The Ideal Cruiser - a long range passagemaker

[Vega]

Originally Posted by MikeJohns

Vega

Ugly? This is a prejudice that I think you should be cured of.

Wrong, that is an incurable disease, I am allergic to ugly things (I am an architect)

You know, God, the greatest of all architects, when designed the shape of things, made them without sharp bends, all soft curves with beautiful transitions. How can I like sharp bends in an apparently curved surface? That's Anti-Natural

Originally Posted by MikeJohns

Chines make very little difference at all to performance; tank tests have shown some chine forms to actaully have lower drag.

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.

Originally Posted by MikeJohns

Modern chine designs are very sensible for a sheet material, are easy to build and to repair. Also construction cost is significantly less.

Yes I agree if we are talking about steel. I also agree that steel is the material to use if it is a boat to be built by an amateur.

But the price of a hull is less than 1/3 of the total cost of the boat and as Van de Stadt Design team say "Aluminium is at least as strong as steel but considerably more expensive. The advantage is the weight: lighter hulls, by which speed and handling is better. For larger ships (the biggest plan they offer is a 56' and the smaller a 30’) the cost share of the hull is relatively small."

Aluminum work is difficult and needs control of the ambient damp, drought and temperature. It is not well suited to be used by an amateur.
The difference in price between an aluminum chine hull and a nice round bilge hull, made by a well equipped shipyard is not significant, if we take into account the total cost of the boat..

So if you want a fast and strong boat, aluminium and round bilge is the way to go.

Originally Posted by MikeJohns

Jim's correct in that collisions are commonplace…

Jim didn’t say that. He said: ”Cruising yachts run aground all the time”

I don’t really know what he means with “all the time” or what you mean with “commonplace”. Fact is that I know a fellow countryman who has recently finished a two year around the world voyage (in a very light boat) without colliding with anything, or going aground. The vast majority of cruising people that I know never collided with anything big enough to cause any problem…so it is a little difficult for me to understand your definition of commonplace.

Anyway that can happen, if relatively improbable in the lifetime of a boat…..that’s why I prefer an aluminum hull “at least as strong as steel”.

[blared]

I say 40ft fiber twin diesels and a big gas tank.

[MikeJohns]

Vega
The chine form has a lot to offer and it can look nice if you remove your blinkers, you may have seen many chine boats that you did not even register as such. The red comments are mine:

Originally Posted by Vega

Wrong, that is an incurable disease, I am allergic to ugly things (I am an architect)

I dont like ugly either, consider a blunt stern , does it look better as a "bubble butt" or as a sharply defined transition.

The sheer is similar to a chine, chines can sweep gracefully too.

On a boat there are many dominant straight lines in the mast and rig. Unless you sail with a sagging forstay because you prefer a curve ?

You know, God, the greatest of all architects, when designed the shape of things, made them without sharp bends, all soft curves with beautiful transitions.
That was woman ............ the rest is claws, teeth and sharp edges


That's why racing sail boats have chines

Aah not the racing boats argument !

...stability? ....strength?...durability? ....suitability for cheap construction?........owner builder?..........good load carrying capability?....comfortable at sea?...low maintenance?..................I thought we were talking cruising boats?

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.

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.

Yes I agree if we are talking about steel. I also agree that steel is the material to use if it is a boat to be built by an amateur. But the price of a hull is less than 1/3 of the total cost of the boat and as Van de Stadt Design team say "Aluminium is at least as strong as steel but considerably more expensive. The advantage is the weight: lighter hulls, by which speed and handling is better. For larger ships (the biggest plan they offer is a 56' and the smaller a 30’) the cost share of the hull is relatively small."

Last quote I got here was $100k for the bare developed hull and $60k for the chined hull (same design) .

Total cost is a bit nebulous , it depends on many factors..new 2nd hand brand names, level of interior fitout.... amount of 'KISS'.

As for the other issues: speed weight, strength, comfort, you need to decide what you want the boat to do and how it will behave before you design it and choose your material.

Aluminum work is difficult and needs control of the ambient damp, drought
and temperature.
Control the drought
The difference in price between an aluminum chine hull and a nice round bilge hull, made by a well equipped shipyard is not significant, if we take into account the total cost of the boat..

So if you want a fast and strong boat, aluminium and round bilge is the way to go.
There are plenty of steel, wood and GRP fast strong boats too.
We have discussed the Aluminium/steel comparison elsewher on the forum. Aluminium is not as strong, when welded, it abrades and fatigues it is very prone to rapid corrosion under certain conditions. It is a good material for topsides and deck but I feel steel is far better for the hull.


Jim said: ”Cruising yachts run aground all the time”
I don’t really know what he means with “all the time” or what you mean with “commonplace”. The majority of cruising people that I know never collided with anything big enough to cause any problem…

Exactly !...... thats what good design is all about..

so it is a little difficult for me to understand your definition of commonplace.

You and none of your existing friends and relatives have ever been in a fatal car crash. Yet 2 people die (worldwide) in a fatal car crash on average every minute. Fatal car crashes are commonplace and happen all the time.

Most cruising boats I survey have evidence of underwater collision.

Anyway that can happen, if relatively improbable in the lifetime of a boat…..that’s why I prefer an aluminum hull “at least as strong as steel”.

[Milan]

"… the greatest of all architects,… all soft curves with beautiful transitions. .."

That may be so, but all other architects are using a lot of sharp edges and they still design beautiful buildings. Just kidding, back to boats:.

"… 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. Van de Stad's Zeevalk, Spencer's Regtime and at least one of the Tabarly's boat, to name the few.

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.

It should be primarily question of the nature of building material. Chines don't make a sense for the fiberglass or strip planking for example, but it's a very sensible for all sheet materials.

There is also "origami" method where chine(s) stay under water and boat have a look of round bilge boat.

http://groups.yahoo.com/group/origamiboats
http://www.justmueller.com/boats/
http://www.origamimagic.com/

In the and, take look at the recent plywood, single chine design:

[ryan nolan]

xxx im lukin at building a bout, 2 voyge on for long periods of time, but i dnt have a clue where to start, can ne1 help???

[Vega]

Nice stuff... the Origami thing.

Nice boat...but it would be nicer without any chine in it

[stewi]

I fear this is not quite possible.
Here are some nice drawings explaining the development of a hull.
http://www.formz.com/web_site_2000/c...tml?1107182725

[Bergalia]

[quote=Vega] I am allergic to ugly things (I am an architect)

Oh Paulo, if only you'd been around when they built Canberra....

[Bergalia]

Originally Posted by ryan nolan

xxx im lukin at building a bout, 2 voyge on for long periods of time, but i dnt have a clue where to start, can ne1 help???

Ryan try www.yachtdesign.info/Boat_Plans/Free_Boat_Plans

[JimCooper]

(Mike in red Vega in black)

Jim said: ”Cruising yachts run aground all the time”
I don’t really know what he means with “all the time” or what you mean with “commonplace”. The majority of cruising people that I know never collided with anything big enough to cause any problem…

Originally Posted by MikeJohns

Exactly !...... thats what good design is all about..

so it is a little difficult for me to understand your definition of commonplace.

You and none of your existing friends and relatives have ever been in a fatal car crash. Yet 2 people die (worldwide) in a fatal car crash on average every minute. Fatal car crashes are commonplace and happen all the time.

Most cruising boats I survey have evidence of underwater collision.

Vega, Mike

Well put Mike thats about what I meant. I wasn't implying that everyone who sails an extensive time runs from sand bank to reef to bar. Just that on the law of averages you'l have to march under a banner of collision likely at some stage for most.

So design your hull for the event.

Cheers
Jim

[yipster]

i was just reading an article bout forces running aground. according to the american bureau of shipping forces on two 10 meter boats each having the same displament and speed the short 2 meter deep torpedo keel encounters almost twice the forces of a 1.60 meter deep but longer keel that gets 8 ton bottom suction in front of the keel and the same pressure up to hull behind the keel. while bottom keel horizontal force backbards is an equal 7.5 ton for both. more specs are missing but it gives some idea.

[dougfrolich]

Keep in mind what can happen if you do not consider grounding see photos of a Bravaria 42.
I saw a J-35 hit a rock off Angel Island several years ago, it was traveling at about 7.5 kts. and came to a stop almost immediatly, several people were thown forward one of them bruised some rids. The damage was mostly around the aft end of the root of the keel and the floor over that area was cracked. No water entered the hull, and the keel was still attatched soundly (considering). The damage required considerable repair but the boat was never in danger.

[yipster]

Originally Posted by dougfrolich

No water entered the hull, and the keel was still attatched soundly (considering).

seeing the pic i asume that due to a inner keel shell?

[dougfrolich]

No the picture is of a damaged or "Failed" Bravaria42 illestrating the need to concider grounding loads sice it seems Bravaria blames the failure on the boat being run aground at some point.
Not the J-35 mentioned above, that survived a full speed grounding without catastrophic failure

[safewalrus]

Hey Bergalia was that the 'town' or the 'plane?

Doubt if this guy knows any of the architects I have to work with! Dangerous, ugly and downright imposible and that just the 'bricks and mortar' men (actually 'tis more likely reinforced concrete these days!

We all know the man they make to build and maintain these things - he's 3 feet tall with 17 feet long arms and on the marine side he's even better! Keep architects (of any pursuasion) out of it!