Switching an inboard for an outboard

Mar 15, 2021
51
Macgregor Venture 22 Brooklyn
Silver Maiden's conversion was not without challenge. I do plan to document it at some point as I took pictures. The 1GM10 is physically much smaller than the P60 that was pulled out. Both are raw water cooled and both have the same shaft output RPM from the transmission. I did convert the 1GM10 to fresh water cooling. My first challenge was building up the engine bed to hold the LOWER output shaft at the right height.

I used black locust for the engine bed. It is hard to find, but worth the look harder than teak or oak and pretty much will not rot. You just have to work it slow. Once I worked out the rebuild of the engine bed it was pretty easy to swing the 120lb motor into place with a 4 part block rig. Held the motor with one hand and positioned with the other the dropped on the bed and just used body English for final alignment of the shaft.

The other thing I had to work out was the fresh water cooling circulating loop including finding a heat exchanger (gift from the owner of the marina), a circulating pump and deciding how it should all work as well as proper routing of the raw water to still be sucked by the raw water pump and shoved through the heat exchanger to the exhaust elbow.

I also had to plan the return for the diesel that does not go into the injector.

Looking back there was nothing hard about it, it just took planing and of course adjusting the plans as I went along and discovered how things would fit or fasten or whatever.

After doing Silver Maiden I would be willing to do a repower myself of pretty much any boat I might own. If you are handy and you are not rushed it is not beyond the skilled weekend mechanic. I did Silver Maiden over the winter and had her ready for spring.
 
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May 25, 2012
3,837
john alden caravelle 42 sturgeon bay, wis
as a kid, first 2 boats dad had had no engine, they where called sailboats. docking was easy. we used sailboat skills to dock. then dad got a 38' sailboat with an offset 71/2 hp outboard. it was easy to dock too. we still steered with the vessels rudder, the engine was locked straight ahead. when i read about people steering off the transom with the outboard. or claiming that their outboard was out of the water 1/3 of the time, i pause. i pause.

dad had that boat 13 years and we never had any of those issues.

the motorboat world is getting rid of inboards. for very good reasons. a few adjustments to transom design and every sailboat will be using them too. the inboard is dead. allot of people just don't know it. :poke:
 
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Aug 24, 2014
140
Aphrodite 101 148 Coeur d Alene ID
as a kid, first 2 boats dad had had no engine, they where called sailboats. docking was easy. we used sailboat skills to dock. then dad got a 38' sailboat with an offset 71/2 hp outboard. it was easy to dock too. we still steered with the vessels rudder, the engine was locked straight ahead. when i read about people steering off the transom with the outboard. or claiming that their outboard was out of the water 1/3 of the time, i pause. i pause.

dad had that boat 13 years and we never had any of those issues.

the motorboat world is getting rid of inboards. for very good reasons. a few adjustments to transom design and every sailboat will be using them too. the inboard is dead. allot of people just don't know it. :poke:
the current transom design added quite a bit of cost to the mount. Not only does it have a steep angle it also has a slight curve from side to side.
 
Jul 7, 2004
8,003
Hunter 30T Cheney, KS
Would the cost of an outboard and a mount not have paid for the inboard overhaul? Are you going to remove the engine and seal up the shaft hole?
 
Aug 24, 2014
140
Aphrodite 101 148 Coeur d Alene ID
Would the cost of an outboard and a mount not have paid for the inboard overhaul? Are you going to remove the engine and seal up the shaft hole?
An overhaul was not a good option due to the age of the engine. Tried to switch to another inboard but the stringers would have to be reconfigured. the outnoard conversion was more expensive than originally expected but feel it will be worth it. time will tell...
 
Oct 26, 2008
5,011
Catalina 320 Barnegat, NJ
I know that you already made the conversion and I hope that works well for you. It is a pretty good looking conversion as far as hanging an outboard off the back end goes!

I did find it surprising that you could not fit a 2YM15 in your space. I see @Whatfiero1 showed his installation. I did the same thing ... I replaced a 1GM and put in a 2YM15 in our Starwind 27. The foot print was a close enough match to work. The width of the 2YM15 mounts is exactly the same as 1GM. The length is 2" longer. I could not move the shaft coupling back, so the rear mounts stayed in the same place and the front mounts were pushed 2" forward. The rails did not need to be modified, but I did have to push the front cover 2" forward. Luckily, the counter top had just enough overhang to accomodate the new cover location without affecting the teak trim. I lost some space under the sink and could not fit the original trash bin. I had to add an antifreeze receptacle and added the fuel filter in that space anyway so the trash bin got sacrificed. I just built out the framing to make the cover fit and the companionway steps still landed on the platform so it was a relatively painless modification to the engine cover framing to make it all fit.
IMG_2029.JPG
 

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Mar 15, 2021
51
Macgregor Venture 22 Brooklyn
as a kid, first 2 boats dad had had no engine, they where called sailboats. docking was easy. we used sailboat skills to dock. then dad got a 38' sailboat with an offset 71/2 hp outboard. it was easy to dock too. we still steered with the vessels rudder, the engine was locked straight ahead. when i read about people steering off the transom with the outboard. or claiming that their outboard was out of the water 1/3 of the time, i pause. i pause.

dad had that boat 13 years and we never had any of those issues.

the motorboat world is getting rid of inboards. for very good reasons. a few adjustments to transom design and every sailboat will be using them too. the inboard is dead. allot of people just don't know it. :poke:
I learned to sail in 420s, Interclubs, and Rainbows. I can generally sail my Ericson 27 on and off a mooring or in and out of a dock. I rarely fired up the engine unless I had to get someplace and the wind did not exist or was so adverse that I could not use it, like a northerly while trying to travel up the Hudson river.

Now however I find myself in the position of not really being able to move either boat in and out of their docks without a motor. Both are at the ends of long and winding narrow canals with even more narrow navigable channels. No matter the wind direction some leg of the canal will not be passable under sail. The bar at the entrance of the canal the V22 is in is 2 feet. No going over it with the CB down. Your implication that someone advocating for easy to use, reliable aux propulsion can not sail was totally uncalled for.

Until the V22 I never owned a sailboat with an outboard. I have not yet taken her out from the dock, but that will happen in the next couple of weeks. My observations regarding handling of sailboats with outboards were largely informed by watching others who use outboards on their 22-29 foot boats in the marina I used to be in before and to a lesser extent my experience with a temporary outboard on Silver Maiden when I was in the middle of the repower.

I am not sure where you sail, but I can assure you New York Harbor and the Hudson River can get enough wave action that an outboard mounted on a sailboat will be both popping out of the water and cavitating if things blow up. Six foot short period waves, which do happen in the River and NY harbor can play real havoc with trying to keep a prop in the water when an outboard is in play.

Yes as sailors we should be able to handle our boats without power, but if we have power we should also have it installed such that it is of maximum utility. I have had to make trips up and down the Hudson River without power on occasion and I can tell you it was no fun. It meant doing things the same way the old river schooner scows did 100+ years ago. Anchoring for hours at a time waiting for the tide to turn before getting underway again.

If I were buying a boat that originally had an inboard and she was fitted with an outboard I would discount the offer considerably.
 
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Mar 15, 2021
51
Macgregor Venture 22 Brooklyn
Nice job Scott. Had I not gotten my 5 hour 1gm10 well below market that is what I would have put in my Ericson 27.
 
Mar 15, 2021
51
Macgregor Venture 22 Brooklyn
Jon-

I see your Balderdash and raise you tens of thousands of miles criss crossings the oceans of the world in everything from 54 foot aux sail to 700 foot freighters.

When you have conditions that produce this kind of motion
on your little sailboat the prop will be popping out and cavating part of the time when it is in.

6 foot waves on short period are about all it will take for most small vessels. I guarantee the vessels in the above video were exposing their props some of the time and that was with properly designed inboard systems. I have watched the RPM change as the stern popped out of the water on freighters. You will note the red ship above has it's prop such that she is seeing cavatation. Imagine an outboard on that red ship where would the prop be? Yep you have it. Spinning in the air.

Maybe some on here are fair weather sailors. That I will not fault, but I know one sometimes can not avoid rough conditions, so better to be prepared.

Another disadvantage I see to the outboard is if you have waves breaking over the stern there is some chance one will suck water into the carb. Not a good thing.

I am not saying the outboard does not have it's place. I am just saying if the boat is designed with an inboard I would do my best to keep it as it has advantages.
 
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May 25, 2012
3,837
john alden caravelle 42 sturgeon bay, wis
:yikes: been there, done that. ......................... but lets get back on point. the OP lives in Coueur d Alene ID. sails the local lake there. his conversion to an outboard is a good, viable option. he now has done the conversion. clearly a good fit for his needs. he sails on harrison slough. he will never see any waves like in the video and like what you and i have driven through. this thread is about repowering a sailboat that is sailed on harrison slough in the great state of Idaho.
claims by some that the boat will not handle docking well are in my experience not warranted. claims by some the he, on his lake, will have the outboard out of the water 33.3% of the time are very misleading. (that's right, i was being nice for once.)

so, you like poker too. my standard bet is $0.05 when betting on the internet. i'll see your raise and raise you back a 1,000ft ship and well over a 1,000,000 miles at sea. been sailing sailboats for 62 years. i own boats with inboards, outboards, no engines, right today.

i believe you owe me a nickel :poke:

let's be friends, let's share opinions, this is a fun web sight to do such.

....................... and yes, i have sailed my old alden through NY harbor :cool:

more sail
 
Jul 27, 2011
4,530
Bavaria 38E Alamitos Bay
An overhaul was not a good option due to the age of the engine. Tried to switch to another inboard but the stringers would have to be reconfigured. the outnoard conversion was more expensive than originally expected but feel it will be worth it. time will tell...
Time will tell that you will likely find it a compromise solution, nothing new there, that works OK some of the time but not so well at others. Sailboats designed for use with outboards have a “window” in the cockpit sole through which one can mount an OB (old Cal20s) or a cut away at the transom where the OB is mounted and where the leg resides more directly under the boat. I once sailed in a Ranger 29 with that type of mount, similar to what you see in the Mac 26. Worked OK. But OB’s then, when those boats were built were 2-strokes, quite a bit lighter than the 4-strokes of today. Also, a powerboat is steered by turning the engines. Fixed-direction thrust well aft of a rudder—that might prove difficult.
 
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Nov 24, 2014
130
Catalina 310 Staten Island
I have a 33' Aphrodite 101 after 40 years the one lung Yanmar needs to be retired. Changing it out in kind has proven to be a real hassle. A firm that rebuilds Yanmars, highly respected, talked me into going one size larger. When it arrived it was determined there was no way it was going to fit.
As anyone who has a one lunger knows they are loud and it's there job to try to beat themselves to death...
An alternative I'm considering is to just attached a 10 hp 4 stroke to the stern. While the boat was designed to sail in the North Seas we only sale it on a fresh water lake.
Does anyone have any experience with converting to an outboard?
Never considered it myself, but my experience with one of my previous boats should serve as a cautionary tale. from 1991 to 2005, I owned a Tanzer 7.5 meter sloop; a 24.5 foot long vessel weighing about 2 tons. It was equipped with an 8 horsepower Evinrude outboard on a tilt bracket mounted to the side of the rudder. It's major flaw was a lee helm in light air. Had I fallen overboard while singlehanding, that boat would have sailed off by itself to the Canary Islands while I swam to shore. At the end of every season, I noticed barnacles and algae on the stern of the boat, above its intended waterline. As it turned out, this model had a space below the companionway which looked like it could have accomodated a small diesel engine. I did a little research and found out that it was the designer's intention to do so, but when the molds were finished, the space was a little too small for any existing inboards. Rather than scrap the model, or re-design it, the builder went on the cheap and placed an outboard bracket on the stern, causing it to squat backwards. Having sailed windsurfers a few times, I remember how leaning backwards would cause it to sail off the wind. To make a long story short, on a small vessel, this change could possibly throw the boat off its lines, causing a hazardous handling characteristic. If one is stuck doing this form of repowering, I would suggest leaving the seized engine in place, in the hope of minimizing this effect