New guy's FE 1/8th Alaska Air Sport Hydro build

[Shaun Rasmussen]

Yes, you read that right. Since I won't be racing this boat, I'm going to make it look like the airplane I fly. Why not? I was thinking of the Boeing plane, but I don't fly a Boeing. I was thinking of the Qatar boat since I think it looks cool, but I think I'd rather have a one-off boat.



I started building this ML Boatworks 172 kit early September, and I'm making slow progress on it. Since I don't know what I'm doing, I'm having to learn pretty much everything required to know for every step of the build. I had a thread on OSE, but I was told I may get more/better help over here with my questions.

Shout out to Bill Brandt at Rattlesnake RC. Super helpful. From him, I got a HET 700-98-840kv motor with a ZTW 150amp ESC. I plan on running it 8s.

Here is what the boat looks like now:



Yes, I'm building this outside, btw. Fun times keeping everything from warping. The jig was a must for me.

 

[Shaun Rasmussen]

Currently, I'm trying to figure out how to lay out the electronics on the inside. Any issues with mounting the ESC right next to the side of the motor? There is clearance, but not a lot. I'm not sure what the issue would be if it wasn't a good idea, but I want to make sure I'm not missing anything. Batteries will go in the front.



I have a few other questions as well. I'd appreciate it if someone could help point me in the right direction with them. First, the strut - how low and at what angle should it be? I'm guessing at the same level as the bottom of the ride pads, and level with the bottom of the boat. Can anyone confirm?

Also, I've been given a Octura x560 prop. Would this be a good enough prop to start with?

I'm going to need a new transmitter. I'm currently using a $40 transmitter for my other boat (home built 63" gas mono), and I don't trust it for something like this boat. I think I'd like to get a transmitter that is good enough to keep for a while and use on other potential future boats as well. I'm thinking about one of the Spectrum DX5 transmitters. They seem like a fair price range and high enough quality to last a awhile. Thoughts? Suggestions? I'd like to have telemetry- worth it? or waste of money?

 

[Hydro Junkie]

I'd go with a Futaba 4PM:
https://futabausa.com/product/4pm/My reasons are simple:
1) multimodel memory so you can use it with several boats
2) Telemetry, it will let you keep track of your battery voltages, motor temperature and whatever else it's capable of by adding whatever sensors are needed
3) Futaba is a known commodity with after purchase support
4) I'VE NEVER HAD A FUTABA SYSTEM FAIL
Let the flaming begin

 

[Grimracer]

Is that a Savox Servo?

 

[Shaun Rasmussen]

Thanks, I'll add the Futaba 4PM to the list of ones to look at closer.

Not a Savox servo, probably a Savox knockoff.

 

[Hydro Junkie]

Thanks, I'll add the Futaba 4PM to the list of ones to look at closer.

I have a pair of 4PLS transmitters, never had an issue with either one. What I like is the fact that, by adding sensors and an Sbus hub, I can see my engine temperature, RPM and receiver battery voltage just by looking at the display. I just pick what I want to see and go run. With that said, I run nitro boats but, with electrics, you can also see the voltage of your drive packs as well

 

[Paul Cooper]

Good to see ya posting here Shaun.

 

[Shaun Rasmussen]

Thanks for recommending I come over Paul! I hope this works out a little better for me!

I got an order today including the turn fin. With how the kit is made, there is only room to mount the turn fin so it is right at the edge of the ride pad. That doesn't seem right, but what do I know? Seems like it would be better to modify the area above the ride pad to mount it outboard a little further. Thoughts?

Right at the ride pad- easy install:


Or modify it so that it can be mounted here:



And this picture, because the lighting is cool:




Also, since nobody has anything to say about my electronics locations layout, I think I'll go with it. Batteries come in the next day or two, so I'll use those to verify it will work, and then get going on making things permanent.

 

[Hydro Junkie]

I would add a spacer block somewhat wider than the skid fin bracket with enough vertical room to allow some up and down adjusment as far out on the sponson transom as you can. You might also want to add a wider block between the vertical and sloped transom pieces to help handle the load placed on the bracket when turning. The only thing you would have to figure out is how to secure the bracket mounting screws:

1. threaded inserts
2. blind nuts on the inside of the vertical transom piece
3. an aluminum plate secured to the inside of the transom that can be drilled and tapped

 

[EugenePierce]

L

Thanks for recommending I come over Paul! I hope this works out a little better for me!

I got an order today including the turn fin. With how the kit is made, there is only room to mount the turn fin so it is right at the edge of the ride pad. That doesn't seem right, but what do I know? Seems like it would be better to modify the area above the ride pad to mount it outboard a little further. Thoughts?

Right at the ride pad- easy install:
View attachment 284122

Or modify it so that it can be mounted here:

View attachment 284123

And this picture, because the lighting is cool:

View attachment 284124


Also, since nobody has anything to say about my electronics locations layout, I think I'll go with it. Batteries come in the next day or two, so I'll use those to verify it will work, and then get going on making things permanent.

Thanks for recommending I come over Paul! I hope this works out a little better for me!

I got an order today including the turn fin. With how the kit is made, there is only room to mount the turn fin so it is right at the edge of the ride pad. That doesn't seem right, but what do I know? Seems like it would be better to modify the area above the ride pad to mount it outboard a little further. Thoughts?

Right at the ride pad- easy install:
View attachment 284122

Or modify it so that it can be mounted here:

View attachment 284123

And this picture, because the lighting is cool:

View attachment 284124


Also, since nobody has anything to say about my electronics locations layout, I think I'll go with it. Batteries come in the next day or two, so I'll use those to verify it will work, and then get going on making things permanent.

I have the same boat only different name I'm repairing due to a crash heres how I did mine with a aluminum plate inside drilled and taped

 

[brad nichols]

Install a 1/8 aluminum plate inside and drill and tap. Modify it as picture #2

Brad

 

[Paul Cooper]

Like mentioned above I would go with your second picture. Mine for reference. Not saying mines right . This is where I mounted it after a lot of reading and watching Scott's videos.

 

[EugenePierce]

I should have said my turn fin is a Virginia craftsman fin

 

[Shaun Rasmussen]

Seems that the consensus is to mount it further outboard. I'll work on that. I need to re-watch that video Scott did about turn fins as well. I won't be able to copy that exactly, but I'm sure I'll learn a bunch. I have aluminum plate on the way- for building mounts for the rear wing, and making a backing plate for the turn fin. Seems like a lot of forces get transferred through that little fin, so I want to make sure I mount it in a way it will survive that.

Thanks everyone for the input. Will report back...

 

[Mike Cathey]

You definitely want the turn fin back from the sponson transom far enough so if the turn fin gets kicked up it doesn't get into the deck.

 

[Shaun Rasmussen]

I ended up cutting back the angled part of the rear of the sponson to make a flat spot in the right area. I put on an aluminum backing plate inside the sponson to spread the forces around.

 

[EugenePierce]

Shaun, what turn fin is that?

 

[Shaun Rasmussen]

It's a Speedmaster sport hydro fin.

The one on the bottom of this page: TURN-FINS

 

[Shaun Rasmussen]

Got all the barrel connectors soldered onto the batteries, motor, ESC, and charging cords. It isn't easy soldering that big of a connector, but I got it mostly figured out by the time I was done. Also epoxied down the mounted the motor mounts, and got the... bigger stuffing tube that the actual stuffing tube fits into... put into place. I used Polyester resin for that one instead of epoxy since epoxy tends to sag right before it sets. Polyester just starts getting hard, so I like it much better for making shapes since it stays in those shapes (fillet around the tube) much better.

Getting ready to start mounting front and rear wings. Just can't find what angle to set them. I'd assume a positive angle of attack? Something small like 1-2 degrees? Or would the front get a slight negative angle of attack? I'm making them so they will have a bit of adjustment, but I don't know what to have as a zero to adjust from. Also, I've been trying to figure out what angle the vertical fins are mounted. I can tell they aren't vertical, and they angle out, but anyone have any idea about what angle? Or, could someone measure the width of their rear wing? It would be much appreciated!

 

[Hydro Junkie]

I would go flat or up to three negative on the canard and flat at the rear initially. Be sure to make them adjustable, at least to begin with. The biggest thing to remember is that the canard and wing are used to trim the boat's ride and not to correct for an improperly balanced hull. I've seen boats that were massively tail heavy with the wing set with an insane amount of positive attack angle. The person that built it just assumed that's what the wing was for and found that the boat tended to drive the front down at higher speeds and drag the transom at slower speeds.
So, let the flaming begin since I know someone will want to do so