What can I do to make my boat turn better?

[high-tech]

It seems that the back of the boat wants to slide out towards the outside of a turn and causes the boat to spinout sometimes ends up heading the opposite direction

A link to my scratch build http://forums.offshoreelectrics.com/...KI-VEE-Project

I built this boat from scratch, it's a 19in. SKI VEE, I got this boat up on plane and it straight lines perfect and gets right with it, it's also running straight rudder. I seem to find that just firm enough to stay right side up in race water sweet spot easily.

I don't understand what I need to do to make "force" this boat to turn better. I took a pic with some wood taped on the bottom, would this or something like this help? If not than please give some of your wisdom and magic

One more thing when she is up on plane it's running on that taped out little patch in the pic, maybe even a little less than that

[Fluid]

It is not possible to tell from the photo, but the usual causes are not enough rudder and not enough turn fin. The current rudder may be okay, but you will need to either run the existing fin deeper, or use a larger fin. Too, if the trim tabs are set too low the can force the transom up when turning, exacerbating the tendency to spin out.



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[ray schrauwen]

Strakes would help a bit from letting it slide out in the turn.

[photohoward1]

May just be the nature of the hull. It has a very flat bottom. Shallow "V"...It probably runs a bit like a CrackerBox. What size prop are you running?

[high-tech]

May just be the nature of the hull. It has a very flat bottom. Shallow "V"...It probably runs a bit like a CrackerBox. What size prop are you running?

Right now I'm running a x435 and it brings it right out the water and torque rolls if I'm drag race starting.
I have never run a crackerbox but you tube shows them doing the same thing only not so drastic as mine but yeah I think this boat was a spin off the dumas cracker

[Fluid]

The boat has much more deadrise than a CBox, check out the build thread. The Dumas SkiVee design has been around since the 1970s (long before their CBoxs) and was considered a "deep vee" hull back then. I raced an FE CBox for years, and with the right keel-mounted skid fin (not needed on a vee) it didn't slide too much.


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[high-tech]

I did some research on some information that fluid suggested in a post about a keel mounted skid fin.

Well this is what I found. (pic) I cut a piece of foam to use for demonstration purposes and don't have any idea if this is the right positioning or profile or XYZ or all of the and if anybody can chime in here I would appreciate the support or critique.
Thanks for looking and have a great day!!!

[T.S.Davis]

Pretty shallow looking at that side view. It's going to want to slide through turns. Until it reaches a certain point. My Mystic is like that a bit. Runs like a drift car until you change the direction enough to drop the nose a bit. Then it can hook.

Strakes might help as Ray mentioned.

Can't tell what angle the prop shaft is at but that can make things wonkey too.

Put a straight edge down the keel and see how much angle positive or negative you have. It could be that the angle is making your issue harder to remedy with the fin. Get the boat to run flat.....ish and it will turn better. Not stone flat and all wet but flat....er. So that the keel is in the water some through the turn. My pennies worth.

It also looks like the outside edge (chine) is rounded. That will have a hard time biting into the turn.

[high-tech]

Pretty shallow looking at that side view. It's going to want to slide through turns. Until it reaches a certain point. My Mystic is like that a bit. Runs like a drift car until you change the direction enough to drop the nose a bit. Then it can hook.

Strakes might help as Ray mentioned.

Can't tell what angle the prop shaft is at but that can make things wonkey too.

Put a straight edge down the keel and see how much angle positive or negative you have. It could be that the angle is making your issue harder to remedy with the fin. Get the boat to run flat.....ish and it will turn better. Not stone flat and all wet but flat....er. So that the keel is in the water some through the turn. My pennies worth.

It also looks like the outside edge (chine) is rounded. That will have a hard time biting into the turn.

I played with prop angle a bit, I used a brass tube the same size as prop shaft and I ended up with less than 1 degree pos angle and then I got 2 degree to the right for prop walk... and it planes real good and just firm enough for race water, so I really think I'm dialed in with the prop angle in relation to the world and its forces...

I'm still in the research phase of this turning problem, I haven't applied anything and run it yet. I'm gonna try a flat sharp skid fin and see what happens and if it works i'll report and if not i'll be back here ringing door bells for help. Thanks for your input

[RandyatBBY]

Strakes will cause the hull to lift on the launch and help ride the hull on plane. They also cause the water to roll up and stops the boat from sliding in turns. Turn fins will stop the rear of the boat from spin outs.