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Old 27-07-2010, 14:16   #1
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A Torpedo-Shaped Keel - Costs Involved

Hi there,

In class I have been set a task that I cannot find any conclusive answers! Its like banging your head against the wall.......

I need to be able to cost the equipment (sourced from the UK) for a keel that is torpedo like in shape and suitable for a 30 foot sailboat.

I had to first decide the materials, and then find the prices (and quanitities/sizes) required and write a report.

I think that fibreglass would be the best solution, so what would be required to build it?

I appreciate your time and help on this and I look forward to your replies.
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Old 27-07-2010, 14:30   #2
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the best solution would be lead. do the google thing on "bulb keel."
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Old 27-07-2010, 14:35   #3
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Call Mars Metal. They do this all the time.
MarsKeel - Technology
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Old 27-07-2010, 14:39   #4
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Thank you bash, thats the first I had heard of a bulb keel.

Lead isnt an option that was given to me (sorry for the oversight in not listing the options)

Wood
Fibreglass
Carbon Fibre

I eliminated Wood for the erosion
I eliminated Carbon Fibre due to the costs involved
Which left me with Fibreglass.

I figured that in my designs, I would explain how I would make the shape using wood, then coat it with fibreglass. Is this right? That is how I have seen it in other boat building manuals.
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Old 27-07-2010, 14:52   #5
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Forgive me for asking, but you do know a keel has to be really heavy, right? You can fill a fiberglass keel with lead, gold, spent uranium or such, but wood? Sub-optimal. Cast iron? not really. Tire balance weights or lead shot encased in epoxy? Nope. Good old cast lead doesn't even need a container!
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Old 27-07-2010, 15:01   #6
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Sandy, I do understand the point you are making, the assignment isnt to create a keel, just a torpedo type tube that would connect underneath the keel it. Lead wasnt an option in our criteria.

One of our objectives is to minimise the effects of the torpedo by using streamlining.
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Old 27-07-2010, 15:15   #7
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Interesting, but I find your description of what you have to design is still pretty confusing - why don't you post the exact assignment question as it is written so we can understand the exact issue and lend an informed hand.
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Old 27-07-2010, 15:45   #8
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Quote:
St Theresa’s is a local Secondary School looking to help students develop an interest in marine life. The school recently held a sponsorship fayre where all students ran a fundraising effort. The school then found a cheap 30 foot sailboat that they decided to develop to help the students.
To compliment this goal, St Theresa’s has requested a new feature that allows students to study sea life using scientific equipment.
The design must not hinder the boats buoyancy, and it must be able to cut through water without affecting the speed.
As costs must be kept to a minimum, the only materials that can be used is wood, fiberglass or carbonfibre and must allow room for small scientific equipment.
Please explain the process of design and provide a 3d model for testing purposes.
Presentation and Structure of Content
Introduction
General and very brief over view of the topic, and the purpose of container.
Materials
The three materials you considered, and why they differ from each other – consider costs, weight and design problems.
Source Materials
Description of the materials used and the costs involved – quality and standard of resources, and some justification for use.
Design Process
Steps taken in order to complete the design.
Reflection
What you like or dislike about your final design, and what you would do to improve it.
Appendices
All planning prior to the actual design.
Resources
List of all resources used in the design (sources) – text, pictures, etc.
Bibliography
Evidence of reading
After reading this, I decided on a torpedo styled tube that would bolt onto the keel. Inside would be a plastic pipe with grids at either end to allow the water to pass through. The pipe would be hinged to allow opening and equipment being placed inside.
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Old 27-07-2010, 16:22   #9
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Whole new ball game!
I would suspect that the pod would carry cameras, fish finders, and water sampling equipment. It should provide both water-tight spaces for connecting cabling, probably requiring cable glands that can take adding and removing caulking easily, and some replaceable panels that can be modified to mount cameras and instruments. As such, these panels should be flat to simplify mounting these devices as flush as possible. This suggests a long box with well radiused corners. It would certainly simplify things if the boat didn't have to be hauled every time you had to change something, or even clean a lens! Rig it to pull down from the water's surface and latch into secure mounts. This will require a tube or two that run up the keel to open well above the waterline. This could be the biggest challenge. I hope its an older boat with berths on either side of a dinette. This would allow seating for a number of kids to watch or operate the gadgets.
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Old 27-07-2010, 16:45   #10
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Thats great Sandy, thank you so much! I have to make clear though, its just an assignment, there is no boat nor is there a school lol

The equipment will be temprature gauges, speedometers, some sort of pollution sensors etc, nothing that needs to be moved about once setup.

The children would see the results on deck via a live feed. (Theoretically anyway!)

All I need now is to find out the dimensions, materials required so that I can do a cost benefit analysis........god help me!!! lol
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