Intro and Harbor Freight boat build question

[Apbling]

Hi all. New to the forum. Been lurking for a while but decided to join. My kids got a couple harbor freight boats from my folks for a gift and love them. I?ve since gotten a stealth wake, recoil 26 and my kids have an FT009. We love tinkering and running them.

On to my question. Me and my boys are wanting to build a boat using one of the harbor freight hulls and extra parts we have around. Doesn?t need to be a speed demon, but just fun and a learning experience for us all. I?ve gutted everything out of the boat and was going to go w a single prop 550 brushed motor and a rudder from my stealth wake. Steven has recommended the TFL stinger and flex shaft, which I don?t have a lot of experience with. I was doing some research and I?m a little concerned about the length of the stinger. The hull is 24? x 8? and is a shallower v hull, abs plastic and a bit light (I plan on glassing to beef it up). Anyway, the stinger is 2.83? at its shortest and the leading edge of my rudder is 2.25?. This would put the prop likely behind the rudder. Is this an issue? Also is having a prop this deep on a boat like this too much? I saw a guy put this on his stealth wake (a 24? deep v) and he couldn?t get a deep enough negative angle and had to move the stinger up (not sure how that affected the angle, but that?s what he said).

Any help is appreciated!

[sciesielka]

the stinger is 2.83? at its shortest and the leading edge of my rudder is 2.25?. This would put the prop likely behind the rudder. Is this an issue?

What I have read about race boat setups, at least on monohulls is that you want to keep the strut or stinger a maximum of 10 percent of the length of the hull, so on a 24 inch boat, the end of the stinger would be 2.4 inches from the transom. I read where people had issues turning when it was longer.
Although, when I was looking to upgrade the Stealthwake, I saw two guys on the forum who modified a Stealthwake and in both cases, the prop sits behind the rudder and they had great success (look for fweasel's and arrover's Stealthwake mods). So maybe the 10% rule isn't so hard and fast for sport boats. Just make sure that you have enough room for your prop that you don't hit the rudder if you're in-line or almost behind it. On both my upgraded Stealthwake and the Shockwave, the props are almost in-line with the rudder so if I go too big on the prop diameter I'll hit the rudder when turning left.

couldn?t get a deep enough negative angle and had to move the stinger up

As far as depth and angle, the reason to use a flex shaft is so you can get the prop parallel, or 0 degrees, to the bottom of the hull. You want to have the prop shaft at a neutral angle. Then, with a stinger or strut, you can change the angle a few degrees to get the bow up or down depending on the waves and wind. Or, you keep it at 0 degrees/neutral and use trim tabs to adjust the ride attitude. As far as depth, or what I assume was meant by vertical movement from the keel, what I understand is if you move the strut/prop up or down (keeping the angle at 0 degrees) you change how much of the rear of the boat is in the water. If the prop is close to the keel, very little of the hull is in the water. If the prop is raised up from the keel, more hull is in the water meaning, usually, more control. That's a very brief description anyway. I'm sure others with more knowledge can explain better. Again, with a "sport" boat, the vertical adjustment probably isn't as important as the angle.

If you have a solid shaft like the Stealthwake, the angle is always going to be negative (-6 degrees on the Stealthwake) because you can't get the motor below the keel. You could get the prop shaft closer so it's not at such a negative angle but you'd have to use dog-bones or a rotate-able universal shaft coupler to make up the difference in angle. I use those on my PT boats to get the motor shaft which is parallel to the hull connected to the prop shaft which is on a steep angle for the sub-surface drive.