Outboard Cutout Dimensions on E27

Dan Mendat

Junior Member
Could someone out there with an E27 that has the outboard cutout in the transom please give me some measurements. I'm gonna be mounting a 25" longshaft OMC classic 2 stroke and need to know where to cut. A simple measurement from the base of the transom to the top of the mounting surface of the cutout where the outboard mounting bracket will rest is really all I need as the side cuts are pretty much self explanatory. A close-up picture of your particular boat's cutout from the rear and cockpit would be greatly appreciated. No outboard bracket will be installed. Just a mounting block on outside/inside form motor mounting bracket. I'll try to document this process.
The original inboard has been removed and the stern tube filled in. I'll be using the existing inboard gas tank and plumb the outboards fuel line into it. I'll most likely use the exhaust outlet on the rear to run my fuel and electrical lines from the outboard into the cockpit locker. I was originally gonna be installing an E-Pod form re-e-power, but do to demand the wait time is too long and I need to get sailing. Can't wait, its been too long of a winter!
Any help would be greatly appreciated. And please, I just need relevent information on the cut out and not on outboards or inboards. I say this because some earlier posts about the cutouts get off topic and talk mostly about motor choices.
Thanks
Dan Mendat
1974 Ericson 27
 

G Kiba

Sustaining Member
Dan,
I'll try to get to my boat today and make a quick measure. We had strong winds in the area yesterday and last night so I need to check in on her anyways. How about a measurment from the top of the transom to the top of the motor mounting surface?

Grant Kiba
'73 E27
Antioch, Ca
 

Dan Mendat

Junior Member
Thank You in advance!

Dan,
I'll try to get to my boat today and make a quick measure. We had strong winds in the area yesterday and last night so I need to check in on her anyways. How about a measurment from the top of the transom to the top of the motor mounting surface?

Grant Kiba
'73 E27
Antioch, Ca

Grant,
That would be awesome of you to do that for me. I'm really looking forward to hacking away at the cutout area of the transom but need to know where to stop. LOL! Seriously, that would be great if you could measure from the top to the mounting surface. I'll assume that is a factory cutout you have and it should be right on the money dimension wise. Do you have any wishes for your cutout to be taller/shorter so as I may make the change now? Do you have any interior shots of the cockpit to give me a better idea of the layout of motor mounting/support? Also, did you ever notice any other support material underneath inside the transom (only visible from quarter berth access hole)? I looked in there and only see the cockpit drain pipe and thru-hull fitting and no other real noticable items. I'm gonna assume that cutting the opening and then mounting some good hardwood or dense plastic blocks/spacers for the outboard to hang on will do the trick along with finishing the rough edges with glass/resin.
Thanks again Grant!
Dan Mendat
1974 Ericson 27
 

G Kiba

Sustaining Member
Dan,
From top of transom to top of mount is 22 1/4. I didn't get pictures of the inside but here are some of the outside.
 

Attachments

  • gk2.jpg
    gk2.jpg
    76 KB · Views: 197
  • gk3.jpg
    gk3.jpg
    35 KB · Views: 150
  • gk1.jpg
    gk1.jpg
    68.1 KB · Views: 151
  • gk4.jpg
    gk4.jpg
    56.4 KB · Views: 149

Dan Mendat

Junior Member
Thank You Grant!

Dan,
From top of transom to top of mount is 22 1/4. I didn't get pictures of the inside but here are some of the outside.

Grant,
Exactly what I needed! Thank you very much! Next time you're in the Northeast Ohio area, beers are on me! Really appreciate it.
Thanks
Dan Mendat
1974 Ericson 27
 

Dan Mendat

Junior Member
Cutout Complete!

Well lets start off saying the usual statement..."What a Good Old Boat"! The Transom on the E27 is 2 3/8" thick where the outboard cutout is. Very difficult to cut through even with the saws-all with the aggressive dewalt blade on it. We started with a 2 1/4" hole saw and made the radius cuts on the lower corners. That process burned up two hole saws and some serious muscle tissue. Then straight cuts down with the saws-all and then across. 80 grit sandpaper on a heavy duty palmsander eventually knocked down any irregularities in my cutting and smoothed it to a nice smoothness. I then coated the exposed edges with two coats of fiberglass resin. We plan on repainting the decks soon, so no coloring needed in the resin. All in all, not that bad!
As far as internet experts talking of the added weight of an outboard hanging off the back of the transom on the E27, the cutout weighs almost 40 lbs by itself!! I wish you could have heard the sound it made when it crashed to the ground after the final cut! So my 2 stroke outboard which only weighs around 80 lbs is gonna be pretty insignificant hanging off the transom. Not to mention the removal of the 240 lb volvo inboard and shaft/propeller. I will be using the original fuel tank since it is already vented with blower in the bilge (safety first). I'm actually really looking forward to the performance numbers that should increase with this weightloss and dragloss.
Fair Winds,
Dan Mendat
1974 Ericson 27
 
Last edited:

bigd14

Contributing Partner
Blogs Author
Any photos?

I am contemplating a similar project. Do you have any photos of the cutout during the project?

Thanks,

Doug
 

Dan Mendat

Junior Member
outboard cut-out

Doug,
Sorry I didn't respond for so long. No, I don't have any pics. My pics would however look just like the ones posted in the earlier replies of this thread if I had taken any. I used a hole saw to make the large radius corners at the bottom corners of the cutout. After they were cut, I used a recipricating saw to do the rest. Be patient!!! Takes awhile to cut through 2' 3/8" thick material. After cutting it out (watch out were it drops!!! 30 lbs +++), use a sander with heavy grit to level the cuts and smooth the the finish to get it ready for paint. I was able to do this without hardly any damage to the exterior/interior finish.
As far as performance with an outboard as compared to inboard, its pretty bad in reguards to maneuvering. The inboard put the prop in front of the rudder which gave you more maneuverability in tight quarters allowing you to turn the boat on a dime. No longer is this possible. If you need to turn in tight quarters with the outboard, get some speed then cut the throttle on the outboard. Any thrust from the outboard tends to want to keep the boat going in the direction the outboard is facing (which is straight) thus reducing the rudders effectiveness. Reverse is pretty much the same as the inboard was. All in all though, I'm still very happy with my decision to remove the gas inboard and mount the outboard. The boat is definitely quicker with the outboard tilted out of the water (reducing drag). Also, I love the fact that my motor can go home with me in the trunk if any repairs are needed. By the way, I have a 1984 Evinrude Yatchtwin 9.9 25" shaft. No issues with the prop coming out of the water and the power is as comparable to the 15hp inboard volvo, if not better.
Good Luck,
Dan Mendat
1974 Ericson 27
"Second Wind"
 

bigd14

Contributing Partner
Blogs Author
outboard cut out

Thanks for the additional info Dan. Does anyone with the cut out (factory or custom :)) find that an extra long shaft drags a little in the tilted up position? And does the motor compromise much space in the cockpit when its up? I'm still trying to figure this whole thing out!

Thanks,

Doug
 
Last edited:

bigd14

Contributing Partner
Blogs Author
More questions on transom cutout!

OK, so I have started seriously exploring the cutout option, but what I am finding sounds a little different than what Dan found. I drilled an exploratory hole through the cutout location, and discovered that my transom has no core, just two fairly thick sheets of FG. The stern portion is probably 1/4" and the cockpit portion is about 1/8'. In between is just a void. This sounds different from the solid piece that others have found. I have hull #195 with tiller steering and Atomic 4. I wonder if the early hull numbers had a different construction?

So I am thinking about leaving a 2-3 inch bridge across the top (like the boat that Loren mentioned in an earlier post), and placing marine plywood or something in the void spaces left around the cutout, then glassing over them. That should maintain most of the integrity of the transom structure. Loren, do you by chance remember what year or hull # the E-27 was with the transom bridge that you described? That seems a little unusual to be a factory option. I wonder if the top of the motor would hit it when its tilted up?

Attached is a photo of a boat that looks like someone did a custom cutout. Seems like it should be a pretty stable structure.

Any thoughts on this plan of action are welcome. Thanks!
 

Attachments

  • E27 Transom Cutout.jpg
    E27 Transom Cutout.jpg
    35.1 KB · Views: 618
Last edited:

G Kiba

Sustaining Member
Transom Cutout

Doug,

I have a 2006 9.9 Tohatsu with the 25" shaft. Tilted up, the motor does not drag until 7+ knots downwind; then the prop drags about an 1" in the water.

The issure about stearing that Dan mentioned is correct. Reverse puts the prop thrust into the rudder making things a bit tricky. Stearing is best done with the outboard and tiller together. However my Tohatsu is too large for the cutout to allow the motor to be steared in both directions. As it is, I favor left turns when going forward.

Grant Kiba
'73 E-27
Antioch, CA
 

bigd14

Contributing Partner
Blogs Author
Cutout is cutout

Went ahead with the cutout today with some trepidation. But it went much easier than I thought. In my boat, the cutout was cored (mostly) with plywood. Strangely, there was a vertical void about 2 inches wide (of course it was where I drilled my test hole so I thought there was no core originally!). Somehow the area had filled with about 2-3 cups of water, so the core material was totally saturated. Must have been in there for many years, since the all the possible holes in this area were filled (the open holes in the photo are my test holes). Sawzall and a Multimaster made short work of the glass layers, and luckily the plywood was only bonded on the cockpit side. Next up is filling the voids with dry plywood or white oak and thickened epoxy, then a bunch of layers of fiberglass, paint and she'll be ready to roll. Looking forward to getting rid of the rusting hulk down below...

Also, see my post about the reason for the transom cracks in other E27s...

Doug
 

Attachments

  • Transom Before.jpg
    Transom Before.jpg
    36.2 KB · Views: 131
  • Water in transom.jpg
    Water in transom.jpg
    279.7 KB · Views: 144
  • Cleaned out.jpg
    Cleaned out.jpg
    131.6 KB · Views: 130
  • Transom after.jpg
    Transom after.jpg
    205.7 KB · Views: 133

robert.punzalan

New Member
Hello e27 fellows; does anyone got your transom (height) measured? I do have the ‘79 E27, somehow i have the 2006 honda outboard 8HP power thrust, long shaft & bought it 3 months. As a Field Tech Engineer, lol precision is my nature. Therefore, I’d like to know your transom measurements & see the comparison from the last model i have now. From my research of checking the outboard motor, isn’t quite right to have an 8HP. Base on the displacement value & divide it with that ratio, turned out an ideal of 12.7 HP= 13 HP which i decided to replace it with a Suzuki 15 HP DF15AEL4 Outboard. Your inputs is highly appreciated.
 

bigd14

Contributing Partner
Blogs Author
I don't have transom height measurements anymore, but if you have the stern cutout you want an XL shaft which I think is 25 inches. The Yamaha 9.9 Hi-Thrust XL shaft version is one of the best solutions for the E27 with cutout. It has lower gearing than other outboards to deal with displacement hulls better. The prop is larger compared to other outboards. https://yamahaoutboards.com/en-us/home/outboards/jet-drive-high-thrust/high-thrust

The one I put on my former E27 was a 2005 or so model and is still running strong. Great motors.

Fishermen up here in the PNW use them for kickers so there are often used ones available on Craigslist.
 

Stuphoto

Member III
Just my humble opinion,
Try making the cut as clean as possible and keep the cutoff.
Then some sort of clips or flange on it so you can easily slide it in place whenever you want to sail without the motor or show the boat off.

I wish I had that cutoff from mine.
 

G Kiba

Sustaining Member
Hello e27 fellows; does anyone got your transom (height) measured? I do have the ‘79 E27, somehow i have the 2006 honda outboard 8HP power thrust, long shaft & bought it 3 months. As a Field Tech Engineer, lol precision is my nature. Therefore, I’d like to know your transom measurements & see the comparison from the last model i have now. From my research of checking the outboard motor, isn’t quite right to have an 8HP. Base on the displacement value & divide it with that ratio, turned out an ideal of 12.7 HP= 13 HP which i decided to replace it with a Suzuki 15 HP DF15AEL4 Outboard. Your inputs is highly appreciated.
You don't need 15 HP or 12hp on an E27. 9.9 is overkill but usually gives the options of electric start and two smooth running cylinders. I would hit hull speed at 1/2 throttle with my Tohatsu 9.9, 25" shaft. The only problems was the standard cutout in the transom is not big enough to allow turning with the motor. I had to steer with the boat tiller.
 

Stuphoto

Member III
Grant, or anyone else with this setup,
Is your rudder notched to make room for the prop?

The reason I ask, is mine is on my E25.
I assume it got chewed up in the prop but the former owner seems to think it was factory.
 

G Kiba

Sustaining Member
The E27 rudder is well forward of the transom. So the prop does not hit. However in reverse, the thrust can rip the tiller out of your hands if you have too much throttle. I liked the tiller position on the E27. Makes it real easy to singlehand. You can also steer the boat while standing on the companionway steps out of the wind.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
The reason I ask, is mine is on my E25.
I assume it got chewed up in the prop but the former owner seems to think it was factory
The 25 has the motor cutout on one side of the transom with a transom mounted rudder - making it possible for the prop to strike the rudder when the motor is turned too far. The 27 has a spade rudder with the OB-configured-transom having a cutout in the center.
 
Top