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Author Topic: creating bulkheads  (Read 3283 times)

Arminius

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creating bulkheads
« on: January 14, 2009, 11:32:05 am »

Hi

I want to reinforce my GRP hull with some wooden bulkheads.  The hull is U-shaped of course, but how can you make a bulkhead that nicely fits into the hull (so I need to have the positive image of the hull's U-shape).  Is there a simple trick for this?

Thanks

Arminius
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Martin [Admin]

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Re: creating bulkheads
« Reply #1 on: January 14, 2009, 11:36:45 am »

I use thin cardboard and scissors until it fits properly......
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tigertiger

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Re: creating bulkheads
« Reply #2 on: January 14, 2009, 11:41:58 am »

I am thinking. Do you need bulkheads, or do you just need beams and timbers along the sheerline.

If you have a bare FG hull probably all it needs is some bracing up.

Bulkheads may cause you problems when you come to fit motor, radio tray, battery, ballast etc.
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DickyD

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Re: creating bulkheads
« Reply #3 on: January 14, 2009, 11:44:58 am »

Thin strip of lead pushed into the hull widthways and pushed down to the shape of the hull will give you the shape.

It is best to use this to mark a piece of cardboard first and see if it fits, then use the cardboard as a template. :-))
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andrewh

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Re: creating bulkheads
« Reply #4 on: January 14, 2009, 11:56:20 am »

Arminius,  
I remember seeing you at the bridge :}.  How is horatius these days?
I do like Martin and chop myself a template out of card or whatever

There are a couple of wrinkles that may help:
If the hull shape is very curved and tapered I have a long thin length of lead strip about 4mm square, and I press this into the hull at the right position - then draw round the shape to get the first trial with the cardboard nearly right
Sometimes it is easiest to just make a bit of card which fits in the hull at the right station even if it is 1/2 inch from the hull in places, then cut seperate bits of card and glue them to the face of the template so that the edge of the "added" bit touches the hull.  Do this with as many extra bits as required (I use pritt stick or hot-melt glue) then run round the messy template onto a better one and adjust to fit.  
Let me know if a sketch of this wordstorm would help :}

Worth bearing in mind that you are aiming for a loose fit, especially if you are bonding it in with polyurethane (gorilla glue) or resin and glass  - about an 1/8th (3mm)  gap is fine.  Too tight and you may well distort the hull!

andrew
same as Martin, only lots more words!

 
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Proteus

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Re: creating bulkheads
« Reply #5 on: January 14, 2009, 12:12:05 pm »

I make them out of thin card, but make just for one side with an overlap when it fits one side copy for the othere side and then trim to fit (as they are allways slightly different) then stand them in the hull and eather staple them together or use double sided tape, its essayer to do just one side at a time.
also I like bulkheads as you can separate battery's from radio gear  and if you do get a little bit of water in it does not run up and down the hull, i do steam so its handy to put parts away from heat.

Proteus
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DickyD

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Re: creating bulkheads
« Reply #6 on: January 14, 2009, 01:25:16 pm »

Arminius,  
I remember seeing you at the bridge :}.  How is horatius these days?
I do like Martin and chop myself a template out of card or whatever

There are a couple of wrinkles that may help:
If the hull shape is very curved and tapered I have a long thin length of lead strip about 4mm square, and I press this into the hull at the right position - then draw round the shape to get the first trial with the cardboard nearly right
Sometimes it is easiest to just make a bit of card which fits in the hull at the right station even if it is 1/2 inch from the hull in places, then cut seperate bits of card and glue them to the face of the template so that the edge of the "added" bit touches the hull.  Do this with as many extra bits as required (I use pritt stick or hot-melt glue) then run round the messy template onto a better one and adjust to fit.  
Let me know if a sketch of this wordstorm would help :}Same as me too you bu**er.  ok2 ok2

Worth bearing in mind that you are aiming for a loose fit, especially if you are bonding it in with polyurethane (gorilla glue) or resin and glass  - about an 1/8th (3mm)  gap is fine.  Too tight and you may well distort the hull!

andrew
same as Martin, only lots more words!

 
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andrewh

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Re: creating bulkheads
« Reply #7 on: January 14, 2009, 01:42:43 pm »

Richard

Percisely the same as you, too :-)) :-))  You posted while I was writing my screed :}
andrew 
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toesupwa

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Re: creating bulkheads
« Reply #8 on: January 14, 2009, 02:51:19 pm »

.. or you could use a Profile Gauge..

http://www.fine-tools.com/kontur.htm
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BobF

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Re: creating bulkheads
« Reply #9 on: January 14, 2009, 06:19:13 pm »

On a couple of my hulls which were rather thin. (50"  Marblehead yacht hulls) I cut the B heads under size, and used silicon sealant to fill the slight gap. This helped to prevent a hard line in the hull. And of course it makes life easier.
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