Drive alignment Toe in or Toe out
 

Searched ALL of OSO and seems like there is no agreement on which way outdrives should be aligned, toe in or toe out. Actually no one even agrees what the definition of "toe in and toe out" even is! Plus some say it depends on V or cat. Some say it depends on if your props spin IN or OUT. Then Reggie Fountain wrote that all drives should be adjusted the same no matter what rotation! About the only part of any answer that has a majority is 1/16th to 1/8th in. I understand all boats are different but having a baseline to go off of would be nice.

In each reply could you PLEASE define what "IN" or "OUT" is

PLEASE describe WHY you recommend what you do

Thanks!

IMO Toe in is forward tip of drive in towards center line of boat, toe out away from center. Props spinning out wants to pull drive out so toe in, opposite for spinning in. Mine are set at 1/8" toe in, 32' cat spinning out.

been wondering same. what is the 1/8th inch? diff between propshaft centers and nosecone centers? and both of mine spin cw. do i toe it straight? i could toe 1 in and 1 out, but it would go around in circles...

Yes, first you have to determine that they are straight. I measure each side tip of prop shaft to trailing edge point of keel and transom, then both prop shafts and leading points of each drive must be equal measurements. On a V hull I would go from prop shafts th lowest point at keel and transom. Once that is determined then adjust each side in or out same amount using tie bar hiems. Derek for your twin CW set up I would say do the straightening adjustments and let it go at that. Any thing after that is corrected at the wheel. Drives aren't fighting against each other. IMO

Thanks for the reply but still confused here.

So nosecones closer together "toe in"
Props spin out
Props pull apart pushing nose cones together
so thats why you toe in?

Some say that you should toe the nosecones out if the props spin out so that after the props pull away from each other the drives will straighten out from the force of the torque?

I hate to contradict another guy's advice - especially when the answer may be right in his circumstances.

On a 33 Outlaw, I would say that the drives should be 1/8" closer together at the REAR (measured at the center of the propshaft). This is because, at the 70mph speed range, the water flow is separated ito RH and LH streams by the vee of the hull, passes over the drives, and moves back together towards the center behind the boat. At the point of the outdrives, the water flow is already trying to move back towards center. If the drives are perfectly straight, they will incur significant side force squeezing them together. Slightly aiming the drives back towards center eliminates this side load and is easier on the gimbals.

At speeds over 100, the equation changes a little, but for the speeds this boat will run, I think it is better served by the above recommendation.

MC

Does 102 count as over 100? :evilb: Thats the goal at least, been very close.....updates soon.

Well Thats how I have my drives set and will let everyone know how it works. I had my Imco's rebuilt and while reinstalling a friend decided to play with the tie bar so I do not know how they used to be
adjusted. But the boat ran amazing before so lets hope it runs at least as good or better now!

I still would love to learn reasons why drives need to be toed a certain direction. So far I have gathered
Direction of prop rotation
V hull wake drives need to have nose cones closer together to follow the direction of the water
V hull wake drives need to have props closer together due to the water reemerging back to the center

Still have not figured this one out.

So first I want to understand what forces the props have on the drives. For example. If the props are spinning out do they PUSH the props closer together which pulls the nose cones apart or...

Do the props grab the water and pull outward forcing the nose cones together and spacing the props further apart?

Once I understand this I can understand how I want to toe my drives. I need to just try them each way and see but I never got around to it last summer.

to answer your prop question what ever direction the lower half of the prop is moving it will pull the drive in opposite direction, so a clockwise rotating prop wants to move the rear of the drive to the right. I hope thats not confusing.

your both saying the same thing,,,,one is talking about the front of the drive being out from center line,,,and another is talking about the rear of the drive being closer together

[QUOTE=offshorexcursion;3940858]Still have not figured this one out.

So first I want to understand what forces the props have on the drives. For example. If the props are spinning out do they PUSH the props closer together which pulls the nose cones apart or...

Bingo. Turning out will push props together. Turning in will push props away.

Assuming your 36 is set up like most conventional V bottoms. Your props should turn out. You want your drives "toed in".

Still confused

Pstorti thinks props spinning out spreads the props further apart (clockwise on the starboard drive, counter clockwise on the port drive)

PowerplayJ thinks props spinning out pushes the props closer together

????

No offense to anyone, I have read EVERY thread on this website and NONE of them say the same thing!!!! UGHH! LOL!

The only thing that 99% of users agree on is to toe in or out the measurement of 1/8th of an inch. Got that part down. I will set them at a 1/8th inch difference.

I have my own opinion but I want to hear what others think.

What force does the prop exert on a drive, does it make the drive go to the right or the left when spinning clockwise?

Test 1/8" in, 1/8" out and then neutral in back to back test in flat water. The GPS will give you the answer and you won't care about "who's on first"....

Go out and test. Start with them dead nuts straight. Go out and base line. Then turn in and out till you get the best speed. Bingo, Testing is the fun part.

That's not what I said i am talking about one prop on one drive so you get the concept of the force each prop exerts on the drive, once you grasp that then two props in or out are easier to understand. No offense to PowerplayJ but he is wrong it is opposite of what he wrote.

But really who cares Ben and bwd are right tinker around with it and see what happens, just make sure you do all 3 tests on the same day and in both directions.

I agree that I need to try it each and every way for my personal boat

It would be nice for us all to come to a common understanding on the what, why, and how of this entire concept.

Does a RH rotation prop push the rear of the drive to the port or does it pull it to the starboard?

Does the water flow separation of a V-Bottom have any affect on drives

Etc etc.

Thanks for all the reply's so far.

If props spin out, then the leading edge/front of the drives should be 1/8" closer together than the propshaft centers.
Spinning out pushes the props together and the leading edges farther apart.

That is exactly what I said. Are we both wrong? :D

You said out on both adjustment situations.

My brain can understand how props spinning out can force the props closer together

I also can understand how props spinning out can pull the props apart.

to confuse us even more. I would think a surface style drive (Arneson, #6, NXT, Indy, M8, SCX-4) might be different because only the lower half of the prop is in the water.

There was a decent article in the May 2013 Performance Boats Magazine in the Teague on Tech section on this very matter. Since I don't have a twin, I honestly don't know if it was good information or not, but a good read....

yes it is opposite of what you and Griff are saying. Spinning out is starboard clockwise and port counterclockwise, the bottom half of the prop is what pushes the drive, so a clockwise rotating prop wants to move the rear of the drive right (starboard, out), a counter clockwise rotating prop wants to move the drive left (port, out).

I don't understand how you guys figure it works the other way.:confused:

the effect is worse because the top half of the prop isn't offering any opposing force. But a surface style drive example just reinforces my point.

Makes sense. I was thinking of the down turning blade pushing the transom up and drive in. BTW P thanks...

So what speed and or handling difference being 1/8" off do you think it would make.

Reggie fountain wrote on a thread here and Bob Teague wrote in that article quoted in this thread, that the nosecones should be closer together then the prop shafts due to the V Hull Water flow. Neither of them explain what forces the props have on the drives in a submerged (standard bravo style) condition.

Now Bob does explain in the article linked more details on surface drives and cats. Lets not get that confused with a standard bravo style V bottom.

So YES, on a SURFACE drive the bottom half of the prop is what pushes the drive, I have not read anywhere that the same is true WHEN the prop is FULLY submerged??

Still a little confused but learning more and more everyday!

Still going to try different ways on my personal boat, but just like to understand the science behind what I am doing also.

The same is true for any prop, the reason the prop pushes the drive has to do with water pressure differences due to depth and differences in water speed due to the effect of the hull, as you get deeper the pressure increases which give the lower half of the prop better bite and allows it to dictate the direction of force, also the water coming off the hull can be moving faster than the water deeper down which. Obviously on a 15" prop it is a very small difference but its enough to cause an effect. on a surface drive the difference is large because the water pressure is zero on the top half of the prop and the hull has no effect on it. Think about how an airplane maneuvers minute differences in air pressure are all that is needed to make a huge jet change direction. Same principles different fluid. If you have ever driven or been on a marina launch the kind used to get boaters to moored boats, or any single screw inboard with a rudder. They will crab sideways in one direction easy as can be in the other direction not so much, the reason is due to the prop rotation and its tendency to walk left or right depending on the rotation. Do a search on prop walk and you will find lots of explanations. The reality is that every boat is different and either trial and error or talking to somebody with experience setting up your hull are the only ways to figure out the best setup.

I've read the whole thread. Try this. Take your props off. Measure you're current toe in or toe out measurements. Now take a cinch strap and wrap it around your port and starboard prop shafts and apply some pressure on them. I guarantee you'll see your statics specs fly right out the window and your drive will also go out of parallelism too. Static settings are all depending on the play in the hinge pins, gimble ring and tie bars etc. Trial and error are the only way I know to obtain the best handling and speed for any given setup and propellers.
Just my own personal experience and two cents worth.
SRQ

UPDATE!

Tried the Drives toed both ways and could not tell a difference in speed or handling!

No biggie, its fun to learn and try new things.

I've been doing some significant changes to my 31 Sonic. Ground down both drive bullets... took off a lot of material and fared them up. Brought both drives to a nice pointed edge.. this affected the feel a lot.. very crisp feeling after this was done. Removed roughly 3/8" hook from strake to strake. Sharpened all the transom lines. Removed 1/8" hook from lower strake ends. Smoothed out bottom of both trim tabs.. heavy orange peel. Took every thing out of the cabin of the boat that was loose or could easily be removed including the quite heavy modular center sliding cushion. All said and done.. Top speed was unchanged. Top speed stuck at 85. So far the only thing that's been noticeable was the sharpening of the leading edge of the drives. I only know this because I intentionally did this last.
Then I spent some time measuring the toe of the lower units. I found 28 1/2" space forward and 27 1/4" at the rear. This had me excited. I added and inch to 28 1/4" and saw no gain, but the boat did seem to react a little less to trim, and top speed was achieved with less total trim. To my way of thinking, if the 2 drives are not exactly parallel they will be adding transom lift which will in theory give you a wetter bow. I plan now to apply the tension pushing the rear of both drives together and then adjust them to be perfectly parallel.

So I finally got it back on the water with the drives set to exactly parallel. Talked with the guys at Hering and they said my 5 blade props spinning out would be pushing the water towards the center and I should go slightly toe out to compensate. I used a strap and with a fare amount of tension the drives didn't move in either direction. I do have all new hardware so maybe Merc has improved on their transom assemblies. Anyway no change in speed but my slip improved by a decent amount. Same speed but 200 rpm lower. Conditions were not as favorable the lake was not very choppy and I had a 3rd person on board so maybe running the exact same top speed means I did improve slightly.

Great info, I love it!

Thx for taking the time to post.

Validates what I found decades ago.