100 feet aluminium semi plaining hull

[VexCore]

Design for 90' with a beam of 26'. Make your bottom beams angle upward at
18.5% off the keel ( 4/12 pitch ) and space them apart 40" on center and run these forward 70' before steepening the pitch for the bow. Now see what you can fit into that using 2 - 800 hp diesel engines. It's a starting point. Make the final pitch of the bow down to the keel at 55 degrees. For some pictures and sizes and layouts for a boat that size Google US Navy
PT boat designs ( WW 2 )

mkay thanks for the idea

 

[VexCore]

What you can do is this- tell your boss you do not have enough information to design anything from a list like that, regardless of your education or qualification.

There is no purpose stated? Is it a fishing boat, a passenger ferry, a submarine??? What does it need to do??????? It is the designers responsibility to determine most of the items on that list, they should not be dictated by anyone except the designer, who determines them based on the operational requirements of the boat.

So you cannot find answers to your questions, because you are not asking the right questions...

I know this is far from standard procedure, and i do not expect this project to ever see the light of day. from what i can figure out the items on that least do not even add up. I just wanted to know if a better and more experienced mind than mine can make something of it.
I still have to present a general arrangement diagram. But what should I base that on if i do not have a hull shape?http://www.boatdesign.net/forums/images/smilies/mad.gif

 

[Mr Efficiency]

The 50,000 litres of fuel intrigues me, surely not !

 

[groper]

I know this is far from standard procedure, and i do not expect this project to ever see the light of day. from what i can figure out the items on that least do not even add up. I just wanted to know if a better and more experienced mind than mine can make something of it.
I still have to present a general arrangement diagram. But what should I base that on if i do not have a hull shape?http://www.boatdesign.net/forums/images/smilies/mad.gif

Youve got it backwards... your general arrangement will dictate the hull shape, not the other way around!

To determine a general arrangement, you first need a purpose! What does this boat need to do!!!!?

 

[TANSL]

VexCore this work they have commissioned you seems totally absurd. I do not know what your boss wants to get, of course I'm sure he does not want a proper boat project. He probably wants to test you and see how you react but it sure whatever you are able to do is not going to help anything.
So, given the absurdity of the issue, I think it's not worth continuing this matter. It does not seem possible to give you a help.
Tell your boss that is good and normal for the person who designs a boat to have some knowledge about boats.
Maybe your boss is waiting for you to have the courage to tell him what he is asking for is a huge nonsense.

 

[CDBarry]

The best bet is to use the NPL high speed craft series by Bailey, available from RINA.

 

[NavalSArtichoke]

This is a sample 105-ft crew boat from Swiftships:

http://www.swiftships.com/commercial-vessels-specifications/105-ft-crew-boat/

This design takes about 2150 HP to make 27 knots. (3x715 BHP engines)

It also has about half the fuel capacity from your spec.

You can find other examples. Google is your friend here.

 

[groper]

The best bet is to use the NPL high speed craft series by Bailey, available from RINA.

Or free here...

View attachment npl.pdf

Probably a good start, assuming a bucket load of "probable" usage requirements, most notably the challenging speed and range requirements...

 

[Mr Efficiency]

Someone has millions to spend on a new boat and wants a novice to design it ? Does not compute, imo !

 

[VexCore]

Youve got it backwards... your general arrangement will dictate the hull shape, not the other way around!

To determine a general arrangement, you first need a purpose! What does this boat need to do!!!!?

Ok...how can the general arangament dictate the hull shape? I mean for example I put an engine of x size and weight. on what do i base that if i do not have a total resistence encountered...How do i know how to arrange all the machinery and auxiliaries if i do not have a set phisical space... If i received the hull design i could then proceed to do "my thing" and establish all the machinery and pipelines needed but i did not.
I know that this thread will probably annoy the pro's and trust me this makes me feel like a big joke but I'm just trying to get a feel of how these things work so I, at least, know what to say when I will be asked for progress reports.

 

[Ad Hoc]

I am trying to figure out how to shape a semi plaining boat of about 80 - 100 feet so it can go at 18 knotts but still be able to reach a max of 25 knotts.

Forget the shape...look at the SOR.

This amounts to circa 130 tonne full load. With a speed req't of circa 25knots...you're going to need around 1000kW per engine..and 3 off, i.e 3000kW total.

You need more than a simple hull shape. You need a naval architect to DESIGN it for you. Your question is far beyond a simple one line reply...which will not satisfy the SOR anyway.

 

[PAR]

Has has been hinted at, the design spiral will develop the project, so no real short cuts or quick replies for your bosses. An inclusive, preferably extensive (considering the scope of this project) SOR will guide the preliminary efforts.

You can try it some other way, but it'll take longer and may not meet the SOR's requirements as well, which will piss off the owner pretty good.

 

[Mr Efficiency]

Can anyone tell me how to design a jetplane ? I promise to take all of you on the maiden flight, free drinks included.

 

[VexCore]

Yeah way this is going that is what i will be asked for next...

 

[groper]

Ok...how can the general arangament dictate the hull shape? I mean for example I put an engine of x size and weight. on what do i base that if i do not have a total resistence encountered...How do i know how to arrange all the machinery and auxiliaries if i do not have a set phisical space... If i received the hull design i could then proceed to do "my thing" and establish all the machinery and pipelines needed but i did not.
I know that this thread will probably annoy the pro's and trust me this makes me feel like a big joke but I'm just trying to get a feel of how these things work so I, at least, know what to say when I will be asked for progress reports.

Well let's say you need x amount of open deck space for fishing gear or cargo, with no roof and a crane to unload the cargo. This determines the general arrangement above all else doesn't it? And how will you know the physical size, length and beam, if you do not know how much cargo she is required to carry? You can't design anything without a purpose! And as such, you have given us no purpose, other than a boat which can travel 2000Nm at 18kts... Now you could design an efficient boat to do it, and carry nothing except the fuel required to do it. But If you need to carry 100people, a bunch of cargo, and the fuel to do it, the Arrangment will change, the propulsion changes, perhaps a second or third deck may be required, and the entire ship is completely different. Depending on the purpose, a catamaran may be a better hull form, who knows? Not even a professional naval architect can design anything from the information you have given... A professional, would ask for this information, you should do the same...