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Old 05-03-2015, 11:16   #31
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Re: Sub-30 Foot Sailboat Power

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Originally Posted by ranger42c View Post
FWIW, there are outboard models with power tilt and trim.

-Chris
Yeah I know. Everything is a compromise. More gear on the stern to raise and lower and trim means more weight where I don't want it. Besides I don't want anyone changing my mind once its made up. So there. : )

You opened the electric can of worms. The electric Torqeedo Cruise 2.0 (24V) on our club's Folkboat (2.5 tons +people and gear) has been a big hit. It's rated at about a 6hp gas equivalent. We use 2 deep cycle 12v batteries under the forward end of the cockpit to power it. It looks like H but pushes the boat to hull speed and has plenty of kick in the river when we need it. We sail the boat and don't have to motor much except in tight quarters or up a river. The lighter 12V 1003 travel model doesn't push as well and the battery and controller have developed wiring and charge problems after just a couple years use. A battery pack for the lighter 1003 torqeedo is very costly. The 1003 model is better used on a dinghy than on a Folkboat.
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Old 05-03-2015, 11:31   #32
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Re: Sub-30 Foot Sailboat Power

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Yeah I know. Everything is a compromise. More gear on the stern to raise and lower and trim means more weight where I don't want it. Besides I don't want anyone changing my mind once its made up. So there. : )



But I don't think it adds much weight to the outboard, in the grand scheme of things. Still, it's a point.

Don't blame the electric discussion on me; that was somebody else

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Old 05-03-2015, 11:58   #33
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Re: Sub-30 Foot Sailboat Power

Good discussion. Reefmagnet's analysis was spot on.

I have been discussing this very subject with a friend of mine who is now vacationing in Florida from Chicago (great time to be south!).

He was looking at a Catalina 25 with an inboard diesel. They made only a few in the entire line of over 6,000 hulls.

I also owned an outboard powered Catalina 25 for 13 years and am very familiar with that boat.

Re: the OP of engines for boats UNDER 30 feet, additional considerations are:

1. access for service - my friend showed me a picture of this small diesel (don't know for sure which engine, but definitely a Universal) shoehorned under the companionway stairs with NO, repeat NO access to anything: dipstick, alternator, secondary fuel filter. If it was raw water cooled, you couldn't even see, let alone get to the HX!!! None. From his picture I couldn't even see how they could add oil, since access was needed from the top of the engine where the filler cap is. This engine worked fine for its new owner, but then stopped starting (after his first month of ownership - not my friend, some other guy he met had this boat). The simple solution for all Universals is the stupid fuse and fuseholder between the ignition button and the starter solenoid. He simply could NOT get to it!

2. Stuffing box - In almost every case of inboard diesels on small boats, like this Catalina 25 and Catalina 27s I have seen, access is IMPOSSIBLE. If you can't get to it, you can't service it.

So, the biggest downside to inboards on boats smaller than 30 feet is access for servicing.

If that can't be done, other means of propulsion are required.

PS - most smaller boats are designed for outboards anyway, so the "argument" about the extra weight on the stern is meaningless.
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Old 05-03-2015, 12:55   #34
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Re: Sub-30 Foot Sailboat Power

My outboard weighs about 58lbs so it's easy to counter balance that with a few bottles of water, a couple cases of beer, or whatever. It's not a problem.

I'm using a 2011 Mercury 5hp 4 Stroke 25" Extra Long Shaft Outboard to push a boat with gear of around 7.000lbs. So far so good and my main sailing territory is where the Chesapeake Bay meets the Atlantic so the waves do get quite close, steep etc.

But do I motor in 25 knots? No. I sail.

I did use the outboard once in large waves though. The wind dropped off but the waves were still up. I had the sails up and motor running. It was coming out of the water due to the boat rotating laterally. (sailing semi downwind) The outboard has a governor so I just kept sailing but soon discovered if I sailed a slightly different course the motor would stay in the water.

I don't like to carry too much gas onboard though which would be a problem if you were doing true cruising. I was reading where Tania Aebi motored 72 hours between Bermuda and St Thomas due to lack of wind.

I may be able to motor 30 hours with my approx 7 gallons which includes the 40 oz internal tank. I reckon I could store some gas in a couple 5 gallon plastic Jerry Cans on the bow though.

Oh yeah, and I can mount my engine on the aft rail or take it below and store it when not in use!
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Old 05-03-2015, 16:41   #35
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Re: Sub-30 Foot Sailboat Power

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Originally Posted by SkiprJohn View Post
You opened the electric can of worms. The electric Torqeedo Cruise 2.0 (24V) on our club's Folkboat (2.5 tons +people and gear) has been a big hit. It's rated at about a 6hp gas equivalent.
Glad you brought this up. I have heard that the 2KW (2.X hp) electric acts like a bigger hp petrol but I admittedly don't understand electric math. I do get the instantaneous torque stuff. So maybe it's a propping thing.

I presume the batteries get plugged into a charger. And why I contend they are great for the case where you can plug them in.

As a replacement for hydrocarbons many advantages disappear when you have to have a large battery bank and tons of solar to charge it.

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Originally Posted by thomm225 View Post
My outboard weighs about 58lbs so it's easy to counter balance that with a few bottles of water, a couple cases of beer, or whatever. It's not a problem.
Moment weight math counts. It's how we balance airplanes.

I don't think counterbalancing the outboard is the issue. In fact I think most conversions end up light in the stern.

So with that nice clean engine bay available add some battery and add some solar on the bimini!
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Old 05-03-2015, 17:37   #36
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Re: Sub-30 Foot Sailboat Power

One thing that hasn't been brought up, but when you buy a new outboard, you get a brand new everything, Thru hull, drive shaft, prop, stuffing box, fuel tank, exhaust hose and water lift muffler, transmission, the whole shooting match.
I'm sure I could easily rig a winch to lift the thing, think cheap trailer winch, and as far as steering form a tiller, take a look at mid size fishing boats that use a "kicker" to troll with as the inboard motor or outboard is just too fast, even at idle.

Where it makes the most sense to me, is price a good sub 30 footer with a blown or seized Diesel, then the outboard seems to be more attractive.

Electric I'm convinced is the future for weekend warriors etc., just ain't quite there yet for most of us, but you guys doing it now, are the pioneers


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Old 05-03-2015, 17:38   #37
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Re: Sub-30 Foot Sailboat Power

Oh, weight and balance is easy just remember WAM
Weight x Arm=Moment


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Old 05-03-2015, 17:52   #38
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Re: Sub-30 Foot Sailboat Power

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Oh, weight and balance is easy just remember WAM
Weight x Arm=Moment


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Until some smart guy places the datum on the firewall and then you got negative moments to noodle with - LOL...

But then decides A&Ps can't do negative math so places the datum 5'3" forward of the firewall - basically in space - LOL...
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Old 05-03-2015, 19:55   #39
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Re: Sub-30 Foot Sailboat Power

[QUOTE=Ex-Calif;1766425]Glad you brought this up. I have heard that the 2KW (2.X hp) electric acts like a bigger hp petrol but I admittedly don't understand electric math. I do get the instantaneous torque stuff. So maybe it's a propping thing.

I presume the batteries get plugged into a charger. And why I contend they are great for the case where you can plug them in.

As a replacement for hydrocarbons many advantages disappear when you have to have a large battery bank and tons of solar to charge it.

We have two solar panels that keep the batteries charged. Not a problem since there is a lot of solar time in between need for the torqeedo.

I too don't know the conversion between kw and hp but it was explained in one of our club's site threads and finally made a little sense. It's supposed to be equal to 6hp and seems to push the boat about the same as a 6hp however will not last as long as a small fuel tank as you know.

"Newtons 2nd law says that force = mass times acceleration.
The drag, or friction, force on an object like a boat hull moving through water increases with mass and speed, approximately as mass times speed squared.
The 2 things above mean that when you push on a boat with a constant force, it will accelerate until it reaches the speed where the drag force equals the pushing force and then the speed will be constant (zero acceleration). A heavier boat will accelerate slower (high mass) and will generally have a larger drag force at a given speed because it displaces more water.
In electrics, power (P, in Watts, W) equals Voltage (V in Volts, V) times current (I in Amps, A), so for example a 12V motor drawing 10 Amps is using 120W of power. P=VI, I=P/V, V=I/P
Horsepower (HP) ratings are physically a power rating. For lots of calculations, it's easier to work in Watts (W) or Killowatts (kW) (1kW = 1000W).
If you push against a resistive force (like drag) then pure physics tells us that the power you use is equal to the force times the velocity (P=vf)
Electric trolling motors have thrust ratings, in pounds (lb or strictly, pounds of force, lbf). This is a measure of the static thrust generated by the motor, ie if you attach the motor to the dock (or something else that will not move) and run it, it is a measure of the force with which the motor will push on the dock. Note that once the thing being pushed starts to move (like a boat will), the amount of force may change). For lots of physics calculations, it's best to work in units of Newtons (N). 1 lbf = 4.4N.
You might see from the above that converting from a static-thrust rating (lbs) to a power rating (HP) cannot be done by pure physics or like a unit conversion - there are many assumptions about the propeller in use and boat that is being pushed that need to be made. Different manufacturers will almost certainly make different assumptions, presumably depending on the boat they have in mind for their products. The main thing here is that it's very different to be driving a small dinghie like a walker bay, than it is to drive something like a Folkboat.
Gas engines

For the record, gas engines are rated by peak power output, usually measured in HP.
[edit]Minn Kotas

These are marketed as trolling motors for small boats and dinghies. The 12V ones come in 20-50 lbf static force versions. Minn Kota make more powerful motors that come in 24V and 36V versions. They make "outboard" versions like the ones we have and also ones that are designed to be permanentely mounted to the hull. Some of the fixed mount ones are actually double motor, double screw pods. This is because it's cheaper / easier to have 2 smaller motors than one larger one.
I read on a website that a good rule of thumb is that a 1 HP gas engine is approximately equivalent to 75lbs.
The largest 12V Minn-Kotas are 55lb thrust. They make more powerful ones in 24V, 36V and 48V. You can get these voltages by connecting 2, 3, or 4 12V batteries in series.
They use higher voltages for higher power because the size of wire you need and the resistive losses in the wire all depend on the current. Because power = current * voltage, you can keep the current from getting too large by using a higher voltage for higher power.
I think it's reasonable to say that the 55lb Minn-Kota is borderline for Cheers. Often it's adequate, but it would be nice to have something stronger.
[edit]Torqueedo

I thought some notes on the torqueedo would help. These are generally marketed towards bigger boats than the Minn Kota target audience.
Rather than the Minn-Kota lb rating, Torqueedo give their motors ratings that they claim are the gas engine equivalent sizes. They make a 6HP and 2HP version.

The 6HP one is actually a 2kW motor (physically 2.7HP). It's powered at 24V and draws about 83A at full power. It generates 120 lb of static thrust.
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Old 10-03-2015, 12:14   #40
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Re: Sub-30 Foot Sailboat Power

We have had temps between 20-30 degrees for the last month or 2 so I figured I'd better start my engine which is a 2011 5HP 4 Stroke Mercury Outboard.

Since I'm at the boatyard, I just put my Wet/Dry Vac Tank on a boat stand under the engine to run it. It started on the 4th pull.

Yesterday I was thinking how nice it is to have a practically brand new engine on a 40 year old boat.

Since the engine only weighs 58 lbs, it's also pretty easy to relocate it if you wanted.

Between the sails and the outboard, I have had no trouble coming and going.

Also, having a tiller positions the skipper (and his weight) further forward than wheel steering. I've looked at several boats with wheel steering and the driver is way aft. Seem weird to me. I guess I'm just used to being closer to the dodger and cabin.
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Old 10-03-2015, 12:54   #41
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Sub-30 Foot Sailboat Power

I believe it comes down to what your doing with the vessel.
I wouldn't have a out board in the open ocean, unless it's flat, rarely is.
The inboard, is no problem ,however like any Boater, we should all learn to repair in situ.
In the bay, except maybe SF Bay you can motor with an OB.
When it gets choppy, forget the OB, better you sail.
The Inboard will safely motor in chop, and rainy weather.
You can draw heat as well ample Power for your comfort.
There are less expensive setups, but we should all learn to do most of our own repairs.
Just makes sense.


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Old 10-03-2015, 13:35   #42
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Re: Sub-30 Foot Sailboat Power

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I believe it comes down to what your doing with the vessel.
I wouldn't have a out board in the open ocean, unless it's flat, rarely is.
The inboard, is no problem ,however like any Boater, we should all learn to repair in situ.
In the bay, except maybe SF Bay you can motor with an OB.
When it gets choppy, forget the OB, better you sail.
The Inboard will safely motor in chop, and rainy weather.
You can draw heat as well ample Power for your comfort.
There are less expensive setups, but we should all learn to do most of our own repairs.
Just makes sense.


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My boat had the diesel at first, and it had about the same power as the outboard. It was an old Bukh 10.

Neither of them could motor in the Lower Chesapeake against big chop.

Lots of folks sail the trade winds and their only power is an outboard. I can show you youtube examples, but I'm sure you are aware.

My first four sailboats didn't have engines so any engine is a plus.

The only drawback would be amount of fuel. I wouldn't want to carry too much gasoline onboard. Now max I would carry at any one time would be around 7.5 gallons or so in different containers plus the internal tank.

If I were to cruise offshore in this boat as is I might add a couple 5 gallon jerry cans and store them on the bow someplace. Of course any heavy weather might take them overboard so I'd have to move them to the bilge below where the diesel used to be in that situation.

That would give me around 60-70 hours of engine runtime at least.
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Old 14-04-2015, 09:39   #43
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Re: Sub-30 Foot Sailboat Power

It looks like my universal 5411 may be shot.
Just to prep the alternative, I'm interested in the opinions of the outboarders on this thread.
The Pearson 28 has a pretty narrow stern, with a slight reverse angle to the water (from the water, the transom slopes towards the bow), and a spade rudder whose trailing edge stops just short of where the transom meets the water.
Where is the best place for the outboard? I see them mounted centerline as well as to port and starboard. I would think that lowdown in the center would be best, and I think I can avoid my rudder with most of the brackets I've seen.
I have mainly used my engine for negotiating narrow channels when I'm into the wind, crowded mooring fields, and taking me off sandbars when I've run aground, rather than for passage making. If I could, I'd like to get something lighter that I can easily transfer to the dinghy, like a 5hp; but would that move my 8500-9000 lbs with any degree of alacrity in that moment when I needed it?
I have a line on a high thrust 9.9 long shaft, is the high thrust absolutely essential in terms of motor life, maneuverability, etc. ? I helped move two of these things out of a seawind, and they are heavy and ungainly, and I'd prefer not to go that route. Thanks,
Dan


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Old 14-04-2015, 13:07   #44
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Re: Sub-30 Foot Sailboat Power

My friend put a Honda 7.5 hp on his Columbia 28. It was not a high thrust. The Columbia is about a ton lighter than your Pearson. The engine pushed his boat along every bit as good as the old Atomic 4 he had in it and sipped gas more efficiently. If you can find a good light engine between 4 and 8 hp I'd opt for it.

Centerline is better because your engine won't be under water when you're on a tack that puts the rail down on that side.

The problem with transferring your outboard to your dinghy is that a long shaft will stick way down into the water and not be good for cooling. You can build up the transom of your dinghy to make up for it but then that changes the thrust angle and torques the transom as well as takes up more space for stowage. Putting a short shaft on your Pearson will mean you'll have to reach over the stern to pull it up out of the way and when you are out at sea the engine parts will be underwater some of the time.

Everything is a compromise?
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Old 14-04-2015, 14:41   #45
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Re: Sub-30 Foot Sailboat Power

I'm not an expert in this area, but if you are going to put an outboard on a 28 foot sailboat you should look for an extra-long shaft outboard (25 inches vs 20 inches for a long shaft.) It shouldn't be too hard to fashion a support to mount something like a Panther outboard bracket which will allow 16 inches of vertical travel. I don't think you should mount the outboard directly behind your rudder which I believe would tend to add to cavitation problems, most are offset to one side which seems to work just fine. The transom may need to be reinforced with a backing plate etc.

Instead of expensive control extensions, an outboard with a tiller can be fitted with a $30 tiller handle extension and you will be steering with the sailboat's tiller most of the time anyway, and just making gross adjustments to the outboard.

This application would be perfect for a well cared for 2 stroke motor especially due to weight considerations. I have an 8 HP Yamaha 2 stroke outboard which weighs only 58 pounds. I paid $325 for it and spent a few dollars and hours fixing it up and it is completely reliable, I used it walleye fishing as a kicker for hundreds of hours on a Boston Whaler.

The "high thrust" motors are much better for pushing large masses around at a slow pace and are designed for a much larger prop.

An XL shaft would obviously not be a good motor choice for a dinghy due to excessive drag.
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