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

[oldmanofthehills]

The actual problem is that unless one chops down the main boom and sail, one has to go for a yawl not a ketch. And that means a bumkin out the back to attach the mizzen sheet, and possibly the running backstay for when going down wind. Not rocket science and less onerous in terms of strength than a bowsprit - which I have done twice - but still a notable task.

Will the aft deck support a mizzen mast base, and can you keep forward mizzen stays clear of main boom?

Having sailed a lugger with a bumkin I can asure you that it makes harvours and marinas interesting to enter as the stiff tail swings into quayside etc as one turns.

 

[Laminar Flow]

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).

At 10 degr. weatherhelm and 6kts, a finely profiled rudder of 5 sqft (as in mine) generates the same resistance as a fixed 3-blade prop. If the rudder is of poor shape or flat the drag will be 3 times as much. Also, any turbulence ahead of a rudder, including the prop, can cause weatherhelm by impacting lift across the rudder. A common observation by sailors who switched to a folder or feathering prop is that it improved or stopped weatherhelm.

From what you say your weatherhelm is certainly pronounced. I would not put too much faith in the intention of designers and there is much that can happen between his pen touching paper and the launching of the final product. By all accounts, the hand that drew the lines of my tub was supposedly guided by divinity, but when it came to the steering end of things, said deity must have been on coffee break and the job was finished by the mail boy.

 

[roaringgirl]

At 10 degr. weatherhelm and 6kts, a finely profiled rudder of 5 sqft (as in mine) generates the same resistance as a fixed 3-blade prop. If the rudder is of poor shape or flat the drag will be 3 times as much. Also, any turbulence ahead of a rudder, including the prop, can cause weatherhelm by impacting lift across the rudder. A common observation by sailors who switched to a folder or feathering prop is that it improved or stopped weatherhelm.

From what you say your weatherhelm is certainly pronounced. I would not put too much faith in the intention of designers and there is much that can happen between his pen touching paper and the launching of the final product. By all accounts, the hand that drew the lines of my tub was supposedly guided by divinity, but when it came to the steering end of things, said deity must have been on coffee break and the job was finished by the mail boy.

There's a skeg and a feathering prop in front of the rudder. But anyway, the only thing to be done about it, is to balance the sails as much as possible and use the right sailplan for the right situation!