aluminium and composites planing hulls and fast attack crafts

[daiquiri]

I read the opening post three times and no idea what the question is, let alone the answers !

He wants to design, or perhaps build, a fast attack boat. The term "fast attack boat" is very broad and can include a wide variety of vessels, depending also on the language proficiency of the writer. For some people it might mean also a small planing vessel for carrying out pirate or terrorist attacks.

So - how big it is and with what weapon on-board, we don't know.
Why and what purpose of the boat, we don't know.
Is it a school or professional project, we don't know.

Ergo, although I feel that PAR is correct in assuming it is a school project, I don't feel like giving any help for this thing until the above questions were sorted out.

 

[PAR]

You'll notice I generally don't get into these discussions for precisely the reasons you've hinted at Slavi. Though I suspect this OP is simply looking to finish some homework or something, it's equally as possible there's an another motive in play, possibly not a good one, so without some previous participation here, I can't feel good about recommendations.

We've seen new members looking for help with home made submarines, swath and other "interesting" requests. Maybe I'm just old school and am too familiar with "be careful what you wish for" rational.

 

[gdavis]

The guy was just asking for some advice!!!! Anyone know of a similar site where the high and mighty are lower to the ground? Or maybe we should just bow to you..............................................................g

 

[gonzo]

He ask for help. We asked him basic questions to narrow the focus, but he never answered.

 

[PAR]

It's very common for students from this area of the world (and others) to do their home work or exams on this site. It's also not unheard of, for a dilettante of a drug lord to ask for information, about various aspects of design or construction, say water tightening a submersible. They usually make no reference to what it's about and often don't provide any parameters. The OP joined on about a week ago and ask his difficult to understand question(s) and hasn't replied since. He either opened one of his text books and figured it out, skipped this question on his semester end exam or he'll be designing a fast patrol craft with less than desirable expertise.

 

[ankitnehra1990]

It's very common for students from this area of the world (and others) to do their home work or exams on this site. It's also not unheard of, for a dilettante of a drug lord to ask for information, about various aspects of design or construction, say water tightening a submersible. They usually make no reference to what it's about and often don't provide any parameters. The OP joined on about a week ago and ask his difficult to understand question(s) and hasn't replied since. He either opened one of his text books and figured it out, skipped this question on his semester end exam or he'll be designing a fast patrol craft with less than desirable expertise.

sorry if my absence has offended u.due to urgent requirments i was away from my work.
as to ur questions regarding the scope , i m well aware of all basics .
i m working on a size regime as mentioned by me earlier as in knowing the bracket of dimensions, an approx. one,eg - aluminium can be used in making of such vessels from 35 - 55 m or from 25 - 45 m or 40 - 65 m.n the query regarding composites , it is well known fact that these vessels are not ocean going and will operate near the coastline so even in extreme cases of fire aid can be provided at the earliest and new technology has provided us options that we can use a separate fire protection coating over the composites that will prevent fire.
and also if the length of the hull goes in excess of 50 m in these vessels, then is it better to use steel of frp or aluminium .because of the increasing pressure on these vessels due to their fast speeds ( excess of 30 knots) and keeping in mind that these will be equipped with guns and missiles that will offer substantial impact,explosion and other loads on the hull.

 

[gonzo]

I don't think there is a theoretical limit lower than your size range (65m). However, guns can go from .50 caliber to 5 inch deck guns. Missiles also have a huge difference in sizes and launch requirements. As you are aware of the basics, could you be specific about the parameters of your design? If the only thing now is to decide between aluminum and composite, everything else must be already specified.

 

[ankitnehra1990]

i m not inclined towards designing a particular boat but working out the range of dimensions of the hull which would then decide whether hull is of composite or aluminium or steel.
like if i am told that boat is to be 45 m,8m,5m in dimensions then i should be able to tell that the boat is to be of what material and similarly if the specifications then what will be the hull material if the vessel is to be equipped with 1 main gun and 1-2 missile launchers.

 

[ankitnehra1990]

also if the no. of missiles , launchers or boats on the vessel is increased then would it effect the material composition .
will aluminium be good in that case or steel is to be preferred in that case given the fact that the visby class of ships are carrying far more firepower than what a fast attack craft or a missile boat or any small boat will carry

 

[gonzo]

Any of the materials can be adequate. The design will be different though. Also, depending on the government or private organization buying the boat, there may be restrictions/specifications that will make you decide between one and the other. Sometimes, there are combinations. The USCG has steel hulls with aluminum superstructures in some cutters.

 

[TANSL]

Saying "Any of the materials can be adequate." is not correct because depending on the project´s SOR a material will be right or not be.
These boats are usually ordered by governments of a country and therefore is not normal to be left to you to select the type of material.
Most modern passenger ships with large number of decks, whether or not the USCG, have the upper parts of their superstructures in aluminum. What is harder to see, though not impossible, is a combination of FRP and aluminum, but does not seem to be a logical combination for fast attack vessels.

 

[gonzo]

These are not passenger ships. The composites they are using for superstructures are using other types of fibers than glass though. Also, they are often designed to minimize radar signature. There are some new techniques pioneered by Shivakumar to lessen the danger of fire damage in composite vessels. It is a study that focuses on military uses. The combination of aluminum hull and composite superstructure may make sense in some applications. FRP is transparent to radar which is one of its possible advantages. Fast patrol vessels are often used for smuggling interception. Smugglers usually carry only light weapons.

 

[TANSL]

I have spoken of passenger ships as an example of ships that combine steel and aluminum. To show you that this is a relatively "normal" solution. There are also yachts PRF with aluminum superstructure. But I guess you know that the type of cargo, passengers, or whatever, carrying the boat does not have to define the type of material of its hull. By the way, did I mention the glass in my previous post.
I'm not sure what you're talking about, even if you know. I think interceptors, or fast attack boats, no account at all its radar´s "signature". And of course, the material of their hulls does not depend on weapons to be carried but on efforts the hull must support. But, as usual with you, we are entering the realm of the obvious.

 

[PAR]

Typically any proposal for these type of craft will come with a long list of standards and requirements. For example if they want a GRP hull, they'll usually specify the laminate type (commonly all roving for example), so this concern is addressed and the proposal has to include it, unless another approach is offered and can be (highly) justified. Governmental organizations are pretty good about making huge lists of things the prospective design must meet, so a lot of the guess work is eliminated and you're working within a well defined often quite restrictive frame.

I seriously doubt the OP has any real interest in a "fast patrol" vessel, other than what he'd hope he would discuss, before he realized he was in way over his head, a half a month ago, when he last posted.