component, but will not adhere to epoxy and vice versa. I know for a fact that commercial 2-component waterborne polyurethane will stick to epoxy as does oil based polyurethane.. but epoxy won't stick to polyurethane. Some automotive paints are urethane based and others are lacquer based. I think it fair to say that a urethane paint will be a "slam dunk" whereas lacquer may not. You would need to do some test spots to determine adhesion before painting the whole thing. At minimum, use scotchbrite to break the sheen of the epoxy to aid adhesion. Better yet, use some 220-320 grit abrasive (sandpaper) to break the sheen. A quality finish/paint should adhere provided the substrate is adequately abraded. I may be making a mountain from a mole hill, but I'd hate for someone to have their paint peel.
As for the rudders - I haven't found a huge benefit from the height of the rudders as much as depth. Meaning a rudder that is wider (protrudes farther off the back of the boat) will provide more positive control than a narrower but taller rudder. If you read my thread about my SI3 flat bottom boat, you will see the "evolution" of my rudders on that boat starting with the rudders the plans outlined and the two revisions I made to improve steering control and response. Post #43 http://www.rcuniverse.com/forum/rc-a...-bottom-2.html
You don't expressly need to have your rudders' height match the height of the propwash. 1/2-2/3 of the propwash is totally good provided the width of the rudder is adequate. Do test your initial rudders first though - if it doesn't respond quickly or turn sharply, you will need to adjust the throw and/or the size of the rudders.
Besides building a strong hull, your rudders need to perform A-1 perfect. It's a real PITA if your boat don't turn for crap and she gets stuck in the weeds requiring going for a swim or canoe ride to recover it. I learned the hard way a time or two.
As for the rudders - I haven't found a huge benefit from the height of the rudders as much as depth. Meaning a rudder that is wider (protrudes farther off the back of the boat) will provide more positive control than a narrower but taller rudder. If you read my thread about my SI3 flat bottom boat, you will see the "evolution" of my rudders on that boat starting with the rudders the plans outlined and the two revisions I made to improve steering control and response. Post #43 http://www.rcuniverse.com/forum/rc-a...-bottom-2.html
You don't expressly need to have your rudders' height match the height of the propwash. 1/2-2/3 of the propwash is totally good provided the width of the rudder is adequate. Do test your initial rudders first though - if it doesn't respond quickly or turn sharply, you will need to adjust the throw and/or the size of the rudders.
Besides building a strong hull, your rudders need to perform A-1 perfect. It's a real PITA if your boat don't turn for crap and she gets stuck in the weeds requiring going for a swim or canoe ride to recover it. I learned the hard way a time or two.
03-26-2017, 03:37 PM
#127
Did you read the post and look at the pictures referenced in my last post? The pictures will show exactly what I meant in my last post. In a nutshell, it isn't necessarily required to go up in height as that can raise your CG to an unhappy point. Going deeper makes more sense and does work very very well in my testing. I did raise the height of my rudders in my last referenced post, but only by about an inch. I added almost double the depth though - which did the trick. The top left photo was the first rudder I made per the plans. Second rudder is too right, and the last one bottom left. Original rudder compared to final rudder bottom right.
Last edited by 1QwkSport2.5r; 03-26-2017 at 03:41 PM.
03-27-2017, 07:06 PM
#129
03-28-2017, 11:33 AM
#130
Senior Member
Thread Starter
Join Date: Feb 2017
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
Back to my problem with the epoxy not drying. I am fairly convinced now it was an issue of poorly mixing the two parts, not the ratio. The last two batches have been just fine and were mixed well.
03-28-2017, 11:35 AM
#131
03-28-2017, 12:30 PM
#133
That's what I use as well. If you do thin it, use acetone or methanol, and only add maybe 10%. It doesn't take much to thin it. Also, only thin the resin AFTER mixing the resin and hardener thoroughly.
03-28-2017, 06:01 PM
#135
Not knowing what finishing resin/epoxy you are using, I cannot help too much. But if it is something like West system, the mix ratios are NOT 1:1. There are special mixing pumps available for those. Others may mix 1:1. What brand are you using?
03-29-2017, 03:53 PM
#139
Looks really nice. I understand trying to keep the wood showing. But this also adds a good waterproofing. Also I should note, I assume that your epoxy finally cured as you have painted it?
03-31-2017, 03:40 AM
#140
Senior Member
Thread Starter
Join Date: Feb 2017
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
1QwkSport2.5r
I plan to install the control lines this weekend. To get from the hull to the throttle means a bend in the line and i am wondering if there is a minimum radius for push rod movement or if they are pretty forgiving? I am using the all plastic rods; no cable.
03-31-2017, 05:04 AM
#141
1QwkSport2.5r
I plan to install the control lines this weekend. To get from the hull to the throttle means a bend in the line and i am wondering if there is a minimum radius for push rod movement or if they are pretty forgiving? I am using the all plastic rods; no cable.
The nylon control rods need a larger radius than the metal control rods. The section of cable that is glued within the hull as straight as possible and where the cables exit the hull give it as big a radius as you can without the cable binding. What I do is set the cable in the hull as I plan to install it and then radius the cable (for throttle as an example) to how you would mount it and test the cable to see how well it moves within the sheath. If it moves smoothly, then your set. If the cable sticks or doesn't move smoothly, adjust the radius until it does. In the end, you want the cable to move freely, so run the cable as short and as tight a radius as you can while still allowing free and smooth movement. If the cable binds, it will strain the servo.
04-01-2017, 08:20 AM
#143
Senior Member
Thread Starter
Join Date: Feb 2017
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
Now we are attempting to understand the transmitter set up...yes we are new to it all! Somewhat intuitive, but somewhat confusing as well! Wish there was a simple YouTube tutorial or something.
04-01-2017, 11:15 AM
#144
04-02-2017, 01:52 AM
#145
Senior Member
Thread Starter
Join Date: Feb 2017
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
I have the Spektrum 4210 DX4C DSMR 4-Channel AVC Radio w/ SRS4210. I am trying to understand all the functions! I assume there are ways to control the speed of servo travel, distance of travel, trim servo position, etc.
04-02-2017, 06:43 AM
#146
If you haven't read the manual yet, I suggest doing so. I have a DX3S, different than the DX4C in several ways, but it looks like the menus are similar. The menu requires pushing the roller button below the screen to open the menu, then scroll through the menus with the roller. Press the roller button to open the menu. The only settings I mess with are whether the servo needs standard movement or reverse movement (REVERSE), servo travel (TRAVEL), end point adjustment (EPA), and in some cases, sub trim (SUB TRIM). The menu "terms" I listed are within parentheses. I recommend setting the EPA to 100% and verify the throw. If you need more throw, I think you can go up to 125% I believe. If you need more throw than that, you'll need to adjust the mechanical linkage and/or change the servo horn/linkage position on the servo horn.
There are quite a few videos on YouTube that may be of assistance to you in learning how your radio system works and how to set it up. Might be worth a look.
Last edited by 1QwkSport2.5r; 04-02-2017 at 08:14 AM.
04-03-2017, 03:12 AM
#148
The AVC system may need to be turned off in a boat. I don't believe that radio is "marine ready", so it is worth reading into things a bit to ensure there aren't any hiccups when running your boat.