The Ideal Cruiser - a long range passagemaker

[yipster]

Guilermo, see you listed a max wave height in the spreadsheet
monsterwaves excluded, what was the max angle of a wave?
did read bout wave specs before but cant find it back under favorites
btw, nice site you got with a handy triangle calcutor

 

[Guillermo]

Guilermo, see you listed a max wave height in the spreadsheet
monsterwaves excluded, what was the max angle of a wave?
did read bout wave specs before but cant find it back under favorites
btw, nice site you got with a handy triangle calcutor

Max wave height is the one considered for the asigned Design Category. It's the significative height, so ocasional waves may go up as big as twice this height, so 14 m.
Thanks for the nice words on the site.
Cheers.

P.S. Here an useful glossary on waves: http://www.islandnet.com/~rkashino/waveglos.htm

 

[yipster]

"Fully-Developed Sea - A sea state in which waves have reached maximum energy.
Additional energy added to the spectrum is dissipated by wave breaking."
happens at what water degree angle ?
i'm sure i've been reading bout this max angle, maybe still got it somewhere

 

[Eric Sponberg]

Answers to questions

Guillermo,

I also found that error in the STIX spreadsheet and corrected it, and then added some other user-friendly features of my own for in-house use. The HCE is 9.116 M, and the HCL is 0.646 M, which are slightly different from your numbers, but coming to the same total.

Marshmat,

The masts themselves are not modelled in the hydrostatics and stability model yet, so I don't have a definitive answer for you in the shape of a revised stability curve. But what would happen is that the righting arm curve will start turning upward at about 110 deg of heel, and provide such a lever arm and buoyancy as to completely eliminate the negative side of the righting arm curve. The curve will be a huge peak that will be as great or greater than the hump at 60 deg.

Thanks for everyone's interest.

Eric

 

[Eric Sponberg]

Guillermo,

Your coefficient of flotation is what we call the Waterplane Coefficient, Cwp, and for the Globetrotter 45 at the 30,100 lbs displacement, it is 0.748. Therefore, the pounds per inch immersion is 2,095.5 lbs/inch.

Eric

 

[Guillermo]

...happens at what water degree angle ?

With an slope of 1/14 or higher, a wave cannot support itself and breaks.

Eric:
Thanks a lot for the numers.
Those masts are able to survive a full knockdown?

 

[yipster]

With an slope of 1/14 or higher, a wave cannot support itself and breaks.

thanks for the reply, thats what i meant, however a slope of 1/14 say 5 deg seems low..
however; for a 14 meter boat viewing the crest from a through on ten boatlenghts thats a 10 meter wave !

 

[Guillermo]

thanks for the reply, thats what i meant, however a slope of 1/14 say 5 deg seems low..

Sorry. I expressed the thing incorrectly. A wave breaks when its height is bigger than 1/7 of the wavelength (Steepness, not slope). Other authors state 1/8 instead of 1/7. Minimum angle at the cusp before breaking is 120º.

 

[yipster]

more scary but correct, a search also learned fully develloped waves coming together, prolonged storms sometimes combined with breaking gulfstreams can create monsterwaves, interesting those waves and good to know what were talking about, thanks

 

[Vega]

chines make a boat slower and mainly they make a boat ugly.

Vega
Chines make very little difference at all to performance, tank tests have shown some chine forms to actaully have lower drag . Also consider that the chine adds significantly to roll damping.

That's why racing sail boats have chines

You know, the difference between a fast boat and a slow boat is made of a lot of "little differences", chines is one of them.

Vega
Tank tests on the same design that I am aware of (one developed round bilge one multi chine) show a samll drag increase that would amount to a fraction of a knot. Tests at Southampton showed that carefull chine placement could reduce drag in displacement hulls such as yachts

"… the difference between a fast boat and a slow boat is made of a lot of "little differences", chines is one of them…"

True, but very, very small one. (If it is double or triple chine), compared with other factors.

"…That's why racing sail boats have chines …"

Well, actually, some of them does have them, a lot of dinghy classes use them and in the period of plywood there where large, single chine keel boats that where very successful. ...

These days, we don't see chines oftenly on the racing keelboats but some of them are almost chine boats having very tight curves between basically flat sections of the bottom and hull sides. Actually, as modern boats plane easily, I wouldn't be suprised if we see the chined hulls more in the future. One of the boats taking part on the last Vandee Globe has a chine.

Single chine hull have a bit more wetted surface then round chine = more drag, but at the same time it has a bit more initial stability so can carry a bit more sail area. That would compensate additional drag.

Well, I have picked up this old discussion about chines and speed because in this year edition of “La Route du Rhum” (begins tomorrow – 29/10), there are two sisterships (design by Jules Marin) that have chines (and are made of wood), on the new 40 class.

Fact is that Jules says that the chines help the boat to plan faster.

I am very curious about the performance of these boats, compared with the other 23 class 40 boats.

And even if I prefer round bilged boats, I don’t find that boat ugly….but I guess that these are very “soft” chines .

About performance, even if the boat is not faster (we have to wait to see) it’s obviously a very fast boat…So I guess that, if well made, chines have not any noticeable influence in the performance of a cruising boat. Of course, here the well made assume a huge
Importance.

 

[Guillermo]

I really like this one:
http://www.efesyat.com.tr/homepage/index.asp

 

[LAZYJACK]

To all still picking up on this topic.
I've cruised through this thread (I admit not having read all posts) and have seen many interesting things. Taking into account that originally the question was ..."live-aboard capacities, long enough to live aboard and not too big to be unaffordable", many of the designs seem to me to be well over the affordability issue. Obviously available budget means many different things to each one of us.
Personally I would like to see something in the € 250.000,- range, absolute maximum. An additional important criterium would be simplicity. I have seen a design that comes close. Make it into a 41-43 ft, add a few modifications (U-shaped galley, proper shower/head, ...) and Id would seem that this design might fit the profile.
Please have a look at
http://www.chantiermer.com/presselordjim.htm
http://www.lordjimcroisieres.com/fr/index.php
and give me your impressions and critiques.

 

[Vega]

Personally I would like to see something in the € 250.000,- range, absolute maximum. An additional important criterium would be simplicity. I have seen a design that comes close. Make it into a 41-43 ft, add a few modifications (U-shaped galley, proper shower/head, ...) and Id would seem that this design might fit the profile.
.

Nice boat with an attractive and unusual interior. If this is the boat you want you are a lucky Guy, because I think that the boat is inside your budget. All you have to do is to talk with the Architect and have the interior modified the way you like.

http://www.chantiermer.com/contact.htm

 

[Guillermo]

Lazyjack,
What about this one?
http://www.radford-yacht.com/dsn047.html
A nice 44' globetrotter you can build by yourself.
She has a 180º AVS, and I have estimated an STIX of around 57 for her.
Cheers.

 

[LAZYJACK]

Guillermo.
Thanks for the reply.
I have been attracted for a long time towards metal hulls, specifically aluminium, for reasons of security (metal hull=stronger).
I currently own with 2 friends a cold molded 3 layer mahogany wooden Sparkman & Stephens 41 (solidly build in 1973). Last year we had a collision and I have experienced personally how fast a wooden hull can be holed. Thus yes, I might still opt for an aluminium hull if my sailing program were the high latitudes. However, I do think that a well designed and solidly build woodcore (which the design I submitted is not, by the way; it would have to be modified) or similar type construction with composite materials (hence my question on another thread regarding a material called Strongplank) can deliver a very secure boat for most sailing programs.
A few things in your design which I don't like :
- galley far forward, not exactly the most comfortably place to cook.
- 2 berths all the way up in front; not many people have a stomach solid a enough to sleep there in somewhat rough weather.
- do you think construction price can be kept under 250.000 €/dollars ?
By the way, your design reminds me of the Patago series by Jean François André, a French architect.
There is one thing I like very much and that is the impact of loading on waterline. This is virtually never mentioned in any description of a yacht-design, and is clearly a crucial point for a long range passage boat where load will be important.