Hydroplane fin

[Kanopiss]

Is it possible to place the turn (skid) fin in a position that would allow decent steering in both directions. Im not into racing.

 

[airshot]

What is a skid fin ??

 

[mr 88]

A hydroplane fin is designed to keep the flat bottom hull from sliding away from the corners . Gives the hull a little bite so you can turn in any direction . What sort of hydroplane do you have ?

 

[Kanopiss]

I’m building an 8’ Tiny Titan with plans from Glen-L. It will have 9.9 hp outboard. It’s for my grandkids. Not sure where to put fin to allow for good steering in either direction. The directions say left side because most races run counter clockwise.

 

[BWR1953]

I’m building an 8’ Tiny Titan with plans from Glen-L. It will have 9.9 hp outboard. It’s for my grandkids. Not sure where to put fin to allow for good steering in either direction. The directions say left side because most races run counter clockwise.

From the context, it sounds like you're talking about the trim tab at the base of the engine, above and behind the prop. Is that right?

Looks like this.


If that's the case, it needs to be adjusted like the one in this video that I found. The video shows a much larger engine, but the principle is the same.

 

[flashback]

He's referring to a fin that is installed on the trailing end of the port sponson to hold the boat in turns. I suppose you could either add one to starboard or eliminate it altogether, I don't suspect it will have much effect on a small low power boat.
The boat I built has a small fin on either side of the outboard on the transom..

 

[roffey]

I had a small hydroplane when I was much younger. There was a fin on it but I took it off as it was hard to pull it up on shore or the dock. The boat still turned fine, just not on a dime.

FYI mine had a 9.9 as well and I could almost hit 20 MPH... that was absolutely flying across the water.

 

[Alumarine]

I had a Tiny Titan when I was 13.
Without a fin turns were fine just wide and a bit of a slide.
One time I had a friend sitting in front on the bow and when I cut the throttle the bow caught and we must have submerged about 3 feet before popping up!

 

[Scott Danforth]

ski boats have 3 fins, the center one is just forward of the Port/Starboard ones

 

[Kanopiss]

Thanks guys. Some great advice to work with. I wasn’t sure how crucial it would be. Sounds like maybe I should start with no fin and see how it goes. Guess I can always add one later.

 

[Texasmark]

I ran an 8' wooden hydro...stepped hull with a 10 HP Scott Atwater, all stock including 2 blade alum. prop, without a fin and never felt that I needed one when I was a kid...my first boat. Maybe the step made a difference, I don't know. Only fins I have seen were mono-hull, semiVs and it was centered on the hull, both on the keel and midship like one of my running buddies dad had on his mono hull with his opposed 4 cyl. 50 hp Johnson.....a long way from being stock......he raced it.

Just a comment, sitting that close to the water I felt like I was going 90 miles an hour but in reality if I were hitting 25 I'd be surprised thinking about it today.

 

[Kanopiss]

I ran an 8' wooden hydro...stepped hull with a 10 HP Scott Atwater, all stock including 2 blade alum. prop, without a fin and never felt that I needed one when I was a kid...my first boat. Maybe the step made a difference, I don't know. Only fins I have seen were mono-hull, semiVs and it was centered on the hull, both on the keel and midship like one of my running buddies dad had on his mono hull with his opposed 4 cyl. 50 hp Johnson.....a long way from being stock......he raced it.

Just a comment, sitting that close to the water I felt like I was going 90 miles an hour but in reality if I were hitting 25 I'd be surprised thinking about it today.

Thanks for the info