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Old 09 June 2006, 17:37   #11
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Quote:
Originally Posted by Mr-d
So don't use woven roving at all, and just use Cut Strand Mat (450g)
Chopped Strand Mat, yes.
Quote:
I take it that 1 layer of CMS/Resin is about 1MM thick when set. so say 6 layers.
Varies with your technique. I usually work on about mm per layer. For your first attempts, err on the side of too much resin. That's certainly preferable to too dry a laminate
Using the technique you proposed, you need to ensure a very even layer all over or the result will be an uneven surface because of the varying thickness. This is difficult to achieve. If you take a mould off your plug (your mould), when you make your consol, you can use varying thickness in the laminate to strengthen various areas. For instance, I would use 3-4 layers for the sides but reinforce the corners with a couple more layers and the face which carries the steering wheel will need to be thicker still and/or reinforced to brace the helm mounting area. The steering wheel becomes your main hold on the boat when underway. The mounting flange for the deck will need to be much thicker and, preferably, feathered out into the laminate so as not to produce a high stress area.

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If i chose to use the first version as a mould i should ideally use gelcoat right at the start for the first layer.
After polishing it with the wax. I know laminators don't like it, but I'd also use a layer of release pva on top of the wax on a less than perfect surface to ensure a good release. Do this too on the first pull from the mould, especially if you are in a bit of a hurry and the mould may not be fully cured.

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Even if i decide not to use woven roving, will i still need two layers of something finer than 450g?
No, it'll be fine. If you were trying to produce the finest of work, you may want to put tissue onto the gel and then back that with 1oz csm but that's overkill for the type of job you are producing.
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Old 09 June 2006, 18:24   #12
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step by step guide

Hysucat jocky seat project
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Old 09 June 2006, 19:06   #13
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I've just been talking to my dad (who built a boat 30 years ago) and he says that i need woven roving, as it will add more strength for weight than CSM, the CSM only to be used for final layers and inbetween the layers of Woven.
I just started working out the cost of the material needed, and its pretty scary!

9.5M 450g CSM -15.00
5M 600g Woven -18.00
2.5L Gel Coat - 15.00
20L Resin - 65.00
Release Wax - 15.00
Implements - 20.00
--------
Total 148.00

And that's WITHOUT postage!

I need 18827cm for each layer, so that's 1.89m so say 2m
Decided to go for 4 layers of CSM and 2 layers of Woven.
2.5KG Resin to 1KG Fibre.

p.s. Prices obtained on ebay, anyone know anywhere cheaper?
*EDIT* CFS Fibreglass works out at around the same.
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Old 10 June 2006, 04:06   #14
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Old 10 June 2006, 04:26   #15
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Quote:
Originally Posted by Mr-d
I've just been talking to my dad (who built a boat 30 years ago) and he says that i need woven roving,
No, you don't. It does give improved tensile strength but only in the direction of the weave. It also doesn't give bulk and rigidity. You can use it if you want but you will be giving yourself more expense and difficulty than you need to. You will also be surprised how strong a 4-5mm csm laminate is. After it's cured, it will easily stand the impact of a large hammer.

One thing which did occur to me, you mentioned a varnish finish on your mould. What type of varnish have you used because the styrene in the resin may well attack it?

Finally, if your dad knows how to do this, why are you asking us?
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Old 10 June 2006, 06:51   #16
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Jwalker,
According to my dad the woven material is interwoven, and has strength in every direction (see attached picture). The weave is the same for lengthways or top to bottom.

at varnish, it never occured to me! It is that long ago that i can't remember I hope that the wax will cover this and protect it.

Don't get me wrong, I know that my dad has used Fibreglass before, but it is that long ago that he can't remember (30 years). I'd rather have an opinion of people who have also done this, so I can be sure. I really appreciate your input!
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Old 10 June 2006, 19:08   #17
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Don't bother with the woven rovings for a jockey seat. It will be bulky and more difficult to work with than csm and unnecessary for this project. Take a look at jockey seats produced by professional RIB laminators.
Three (or four if you're keen) well laid-up layers of 450 csm should produce a very good product.
I would recommend making a female mould from melamine faced chipboard, with radiused plasticine to 'round-off' the edges. This will give a much better finish than a male plug with flowcoat around the outside.
Good luck - let us know how you get on and post some pics of your handywork.
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Old 11 June 2006, 04:54   #18
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Quote:
Originally Posted by Downhilldai
Don't bother with the woven rovings for a jockey seat. It will be bulky and more difficult to work with than csm and unnecessary for this project. Take a look at jockey seats produced by professional RIB laminators.
Three (or four if you're keen) well laid-up layers of 450 csm should produce a very good product.
I would recommend making a female mould from melamine faced chipboard, with radiused plasticine to 'round-off' the edges. This will give a much better finish than a male plug with flowcoat around the outside.
Good luck - let us know how you get on and post some pics of your handywork.
A build of this type will also give excellent underwater properties.
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Old 11 June 2006, 05:12   #19
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