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I have added this Q and A page because there are many questions which are asked of my designs over and over again. I am always happy to answer questions, and love to chat, but this page may help also. Questions are grouped by subject.

Lets begin with the most common questions. Others will be added as time allows.


Q.  How much will it cost and how long will it take ?

These are the most common questions asked of a designer, and most designers consider them the two unanswerable questions.

A. How much - the fact is that for amateurs the cost can vary enormously from boat to boat, and from country to country. Materials can vary enormously from place to place, and fittings and sails etc can also vary widely depending on type, quality, sailmaker etc etc. Where many successful boats have been built a designer might be able to provide an 'average' cost for a particular area, but that is all it will be. It will not tell you how much it will cost you personally, just how much it has cost some builders in the past. And don't forget that our hobby gets more expensive every day. Like many designers, I can only honestly provide a rough ballpark, if at all. I cannot guarantee these figures because I do not know what choices you will make. Also, in todays economic climate, prices change on an almost daily basis.

Like all good designers I provide study plans which include materials lists and sail / rigging plans. The best option is to obtain the studies for boats you have narrowed down to your final list, and do a costing in your local area, with your chosen materials and your chosen suppliers.

A. How Long - Again some designers will provide a man hours figure, but in my opinion these are again only averages and are not very honest ones for an amateur. How good a builder are you? How fast and accurately do you work? Do you, like me, spend as much time admiring your creation as you do building it. (I used to have an armchair set in the best viewing position.) The designer can give you an idea if the boat could be built in a season, or if it is a long term project of several years, but that is about all, realistically. Most 'man hours' figures are generally taken from the work of an experienced builder, except where many, many boats have been built to a design, in which case they may be an average. They may bear no relation whatsoever to what your building time might be.

Please do not expect me to give precise answers to these two questions. Some designers will - I prefer to be more honest with you.


We often hear comments that some of our catamaran designs are heavier than some comparable designs. This is not strictly correct, and it is unwise to compare designs based on published weights or length alone. There are two main reasons for this.

1. Comparing apples to oranges.  Our cats are designed for extensive long range live aboard cruising, and as such are generally higher volume, and more strongly constructed. than some of their closest competitors. Both of these factors mean heavier materials weight. However, these differances are not as great as one might think, because...

2. There are 3 differant weights which are commonly quoted as a boats 'displacement'.

      (a)  The actual bare weight of the boat, not including operational gear and equipment'

      (b)  The complete vessel weight, not including add on payload. This figure is frequently quoted as the displacement of the vessel, which is incorrect.

      (c)  The actual displacement, which is the amount the boat will weigh when it is floating on it's designed waterline. This should include the vessel weight (b) plus one half (1/2) at least, of the maximum add on payload.

Additionally, add-on payload should include only the crew, their gear and supplies, liquids (fuel, water) and any extra gear that is not part of the operational gear of the vessel. All operational gear, including engines etc, galley equipment, matresses, cushions, ground tackle, batteries, fittings and so on, should be included in vessel weight (b).

The figures quoted for our designs are always (b) for vessel weight, and (c) for displacement. Our vessel weights (b) include all normal operational gear, including the kitchen sink and do not include payload. Some designers quote the bare weight (a) as vessel weight, and vessel weight (b) as displacement, which is incorrect.

If you do wish to compare boats by weight, make sure first that they really are compareable, (and not just the same length overall), and check to see whether the published displacement includes payload - i.e. is it really the displacement, or is it the vessel weight. If (b) does it include all operational gear?.  If  (b) will the boat float to it's waterline at that weight. (If it does you have a major problem because the boat will be below its waterline as soon as you carry yourself and your gear / supplies on board.)


Q.   Are they a derivative of the Wharram Cats.

A.    No, they are not. The Coral Sea Cats share 3 things in common with Wharram cats. They are plywood, they have seperate hulls with cross beams, and they have flared hull sections derived from the 'V' shape. That is all, and these characteristics are shared by many designs from many designers around the world.

While the Coral Cats are similar in the above respects to the Wharram cats, and may share something of the same basic concept, they are very differant in most other respects.

The Coral Sea cats have a 'Truncated V' hull section, which has a narrow flat bottom and sloping sides. Resistance wise it is marginally more efficient than a straight 'V'.

They have raised coach roofs on each hull - this allows the accommodation to be raised higher in the hulls for more accommodation width where it is needed.

They have transom sterns.

They have mini keels for optimum performance. They are more oriented to windward performance.

They also have rigid cross beams to allow stiffer, more efficient rigs. Because of this, they are necessarily more strongly constructed.

They feature center cockpit modules.

For a given length they have more accommodation.

Q.  What are the main differences between the Coral Sea and Coral Cove Cats.

A.  The Coral Sea cats are simpler than the Coral Cove cats. The Coral Sea cats have a truncated V hull, while the Coral Coves have a multi chine hull, and are full bridge deck cats. Also the Coral Coves have added features such as hull pods to allow better internal accommodations etc. They cost more to build than the Coral Seas (comparatively) but are more substantial vessels overall.


Q. Is this boat trailable within normal road limits in the United States of America and Europe.

A.  Yes!  We have been advised the Federal and standard road width limit for trailing in most states of America is 8' 6", and the TC670 fits easily into this requirement. In Hawaii the limit is 9 ft. There are 8 states with a state limit of 8 ft, and they are Arizona, District of Columbia, Kentucky, Louisiana, Maryland, New Hampshire, New Jersey and Oregon. In these states the 8 ft limit only applies to roads which are not classed as federal roads. For all federal roads the limit is 8' 6" which is the federal standard for the U.S.A. (we have been advised privately that because of this inconsistency the 8 ft limit is rarely enforced in those states where it applies, however we cannot testify to the accuracy of this and advise that you should make your own enquiries if you live in one of those states. Note that is is extremely simple to build the boat a few inches narrower so she will fit the 8 ft limit.)

We have been advised that the width limit in Europe is generally 2.5 Metres.

Q.   The weight quoted as trailer weight for this cat is greater than for similar cats of this size and type. Why is that?

A.     You have to be very careful about which weights you are talking about. There are three weights of importance.

1. The Displacement weight - this is the amount the boat should weigh when floating to it's designed waterline, and normally includes the boat with all operating gear, and half the add on load (the crew, stores, junk etc.)

2. The dry weight of the hull. This is the weight of the dry, stripped out boat, and normally does not include the rig, any gear etc.

3. The trailer weight. This weight includes all gear which will remain on the boat during trailing, such as the rig, and perhaps even the motor.

The weight I quote are the displacement and the trailer weight. The dry weight (which is often quoted) is of little value for a trailer boat. Weights which seem widely differant to this, for a boat substantially the same size and construction, may be dry weights, or alternatively, the boat may be much more lightly constructed. Because it is intended to be hauled on and off a trailer, time and time again, the TC670 is soundly constructed.

Q.   How does the boat behave with a single rudder and centerboard

A. The single rudder / board combination has proven to be very effective on narrow catamarans, giving the boat a surety of steering and pointing more akin to a monohull. This is not a new idea, having been used in a variety of designs over the years, particularly by Derrick Kelsall. The setup has also been used by other designers, and has proven very successful as long as the rudder and board are both on the centerline. The TC670 performs and handles well on all points of sail.

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