Twin engine props turn in vs out and toe in vs toe out?

[DangerNewb]

Anybody care to share some knowledge on handling
and performance characteristics between props turning in vs out and recommended direction and amount of toe?

[rgsauger]

What kind of boat?

[DangerNewb]

What kind of boat?

25 Liberator with center pod.

[FUJIMO]

...randy & liberator should know best on this...

[Davidlake]

There has been a lot of discussion about prop spin on this site.
Out = stern lift.
In = bow lift.

Toe: parallel for speed.

[Instigator]

I’ve plaid w/it a bit but only on vee’s.

All I know for sure is, listen to what the experts tell you, then try it yourself.
My results have been contrary to common wisdom.

[DangerNewb]

I’ve plaid w/it a bit but only on vee’s.

All I know for sure is, listen to what the experts tell you, then try it yourself.
My results have been contrary to common wisdom.

Yep, one thing I can say about boats, is everybody has an opinion and plenty of opinions contradict one another. What has been your personal experience? I've been told I want toe in for props turning in and toe out for props turning out. When I say props turning out, I mean right hand rotation on right side and left rotation on left. Toe in, bullets closer together than prop shaft, toe out, bullets wider apart than prop shafts. Also been told you want toe in, no matter what prop rotation.

From a non expert, seems straight would make the most sense. But what do I know??? It's all fun experimenting.

[chevy355mark]

I'm no expert here, but after reading through tons of these threads where barely any information is ever made clear on this matter I can at least sum up what I've gathered.

My understanding is that you want to tow in if they turn in, tow out if they turn out. You will read some guys saying to tow it this way or that way for bow or stern lift but in reality the tow is just an accommodation for the direction the props turn. Turn out for neutral/bow lift, turn in for stern lift. Setting the tow out or in will not create any bow or stern lift in and of itself, its the direction the props turn that changes the handling and the tow that accommodates whatever direction they turn in. The confusion(at least for me) is what is considered as toe out or in. What makes logical sense to me is the propshaft centerline measuring less distance then the nosecone centerline means towed in... which is incorrect. I wish people would just speak in terms of measurements when it comes to these threads.

My motors turn out, left-hand motor on the port side as most boats are. the nosecone centerline is 1/2" larger in measurement as compared to the propshaft centerline... Before I installed the solid mounts, the boat would chine walk if it had no tow at all. now without any rubber mounts it likely will make no difference on a 64mph fishing boat. I had them almost at a full inch of tow and adjusted them down to 1/2" and didn't really notice much difference.

I believe on a slow boat with rubber mounts and soggy seastar steering, its helpful to have a bit of tow to keep them torqued up against each other. who knows what the tow really is by the time the 1/2 piece of trash seastar calls a tiebar bows up between the motors anyway lol(in my case anyhow). On a real boat with real steering and solid mounts, closer to strait is probably going to be the fastest unless your trying to solve a handling problem. just me speculating... again, no expert here.

[DangerNewb]

Thanks Chevy355. Your idea of stern lift or bow lift/neutral is opposite of what David said above. Like I said, everybody has an opinion and many contradict. Assuming we are all in agreement that:

Turning in = left hand rotation on right/starboard
Turning out = left hand rotation on left/port

Toe in vs. toe out, think of the bullets as the toe:

Toe out = bullets (toes) are wider than prop shaft
Toe in = bullets (toes) are narrower than prop shaft

It's a bit ironic, but turning out, the actual force on the engines is to push the engines apart since the bottom of the rotation (where prop is in the water on a surfacing application) is actually turning in.

So there seems to be some common sense that turning out, pushing the engines apart, would warrant the toe out (prop shafts closer than bullets) since the actual force on the engines is pushing them apart.

At least that's what seems like commons sense to me. I have 1/8 inch toe in (bullets closer than prop shafts) right now but that's all the adjustment range I have on the tie bar. Thanks for the thoughts.

[rude tim]

When I was on the Renegade offshore team 36’ skater we would run the props spinning out for rough water races because the driving tip of the prop was further out side making the boat more stable. When the water was smooth we would turn the props in and remove the 1.5” spacer, this would free up the boat and it would run faster. ​Note* we ran the boat in smooth water testing without the spacers turning the props in and out and it was faster with them turning in. Most boats will run faster with the props spinning in but you give up some stability.