Ferry boat

Hi, I'm going to design a ferry boat coastal area. I have got this hull form from the Freeship free files "Ferry.fbm". Have anyone of you have known this hull form? Got anything to say about this hull form. it is going to be 20m with a capacity of 180 pax. twin 255hp's, fiberglass construction. Whether it's a proven hull or are similar forms are already in the market?

 

There are many aspects that influence the shapes of a boat so without knowing anything else about your boat can not issue a valid opinion. Are you the only one who can determine if these forms are appropriate or not for your boat.
By the way, make sure you have enough space in the stern for propellers and the clearances of them with the hull are correct.

 

Waterline of this boat looks strange, but is too much information missing to say anything for sure.
What is prediction of cruise/max speed for the boat?
Anything about center of gravity?

 

Yes kind of me alone as a naval architect. My theoretical results show good performance. The only thing is that I haven't seen this type hull form of this length under operation. So guessing someone might have an idea about it's real performance. We aren't able to do any tank tests here. The speed is going to be within the semi-displacement range.

 

Loaded waterline is 0.65m. Min speed of 13 knots. Center of gravity at 36% (7.3m from AP). The table on the left of the picture with 3D hull shows its main parameters.
Thanks in advance!

 

Are you a naval architect?

 

What a nosy!. Will it affect anything?

 

Yes. It would explain why a person (presumably responsible for design and safety of a vessel) is not doing the actual design work in a traditional disciplined sense but is grasping a free template from a free software. This sounds highly questionable for anything but a lazy student project.

I am no NA but wouldn't following design spiral and defining SOR and making buest guess weight study be the logical start.

 

180 passengers in a 20 metre boat ? Sounds a bit crowded !

 

One would hope so. Shorter learning curve if nothing else.

 

Yes I am a naval architect. However, probably I am mistaken with the purpose of this forum. I wasn't going to use a free template as it was. I have my weight calculations and necessary parameters to go with. It is always good to start with an existing hull form and do the modifications as necessary? Its not worth to "invent" a form most of the times, given the limitation of time and budget. Are you going to call those who use NPL or Series 64 lazy? There are some extent to which theoretic results go. I wanted to know if someone have seen this similar form in service, have seen how it behaves in waves etc. Just to see if I'm missing anything in my analyses.

 

Yes, twin decks.

 

If we're talking about behaviour in waves you sholud give information about enviromental conditions.
What is design category sheltered water, inshore, offshore, ocean?
180 passengers for 20m boat is a lot. Have you consider stability issues yet?

I mentioned earlier about strange waterline, I thought about shape of the waterline not draft.

 

Nishan, contrary to what many might believe, the NA always start from a known forms of boat, a 3D model Rhino, or a body lines plan of a similar boat. I do not know anyone who has invented from scratch, without having in mind previous projects, shapes of his design. The spiral of the project allows to adapt the initial forms to the final of the current project. Even it is very normal to start with a SOR of an existing ship.

Is it really that information (professional qualification) what we need to know at this time to answer OP's questions?
In this forum there are many members who, not being NA, have very clear concepts on naval architecture and shipbuilding and say interesting things that everyone, including NA, respect. So my opinion, and I respect other opinions, is that the title one person could have does not need to be decisive. Why is it necessary to know the titles of a person ?. We can analyze and evaluate his comments without knowing anything about all that. Do not you think so? . Have not you ever read something wrong written by a NA?.

Back to OP's questions, seems this hull can give a large initial stability (initial GMt) though, as for any passenger ship, should study the passage to a band, the damage stability and many other things (necessary studies in the later stages of the project). Speed also be decisive in the shapes. It does not seem that this hull is the most suitable for high speeds. We need to have more data. OP should propose a SOR and GA drawing to give a more correct opinion.

Greetings with respect to everybody, NA and non-NA. I, at least, will judge you for your comments, never for your titles.

 

Tropical zone, Coastal area, Wave significant height <2.5m (as per BV definitions).

Yeah 180 is quite a lot. not much recommended. Have got the right to increase the length up to anywhere less than 24. It's still at early stage.

The trips are going to be of 15mins per trip between two islands. The stability analysis shows satisfactory results as it fits well with the IMO "design criteria applicable to all ships", though I still want it more stable so planing to lower the main deck few steps down.
Then it would be waterline at 0.65, main deck at 1.8 and flush deck at 2.6m.

What I'm afraid is the lack of volume forward. Might it be wise to move that shoulder a bit forward and add some volume? I want it to run at semi-planing speed.