Using old hull, to make a fiberglass mold for layups.

[yurkanip]

Hello,

for a winter project..I would like to use an old hull, primed and smooth, to act as a fiberglass mold (that I can remove the hull and not ruin it in the process). I've been doing a lot of research about fiberglass molds and release etc. In a nut shell, I will be tracing the hull, dropping it into a piece of finished wood, cut to exact dimensions of the hull at the seam, clay to fill the seam, smooth etc...(more detail in actuality, but wanted to share a little of what I've read and from videos). 4 layers of Wax, Mold release then gel coat, first layer of fiberglass 4oz, then 3 more layers of 60z glass. Then flip over, and make a mold of the bottom, using the exact same process... I know most molds of any strength especially those you might see for car stereo speaker enclosures, are 12 layers of glass, that is not necessary for a hull...or is it?. I guess my first question is, for those of you who have made molds from an existing hull...have you ruined the hull in the process? (does mold release, work everytime AND what brands work best in spray bottle/aerosol)?

Any input, information, pitfalls or tricks etc for those of you who lay up hulls are all welcome!

here is a quick example of what I am talking about: http://www.cstsales.com/tutorials/fiberglass_mold.pdf

 

[yurkanip]

I was hoping someone would chime in. I know we have a lot of builders here. Phil Thomas, and other thunderboat and scale builders. Any info...would like to hear from you all.

 

[steve speas]

I was hoping someone would chime in. I know we have a lot of builders here. Phil Thomas, and other thunderboat and scale builders. Any info...would like to hear from you all.

what old hull is it?

 

[yurkanip]

I was hoping someone would chime in. I know we have a lot of builders here. Phil Thomas, and other thunderboat and scale builders. Any info...would like to hear from you all.

what old hull is it?

Finlay, 10th scale shovel, but The make of the hull really doesn't matter. Looking for experienced hull builders to chime in any tips are great.

 

[Kez]

I was hoping someone would chime in. I know we have a lot of builders here. Phil Thomas, and other thunderboat and scale builders. Any info...would like to hear from you all.

what old hull is it?

Finlay, 10th scale shovel, but The make of the hull really doesn't matter. Looking for experienced hull builders to chime in any tips are great.

I'm no expert but a self-taught hobbyist. I destroyed 3 wooden plugs before I learned all the tricks.

If your concern is ruining the hull (plug), I can share my experience.

A few things can make the plug lock in the mould, thereby destroying it. Firstly, your plug can not have an re-entrant profile. In fact, you need about a 3 degree draft for the plug and lay up to come out. If you are moulding a fiberglass hull, you probably do not have to worry about this...unless the hull you are reproducing was done in a split mould.

I also found out for the first layup, you need both release wax and PVA. I know someonw will disagree here.

I have not had much luck applying PVA without it either beading up or fisheye. I have used a foam brush, as well as a disposable sprayer.

The most important thing is to have a parting board. On a mono with a flat sheer line it is easy. A flat board will do. However, I think a swept sheer line looks much better on a deepvee and that's how I made the plug. I used a 1/8 ply formed to the sheer line as the parting board. There might be an easier way.

I have not built any hydro before. Obviously if you look at a scale hydro, the parting surface will not more involved.

One final word, I made my own plugs using my own designs. I am against copying existing hulls for the purpose of selling them.

Hope some of what I typed will be useful.

Kez

 

[yurkanip]

Kez, thanks for the input. I was worried about ruining a plug, yes. But from what you said...it is my plan to use wax and pva...together. A shovel with somewhat simpler lines, should lay up ok...

I am going to start with rigger cowls and work my way up from there, with using/building a mold.

Thanks

Patrick

 

[Ray Sametz]

I was hoping someone would chime in. I know we have a lot of builders here. Phil Thomas, and other thunderboat and scale builders. Any info...would like to hear from you all.

what old hull is it?

Finlay, 10th scale shovel, but The make of the hull really doesn't matter. Looking for experienced hull builders to chime in any tips are great.

I think Steve qualifies as experienced Maybe you should answer his question?? :blink:

 

[yurkanip]

The hull I am thinking of molding from was stated in my messages. Again, a 1/10th scale Finlay shovel (read above).

Thanks for your help. Asking for more input is never a bad thing.