Adding a mizzen mast to a sloop boat, good o bad idea?

Converting an existing sloop to a yawl or ketch would require considerable rebalancing of the entire rig and/or lateral plane unless, as designed & built, the boat had serious lee helm. Simply adding a mizzen just does not work.

We currently have a ketch which, as originally designed, was not balanced and had terrible weather helm. This was the result of poor rudder and deadwood design and an imbalanced sail plan. This was fixed by extending and fairing the deadwood by some 10" (moving CLR aft), streamlining the rudder and adding a 6' bowsprit.
I also used to own a Water Witch ketch that also had a brutal weather helm. I have sailed another ketch a fair distance, offshore and in stormforce conditions.

I has been my experience that closehauled the mizzen, operating in the backdraft of the main, is just along for the ride and it's main and significant contribution on this point of sail is drag. Dead downwind, it also acts a bit of a fifth wheel as well, in as much as a staysail or the main on a cutter - someone is always going to be in someone else's way. They excel at reaching, when you can balance the boat and add all sorts of sail in light going.

In the 70ies, any offshore boat, and a number of wannabee ones as well, simply wouldn't float unless it had a ketch rig. Pre furling that might have made sense on a larger vessel, but there were also a whole crop of toy boats built with mizzens the size of a beach towel. Quoting historic craft in this context, such as the Spray is of little help. Slocum not only cut off his main boom when he turned her into a yawl, he also added 10' to her bowsprit and gave her a flying jib as well. So, if you need to make your sloop sail quicker, stick a sprit on her and get a code zero. IMHO, of course.
 
Laminar Flow said:
Converting an existing sloop to a yawl or ketch would require considerable rebalancing of the entire rig and/or lateral plane unless, as designed & built, the boat had serious lee helm. Simply adding a mizzen just does not work.

We currently have a ketch which, as originally designed, was not balanced and had terrible weather helm. This was the result of poor rudder and deadwood design and an imbalanced sail plan. This was fixed by extending and fairing the deadwood by some 10" (moving CLR aft), streamlining the rudder and adding a 6' bowsprit.
I also used to own a Water Witch ketch that also had a brutal weather helm. I have sailed another ketch a fair distance, offshore and in stormforce conditions.

I has been my experience that closehauled the mizzen, operating in the backdraft of the main, is just along for the ride and it's main and significant contribution on this point of sail is drag. Dead downwind, it also acts a bit of a fifth wheel as well, in as much as a staysail or the main on a cutter - someone is always going to be in someone else's way. They excel at reaching, when you can balance the boat and add all sorts of sail in light going.

In the 70ies, any offshore boat, and a number of wannabee ones as well, simply wouldn't float unless it had a ketch rig. Pre furling that might have made sense on a larger vessel, but there were also a whole crop of toy boats built with mizzens the size of a beach towel. Quoting historic craft in this context, such as the Spray is of little help. Slocum not only cut off his main boom when he turned her into a yawl, he also added 10' to her bowsprit and gave her a flying jib as well. So, if you need to make your sloop sail quicker, stick a sprit on her and get a code zero. IMHO, of course.
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It has taken me a very long time to learn how to sail our ketch. The mizzen only comes out when the wind is on the beam or further forward. Putting it up with the wind behind us just un-balances the boat as she tries to round up all the time; keeping it in the bag when heading to windward means we point 10 degrees lower.
 
roaringgirl said:
It has taken me a very long time to learn how to sail our ketch. The mizzen only comes out when the wind is on the beam or further forward. Putting it up with the wind behind us just un-balances the boat as she tries to round up all the time; keeping it in the bag when heading to windward means we point 10 degrees lower.
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That sounds odd - as Laminar Flow said, if the main and jib are sheeted correctly, generally the mizzen is simply in dirty wind from the main. Hence yawls / ketches tend to point lower when sailing under full sail (and why some racing ketches tried extreme spacing between masts to reduce the back winding effect).
To increase pointing ability on a sloop, you would pull the traveller to windward and pull the sheet in till the boom is near the centreline and slight twist higher up. Do you pull the traveller to windward when beating without the mizzen set?
 
dunedin said:
That sounds odd - as Laminar Flow said, if the main and jib are sheeted correctly, generally the mizzen is simply in dirty wind from the main. Hence yawls / ketches tend to point lower when sailing under full sail (and why some racing ketches tried extreme spacing between masts to reduce the back winding effect).
To increase pointing ability on a sloop, you would pull the traveller to windward and pull the sheet in till the boom is near the centreline and slight twist higher up. Do you pull the traveller to windward when beating without the mizzen set?
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I do all the same setting of the main & jib as a sloop, but just add the mizzen, and trim it like the main.

I agree that it defies logic, and I think this is why it has taken me so long to figure out how to sail her to windward. There must be some other factor that you and I haven't taken into account, as empirical evidence definitely shows the mizzen makes us point higher. I have wondered if there's some kind of slot-effect from main to mizzen so that all 3 sails act as one...
 
roaringgirl said:
It has taken me a very long time to learn how to sail our ketch. The mizzen only comes out when the wind is on the beam or further forward. Putting it up with the wind behind us just un-balances the boat as she tries to round up all the time; keeping it in the bag when heading to windward means we point 10 degrees lower.
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I think whether a boat has a tendency to round up downwind may very well depend on a particular boat. We have, on occasion, run in strong winds under mizzen and spinnaker only. In these conditions and with a quartering sea our mentally challenged and lethargic auto pilot had no problems keeping us on course. In fact, I went to sleep while my wife stood watch writing her journal in the wheelhouse.
Taking down a chute on my own and without the lee of a main in short steep seas is another thing entirely.

dunedin said:
That sounds odd - as Laminar Flow said, if the main and jib are sheeted correctly, generally the mizzen is simply in dirty wind from the main. Hence yawls / ketches tend to point lower when sailing under full sail (and why some racing ketches tried extreme spacing between masts to reduce the back winding effect).
To increase pointing ability on a sloop, you would pull the traveller to windward and pull the sheet in till the boom is near the centreline and slight twist higher up. Do you pull the traveller to windward when beating without the mizzen set?
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If I understood roaring girl correctly. they do not set their mizzen to weather. IMHO, on many cruising type boats the windward ability is often limited by the sheeting angle of the jib/genoa due to wide shroud base and spreaders.
 
roaringgirl said:
I do all the same setting of the main & jib as a sloop, but just add the mizzen, and trim it like the main.

I agree that it defies logic, and I think this is why it has taken me so long to figure out how to sail her to windward. There must be some other factor that you and I haven't taken into account, as empirical evidence definitely shows the mizzen makes us point higher. I have wondered if there's some kind of slot-effect from main to mizzen so that all 3 sails act as one...
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I must say, I'm rather surprised by this. It is rather untypical and I have sailed a few ketches.
When we had new sails made for our current boat, I had the mizzen cut flatter to accommodate this, somewhat at least.
 
Laminar Flow said:
I think whether a boat has a tendency to round up downwind may very well depend on a particular boat. We have, on occasion, run in strong winds under mizzen and spinnaker only. In these conditions and with a quartering sea our mentally challenged and lethargic auto pilot had no problems keeping us on course. In fact, I went to sleep while my wife stood watch writing her journal in the wheelhouse.
Taking down a chute on my own and without the lee of a main in short steep seas is another thing entirely.


If I understood roaring girl correctly. they do not set their mizzen to weather.
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You didn't understand me correctly - we *only* set the mizzen to weather!

On our passage from Lisbon to Madeira last year, we had a big following sea. We set the mizzen and genoa. We frequently surfed and at the bottom of the wave, the wind would catch the mizzen and push the stern downwind. The electric autopilot was perfectly capable of correcting for this. However, the electric autopilot hides a multitude of evils, the Hydrovane did not put up with this sail-plan at all, as it couldn't recover from the stern being kicked sideways. On our Atlantic crossing we did all our sailing with the Hydrovane. We kept the mizzen in the bag and goosewinged the main and genoa. We pointed downwind in some big following seas, and didn't have the same problem - the hydrovane coped 24/7 - which indicates to me that she was well balanced on that point of sail.
 
roaringgirl said:
You didn't understand me correctly - we *only* set the mizzen to weather!

On our passage from Lisbon to Madeira last year, we had a big following sea. We set the mizzen and genoa. We frequently surfed and at the bottom of the wave, the wind would catch the mizzen and push the stern downwind. The electric autopilot was perfectly capable of correcting for this. However, the electric autopilot hides a multitude of evils, the Hydrovane did not put up with this sail-plan at all, as it couldn't recover from the stern being kicked sideways. On our Atlantic crossing we did all our sailing with the Hydrovane. We kept the mizzen in the bag and goosewinged the main and genoa. We pointed downwind in some big following seas, and didn't have the same problem - the hydrovane coped 24/7 - which indicates to me that she was well balanced on that point of sail.
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I might add, that since leaving the UK in July 2020, I've asked every ketch skipper I've met for advice on sail trim and sail plans, and they've all shrugged!
 
roaringgirl said:
I might add, that since leaving the UK in July 2020, I've asked every ketch skipper I've met for advice on sail trim and sail plans, and they've all shrugged!
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Does your boat carry lee helm when on the wind and without the mizzen? It could very well mean that the load on the mizzen increases the angle of incidence on your keel and hence points you more upwind which is presumably where one wants to go.

When designing a rig and at the stage of determining balance only half the mizzen area is taken into account in consideration of it's lower efficiency.

Oddly, in Hazen's speed prediction program sails are additionally factored with:
at 27 degr., main 1.5, genoa 1.5 and mizzen 1.3
at 50 degr., main 1.5, genoa 0.5 and mizzen 1.4
at 80 degr., main 0.95, genoa 0.31 and mizzen 1.0
at100 degr., main 0.85 genoa 0.0 and mizzen 0.8
at 180 degr. all at 0.0

This would confirm that the mizzen's optimum performance is at 50 degr and is only slightly worse when close hauled.
 
Wansworth said:
Wasn’t that to lay to waiting for a pilotage job?
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I don’t think many of them were used by pilots. Crew tailors, sailmakers, chandlers, victuallers, and so on, but mostly ships’ agents, running messages. The square riggers and tramps with no radio used to make “Falmouth for Orders” - the orders being the name of the discharge port that the cargo had been sold to.
 
Kukri said:
I don’t think many of them were used by pilots. Crew tailors, sailmakers, chandlers, victuallers, and so on, but mostly ships’ agents, running messages. The square riggers and tramps with no radio used to make “Falmouth for Orders” - the orders being the name of the discharge port that the cargo had been sold to.
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Yes your right,even so they could hang about with just the mizzenmast set very much like modern day west country fishing boats do
 
Laminar Flow said:
Does your boat carry lee helm when on the wind and without the mizzen? It could very well mean that the load on the mizzen increases the angle of incidence on your keel and hence points you more upwind which is presumably where one wants to go.

When designing a rig and at the stage of determining balance only half the mizzen area is taken into account in consideration of it's lower efficiency.

Oddly, in Hazen's speed prediction program sails are additionally factored with:
at 27 degr., main 1.5, genoa 1.5 and mizzen 1.3
at 50 degr., main 1.5, genoa 0.5 and mizzen 1.4
at 80 degr., main 0.95, genoa 0.31 and mizzen 1.0
at100 degr., main 0.85 genoa 0.0 and mizzen 0.8
at 180 degr. all at 0.0

This would confirm that the mizzen's optimum performance is at 50 degr and is only slightly worse when close hauled.
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On the contrary, she carries weather helm, even when we've only got the genoa out. I have concluded that this is because she's very wide for her length (12m long, 4m wide) and as soon as she heels, the lee side of the hull makes her want to round up.
Raising the mizzen somehow makes all the sails able to stay filled at a tighter angle to the wind.
 
roaringgirl said:
On the contrary, she carries weather helm, even when we've only got the genoa out. I have concluded that this is because she's very wide for her length (12m long, 4m wide) and as soon as she heels, the lee side of the hull makes her want to round up.
Raising the mizzen somehow makes all the sails able to stay filled at a tighter angle to the wind.
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Intriguing. Compared to my tub, yours is actually a bit skinnier. May I ask what she is?
 
roaringgirl said:
A Maxi 120, 1977 vintage, she's narrower at the stern, so as soon as she heels, the bulge is in the water, and pushes the bow to windward.
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If I've followed this conversation correctly, other ketches do the opposite to us and only raise the mizzen on a run or ddw - doesn't this just blanket a bit of the main and exaggerate weather helm by pushing the stern to leeward?
 
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For a steadying sail at anchor, run your jib up the backstay. If that's the reason for contemplating such a strange thing, having a small flat sail made would be a much better and simpler solution than adding a mast!
 
roaringgirl said:
If I've followed this conversation correctly, other ketches do the opposite to us and only raise the mizzen on a run or ddw - doesn't this just blanket a bit of the main and exaggerate weather helm by pushing the stern to leeward?
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The optimum peformance angle for a ketch is between a close reach and a broad one, I would say.

I had a look at your boat. She looks rather nice, I have to say, and does not appear extreme in any way to my eye. She has a fairly deep forefoot and it might help to trim her by the stern a bit to raise her up forward.
Some of the pics online showed the Maxi to have some rake to her masts and straightening them up could also relieve some of the weatherhelm.
Lastly, you could check her balance on paper, or the relationship between CE and CLP.
In a ketch the CE should "lead" the CLP by 20% of her DWL, using 50% of her mizzen area. This is easier than it sounds and I would be happy to talk you through it if you like.
 
Laminar Flow said:
The optimum peformance angle for a ketch is between a close reach and a broad one, I would say.

I had a look at your boat. She looks rather nice, I have to say, and does not appear extreme in any way to my eye. She has a fairly deep forefoot and it might help to trim her by the stern a bit to raise her up forward.
Some of the pics online showed the Maxi to have some rake to her masts and straightening them up could also relieve some of the weatherhelm.
Lastly, you could check her balance on paper, or the relationship between CE and CLP.
In a ketch the CE should "lead" the CLP by 20% of her DWL, using 50% of her mizzen area. This is easier than it sounds and I would be happy to talk you through it if you like.
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There's no rake to these masts! My conclusion was that if she has weather helm when going to windward under genoa alone, then it must not be a sail-trim/rig tune issue but perhaps a deliberate intention of the designer of the hull. With careful thought and trimming of the sails I can reduce the weather helm to between 5 and 10 degrees of rudder when close-hauled with all 3 sails up, and she doesn't perform badly - we did a day close-hauled at about 15kts, 40° (appt) from Curacao to Bonaire recently at 6kts (She's 12T before you add water and fuel and a liveaboard family, with a long keel and skeg).
 
roaringgirl said:
If I've followed this conversation correctly, other ketches do the opposite to us and only raise the mizzen on a run or ddw - doesn't this just blanket a bit of the main and exaggerate weather helm by pushing the stern to leeward?
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Certainly on our old ketch the mizzen gave b all drive down wind as anything hitting it would hit main or genoa. It also flapped so was sheeted hard amidships in such a situation. Our boat never pointed high but was steadie with mizzen on the other points between dead down wind and hard to windward. Seemed to make no difference to pointing one way or the other.

The relatively small size of the mizzen compared to main meant it made small difference to weather helm. If it was driving one could always free the main slightly if weather helm was an issue.
 
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