This might be a little dated by the time it arrives.

|> I would like to note that all of the things in your your extended quote are secondary to length being the first order variable for ride quality. So I, who know nothing, encourage you to do that first.

|     The items you left out in the extended quote as being "secondary" are the most important ones in the context of this proposed project.  You describe length as being the first order variable, but it is completely 100% "off the table" here.

My friend, as I said "Beyond the first order variables, all I can do is smile and nod, mostly."

The solutions you propose to your problem are interesting. As I said, I too looked at those cat designs. I find my self replying to your questions with, 'you would not have to do that if this criteria was different'.. If that bugs you I will desist. But I think we are learning a lot about boats fast. I was impressed how you quickly agreed about stern fineness. Facts guided you, not ego. I must respect that. But also, move the mast, change the construction material! Much wisdom. Mad respect!

And you are not alone. With each interaction I also have learned and understood more about boats, and harryproas.

|   Many boats have been and continue to be built by home builders that are in this size range and smaller.

Sure, and how much do they spend building them?

Read this quote
https://au.groups.yahoo.com/neo/groups/harryproa/conversations/messages/11405

If they knew they could build a single hander 60' for the cost of the 30' little boat, how many would change their mind?

Or do you think the Idea of a 60' would be intimidating to most builders? Or is the economics a second order variable?

|     It really is not worth continuing this unless we can set "longer" aside.   We have a case of the irresistible force meets the immovable
|object.   You are hung up on longer, and I absolutely refuse to consider longer.

Then I'll bow out. I don't want to bug you any more.

|   It's about as rewarding as having sex with a lady who continuously complains about the length of your penis..... It just ain't gonna get any longer!

I am confused and entertained with this scenario. I don't see a problem here. In our case, we can, literally, build one the perfect size.

|> Do you have a defined criteria for interior space?

|    I do not have a "defined criteria"..... I'm not sure how one would define it.  

I think you did a pretty good job. Just writing down and talking about an idea can lead to a check list of items you want to make sure you have. Like I don't know I need as much room in the head, but know I have thought about it.

|    I disagree with you about these cats having too much buoyancy aft. 

That's not what I meant. What I meant was, from the point of view of optimal ride, and applying the advice from the quoted source on how to make it better, the advice applied to cats in general, because many cats have to much aft buoyancy.

I cannot speak to how either design rides. All I might be able to do is point you at people who talk about how they ride. So I cannot say they need this change.

| You can't have everything in a 30' cat, so as a designer you don't just say "A 30 cat is garbage, I'll build a 50' cat and have everything", you ask "How can do the best within these parameters".

Agreed. But I think It is better to say, as early as possible, what can I do with 10,000$?. Or what can I do with 50,000$? Etc. It is anti intuitive to me to commit to a platform first, then see what fits.

Also you have made the point of ongoing costs. That also is an important criteria people do not think enough on. In aviation there is a TBO. Which is an accounting idea that tells you the cost to budget for every hour you operate the plane. Afaik, there is not a similar idea in boats. Nobody has a $ per sailing hours for sails, or hulls. Or they do, and I have not found it yet.

But things like Rob's built in tender makes me think he puts thought into it. Embracing trailering too!

|     I won't as you implied somewhere, be grafting the cabin from one boat onto the hulls of another, though I will probably increase the saloon (BH4 to BH5)length from 1.53m to over 6M, as I expect to spend considerable time there, and it also increases the space in the galley, and shop / nav area.

| I'm considering the possibility of a single free standing mast.

| The big problem with lengthening the boat is that every dimension changes, and every bulkhead changes, and or moves. 

It is probably a simpler task to lengthen, as opposed to swapping hulls. Afaik, most lengthen by adding a chunk in one spot in the middle. But I can no more assist with these than the change out of your hulls. I think you may want to get a professional to check your work.