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  #1  
Old 10-01-2003
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a few specific design questions

So, Someone pointed me to Roberto Barros'' Multi Chine 28'' ( http://www.yachtdesign.com.br/02_ingles/index_ingles.htm then go to stock plans, multi-chine 28), which to me looks like the best boat I''ve seen for what I''m looking at, however I''ve got alot of questions now, and things that I, in my ultimate wisdom think could be done better. Of course, I''m a kid who wants to build a sailboat, not a naval architect with years of experience.

In dealing with a designer, is it considered disrespectfull to ask why they did something?

Maybe some of the wiser people here could answer some questions for me.

eg:

Why is the traveler on the coachroof instead of aft of the tiller? Wouldnt this make singlehanding easier?

Why is the mast stepped on the Deck insted of the Keel? Wouldnt this make the boat more robust, and just run through the edge of the leaf table anyway, not realy affecting interior layout or usability?

Why a big headsail and small main? Is this supposed to be an IOR rules beater? Wouldnt a bigger main be easier to handle than a big headsail? (of cours, if the answer is yes, then the mast needs to move, etc.)

How about leading lines aft? can that even be done with the mast ahead of the coachroof? And if so, is there any way that the winches for the jibsheets could be moved forward so that they could serve double duty? Or would that be stupid, eg: if you had to winch on a reefing line (Do you ever need a winch to reef? I never have, but I dont know) while you were on a tack where that winch was in use by the jib etc?

On a positive note, that is the least questions I''ve ever had about any boat I''ve seen so far. The belowdecks looks like a great way to use space. a more sensable aproach combining aspects of 2 of the boats I like best below decks (the Catalina 270 and the Gozzard 31)

But as far as me asking these questions, and suggesting another way to do it, it''s a kid who''s been sailing for under 3 years challenging the design decisions of a naval architect. I feel like an @ss, but at the same point, I dont see why they do that. Anyone know the answers?

Enlighten me.

Thanks agian guys.

-- James
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Old 10-01-2003
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a few specific design questions

There are no stupid questions. Ask away but ask respectfully. Although I have not seen the boat many of the things with the possible exception of the rig design would be easily customised to your specs. You just might learn something too.
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Old 10-01-2003
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a few specific design questions

if you are interested in looking at the boat, the URL is above. It looks rely nice, for a multi-chine design.

-- James
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Old 10-01-2003
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a few specific design questions

James,
There was a good thread about keel stepped vs. deck stepped masts under "buying a boat" not too long ago. It seems like it started with a Catalina 35 question. Check it out if you can find it.
Good luck. You ask good questions I''d like to know the answers to as well.
Kido
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Old 10-01-2003
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a few specific design questions

So there was. Thanks. 1 down. only about a billion to go. and better still, the design I''m looking at has a truley deck stepped mast, instead of a coachroof stepped mast like most boats I''ve seen, which should be much more efficient at transfering energy to the hull and water where it needs to be instead of slowly stressing the coachroof and weakening that area. (I have trouble visualizing how a coachroof, with an extra set of angles would be able to be properly setup to handle the loads of the mast (sideways driving force, not downforce) as well as just on the deck.

Found that the general agreement seems to be for the larger main, and the aft traveler though.

As for leading lines aft, I''m sure it can be done, I just wonder how much hassle is involved.

Now to find out about the 2 winch deal (instead of four)...

-- James
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Old 10-02-2003
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a few specific design questions

A couple quick thoughts here,

I should note that I was unable to open the website and so was unable to actually see what the Barros 28 looks like. You asked whether you could address questions directly to Mr. Barros. As in most things this is a matter of Mr. Barros'' personality. Some people do not mind answering questions and will take time to answer you and others will not feel comfortable answering your inquiry. You should be able to write to Mr. Barros and ask him the kinds of questions that you have raised. That does not mean that he will answer you.

I am not sure that your questions about why the designer chose to do certain things are impertinant. But I am not sure that I would phrase them as you have. Designers are human and can be opinionated just like the rest of us. If you ask these questions in a neutral and non-acusatory way, you are likely to get the designers best explanation of his opinions rather than a defensive or agressive response.

From the discussion this sounds like the Barros 28 is an older style design, especially if it resembles a Cal 2-27. I would assume that is why it has a large jib, small mainsail rather than a more traditional or more modern fractional rig. (For the record, fractional rigs predate masthead rigs and have come back into vogue now that the race rules no longer over penalize them.) As far as relocating the traveler you would probably do best mounting it on the bridge deck where it is in easy reach of the tiller.

Multiple chine plywood is a reasonably good way to build a boat although it still requires all of the skills and care that other forms of composite or semi-composite construction would require.

The deal on a coach roof stepped mast is that you need to develop a moment connection between the jackpost and the base of the mast. In that manner you transmit no more side load into the house than you would with a keel stepped mast, and argueably less if designed properly. With either a keel stepped or deckstepped mast, there should be large knees or a bulkhead adjacent to the mast to distribute the side loads into the deck.


On a 28 or bigger footer you will want redundant winches because there will be times when you want to adjust a halyard or reef while the the winch in question is still in use. These only need to be single action winches and so are pretty inexpensive. On the other hand you might do two speeds so that they can be used with your spinnaker sheets.


You might also look at the Dudley Dix http://www.dixdesign.com/designs.htm designed smaller version of the Didi 26 and Didi 34. These are modern, well thought out smaller boats aimed at amateur construction. From what little opened on the Barros site, it appears that the Didi 34 is roughly the same displacement as the Barros 28 and so should be of similar costs to build and similar difficulty to sail.

Regards,
Jeff
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