Outboard Mounting Holes

Designs for inboard or outboard power

Moderator: BruceDow

User avatar
mrintense
Posts: 2885
Joined: Thu Jun 10, 2010 11:22 am
Location: Austin, Texas
Contact:

Outboard Mounting Holes

Postby mrintense » Mon Jan 20, 2014 5:18 pm

I'm in the process of gluing the motor board to my transom and I want to make sure that I don't place any wood screws were the outboard will eventually mount.

I went online and was able to find the mounting hole distances from center for the Evinrude engines. It's a little over 6 inches at the top. The bottom is around 4 or 5 inches. But I can't seem to find the same information for Mercury engines which seems strange to me given the number of engines out there.

Anyway, I am not looking to drill these holes right now, I know that I can get a template or use the mounting bracket on whatever engine I end up purchasing. Mainly I just need to get some general idea of where these mounting holes will be so that I don't place wood screws in those locations.

Just as a point of reference. I'm planning on buying something in the 100 - 115 HP range. Probably an ETEC but I have not gotten to the point where I know for sure what it will be.

Thanks for any help
Carl
a.k.a. Clipper

Crafting a classically styled Vera Cruise named "Some Other Time"

Clipper's Vera Cruise Build

User avatar
mrintense
Posts: 2885
Joined: Thu Jun 10, 2010 11:22 am
Location: Austin, Texas
Contact:

Re: Outboard Mounting Holes

Postby mrintense » Mon Jan 20, 2014 6:43 pm

From what I've been able to find, this is an AYBC standard pattern . The dimensions I found are

Top holes - 2" down from top of transom (cut out I assume?), 6-7/16" from center on each side

Bottom Holes - 8" down from top holes (10" from top of transom), 4-15/16" from center on each side.

I saw this dimension on the Evinrude pattern and saw a posting from another builder who measured an OMC outboard.

Fell free to weigh in on this.
Carl
a.k.a. Clipper

Crafting a classically styled Vera Cruise named "Some Other Time"

Clipper's Vera Cruise Build

gdcarpenter
Posts: 1354
Joined: Tue May 05, 2009 12:18 pm
Location: Raleigh, North Carolina

Re: Outboard Mounting Holes

Postby gdcarpenter » Mon Jan 20, 2014 7:41 pm

No help here, running a 1959 Mercury Mark35A, old school clamps and all that. Seems, from what you wrote, you can run screws vertically down the center line, then keep clear 8"-10" either side of center. How many screws you plan on installing?
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

User avatar
mrintense
Posts: 2885
Joined: Thu Jun 10, 2010 11:22 am
Location: Austin, Texas
Contact:

Re: Outboard Mounting Holes

Postby mrintense » Mon Jan 20, 2014 7:57 pm

I basically did what gdcarpenter mentioned. Also had to determine approximately where the knee bolts would be .

I used enough screws to insure a good bond across the entire surface.This component will be under stress so I want to make it as strong as I can.

I don't have any way to clamp the center section other than screws so I want to use these. Not going to go overboard.
Carl
a.k.a. Clipper

Crafting a classically styled Vera Cruise named "Some Other Time"

Clipper's Vera Cruise Build

User avatar
Bill Edmundson
Posts: 11076
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Outboard Mounting Holes

Postby Bill Edmundson » Mon Jan 20, 2014 10:07 pm

Carl

I'm not certain. I'll measure tomorrow. I think the Yamaha is 2" down from the transom to the top holes which are 10" apart. Then 8" down to the lower holes which are 8" apart. Don't drill yet :!: I haven't :!: But, for places not to put screws I think I can get that.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

User avatar
Bob Maskel
Posts: 500
Joined: Wed Dec 13, 2006 11:42 pm
Location: Apple Valley, MN (Mpls.) Sea Knight/Malahini

Re: Outboard Mounting Holes

Postby Bob Maskel » Mon Jan 20, 2014 11:00 pm

mrintense wrote:I'm in the process of gluing the motor board to my transom and I want to make sure that I don't place any wood screws were the outboard will eventually mount. Thanks for any help
Wow, why didn't I think of asking on here!! I am in the same mode...have held off attaching the horizontal 2X4 at the transom because I didn't want to run into any interference with the bottom motor mount bolts. I will be watching here closely to see what you find out. Thanks for posting this!
Bob
Sea Knight on the water/Malahini in progress

User avatar
Bill Edmundson
Posts: 11076
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Outboard Mounting Holes

Postby Bill Edmundson » Tue Jan 21, 2014 12:25 pm

I just measured. These were taken in the boat yard from several boats in the 115 to 150 range. Others looked the same.

From the back edge of the transom:
Top hole were down 2" spread 13"
Bottom holes were down 10" spread 10"

Your mileage may very.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

User avatar
mrintense
Posts: 2885
Joined: Thu Jun 10, 2010 11:22 am
Location: Austin, Texas
Contact:

Re: Outboard Mounting Holes

Postby mrintense » Tue Jan 21, 2014 2:38 pm

Bill Edmundson wrote:I just measured. These were taken in the boat yard from several boats in the 115 to 150 range. Others looked the same.

From the back edge of the transom:
Top hole were down 2" spread 13"
Bottom holes were down 10" spread 10"

Your mileage may very.

Bill


That sounds basically identical to the numbers I posted earlier. I think we can probably assume that they are an AYBC standard. Thanks for taking the time to do that Bill.
Carl
a.k.a. Clipper

Crafting a classically styled Vera Cruise named "Some Other Time"

Clipper's Vera Cruise Build

User avatar
Bill Edmundson
Posts: 11076
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Outboard Mounting Holes

Postby Bill Edmundson » Tue Jan 21, 2014 2:55 pm

Carl

It's always good to get a confirmation from someone else. I also think it must be a standard.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

User avatar
Catbldr
Posts: 21
Joined: Sat Jul 08, 2017 8:59 pm
Location: Nags Head, NC

Re: Outboard Mounting Holes

Postby Catbldr » Sat Feb 24, 2018 8:13 pm

I know this is a late post but since around 1985 the mounting holes are standardized. A 4 hole pattern. The template is online. Going to mount my transom knees and transom reinforcement tomorrow.

Brad Tucker
Posts: 322
Joined: Tue Jun 29, 2010 7:20 am
Location: Washington, GA

Re: Outboard Mounting Holes

Postby Brad Tucker » Sun Feb 25, 2018 9:32 am

If it helps I can measure a 1994 MercuryXR 150hp
Last edited by Brad Tucker on Sun Feb 25, 2018 4:35 pm, edited 1 time in total.

User avatar
Bill Edmundson
Posts: 11076
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Outboard Mounting Holes

Postby Bill Edmundson » Sun Feb 25, 2018 10:21 am

Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build


Return to “Power Boats”

Who is online

Users browsing this forum: No registered users and 20 guests