planing in MAcX

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bonati
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planing in MAcX

Post by bonati »

And one more question quite in another subject... ( as you may see I have plenty of ignorance in all fields..)

Is it actually possible to reach planing in Mac X under sails? Anybody to share this experience and the conditions for it?

thks for any reply..
Excatman
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Re: planing in MAcX

Post by Excatman »

In theory, yes, but in reality...Nope :?

You need about 17-20 knots of boat speed to get the X over its own bow wave, which means you'd have to pull up the rudders or they would bust under the strain, so you'd have no steering. Add to that, you'd need empty ballast tanks to lighten the boat, and about 50 knots of breeze to get you to that speed (on a broad reach), so no stability either! I say in theory yes, because with the right combination of sail area, wind speed and direction, absence of ballast or steering...and a fervent death wish, it's possible. :)
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Herschel
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Re: planing in MAcX

Post by Herschel »

Excatman wrote:In theory, yes, but in reality...Nope :?

You need about 17-20 knots of boat speed to get the X over its own bow wave, which means you'd have to pull up the rudders or they would bust under the strain, so you'd have no steering. Add to that, you'd need empty ballast tanks to lighten the boat, and about 50 knots of breeze to get you to that speed (on a broad reach), so no stability either! I say in theory yes, because with the right combination of sail area, wind speed and direction, absence of ballast or steering...and a fervent death wish, it's possible. :)
I agree that trying to do it under sail would be a risky endeavor, but I was under the impression that when we motor, we do get the hull up and planning at about the 10 knot figure. I am certainly under the impression we are planning at the 13-14 knot range. Aren't we? :?
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sunshinecoasting
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Re: planing in MAcX

Post by sunshinecoasting »

First, an answer to your question, no, not on any planet will a :macx: plane under sail but mine planes at about 12-13 knots under motor with ballast out and I max out at about 18 with just me on board, rudders do not bust at 18 knots I do it all the time, the real issue is making sure they are tied in the down position, if not then they would definitely break and the steering would be unusable.
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dlandersson
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Re: planing in MAcX

Post by dlandersson »

My X planes at around 9-10 knots, Since the theoretical max. hull speed under sail is 6 knots (which I've never seen, 5.5 is my personal max with a Hunter 22 sail), it's highly unlikely that you can plane under sail. :wink:
Herschel wrote:
Excatman wrote:In theory, yes, but in reality...Nope :?

You need about 17-20 knots of boat speed to get the X over its own bow wave, which means you'd have to pull up the rudders or they would bust under the strain, so you'd have no steering. Add to that, you'd need empty ballast tanks to lighten the boat, and about 50 knots of breeze to get you to that speed (on a broad reach), so no stability either! I say in theory yes, because with the right combination of sail area, wind speed and direction, absence of ballast or steering...and a fervent death wish, it's possible. :)
I agree that trying to do it under sail would be a risky endeavor, but I was under the impression that when we motor, we do get the hull up and planning at about the 10 knot figure. I am certainly under the impression we are planning at the 13-14 knot range. Aren't we? :?
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Ponaldpe
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Re: planing in MAcX

Post by Ponaldpe »

I am new to sailing , isn't their a different kind of power between the boat out board pushing the boat out of the water and tilt/trim helping the planning . The sail power would be pushing the boat into the water making planning require more speed and power. I don't know just a thought.
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Signaleer
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Re: planing in MAcX

Post by Signaleer »

There are *rumors* it has been done...
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Herschel
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Re: planing in MAcX

Post by Herschel »

sunshinecoasting wrote:First, an answer to your question, no, not on any planet will a :macx: plane under sail but mine planes at about 12-13 knots under motor with ballast out and I max out at about 18 with just me on board, rudders do not bust at 18 knots I do it all the time, the real issue is making sure they are tied in the down position, if not then they would definitely break and the steering would be unusable.
My experience is different. I always put my rudders up when I motor over 6 knots. I never have any trouble steering with engine alone, with or without ballast, except at very slow speed while docking in a moderate to strong wind. Must be all those salt water crocs down there messing with you under water! :P
bonati
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Re: planing in MAcX

Post by bonati »

Friends , how interesting and diverse answers tks a lot to all of you : I would dare myself to comment on some with my prsonal opinions :
- Mac X seems not a pure displacement hull , as per its hull bottom but even so being around 6kn its hull speed , anything clearly above that is to be considered as planning. With my X, and friend´s M we reached ( just today for example) 6 kn, all sails out , full ballast, estimated above 16 kn real wind, beam reach, 18º+ heel ( calculated , do not have much instruments operating..) sea almost flat.
- Reaching planning under sails to a limited extent appears theoretically possible with right ( high) constant wind behind running or broad reach, flat sea ( may be some help from stern ..) ,right position of crew ( towads stern believe ): Any other suggestion..? Of course in this way FB will be rather up and ballast full for security , then planning would be limited on speed ,( lets say 10 kn?) and in time span .
- Planing under motor seems to be lot easier and I see clear that is very convenient to have the ballast empty ( by the way , I can never empty it completely following the directions of the manual) ; but one of you has had the experience to run up to 14 kn ( once up to 18kn) with rudders well fixed down ( me I have done up to 13 kn as well ) This is good news because the instructions say no more than 5mph but in bad sea stream, returning to harbor this did not work for me in one occasion ..
Thks again and welcome any further contribution..
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sailboatmike
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Re: planing in MAcX

Post by sailboatmike »

The answer in a unequivitable YES the X will plane under sail, you would need about 12 knots of boats speed to get her there, this issue is that with all the junk we carry in reality it would almost never happen due to the weight and the disbursement of the weight, having that big outboard on the back and fuel tanks at the back just add to the power required.

When you get on the plane the power needed to maintain planing speed is not great, the transition from displacement to plane requires huge amounts to get her to climb her bow wave because it becomes ever harder as you increase speed the transom drops into the wake causing the bow wave to become higher and steeper. The hull shape of the X somewhat mimics the lifting fuselage design of fighter jets that have short wings such as the F16. F16's have been known to return to base one wing shot off because the fuselage provides the lift at speed
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NiceAft
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Re: planing in MAcX

Post by NiceAft »

F15’s also.
https://theaviationist.com/2014/09/15/f ... -one-wing/

I now return the thread to its original thought process.
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dlandersson
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Re: planing in MAcX

Post by dlandersson »

The diff. is: sail power is free :wink:
Ponaldpe wrote:I am new to sailing , isn't their a different kind of power between the boat out board pushing the boat out of the water and tilt/trim helping the planning . The sail power would be pushing the boat into the water making planning require more speed and power. I don't know just a thought.
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Ponaldpe
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Re: planing in MAcX

Post by Ponaldpe »

dlandersson wrote:The diff. is: sail power is free :wink:
Ponaldpe wrote:I am new to sailing , isn't their a different kind of power between the boat out board pushing the boat out of the water and tilt/trim helping the planning . The sail power would be pushing the boat into the water making planning require more speed and power. I don't know just a thought.


I tell people that all the time sailboat fuel is real cheap, like me, and easy to transport. :macm: :D
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Cougar
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Re: planing in MAcX

Post by Cougar »

dlandersson wrote:My X planes at around 9-10 knots, Since the theoretical max. hull speed under sail is 6 knots (which I've never seen, 5.5 is my personal max with a Hunter 22 sail), it's highly unlikely that you can plane under sail. :wink:
I am surprised about your 5.5 max. I do get to and just over 6 knots every now and then, but maybe that's because I only have a light motor and only one fuel tank. Plus a full batten mainsail, fwiw :)
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sailboatmike
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Re: planing in MAcX

Post by sailboatmike »

Cougar wrote:I am surprised about your 5.5 max. I do get to and just over 6 knots every now and then, but maybe that's because I only have a light motor and only one fuel tank. Plus a full batten mainsail, fwiw :)
Not many 26 foot boat do much better than 6 knots, even bigger boats struggle to be much above that, for example 35 to 40 foot mono hulls 8 knots is considered to be doing doing well.

Thats just the physics of displacement hulls on water and the amount of power required to get to that speed. A typical 20 footer 5 knots is good, wind speed really isnt overly important, generally you wont go any faster is 20 knots of wind than in 12 knots, because 12 knots is enough to power her along at hull speed, so reef down to make the ride easier and enjoy your 6 knots. Keeping the full main up only adds to the stress on the rigging for no real gain in performance and makes the boat harder to handle. Roger recommended reefing at around 12 to 15 knots
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