Appropriate dimensions of ship?

want to design a deep water fishing ship which can stay in ocean for 7days without provisioning. what will be the appropriate dimensions of the ship in terms of length*beam*draught if displacement is 8.5tons?

 

Where does this number come from? Seems to be "a bit" light, don't you think?

This would be a tiny boat which I doubt would endure a week at sea...

 

What sort of fishing? - Trawl, long-line, skipjack, bottom-reef, and any of a number of rigs used in different oceans.
What are the target species? - - Sold to Premium fresh or canned markets?
Need for snap freezers?
Fuel burn to run for 7 days?
Crew accomodation, food, water, dry clothing, shower and ablution facilities and HEAPS MORE ... For vishnu's sake, WAKE UP - - - USE YOUR BRAIN... or have you sold it as an unused organ?

Design tight accomodation, water for crew drinking and galley, fuel for generators and main engine running for 7 days (most engines need a service about then) how much fish do wou need to catch to meet the fuel food crew and other expenses then you are getting an idea of the size and it will be LOTS BIGGER than 8.5 tonnes...

Compare that with my recreational boat of 40 ft x 21.5 ft and ready for a cruise weighs in at around 6.5 tonnes from the original design as a sailing boat of 3.5 tonnes AND I TRAVEL SOLO or with one, at most 2 crew and do not catch fish very often...

 

longest time between provisioning=7days
no of crew=7. crew weight=7*160=1120pounds
stores=6lbs*7crew*7days=294lbs
watr=8.5lbs*7crew*7days=416.5lbs
safety reserve=(294+416.5)*1.5=1066 lbs
personal gear=5lbs*7crew*7days=245 lbs
total weight=1120+1066+245=2431 lbs
min displacement = total weight*7=17017 lbs
7.7tons.
just want to know what type of boat is suitable for these data. hull shape? and dimensions? and material of hull? weight of hull+deck?

 

Seems like you are asking us to do the homework for you. You have to specify parameters. For example, what kind of fishing is it going to do. What climate will it operate in. How much fish is it suppose to catch. How much ice will it carry, if any. How much fuel will it carry. Personal gear will be much heavier, specially in cold weather. My foul weather gear and boots alone weigh more than 5 lbs.

 

please help me out with the problem i mentioned

 

The problem is that you don't understand the basic concepts of ship design. You need to go and study the basics. To start with, determine the parameters the ship has to operate within. Then, you have to see which conflict and have to be modified or deleted. Once you make the modifications, you will find new conflicts. As you evolve the design, there will have to be some compromises. All that will probably have to happen within the constraints of a contract and whatever regulations it must comply with. This is called the design spiral.

 

sujeethmonu,
Following on from the good advice by Gonzo, The work and research to design a boat/ship starts with human needs and your post only scratches the surface, then there is the "engineering stuff" to make the human space work and achieve the purpose of the construction, then there is the ergonomics of human interaction with the machines, space to sleep, toilet (defecate and wash), drink, sleep, and cook and eat and rest. - - Freezer space for food and catch, - - many tonnes for fuel. - - :?: Reverse osmosis watermaker (saves space and weight?), - - flash freezers for the fish, and the list goes on and on.........

Why do you need 7 days duration in India? Fish farming may be the better economic proposition.

At least 3 times your water allocation just for drinking and MORE for tropical work areas, what about washing clothes, washing off the salt, having a shower before evening meal and bed/sleep, water for cooking and general cleaning......

 

I like the ~2.5kg (5lb) of personal gear for a week.

I suggest the OP try living a week with 2.5kg of personal gear. With no water for laundry.


And yes this forum is not for people solving your your home work assignments.

 

Fishing Boat Dimensions

I wouldn't want to specify a boat anything less than 15 metres for offshore work. You are going to need plenty of shelter accommodation for 7 crew on long trips. At this size a steel hull alone is going to be 5 to 6 tonnes, so your final all-up-weight is more likely to be in the order of 15 to 18 tonnes.
You might save a bit going to GRP but getting down to your figure will be, I believe, impossible if you want a good safe offshore boat.
Have you looked at the FAO website? There is a lot of information on boats around this size in all types of materials including specimen designs - a very useful resource.
Good luck with your project.

Graham Westbrook
Naval Architect
Westbrook Marine Projects Ltd.

 

Work up your GA, then a weight study will settle you in, for the first portions of the spiral.

 

I thank everyone for suggestions and advice.