Moderated Discussion Areas
  ContinuousWave: Whaler Repairs/Mods
  Twin Engine Installation Guidelines

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   Twin Engine Installation Guidelines
modeseven posted 04-08-2006 02:06 PM ET (US)   Profile for modeseven   Send Email to modeseven  
I am in the process of mounting twin 140-HP Johnsons on a 1984 Outrage-22. I had a single 250-HP on there that blew up. I am new at this whole process. Is there some kind of mounting template I can use for the bolt patterns?Do [the outboard motors] have to spaced at a certain distance? What do I need to do in this situation?

Any help would be greatly apreciated. Thanks.

Buckda posted 04-08-2006 10:26 PM ET (US)     Profile for Buckda  Send Email to Buckda     
The Center/Center spacing is 29-3/4 inches.

The bolt pattern should be standard BIA. You can make a template using the original motor holes and a thick block of plywood (ganged up to be about 2 inches thick to help guide your drill). Your dealer may also allow you to borrow his metal template (mine was kind enough to do so).

Do a search on this site for "Twins and Installation" and you will find a lot of good information.


jimh posted 04-09-2006 09:34 AM ET (US)     Profile for jimh  Send Email to jimh     
Generally the outboard motor manufacturer will provide installation instructions for mounting the motors. Bombardier has a very extensive installation instruction book. You should contact your local Bombardier dealer and purchase a copy of the book. It will give you a fantastic resource of information on the installation of their outboard motors.

In as much as the document is over 125-pages long, it is difficult for its contents to be summarized and provided here.

Boston Whaler also has guidelines for installation of the outboard motors on their boats. In this instance your fortune is better; you can obtain this information from the REFERENCE section. See: html#engineInstallation

If you are not an experienced outboard engine rigger and installer, you probably ought to obtain some assistance. Because of the expense of the motors and the significant amount of time and labor involved in a twin engine installation, it is unwise to undertake this yourself if you are unfamiliar with boat rigging.

Based on the nature of your questions, I have made an assumption that you are not a professional rigger nor have you done this before. On that basis, I recommend you try to find a cooperating dealer or professional rigger who will work with you and supervise your installation for a reasonable fee.

Within the archives of the website there is applicable information, but there is no concise summary or set of instructions written specifically for your installation.

Tom W Clark posted 04-09-2006 02:17 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Make a drilling template as Dave describes using the BIA standard layout that Jim has provided. Drill the holes 1/2" diameter, not oversized.

Space the engines at 29.75" o.c. as Dave instructs and be sure to set the toe-in to 1/2" - 3/4" (front edges of the gearcases closer than the back of the propeller hubs.)

L H G posted 11-06-2008 08:03 PM ET (US)     Profile for L H G    
As an owner of twin engine Whalers, I have been confused by this toe-in and toe-out designation, since what I have always understood from Mercury is the opposite designation of what Tom is saying.

Now, looking at the Teleflex hydraulic steering manual, page 10-13 (available on line), I see that Teleflex uses the same convention that I do.

They say:

Toe-out = props farther apart than engine centerline (the prop is the "toe" of the foot, the engine gear housing is the heel).

Toe-in = props closer together than engine centerline (pigeon toe!).

So if Tom recommends twin engines set so that the props angle out a little, Teleflex would call that setting your engines for "toe-out", not toe-in.

TransAm posted 11-09-2008 09:25 AM ET (US)     Profile for TransAm    
Yamaha refers to "toe-out" position as props closer together (gearcase is toe, not propeller) and recommends a "toe-out" rigging of less than 1 inch such that the respective wakes meet approximately 20-25 meters behind the boat. I have always understood this to be universal language.
jimh posted 11-09-2008 11:39 AM ET (US)     Profile for jimh  Send Email to jimh     
The TELEX manual loosely cited above appears to use an orientation regarding these terms which is exactly the opposite of everyone else's. In particular, OMC, Bombardier, and Boston Whaler all use the term as Tom Clark has. I quote from their literature in my article on twin engine rigging:


Tom W Clark posted 11-09-2008 01:13 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Yes, we are all in agreement about how the motors should be mounted but there seems to be some misunderstanding as to how to describe the condition.

Lets try a little visual trick: Stand behind your boat facing the direction it travels. Look at down at your toes. If your toes are closer together than your heels, that is a toe-in condition. If your toes are further apart than your heels that is a toe-out condition.

This is consistent with the automobile industry in terms of front end alignment of the wheels.

jimh posted 11-09-2008 01:47 PM ET (US)     Profile for jimh  Send Email to jimh     
I am unable to locate any information from Teleflex which contradicts the otherwise widely used sense of position for toe-in and toe-out. I found a Teleflex publication on twin-engine outboard installation:

Dual Outboard Kit instructionmanuals/IS-7602.PDF

This publication mentions toe-in and toe-out as follows:

"Set the motors in a dead-ahead position and adjust for any toe-in or toe-out in accordance with the motor manufacturer's instructions."

This Teleflex literature does not define toe-in or toe-out in any explicit manner, and it refers one to the literature of the engine manufacturer. I don't find this publication to be authoritative on the definition of toe-in or toe-out, and it actually defers to the engine manufacturer on this topic.

It is also mentioned above that Mercury suggests an opposite orientation of toe-in and toe-out from that used by OMC, Yamaha, BRP, and Boston Whaler. I could not locate any instance of this using GOOGLE: as_qdr=all&

Could we have a URI or cite of where in the literature these alternative references can be found?

towboater posted 11-09-2008 02:27 PM ET (US)     Profile for towboater  Send Email to towboater     
In the Tug world, toe-in or out is used in regards to RUDDER ALIGNMENT.
Toe refers to the leading edge of the rudder.
Toe-in adjustment would bring the leading edge of the rudder IN, towards the keel. My Tug rudders toe-in 1.5 inches each. Toe in reduces bushing slop compared to aligning the rudders square with the keel. Too much toe can be as bad as not enough.

Outboard engines are also rudders.

Note that Tom, Dave and Jim references for toe in distances are close, but not exact. Every setup is a little different, have fun tweeking them and enjoy security of twins. Sounds like a nice setup.

Isnt there a specific way/process to drill holes in the transom that prevents water intrusion in the transom wood? I used a high dollar sealer but cant remember the name and no time to research today. It was similar to silicone but FAR better seal and waterproofing properties.
I purchased this stuff at a marine hardware store...I do remember the price...$16 for a small tube but well worth it.

good luck with your project


Tom W Clark posted 11-09-2008 02:29 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I have a Teleflex SeaStar hydraulic steering installation instructions and owner's manual in front of me now.

Looking at pages 10-13 I see no mention of toe-in or toe-out at all regardless of how it might be defined. In fact, I can find no mention of toe throughout the entire publication.

towboater posted 11-09-2008 02:36 PM ET (US)     Profile for towboater  Send Email to towboater     
BTW, check out CW references for plugging the previous mounting holes in the transom.

seabob4 posted 11-09-2008 02:52 PM ET (US)     Profile for seabob4  Send Email to seabob4     
Toe-in or Toe-out is determined through testing and seeing what works best, performance-wise. Now, to make sure all are on the same page, the toe is the gearcase, or "bullit", the prop the heel.

When I was Hanging motors at Wellcraft, we went with 1/2" toe-in. When I left and went to Stamas Yacht, they hadn't done any testing (no engineering department), I stuck with 1/2" toe-in. Now Proline uses straight alignment, no toe in or out. Yet our sister company, Donzi, uses 1/2" toe-out. So what's the deal?

Now if we look at it from a physical standpoint, toe-in forces the thrust of both motors to the centerline of the boat. I believe in that concept, though have not done any hydrodynamic analysis of it. Toe-out might cause the motor induced wakes to converge sooner, but, so what? Does it increase performance? Questionable. A clean wake is great for trolling when dragging multiple lines, but how fast are you going? 6-7 knots? Convergence of wakes is pretty much a moot point at that speed.

So I'll stick with 1/2" toe-in. IMHO.

seabob4 posted 11-09-2008 02:53 PM ET (US)     Profile for seabob4  Send Email to seabob4     
You are correct about the Seastar manual. Alignment is left up to the installer.
number9 posted 11-09-2008 06:35 PM ET (US)     Profile for number9  Send Email to number9     
I have a couple of Yamaha and one Honda rigging manuals. Depending upon the motor range installed, they have have a minimum center line distance between them.

They both refer to rigging them toe-out, with Honda simply defining: "Toe-out is when the motors' forward measurement is wider than the motors' aft measurement."


Tom W Clark posted 11-09-2008 08:36 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

This thread is two and a half years old. It was resurrected a few days ago by Larry to discuss the ambiguity of the terms "toe-in" and "toe-out". Whether you want toe-in or toe-out is another discussion that has been talked about many, many times already. Likewise, how to seal old holes in the transom is another topic that has been discussed many, many times.

It would seem on the face of it that different outboard motor manufacturers use different definitions of what toe-in is, though we have yet to see any specific reference or URL cited.

It may well be that the terms "toe-in" and "toe-out" are used differently by different manufacturers. This is too bad as it leads to confusion. Perhaps we should agree to avoid the terms and be more explicit when discussing the alignment of twin outboards. I tried to use both descriptors in my post from two and a half years ago precisely to avoid this ambiguity.

Intuitively, the OMC/BRP definition makes much more sense but if Mercury and Honda see it exactly the opposite way, then so be it. We will have to avoid using those terms.

In my trade there has always been an irritating lack on consensus on how to describe how a door swings. There are numerous definitions, all using the terms "right hand" and "left hand" to describe which way a hinged doors swings. You wouldn't think it would be so hard to come to an agreement but it has been for many, many decades.

Every time I order a hinged door, even if I am ordering from one of the same salesmen I have been using for years, we always have to go through this tedious double check or triple check to see if we are both using "right-hand swing" and "left-hand swing" the same way. Of course everybody always tries to argue their way is the only correct way!

Casco Bay Outrage posted 11-09-2008 10:06 PM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
Tom -

Gotta love the door order analogy. Funny memories from past projects. ROTFL.

L H G posted 11-10-2008 05:39 PM ET (US)     Profile for L H G    
If you go to this link, download the "Selection Guide", and see page 10-18 for Teleflex's designation of toe-in and toe-out.

Since they basically own the outboard steering market, used for all brands of engines, I figure they should know what they are talking about?

Plotman posted 11-11-2008 02:28 PM ET (US)     Profile for Plotman  Send Email to Plotman     
Well, after reading the Teleflex manual, it is obvious what the issue is.

You use the term "Toe'd Inwards", when you are referring to propellers closer to each other (as teleflex does) as if one were sitting on the transom with his feet hanging over the back of the boat, but Toe-Out to describe the same condition as if you are standing behind the boat and facing in the direction of travel.

Please make note of this in the CW style manual.

jimh posted 11-11-2008 09:25 PM ET (US)     Profile for jimh  Send Email to jimh     
Larry--Can you just give the link to the publication. The link you gave lists about a dozen.
jimh posted 11-11-2008 09:32 PM ET (US)     Profile for jimh  Send Email to jimh     
Perhaps Larry is talking about this publication:

The section he mentions is talking about hydraulic tie bar installations. I really do not find it to be authoritative. I am not in the least inclined to abandon the guidelines of OMC, BRP, Yamaha, and Honda based on this obscure usage in a Teleflex publication talking about hydraulic tie-bar set up. They clearly got it wrong. Their main problem is they make reference to the propellers. Sorry, Teleflex, but the propellers do not have any toe-in or toe-out. The are, or should be, perfectly symmetrical. It is the propeller shafts that have an offset angle from dead ahead, not the propellers. Referencing the propeller shaft angle and whether or not they are parallel or convergent is the best way to describe toe-in or toe-out. Even if you accepted the propellers as a point of reference, Teleflex's definition only works with regard to aft-facing propellers. It's just sloppy writing, not the "right" definition.

Larry--you also asserted that Mercury uses this same backward-looking metaphor regarding toe-in and toe-out. Can you give us a citation where Mercury is similarly backward-looking?

L H G posted 11-12-2008 11:31 AM ET (US)     Profile for L H G    
OK, I am not arguing with you guys, just giving you some alternative reference material I stumbled upon. As I said, since Teleflex is the world's major manufacturer of steering systems for outboard, sterndrive and Inboard powered boats, and probably works with all engine and boat manufacturers, I am surprised they are considered incompetent on CW. Or maybe it is just a huge typo. But actually they are on to something. Showing the way the props angle in or out. That's what counts. Remember, all that is being dicussed her is NAMING CONVENTION, pure symantics, wheter you are looking at the engines standing to bow, or to stern.

So be it resolved here on CW, Telflex simply has it wrong in their naming convention. I'm just the messenger here.
Angle your "prop shafts" inward or outward at the propeller, and call it what you like.

The only thing I have seen so far is something from bankrupt OMC, quoted by Jim. Perhaps THEY got it wrong, like they did with a lot of other things outboard?

Can anybody show us literature from Honda, Suzuki, Yamaha and Mercury/Boston Whaler in an official publication (like Telflex has done) that shows Teleflex wrong?

The information I had from Mercury was shown to me from a Mercury Rigging Technical Manual, about the size of a tlelphone book, once shown to me by Sundance Marine when first rigging "Whale Lure" and then again shown to me in 2004 by Robert Moore in Stuart. So this would also be hearsay information. I tried to get a copy of this incredibly comprehensive and valuable book, but they wouldn't give me one. It talks about prop wash converging behind the boat in "X" number of feet, etc. When prop wash converges inward, I recall "toe-in" and when it diverges outward, I recall "toe-out". Seems logical to me.
My installation guide for the Mercury HD dual engine tie bar for counter rotating engines, which I am using, indicates "MUST BE" straight ahead position, no toe-in or toe-out.
Does anybody know how BW is rigging their twin Verados, has a copy of their official rigging publication, and what naming convention is being used? If I can't see it writing, I'm not believing it. Not interested in hearsay.

In the meantime, I am willing to stipulate that Teleflex's printed publication is in error.

Tom W Clark posted 11-12-2008 12:23 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I do not think the publication cited above is a typo, but it is important to understand what it is saying.

For starters it does not define "toe-in" and "toe-out" in the context of rigging twin outboards on a boat but rather uses the terms "Toe'd Outwards" and "Toe'd Inwards" in the context of adjusting a liquid tie-bar.

If you are adjusting the liquid tie boar on a catamaran, you are probably doing so from within the boat observing the motors form the cockpit. This is quite different from discussing the performance of a twin outboard boats performance as it moves through the water.

TransAm posted 11-12-2008 05:54 PM ET (US)     Profile for TransAm    
From the Yamaha Rigging Manual ?action=view¤t=YamahaRiggingSpecs.jpg

Tom W Clark posted 11-12-2008 06:11 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
So it would seem that Yamaha also uses the term [b]toe-out[b] to indicate a condition where the leading edges of the gearcase are further apart than the propellers.
L H G posted 11-12-2008 06:53 PM ET (US)     Profile for L H G    
Tom - you're reading the diagram wrong. It says toe-out, clearly shown in the diagram looking down on the engines with props outward, says A (engine mounting centerline dimension)-B (tiebar dimension), should be 1" or less. That means the tiebar should be shorter than centerlines, making the props angle outwards for toe-out. Looks like Teleflex, and I believe Mercury also, is correct.

Even with the Yamaha/Teleflex definition, engine wakes will still converge behind the boat.

thanks for that information, TransAM

Tom W Clark posted 11-12-2008 07:01 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

I grant you that the twelve year old diagrams in TransAm's link are terrible, but a careful study of them will show you that it is you who has it backwards. The second illustration is more clear.

L H G posted 11-12-2008 07:09 PM ET (US)     Profile for L H G    
Tom, I'm sticking with the toe-out diagram, which says" Set the engines with toe-out less than 1". Then it also shows the formula at the bottom of the first diagram of A - B = 1" or less.

So their written and drawn description of toe-out is a tie bar shorter than engine centerlines.

Tom W Clark posted 11-12-2008 07:14 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Uh, Larry? Distance "A" is at the front of the motors. Distance "B" is at the rear of the motors.
L H G posted 11-12-2008 07:18 PM ET (US)     Profile for L H G    
I am reading small case "a" as engine centerline, and small case "b" as tiebar length.

Could anybody else render an opinion on this drawing please?

TransAm posted 11-12-2008 07:35 PM ET (US)     Profile for TransAm    
I believe the diagram is quite clear. The "a" distance minus the "b" distance should be less than 1". Therefore, "a" is still greater than "b", and as such, the gear case is farther apart than the propellers and is noted as "toe-out" position. This is further clarified in the diagram at the top of the second column where it shows the wakes converging approximately 20-25 meters behind the boat. The only way this could occur (aft wake convergence) is if the gear cases are farther apart than the props. Yamaha clearly refers this as "toe out" Sorry Larry, I believe you are incorrect in your interpretation. If you click on the magnification to "full size" the diagram is more clear.
jimh posted 11-12-2008 08:28 PM ET (US)     Profile for jimh  Send Email to jimh     
Yamaha's diagram is ambiguous because it does not clearly denote which way the motors are facing. If you assume the upper portion of the diagram represents the motor facing the bow, then a measurement of


implies what we have been calling "toe-out" and what Yamaha calls "toe-out." But if you interpret the diagram to mean the motors are facing toward the bow in the bottom of the drawing, this reverses everything.

My interpretation is taken from the visual cue of the cowling shape, which is wider in the the stern, and thus I see the bow of the boat as being in the up direction. This make the Yamaha nomenclature consistent with BRP, OMC, Honda, the car industry, Tom Clark, my article, and who knows who else.

L H G posted 11-13-2008 01:44 AM ET (US)     Profile for L H G    
Taking Transam's advice and enlarging the drawing clearly shows the "b" dimension as referring to the engine's lower units at the props, so I was dead wrong in my interpretation. On my smaller computer screen, I thought the "b" dimension showed the engine's steering tongues.

BUT, it is interesting to see that Yamaha recommends the props angle inward, against most other advice I have seen here for V hulled boats. I have always run my 200's that way, with a slightly longer tiebar length than centerlines, as recommended by my Mercury people. They told me it concentrates the power rather than dispersing it.

TransAm posted 11-13-2008 07:20 AM ET (US)     Profile for TransAm    
If you compare the diagram at the bottom of the 1st column with that at the top of the 2nd, there is no doubt which way is forward. The smaller square-like shape inside the cowling outline reflects the rear of the motor, as does the shape of the cowling. This is apparent in the 2nd diagram whereby the propwash/wake is shown emerging from this side of the engines.

Post New Topic  Post Reply
Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.