Changing motor

[Davidasailor26]

It is an interesting idea. Still a little unconventional for my taste if for no other reason than resale value. I also have the same concerns as Tom and Michael about the depth of the prop. The problem you'll have is that the lower you make the prop the more it will eat into your usable rudder space, reducing your control under sail. I'm also still concerned about how much resistance you'll need to add to the rudder hinge to prevent the motor from tilting when heeling. That's still going to reduce feel under sail. One more problem when sailing - usually you'd want to tilt the outboard out of the water to reduce drag, but I don't really see a good way to do that here.

All in all I guess as a powerboat it might be doable, but as a sailboat I think it causes lots of compromises.

 

[Pete145]

Having had several outboard driven sailboats I agree. They work well in calm conditions but are near useless when the seas kick-up.

I am mostly a cruiser in a small lake and the Ottawa river; I don't much worry about rough seas.

 

[Pete145]

It is an interesting idea. Still a little unconventional for my taste if for no other reason than resale value. I also have the same concerns as Tom and Michael about the depth of the prop. The problem you'll have is that the lower you make the prop the more it will eat into your usable rudder space, reducing your control under sail. I'm also still concerned about how much resistance you'll need to add to the rudder hinge to prevent the motor from tilting when heeling. That's still going to reduce feel under sail. One more problem when sailing - usually you'd want to tilt the outboard out of the water to reduce drag, but I don't really see a good way to do that here.

All in all I guess as a powerboat it might be doable, but as a sailboat I think it causes lots of compromises.

I could lower the motor a bit to account for cavitation. The resistance won't be more than with my saildrive now. Also I'm not worried about resale. I think this would a positive New innovation (if it works) and I'm gleaning a lot of insight here. I can use this info to overcome any possible problems.

 

[garymalmgren]

Do it, Pete!
Post lots of pics here so we can follow your adventure.

 

[jssailem]

“Do it Pete!”

Wow Gary. That’s like taunting the kid to stick his tongue on the flag pole.
Sure it will be entertaining to see what happens.

But is that the way we should spend our winters?

Pete inventions only happen when a person takes an idea from concept to test model. This sounds like something to try. Not sure it will be more than novel. But the guy who sealed his car and put a prop on the boot so he could drive it. In the water also had a novel concept he turned into a thing.

Good luck. The task should occupy your winter wait. It might be nice to have a second rudder or at least the plans model of your current rudder, so that in the event you wish to retrace your steps in order to sail next season you will be able.

 

[Pete145]

I would keep the original rudder.......just in case

 

[garymalmgren]

Wow Gary. That’s like taunting the kid to stick his tongue on the flag pole.

I like that one , John. And we are pretty well of a mind concerning Pete's project.
I have to admit my original though was to fix the 2- stroke.
Pete is a engineer and it would be a relatively inexpensive job.
That's what I would do.
Then I thought about all the guys who walked past Joshua as he was working on Spray.
"Sail that thing around the world? You will never get out of Boston harbour."
Or Blondie Hasler. "What is that stupid thing hanging off the stern?"
Pete might fail, but then again he might come across some brilliant idea that no one else has thought of yet.


Gary

 

[jssailem]

Yes Gary, I think we are. And it sounds like Pete is going into whatever it is with an open mind.

If he can manage to stream line his rudder motor so that the cavitation in not disruptive to smooth flow over the hull perhaps the project will enhance not distract from sailing his boat.

As I recall the “Sunbeam boat car” was only ok at ding both tasks not great at either.

My sail boat is better at being a sailboat then it is at being a power boat. And I appreciate that distinction.

 

[Pete145]

Thanks Gary and JSSailem for the encouragement. I'm still in the pondering phase, but am leaning more towards doing it. I'm taking all of your concerns into consideration. I will make a new rudder from scratch and streamline it better than the original. I will also look at old videos and see what the cavitation looks like behind the boat so as to place the motor optimally. (I really hate the look of an outboard off center on the back of a sailboat)

 

[jssailem]

IT is just a look. It actuality is relatively efficient.

 

[garymalmgren]

Hi Pete
Now that I have prodded you I feel a bit of responsibility to fill you in on a few of the drawbacks that
I can see in your plan to fit a (4 stroke) outboard engine directly the the rudder.
If your present outboard is bolted onto an outboard bracket on the transom, you will note that is is pretty beefy and heavy.
I provides two functions.
To hold the outboard at the correct height .
To allow the outboard to swing up out of the water when sailing.
I can see that you are thinking about motoring, but how do you intend to actually sail?

The idea of linking the outboard to the rudder is not new.
Here is a link to a pretty good discussion
http://www.trailersailerplace.com.au/phpBB3/viewtopic.php?t=9213
Zebedee goes throught the options and Aza has pretty well ironed out the engineering.
As John has mentioned the offset outboard is pretty efficient.
I think the key to improving maneuverability is practice.
A full day practicing turning in tight quarters, reversing etc, would do it.
You say your current outboard is noisy, smokey and I think it is coming to the end of its life.
Noisy= earplugs (don't laugh until you try)
Smokey= new 2 stroke high quality oils blends smoke a lot less ( I mean a LOT)
end of life= a rebuild would be just the challenge that you seem to be looking for.
My boat has the noisiest marine engine made (35 year old Yanmar YSE 12), so I turn it off as soon as it is possible to move (even inch along) under sail.
So I suggest.
recon the engine so it is like new.
Leave it where it is and make up a linkage or practice.
And if you don't like the noise, use the engine as little as possible.ing.
All the best
gary
Winter is not that long and you want to have the boat ready to go in spr

 

[DayDreamer41]

Interesting idea especially if you can incorporate the motors lower end into a custom made rudder foil, with a built in lower end you could extend the drive shaft deeper, as for the drag from the prop under sail power, you could always look at a folding prop.
Incorporating the lower drive unit into the rudder assembly would be a really interesting project for sure, but one I think would actually be possible, it sure would solve the turbulent flow issue while under sail and I am sure that the weight and thrust forces could be mitigated with careful design.

 

[Pete145]

Hi Pete
Now that I have prodded you I feel a bit of responsibility to fill you in on a few of the drawbacks that
I can see in your plan to fit a (4 stroke) outboard engine directly the the rudder.
If your present outboard is bolted onto an outboard bracket on the transom, you will note that is is pretty beefy and heavy.
I provides two functions.
To hold the outboard at the correct height .
To allow the outboard to swing up out of the water when sailing.
I can see that you are thinking about motoring, but how do you intend to actually sail?

The idea of linking the outboard to the rudder is not new.
Here is a link to a pretty good discussion
http://www.trailersailerplace.com.au/phpBB3/viewtopic.php?t=9213
Zebedee goes throught the options and Aza has pretty well ironed out the engineering.
As John has mentioned the offset outboard is pretty efficient.
I think the key to improving maneuverability is practice.
A full day practicing turning in tight quarters, reversing etc, would do it.
You say your current outboard is noisy, smokey and I think it is coming to the end of its life.
Noisy= earplugs (don't laugh until you try)
Smokey= new 2 stroke high quality oils blends smoke a lot less ( I mean a LOT)
end of life= a rebuild would be just the challenge that you seem to be looking for.
My boat has the noisiest marine engine made (35 year old Yanmar YSE 12), so I turn it off as soon as it is possible to move (even inch along) under sail.
So I suggest.
recon the engine so it is like new.
Leave it where it is and make up a linkage or practice.
And if you don't like the noise, use the engine as little as possible.ing.
All the best
gary
Winter is not that long and you want to have the boat ready to go in spr

Thanks Gary, my motor is a Zephyr onboard saildrive, so if I had to tell my wife to wear earplugs all day I'm sure you can imagine the result we live on a small lake (Montreal) and would travel upstream and into the wind to visit Ottawa or the thousand islands. It is imperative to motor most of the way there (and sail back). Our real sailing is limited to a maximum tack of an hour or so before we run out of lake or wind. The idea of the rudder mount I must admit is in part the challenge of doing something out of the ordinary that if it works could be revolutionary. The electric Hanse works great so why can't a gas motor? I would manufacture the new rudder over the winter and hang it in spring so no time lost.

 

[Pete145]

Interesting idea especially if you can incorporate the motors lower end into a custom made rudder foil, with a built in lower end you could extend the drive shaft deeper, as for the drag from the prop under sail power, you could always look at a folding prop.
Incorporating the lower drive unit into the rudder assembly would be a really interesting project for sure, but one I think would actually be possible, it sure would solve the turbulent flow issue while under sail and I am sure that the weight and thrust forces could be mitigated with careful design.

I already have a saildrive so there wouldn't be any more drag

 

[Pizzazz]

Pete,

I loved the Hanse 315 electric drive in the rudder. It seems like a perfect fit. I strongly suggest that you consider going that route with an electric motor embedded in the rudder (small, flexible) then add a gas generator in custom locker off the back of your stern. I like this so much that I would even consider reporting my boat this way.

You can have a small lithium battery to give you a short burst in power since the generator will not be big. But you can isolate it and quieter in quite a bit.

The key idea here is that you separate the motor from the power source and this is the big benefit of electric power.

 

[jssailem]

key idea here is that you separate the motor from the power source and this is the big benefit of electric power.

How does separating the power source (batteries and fossil fuel generator - a motor driving a charging system) from the motor (I guess this is the electric motor consuming the stored power) driving the prop and boat in motion, provide a "Big" benefit?

 

[Pizzazz]

Sorry for the testy reply but I am tired of people sticking to old habits. It is a big benefit because the electric motor is small and can easily integrate with the rudder without significant drag or complications. The generator can be anywhere, it no longer needs to be attached to she saildrive. If you need more examples read on why the navy is moving to electric drive on its ships, powered by gas turbines.

 

[Pete145]

Pete,

I loved the Hanse 315 electric drive in the rudder. It seems like a perfect fit. I strongly suggest that you consider going that route with an electric motor embedded in the rudder (small, flexible) then add a gas generator in custom locker off the back of your stern. I like this so much that I would even consider reporting my boat this way.

You can have a small lithium battery to give you a short burst in power since the generator will not be big. But you can isolate it and quieter in quite a bit.

The key idea here is that you separate the motor from the power source and this is the big benefit of electric power.

This was exactly one of my options, but batteries are crazy expensive.

 

[Pizzazz]

Well, not really if you go hybrid. I would get enough batteries to have max power for 15-20 min. The rest should come from the generator. You can start with a gas generator, a Honda gives you 3+ hp, Then move on to a diesel generator with time.

If you go the gas genny route, I would get a cheap one, may be 3kw, put it into a nice enclosure at the stern, so that it is quiet and then find a way to exhaust into the water (not water cooled but just more silent). Then if you find this insufficient, you need to go to a 4.4 kw diesel genny, not that expensive.

You could even consider attaching a generator to the outboard. This is a project I have been thinking about for some time now. The benefit is that you get a cheap watercooled engine for free (many cheap out boards and then you just need to find a way to attach the generator to it. Go for 110V so that you do not have to waste energy converting to DC but make sure it is isolated well.

SV Pizzazz

 

[Pete145]

Well, not really if you go hybrid. I would get enough batteries to have max power for 15-20 min. The rest should come from the generator. You can start with a gas generator, a Honda gives you 3+ hp, Then move on to a diesel generator with time.
SV Pizzazz

Interesting, something else to consider