Building the molds

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Building the molds

Postby haggis95 » Sat Apr 14, 2018 7:43 pm

It seems like the molds are going to be the most crucial part of the whole build, because if they are off, then the whole build will be off.

My question is, how hard is it to build the molds? They seem fairly complex.

Is it worth it to buy the molds pre-made?

And, can you buy the molds without buying the whole kit?

BTW this is my first post! I'm excited to be here!
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Re: Building the molds

Postby Mike » Sun Apr 15, 2018 7:21 pm

Good questions -
Have you looked at Geoff Kerr's videos at Off Center Harbor? I highly recommend that you join and repeatedly watch those videos as you build your boat. They are a "class in a box". Also Iain has published a very good book on building his boats, you should buy a copy.

Regardless of how you get the molds (build, buy used, or buy new); the critical part is how you set them up on the building frame. You have to build a good, solid building frame and make sure that it is fastened to the floor so it can't move around. It needs to be dead level and true. Then you can place each mold where it belongs on the building frame. Now comes the fun part, You need to align the molds to both the frame and to each other. A critical tool is a batten that you make yourself. The batten needs to be square (use your plank thickness as the guide for the batten thickness, i.e., for a 6mm plank your batten would be 6mm x 6mm) and long enough to wrap around the boat at different points on the molds. The purpose of the batten is to help you establish that the molds will produce a fair curve in your plywood planks. Make sure that there are no knots or "hard" places in the batten, it needs to be able to flex equally along its length in order to produce a fair curve.

Iain's plans are designed to avoid you having to loft the boat, but when you set up the molds on the frame you are defining in 3 dimensions the actual shape of the boat. You should spend a lot of time just standing back and looking at the molds on the frame. Your eye is very good at determining fairness, you just have to give it some practice.

If someone hasn't said it before, remember that you are working in wood and almost any mistake can be corrected. Some folks say that a really good boat builder is the one who catches an error and repairs it in such a manner that no one will ever know that a mistake was made.

Back to your original question, I would recommend that you build the molds yourself, it will give you practice in reading and understanding Iain's plans and his notations. I can assure you that as you go along, you will need to learn to look at every plan sheet over and over again to be sure you understand what to do. Also, since the plans cover 2 major versions of the hull and three sail plans, get in the habit of looking at all the sheets. There are details on one sheet that also will apply to another sheet, they just don't occur on both sheets. When you can dream about the sheets accurately, you will be ready to solve any question that arises.

Mike Duncan
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