Stitch and Glue Pedal Boat

[Fred in Wisc]

I missed that.

For planing, we'll require lots of steroids for the paddler. I'll pass on that- I'm already too hairy and I don't need the fits of rage.....

[Jaysen]

Sounds like great outings. Good on you for taking the boys for guy stuff.

...move it against the current while on plane.

Do we think this thing is going to plane?

Last time I was around kids (mine are grown) I lasted about 30 seconds before I needed a nap. They are way to full of energy for me. So yeah... I would expect they will do everything they can to get that sucker up to planing speed.

[terrulian]

I would expect they will do everything they can to get that sucker up to planing speed.

That and a big outboard ought to do it.

[Fred in Wisc]

Mostly figured out the rudder pivot and installed the bracket for it last night. It fastens to the rear crossmember and is made of 3/4 plywood. I think it will be stable enough, there won't be a lot of force on the rudder at the speeds this boat will travel (unless, of course, the kids get some Red Bull and try to plane it.....)

The bracket ends about 2" above the bottom of the hull. I'm thinking the rudder itself will extend down to the bottom of the hull- hopefully that's enough wetted area to be effective. I'd like to have nothing protruding past the bottom of the hull because it will transport better that way, either on my little flat trailer or in the back of the minivan.

I cut a piece of ply, notched it to fit around the existing crossbeam, keeping the top surface carefully squared to the back edge of the rudder so it ends up vertical (or pretty close). used a 1/4 roundover on all the exposed edges so it'll wrap in cloth easier. Glued it in with some epoxy/wood flour.





I measured to the center and then used the 2 squares to make sure it's aligned horizontally and vertically. It worked really well. Sighting down it looks straight to the center of the pedal assembly and front stringer.



Because of the angle of the camera, this looks off, but in reality, the rear edge is nearly vertical. Next step is to tie it into the structure with some fillets and fiberglass cloth, and maybe a small reinforcement from the bottom of the bracket back up to the middle crossmember (I'll see how stiff it seems and only put that in if it seems necessary). Then cut out the rudder, drill and fill holes for the hinges (no complicated stuff, I found some inexpensive gate hinges that have about the right offset in the pin to make it rotate around the center of the boards), seal those things with epoxy, and then work on the steering.

At low speeds is it going to matter if the rudder is tapered? I'm guessing not. It's only 3/4 wide, and it's likely the kids will crash it into stuff going backwards some times. I think durability and ease of manufacture is going to beat out NACA profiling. the rest of the hull is super draggy anyway. OK, I think I convinced myself that the easy way is just fine for this.

Can someone smarter than me recommend an approx. rudder size for this? It will probably have about 4-5" of vertical wetted area and it won't extend below the hull, about how long should it be? I am thinking around 9-12", is that reasonable? I'd prefer to have more control authority rather than less, but don't want to make it unbalanced. Or am I better off to make a smaller rudder with a hinged aluminum "drop keel" on it that drops down below the hull and kicks up if they run it into something (going forward at least)

[Cracker Larry]

I've been in a couple of pedal powered paddle boats. Just rentals on vacation. The few of them I've been in didn't have rudders. They were set up where the starboard pedals were driving the starboard paddle, same on the port. You steered it like a bulldozer, or twin engine boat. Reverse pedal on one side and go forward in the other and spin it around. They were set up for 2 people pedaling though. I'm real sure that I prefer oars to pedals

[Fred in Wisc]

The ones my kids used had some kind of a rudder controlled by a little joystick, but it had little authority. That might have been a symptom of being on a 5x7' flat bottom boat moving at like 1-2mph though. the paddle part was a joke- 2 bladed with a rubber piece about 10-12" square bolted to a shaft propelling it. Least efficient, slowest thing ever. I'm trying to improve on that, using mostly materials that I already have laying around the shop.

You are one of the voices of experience here, does my rudder size plan above sound reasonable?

[Cracker Larry]

I've got no idea about the rudder size. Looks good from here though.

[terrulian]

Seems you could make a mock-up out of cheap plywood and do sea trials without bothering to finish or glass it, then make the real thing when you've got it dialed in. This is such an unusual project, an admirably seat-of-the-pants one, that any general rule for the size of the rudder would be of dubious value anyway.

[Fred in Wisc]

Got the rudder attachment point glassed last night. It was small and odd shaped, so I had to use a lot of small pieces of cloth. Skim coated it with some thin wood flour putty after to get a better finish, there were areas where the cloth had a lot more overlaps and I didn't want it to be all uneven.

It seems plenty rigid and strong, I don't think it will need any bracing.






This pic shows the profile better, the rear edge where the rudder will attach is nearly vertical.



Hopefully sanding tonight, making a "first draft" rudder for testing, and working out the steering over the weekend.

[cape man]

Looking good from here.