Sloop to Ketch conversion

[Rainbow48]

Originally Posted by Boatyarddog

Sorry, I do not see the need to relocate a sloops mainmast to add a Solent Stay, thus rigging as a cutter.

Also, a sloop hull is more likely to be a fin or modified keel design.
Most Ketch rigged vessels have a long or modified keel design, but have not seen a fin keeled ketch yet.

As most ketch rigged boats have a mainmast placed forward of the center of balance, to compensate for the spreading out of the sail plan.
As well shorter mast heights.
Boatyarddog

Traditionally, the cutter rig depends on the location of the mast - somewhere in the neighborhood of 40% of the water line length back from the stem - rather than the placement of a “Solent stay”, or how many jibs or stays’ls the boat carries.

A ketch would more likely have a longer keel in order to make full use of the advantages of the rig.

Cat boats, sloops, cutters, ketches, yawls all have their mainmasts forward of both the center of effort of the sails, and the center of lateral resistance of the hull. Not sure what “center of balance” is being discussed.

[boatman61]

Originally Posted by Boatyarddog

Also, a sloop hull is more likely to be a fin or modified keel design.
Most Ketch rigged vessels have a long or modified keel design, but have not seen a fin keeled ketch yet.
Boatyarddog

Check out some European boats like Westerly and Hallberg Rassey for example..

[Chris 249]

Originally Posted by Boatyarddog

Most Ketch rigged vessels have a long or modified keel design, but have not seen a fin keeled ketch yet.

As most ketch rigged boats have a mainmast placed forward of the center of balance, to compensate for the spreading out of the sail plan.
As well shorter mast heights.
Boatyarddog

Depending on one's definition of "fin keel", they've been around for many years, Tabarly's 1964 "Pen Duick II" being an obvious example of what just about anyone would call a fin. But a decade before that there was "Hoots Mon" (SORC series winner) and if you call any boat without a classic very long keel a "fin" then there were sloops like the 130 footers Vigilant, Ailsa, Satanita etc that were converted to ketches in the 1800s. At another extreme there was Guzzwell's 20' round the world cruiser Trekka. Then of course there were the famous fin keel maxi ketches like Stormvogel, Kialoa III, Ondine III, Windward Passage, etc etc etc.

There's been heaps of fin keel ketches, basically. Many of the racers converted to or from ketches kept the same mainmast and keel position.

I'm mystified as to why the original poster felt that ketches had better motion. Most of them have more weight up high which would theoretically give them a slower pitch, but a greater degree of pitch. But in the grand scheme of boat design, where there are so many variables of such a great extent, that would seem to be a tiny factor.

[Eric ROGUE]

A boat is a balance of features: interior, hull shape, auxiliary, sailplan, etc. The designer of a sloop or cutter you might buy balanced these factors.

You would be unbalancing the design and have to rebalance the whole design, not just sailplan and lateral balance of the hull form.

Ketches generally don't sail very well.

The designs of L. Francis Herreshoff are an exception, as are the hypnotic "just right" beauty of his designs. His designs are now ancient history. And they were wooden boats, carvel planking on frames, but at least one of these antique boats was still winning ocean races a couple or few decades ago (I loose track of time), and a few close variations have been built out of modern materials.

I designed my boat when I couldn't find a boat that met my ridiculous criteria. I have two bookshelves of boat design and rigging boats and I still got it wrong. My boat would have been a better sailboat, just as easy to trailer, and faster and cheaper to build. The bald headed lug schooner rig was chosen because it facilitated necessary qualities in the interior. A different rig would have been chosen had I stretched the spacing between building frames.

It is far easier to turn a grayhound sloop into a pig ketch than you might imagine.

Phil Bolger's 100 Small Boat Rigs is the best introduction to rigs and why you might choose one over another.

[letsgetsailing3]

Find yourself an Allied Mistress in good condition and call it a day.


39', A little older, but overbuilt. Finding one in good shape and well-equipped may be a challenge, but would be a lot easier than doing a conversion. You can put our money into updates.

[hpeer]

Phil Bolger's 100 Small Boat Rigs is the best introduction to rigs and why you might choose one over another.

Wow, $140 on Amazon. $43 used.

[Rohan]

Originally Posted by SailorBOI

However, some sloops in this range may convert to ketch fairly easily if I could find out what keel and rudder shape and configuration is required to accommodate the above-water-line changes.

OK, I'm not a boat engineer but how could this possibly done easily??? You are talking about serious redesign, engineering and reconstruction, this would be akin to moving around the chimneys in a brick house.

It might even be cheaper to build a new boat from scratch. If you were going to do this, I recommend finding a boat that's been seriously damaged that is being sold cheap and start with that.

There's a reason there aren't a lot of ketches on the market. Ketches and yawls were more popular years ago. What is the specific reason you prefer them? If you need a shorter mast for bridge clearance, it would be easier to rig a mast that can retract. Or if you don't have the strength to hoist a sloop mainsail, get electric winches.