Disconnecting Engine Linkage

delevi · Post by **delevi** » Mon Jan 16, 2006 12:18 am

When sailing, I have found the helm much lighter and with a better feel with the engine disconnected when tilted up. I ran into a bit of a schooling session when I took my boat in to the dealer for maintenance a couple of days ago. He saw my setup for a quick disconnect via a hitch pin. He went on and on about how the boat is much more stable with the engine down under sail, therefore no need to disconnect. The point being that you gain a third rudder, the center of gravity is lower, thus adding stability in heavier seas and reduction of heel, since the higher engine weight while tilted would make the boat heel more. It also will reduce the bow pitching and make the boat sail a straighter course. Then, there is the safety issue of having the engine ready to power up instantly If you get in trouble. (no argument there) All this, according to Jeff, far outweighs the slight gain in speed by reducing the drag by tilting the engine up. Also, with the added stability and reduced pitching, you actually will make better overall speed when you consider that you are tracking better. I dont feel much difference in the helm when the engine is down and connected, but when tilted, I would not sail the boat without disconnecting. This conflicts somewhat with what Todd at BWY preaches about always disconnecting the engine while sailing. The counter point to this from Jeff is that Todd sails in much lighter winds in the Seattle area vs San Francisco Bay. He practically insisted about putting my settings back to have the engine permanently connected, which I let him do, but now Im still a bit on the fence. I must say that he does make a compelling argument.

Sloop John B · Post by **Sloop John B** » Mon Jan 16, 2006 5:25 am

Keep trying it out each way until it becomes apparent which is best.

I'm not agile enough to be connecting and disconnecting the motor in high swells and would lose stuff overboard including, perhaps, me

Catigale · Post by **Catigale** » Mon Jan 16, 2006 5:38 am

I dont know about the rudder effect.

On raising the CG - my BF 50 weighs about 250# IIRC - but when I kick it up it pivots so that the centre of mass is not raised by more than 8 inches or so.

If this has such a profound effect on sail performance, you would effect about a 10 times bigger change by climbing from the cockpit to the deck while sailing..changes which I have not observed and do not think the happen.

I dont generally disconnect as I am often on a tight river and need emergency back up often....the rudders are much nicer to handle without the motor though.

I think people have a tendency to overestimate engine drag while sailing. The transom area of the

at least is highly turbulent under sail.

Speedy blue hulls mileage may vary. Speedier white hulls dont feel drag.

Chip Hindes · Post by **Chip Hindes** » Mon Jan 16, 2006 7:17 am

I'm with Steve on all counts. The movment of the motor CG when tilted is more forward than up; without actually measuring I would guess the difference for my Tohatsu 50 2S is less than the eight inches he cited (he's got the Merc BF).

We've had the discussion on the motor (and second rudder) drag when sailing several times previously. The amount of frontal area and wetted surface on the lower unit is so small compared to the total of the boat, you would be hard pressed to measure the difference with anything we have at our disposal, and is no more than a few seconds per mile. This difference might be considered important on a 12-meter America's Cup boat. On a Mac, not so much.

I predict a veritible blizzard of protest from those who insist the difference is measurable in knots; I can only say I believe they're mistaken.

That being said, I accept that the motor causes at least some drag, even if it's not reasonably measurable. Except when I think I might need it in a hurry, I usually raise mine on principle.

A couple of caveats if you leave it down. Make sure you let it freewheel in neutral; the braking effect of a locked prop is considerable. Make sure both rudders and the motor are aligned properly, at least when straight ahead. It's best when they're also aligned when angled in either direction as well, but the differing geometries can make this difficult.

jetta01 · Post by **jetta01** » Mon Jan 16, 2006 8:06 am

I notice about half a knot difference when raising the engine. I have the quick disconnect from BWY and love it. Where I see the most gain is not in the engine in or out of the water, but the pressure relief on the steering system while heeling over. If I don't disconnect and am in 4 + foot swells, the SportPilot doesn't do very well as it is fighting the extra weight of the engine on the system. While disconnected though, it steers great. I can actually hear difference on the strain of the auto-pilot motor.

My only word of caution if you disconnect is to remember that you disconnect!!! I came back in to the docks the last time and all of a sudden I didn't have much control as normal...then realized it was disconnected. Handles much more like a true sailboat when disconnected.

They Theirs · Post by **They Theirs** » Mon Jan 16, 2006 8:25 am

Part of this I agrees with Chip!
Chip wrote:

(We've had the discussion on the motor (and second rudder) drag when sailing several times previously)

Seems weve stirred this bowl of Swill before? This is akin to selling the hairless man a comb.
It didnt sell then, and I doubt there are many so inexperienced to buy it now!

Enhancement of sailing qualities:

The ability to tilt the outboard up out of the water is the most effective (and simple) way yet devised for avoiding prop drag. The drag of an outboard prop dragging through the water is amazingly large and the boat will slow a lot. It will feel like you are pulling a sea anchor along. And maneuverability is greatly reduced. You will be very surprised how much a lowered or dragging outboard will degrade sailing.

BWY's Cure for Wheel Pressure from Flopover:
Disconnecting the motor reduced the load on the steering wheel to just the two rudders trailing off of the stern (We were surprised to learn that the extra point for securing the outboard was a Blue Water Yachts innovation, and Todd and Cheryl sell the parts for this system to MacGregor dealers and owners throughout North America.)
NORWESTING MAGAZINE EVALUATION OF THE MACGREGOR 26Disconnecting the motor reduced the load on the steering wheel to just the two rudders trailing off

Gee I wonder why those manufacturers produce millions worth of folding propellers for boats? Please?

An engine- real convenience when you have to get home on Sunday night.

Jim Cate · Post by **Jim Cate** » Mon Jan 16, 2006 8:50 am

I also have the BWY quick disconnect lingage, and there is a major difference in the "feel" of the steering with the motor disconnected. - Excuse the expression, but it's more like sailing a "real" sailboat, in which the steering system controls just the rudder. Because of the reduced drag felt at the wheel, I think control of the boat, as in tacking, etc., is more precise.

As to whether, or to what degree, raising the motor increases speed, I think it does but haven't actually measured it. - That's something that we could check out, and I'll try to do it next time. In addition to raising the motor, I think raising one of the rudders, which can be done fairly conveniently on a long run, may also help to minimize drag.

Jim

Chip Hindes · Post by **Chip Hindes** » Mon Jan 16, 2006 9:09 am

They Theirs, you can scream this as loud as you want. It doesn't make it so. You are mistaken.

They Theirs · Post by **They Theirs** » Mon Jan 16, 2006 9:15 am

Chip

Ill try to talk as softly as I can. I dont believe so, Im thinking and talking straight up, no fairly tales here, no innuendo or Couda~Shouda~Wouda! Im 100% correct!

DLT · Post by **DLT** » Mon Jan 16, 2006 9:21 am

Maybe the issue here is relative...

Prop drag may be amazingly large for a J-boat, or an America's Cup boat. But, from my experience, it is barely noticable on a Mac, even my 14" prop...

They Theirs · Post by **They Theirs** » Mon Jan 16, 2006 9:29 am

DLT

Relative to Boat Speed? J boats on a beam reach: 8 knots. M on a beam reach: 6 knots

Scott · Post by **Scott** » Mon Jan 16, 2006 9:29 am

Hmmmm, I usually agree with Chips guruness especially since his trailer specs (which he so graciously forwarded to me) worked so well. However in this regard I seem to recall past threads where the consensus was that a raised motor was good for around 1/2 to 1 1/2 knots in a stiff wind.

I seem to recall finding the same via GPS on a day when half way through a sail we discovered a still lowered engine. I do not recall figures and did no search of the archives so this is near pure conjecture on my part. Or maybe Im imagining it.

They Theirs · Post by **They Theirs** » Mon Jan 16, 2006 9:31 am

Probably the closest to being correct Scott

Chip Hindes · Post by **Chip Hindes** » Mon Jan 16, 2006 10:52 am

Scott wrote:consensus was that a raised motor was good for around 1/2 to 1 1/2 knots in a stiff wind.

Consensus doesn't make it any more so than does shouting.

Or maybe Im imagining it.

They Theirs wrote:Probably the closest to being correct Scott

Exactly.

I don't doubt that Scott saw 1 to 1 1/2 knots variation, I only argue that attibuting such to lowering or raising the motor is a giant leap of faith; a triumph of hope over reality.

BTW, 12 meters don't have props, or even anything remotely resembling a motor.

They Theirs · Post by **They Theirs** » Mon Jan 16, 2006 11:12 am

Chip

You win!

When the Mac is sailing at 6 knots and the outboard engine is lowered, the resulting loss is 1 knot. Not so much when under full throttle of the engine!
But then the resulting 25% loss is Huge when sailing.

Now lets take the 20 mph under full throttle on the engine. The loss of 5 knots or 25% is also very large.

MacGregorSailors.com

MacGregorSailors.com

Disconnecting Engine Linkage

Disconnecting Engine Linkage