Hull mounted skegs?

[Techno]

Wondering what are the plusses and minuses of having skegs attached to the hull.
The idea is first if the OBs skeg breaks off you still have directional stab.
The 2nd is if it worked cut the OBs skeg off!
I was thinking of skegs on the sponsons so there wouldn't be any turbulence to the prop. The only problem besides actually doing it is the increased drag.

Figuring if you could cut the skeg off, the prop would do the steering. What am I missing since I'm sure this is an old idea.

[H2Onut]

Talk about sterring torque ..... Need Hulk Hogan arms
I imagine the boat would crab also ?

Even those outboards that had prop in front of the bullet still had a skeg.


However the othe side is jet boats don't have no skeg on nozzle.


Replies will be interesting.....

[Rickracer]

They don't turn unless you're in the throttle. Don't ask me how I know this,

[sosmerc]

Interesting subject. Didn't Merc play with an outboard lower unit design not long ago that didn't have a skeg?
Some of the nicest handling outboard ski boats I've run had a skeg in the middle of the hull (to improve straight line tracking I assume). The Sanger 20ft. Barefoot Skier is a popular outboard powered boat in my area. With a stock 200 Merc and the correct setup it runs easily in the mid 60's and handles excellent. I realize it's not a "scary-fast" boat, but my point is the skeg sure doesn't seem to interfere with anything and it's in the middle of the boat. What would happen if it were moved farther back on the pad? (there is a point where the boat can be made to perform a little "jig" to the right when you are really trimmed out and going for max speed...must be the point where the skeg gets lifted out of the water...it's a bit scary the first time you experience it, but once you are aware it's going to happen you soon learn to handle it and all's well) There's a fellow in the area that has a 2.5 EFI performance engine on his Sanger and it does fly! So I would think either a single skeg toward the stern or 2 small ones on the outside might make it possible to get by without the lower unit skeg. (I do worry about what is going to happen the first time I experience a broken skeg on my 70+mph outboard rig).

[nitro hydro]

In IHBA unlimited outboard you must cut the skeg off. then put on a rutter like the V drives .
John Wright set the 1/4 mile record at 156 mph two years ago here in Augusta and he didnt have a skeg on his motor.
Troy

[laser]

I agree Techno, just from a safety standpoint, having the outboard motor locked in place with the skeg removed and using a remote rudder/s could be a good idea. Having the motor steering locked would also eliminate steering slop handling problems. Cleaner water to the prop couldn't hurt. Could possibly be faster. I would also think that steering torque would be alot more managable.

On the flip side, it could create a problem with a surface piercing prop wanting to walk the stern around if the rudder is not effective.

[Bruce Washburn]

I know that john Wright used a remote rudder. The skeg on the lower unit was cut off.
I think that this is more of a safety issue than a performance issue. As one of the previous post said Wright ran 156. I think when he stuffed the boat at a latter race he was on a run that would have easily surpaased the 156 run. (Rumor had it 122 at 1/8th mile mark.) The problem is with the standard skeg the side tourque loads on the skeg are very high when you get up in the 150 to 160 range. It was suspected that one attempt on the outboard speed record (prior to the V8 record) went bad when the skeg broke and the hydro crashed. The remote rudders are usually steel and a little longer. If I was going to try to go fast in a hydro I think I would want the remote rudder.
Putting fins on the sponsons of a hydro will help it turn but if you have power on and the skeg on the lower unit breaks the ass end will walk around and you are probably going for a ride.
If you are thinking about a hydro, I would find John Wright and get the info on how to set it up.
Remember that when the hydro is running up in the 150's the back of the boat is out of the water and the bullet of the gearcase is also probably out of the water. The rudder is the only thing that makes it go straight.

[Tom Stanley]

Be careful. A fellow here in the northwest put a side skid fin on a superstock flatbottom. It wasn't long before he barrel rolled.
Another thing to consider is that the skeg is behind the turning center of the engine so that it tends to straighten up the engine.
Assuming that you mount it on the inside of the tunnel wall, it could lead to the boat hooking if it was too far forward. Normally a tunnel doesn't need a skid fin, but if you remove the skeg to improve the flow to the prop, it might hook anyway.
For a discussion of skid fin mounting on hydros, see my web page.

[Jeff_G]

Bruce, you are probably thinking about George Andrews in Dick O'Dea's hydro at the kilos in Moorehaven. He was well into the 150+ range when the skeg broke. The skeg had been thinned. George died, no capsule in those days.

I would not try remote skegs or rudders in any conventional boat. A purpose built drag boat is another story.

[Techno]

I was thinking of a skeg mounted on the transom behind each sponson. This on an STV. This is probably more work than I want to do so its mostly academic.

[JTS Racing]

Those of us with unlimited hydros are running a SSM style gearcase with a small prop diameter, so theres little to no torque. Not sure how a large gearcase would react, but there is a guy in ODBA with a white pugh that runs a large gearcase...with std steering. Our hydro's are built for one thing and thats a 1/4 mile blast, straight (hopefully) and shutdown. You CANNOT turn one of these things and anything much over planing speed. As for skidfins, they help on planing steering, but you have to be real careful of the size. If too large and your hull runs with a little crab to it, which most do, if the front falls it can cause you to hook.

The rudder rule was established for safety. Too many were thinning the skegs and thus broken skegs and crashes. The F1 rides travel at 140+ speeds and I would think the stress on those is a lot greater than drag hulls due to the turns. BTW...even though I agree with the rule, it was written by the V-drive boyz. Wonder if they were trying to slow the klamp-onz down

I'm set up for a rudder but took it off and went back to standard steering for this year sinced I'm playing with a new engine and not looking for speeds over 130 or so. You have little to no manuverability at idle speed with a rudder. The push of the prop with the engine being locked straight is more than the rudder control. Once the boat begins to get on plane you can turn.

[Firestarter]

Keith Eickert had advertised on his web sight for some time that he has developed or in the midst of developing a rudder system that bolts to your midsection in the cavitation plate area that places a rudder behind the prop, allowing the removal of the skeg and thus cleaning up the water to the prop, and eliminating the possibility of a broken skeg.

RT

[Techno]

I don't see why you would need a rudder if the OB could still steer. You turn the prop and the thrust goes in a different direction.
Unless your talking about locking the OB and placing a rudder behind it.

[Firestarter]

Nope.
I mean a rudder and still turning the whole motor. I was in boat once that the skeg snapped off at 30 mph in a turn, and the boat never came out of it. We tried to drive it home, and the boat would only turn, and the steering torque is unreal.
Consider that the gearcase is often plaining, this gives NO directional stability. Imagine breaking a propshaft---you would have nothing, and I can tell you loosing a propshaft while still retaining your skeg is a ride you will soon not forget.

RT

[Tinker]

The first time I put a rudder on a hydro was because of a broken skeg. At the time the rules in Unlimited Outboard did not require a locked down motor (straight) so I put a rudder on the right side rear sponson, left the steering cables attached to the wings on the motor and ran a drag link from the motor to the rudder. It worked very well. There was no noticeable loss in steering control and it turned equally well at slow or high speeds. An off- set rudder with a locked down motor needs lots of space to make even a slight turn. It helps to iturn n the same direction as the prop rotation so that you do not have to fight the motor torque. The locked down rule came about as a supposed means of keeping the boat going straight in the even of a broken prop shaft or damaged prop.

A rudder works well on a hydro and probably a tunnel but not sure how it would work on a tunnel boat. The rudder material should be no less than 7075 with a minimum cord thickness of .625. You should also pay close attention to the mounting bracket and turning pin design. Weight and balance will also be affected as the rudder assembly weighs more than you would imagine. What you have to consider is that you are putting a lot of weight on one side of the boat as far aft as anything except the motor.

Jon Wright