outboard mounted on transom

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outboard mounted on transom

Glenn Thomson
I have reached my limit of having my Yamaha f 9.9 sunk in the well of 7.6.   I moor in the Pacific, lots of growth collects on prop and engine.  The mount for engine in the well forces the engine to angle up slightly, which causes the aeration of prop to surface prematurely, hence poor performance and I think that also causes the rudder to waver as the prop wash passes by.  Yes, with some wrestling I can remove the 80 lb. engine out of well, but that is getting old.  Exhaust fumes linger in the well, with or without the seat in place.  There is a vibration that occurs throughout the hull.  And at 3500 - 4500 rpm ( the range of rpm that I can get 5 kts out of her, depending on current) the noise is too much to have a conversation in the cockpit without yelling.  Enough rant.  Has anyone done the engine mounted onto transom alternative?  Please post your findings/opinion!  There is a reason very few salt water sailboat designers produce a well mount.......    
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Re: outboard mounted on transom

Mark Williamson
Administrator
I didn't make the mod but I have a transom mount. Will take some photos and measurements and post here.  

The motor is locked in place. As you might guess the steering is non existent when the boat isn't moving. I have wheel steering and throttle on my 760. Early on I'd thought of unlocking the motor and hand steering but got used to it.
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Re: outboard mounted on transom

David - Moon Chaser
In reply to this post by Glenn Thomson
Hi again Glenn! - So, I am replying in less than 10 years this time - LOL. I agree with almost all aspects of your "rant".  I have the Yamaha High Thrust 9.9. When I bought my boat it had a Nissan 6 or 8 hp (2-stroke).  Talk about stink and noise.  Plus, with the Nissan, I could go down below and make a sandwich while I was waiting for the direction shift to kick in.  So, my Yamaha 9.9 HT is a blessing in comparison.  But not without pros and cons.
Pros:
+ I can use the motor tiller for more turning power / centre-point radius when needed (and it has come in handy several times, like unplanned heave-tos in notable wind).  I also use it to steer me a bit more into a dock by a slight turn on the motor axis - That said, you could do all the motor turning tricks with it hung on the transom.
+ Virtually ready access to the throttle and gear shift when docking.
+ Not haggling with a transom motor lift.
Cons:
- All your points except the problem with the tilted mount (which I get too) but doesn't seem to cause cavitation or power loss. Plus, I get 6 Kts on a smooth day with the throttle at the "Warm Engine" spot.  (Though I wonder if I'd get better high-end speed with the regular motor - not high thrust).  I do plan on an average cruisin g speed of 5 kts.  I set up a removable davit to lift the motor out - But the HT prop needs to be removed due to diameter, which would not be an issue if it was hung off the transom.
- I also wonder if I lose a point or 2 in sailing speed with the motor drag.

Just my thoughts.  Though I am sticking with the motor well placement due to my pros experience, and the Great Lakes do not cause any mentionable growth. (Plus, it's fun when people assume I have an in-board and get confused when they see my motor, LOL.
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Re: outboard mounted on transom

Rick Bera
Hello.
Just saw your post and thought I would add my own two cents re:

Stinky motor:  I have a Yamaha 9.9 standard long-shaft outboard mounted in the well.  I do not seem to have the problem regarding exhaust gas stink.When I bought the boat 5 years ago, I noticed that there were two short lengths of hose protruding through the transom drain thru-hulls. These hoses are connected to a "Y" fitting on the motor shaft, just below the head of the motor. I was told that low-speed exhaust gases are diverted into this fitting, through the hoses and out the transom. High speed gases are exhausted through the prop hub. Thus, very little or no exhaust gases make their way into the cockpit. I do not know the name of such a fitting, but I am sure a Yamaha dealer would know.

Angle of motor shaft: I was able to somewhat modify the angle of the motor shaft by installing a wedge-shaped piece of ply onto the well's motor mount. You cannot use a very thick pice of ply in order to allow the motor to be threaded down into the well. I believe I used a piece of ½" ply, ground down to a wedge-shape, thin edge at the bottom. This does not completely cause the motor shaft to be vertical, but it does help somewhat.

Motor lift-out: I am "of a certain age" and  could not lift the motor out of its well in the Fall for storage and servicing. I had to pay yard staff to use the mast crane to lift out the motor, then pay for servicing and Winter storage, plus motor installation in the Spring.  This amounted to several hundred dollars in total.  Then I thought to myself, why not leave the motor in the boat  and service it myself? After all, inboard engines are left in their boats all winter and my outboard was stored all winter in an unheated outdoor shipping container. The Kelt outboard motor is in a well, the boat is covered over and protected. Only the lower prop shaft is exposed.

So now, each Fall, I use a device which sucks out the used oil from the top of the motor while the boat is still in-water. This device -available online or at most chandleries- uses a thin tube which is fed down the motor's oil filler tube; a hand pump establishes a vacuum and the warmed-up oil is easily sucked out and fed into the attached container. The requisite 800ml of new oil is then poured in through the filler tube. This takes only about 15 minutes.  After the boat is lifted out and placed on its cradle, one can easily access the motor's lower gear oil drain/filler bolts and change the gear oil. A small pump which fits onto a one litre gear oil container is available with the requisite Yamaha drain bolt fitting. One simply pumps in the gear oil until it starts to run out of the top inspection hole, then he bolts are screwed back in.  Spark plug changes or other servicing can also be done while the motor is in its well.  This seems to work for me and has saved me considerable money as a DIY thing.
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Re: outboard mounted on transom

Glenn Thomson
Hi Rick.
Thanks for replying and adding your info regarding motor mount etc.  I also added a wedge on aft side of mount to try and change the angle.  I wasn't satisfied, the motor performed about the same, showing a lot of aeration about 2 feet behind the transom.  I had to trim the wedge a couple times because the cover rubbed on the interior transom. The tubes feeding out the through hulls do make sense, thanks for that. Have you taken any photos of your modifications?
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Re: outboard mounted on transom

Rick Bera


Hi, Glenn.
Unfortunately, I do not have any recent pics. I am trying to insert an image of the hoses that are sticking out of the transom thru-hulls about 2 or 3 inches, (but I am not sure if I have done it correctly). These plastic hoses  are perhaps 1/2" or 5/8" I.D. One might argue that the hoses obscure drainage out the transom, but I do not find it a problem. Thèse are connected to the fitting which I am calling "low speed exhaust diverter" and seem to keep exhaust gases out of the cockpit. I tried to do an internet search for this fitting, but had little success since I did not know the actual part name or number. It was on the motor when I bought the boat. I would expect a Yamaha dealer would know that information.
The wedge on the motor mount probably made about a 10 or 15 degree difference toward vertical, but, like you, I am not totally satisfied. However, at this stage of the game -I am in my 73rd year- I will probably live with it. As they say, "perfect is the enemy of good enough".  Cheers.
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Re: outboard mounted on transom

gandalf
In reply to this post by David - Moon Chaser
David, wondering if you'd be willing to share a picture of your removable davit set up?

Glenn, I'm a new Kelt 7.60 owner as of March currently also trying to figure out how to best deal with the engine well in salt water. Made the fun mistake of leaving the outboard in the well for ~3 months in the Chesapeake and it was quite the barnacle-y mess even with regular use! The previous owner had the the strategy of lifting up the outboard and laying it on the cockpit floor on a thick piece of padding when not in use. I've now switched to their approach, however with the weight of yamaha 9.9, it's not the most ideal/relaxing way to end a day on the water. Although I know it's probably fine to leave it on it's tiller side down, I'd rather find a solution where it could be stored upright the majority of the time.

Aside from adding a mount to the stern, has anyone tried any alternative storage methods just to get the prop out of the water when at the dock?

Many thanks!
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Re: outboard mounted on transom

Lynn Israel
I too am considering a viable way to lift the motor up without destroying my back in the process. I wonder if removable 2x4 boards in the cockpit with straps under the engine and a pulley system would work? The boards would be easy to stow. Also perhaps a sawhorse design attached to the toerail but then storage at the slip is a problem. In the interim, I am considering using a power washer. Cheers.
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Re: outboard mounted on transom

John Peter Mitchell
In reply to this post by gandalf
I purchased my Kelt 7.60 in November 2022 from the previous owner who had owned the boat almost from new.  It's a 1982 model 321B (I'm guessing the "B" indicates a February build) which he purchased in 1983.  He began his ownership with a Honda 9.9hp then downsized to another Honda 8hp and finally downsized to a Yamaha twin cylinder 6hp.  This is the motor which I have to lower and raise in the cockpit well for each sailing use: the motor weighs 90lbs.  My 77 year old body struggles with this and so I was going to make a small davit to help with the raising of this 90lbs, but first I tried attaching a 3 part block and tackle to the adjustable backstay.  That has worked wonderfully well.

I have a small wooden support upon which I can rest the motor, on the cockpit floor, when the sailing is done for the day.  As I sail in saltwater, the engine benefits from a freshwater flushing after each use (the engine manual suggests 15 minutes of flushing).  I do have some pictures which I could try to post if there is any interest from other forum members.
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Re: outboard mounted on transom

Glenn Thomson
Yes.  I would be interested seeing pictures of your device.  I put a carabiner in my aft stay and a less than adequate block an tackle attached it to a motor harness and  used it a couple of times.  Now I am back to pulling it out.  I have a 2x4 that spans across the 2 benches and the motor remains mostly upright, with the prop resting on the edge of the well hole.
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Re: outboard mounted on transom

John Peter Mitchell


Hello Glen,

I will try to post other pictures after this test picture posts successfully.  This is how the motor looks on its wooden storage bracket.
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Re: outboard mounted on transom

John Peter Mitchell
In reply to this post by Glenn Thomson
...and the storage bracket.
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Re: outboard mounted on transom

John Peter Mitchell
In reply to this post by Glenn Thomson
TThe block and tackle, ready to assist my aging muscles with the raising of the engine.
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Re: outboard mounted on transom

Lynn Israel
John, It looks like a great arrangement. Could you please answer a few questions. Thank you, sir.
1. Is your engine completely out of the water when placed on the block?
2. Any concerns about that weight on the backstay? I have a Yamaha 9.9.
3. Could you explain how you flush with fresh water?
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Re: outboard mounted on transom

John Peter Mitchell
John, It looks like a great arrangement. Could you please answer a few questions. Thank you, sir.
1. Is your engine completely out of the water when placed on the block?
2. Any concerns about that weight on the backstay? I have a Yamaha 9.9.
3. Could you explain how you flush with fresh water?

Hello Lynn,

1. Yes.  I will show a picture in a following post.  In that picture you will see that I have a clear piece of plexiglass held down by a piece of plywood to prevent otters from swimming up into the cockpit and making a mess.
2.On the split backstay there is a tightening device which, when pulled downwards, draws the two backstay legs together.  This bends the mast a little, but (hopefully) it will not break the mast.  After all, that is what it's designed to do for efficient upwind sailing: reduces the headstay sag and flattens the mainsail camber.  Recently a 210lbs. friend climbed my mast safely to the top and down again.  My engine weighs considerably less than him.
3.In one of the pictures you will see a black hose connector which allows for a standard garden hose thread to connect to the engine's cooling system.  This hose connector is shown disconnected from the engine, but it must be re-connected before the engine is started.  This is Yamaha's method which differs from other engine manufacturers(?).
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Re: outboard mounted on transom

John Peter Mitchell
In reply to this post by Lynn Israel


Lynn and Glen,

This picture also shows how the previous owner modified the engine mount...
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Re: outboard mounted on transom

Lynn Israel
John, Thank you! That is incredibly helpful. I will work on this project this fall. I'm on the fence about in the future staying with the 9.9 Yamaha or switching out to a smaller engine like a Tohatsu. The Yamaha is such a tight fit now that it's a chore just to get the cover clamps off. And at my age, I have no desire to dead lift 90 pounds so the pulley is a great alternative. Lynn
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Re: outboard mounted on transom

Glenn Thomson
In reply to this post by John Peter Mitchell
Yes I see the mount modification....to get a more vertical perch for engine.  I screwed on a plastic wedge to the backside of the mount and it forced the protrusions on the rear of engine cowling to rub on the inner transom wall.  Not much room to play in that well is there?
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Re: outboard mounted on transom

John Peter Mitchell
Hello Glenn,

The engine is tightly wedged in between this modified mount and the transom.  Once the engine is lowered into running position, it cannot be turned to the left or right.  On the plus side, the engine cannot fall through the hole in the hull, and so is very secure.  The propeller wash is evenly split by the rudder which helps with steering in close quarters.  On balance, I have come to prefer this arrangement over the transom mount method which I had on a previous sailboat (a J29).  

At the marina where I dock, there is another Kelt 7.60 which has a transom mounted outboard engine.  It is owned by a sailing co-operative which has a large membership list: so the boat gets a great deal of use by sailors who possess varying levels of sailing/motoring experience.  The co-op group have linked the rudder directly to the engine so that rudder and engine turn simultaneously.  This seems to have helped the boat's manoeuvring in the marina's narrow fairways.  Cheers, John
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Re: outboard mounted on transom

Glenn Thomson
Hi John.  My question is does the rear of engine rub on the transom. If it does, doesn't that bother you?  Mine annoyingly rattled while under way the more RPM's the more the engine wanted to push itself aft. So I removed the wedge.
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