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Old Oct 04, 2012, 12:24 AM
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Chris Jenkins's Avatar
United Kingdom, Wales
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Build Log
IOM Scratch Build

Hi Guys,

Thought this might be the best place to post my build log for an International One Metre design....so hope it will be of interest and use to would-be constructors, and an opportunity for experienced hands to put me right !

This is my first hull build, as I've been heavily into vintage aircraft and active on that forum for some years.

So here goes with the first set of pictures.

The design chosen was Frank Russell's "Goth"...for no other reason than I love the lines, and plans were easy to scale up from Frank's online download. A "big thanks" to Frank for making these plans available to all....a great guy all round.

The shaddows were cut from 3mm craft board (12 inch sq sheets being obtained from Ebay). These have proved to be really great for pinning, and very much recommended..also easy to cut accurately with and electric jig saw. I pasted the shaddow outlines to the craft board after scalling up on the office printer.

The planks are of 10mm wide 1/8th balsa (3mm) in 36 inch lengths, apart from the lowermost centre keel plank which is from spruce, as are two part planks either side of the centrefin area and the deck strake (uppermost plank).

So far so good, and planking should be completed this week, with final sanding and glassing shortly thereafter.

Note that the planks in the bow area are shown unglued to the stem piece to allow a uniform section to be achieved once both sides arecompleted (they have since been drawn in and finished).

Regards
Chris
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Last edited by Chris Jenkins; Oct 05, 2012 at 02:58 AM.
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Old Oct 04, 2012, 07:49 AM
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Perth Western Australia
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Good luck Chris and good choice in design

Please feel free to ask any question this forum as there are a lot of very knowledgable people on here that will happily answer or try to answer your questions.

Mike
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Old Oct 04, 2012, 06:13 PM
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Goth

Thanks a lot Mike...much appreciated.

Hull planking now complete and sanding will start this weekend. Plan is then to give a sealer coat followed by a filler coat (epoxy & micro/balloons).

Hull has sprung slightly at the transom and first frame forward from there once the pins were removed, so I'll fit some temp balsa cross pieces to keep the skin rigid whilst I sand out.
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Old Oct 07, 2012, 06:17 PM
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Hull Prep

Primary sanding of the hull complete, and no filling required (yet). Sealing coat of epoxy will go on next.
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Old Oct 07, 2012, 07:23 PM
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Another build

I've just started my first build of an IOM. It's a Goth as well. This is my first hobby build of any type, so I am going to be following your build closely, Chris.

What type of material is appropriate for the stem and transom piece ?

Thanks,
Glenn
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Last edited by glennmcd; Oct 07, 2012 at 07:35 PM. Reason: spelling and measurement goof
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Old Oct 07, 2012, 08:12 PM
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Hi Glenn,

Welcome to the club !...how far have you got ?

I used a piece of 10mm wide 3.2mm thick spruce for the stem, and the transom will be 3/16th ply. I'm not going to fit the transom until the internal epoxy/glassing has been completed.and in any case I think it will be wiser to leave it off till the shadows are removed.

Primary sanding is pretty much complete, but I'll look at it critically tonight and then attack with the first sealer coat tomorrow...followed by an epoxy microballon mix to fill any imperfections once this has dried out.

Request for Advice from the old hands: I'm using SP epoxy, what quantity should I mix for these coats...dont want to mix too much, and there again need enough to cover.

Regards
Chris
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Last edited by Chris Jenkins; Oct 07, 2012 at 09:33 PM.
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Old Oct 07, 2012, 10:02 PM
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Just the stations

I've cut out stations and have a jig. I need to adjust the jig, though. It was for a SKA. I decided to go with the Goth, given the chines and narrow lines.

I may have time this week to work on the planking in the evening.
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Old Oct 07, 2012, 11:22 PM
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Quote:
Originally Posted by glennmcd View Post
I've cut out stations and have a jig. I need to adjust the jig, though. It was for a SKA. I decided to go with the Goth, given the chines and narrow lines.

I may have time this week to work on the planking in the evening.
Looking good Glenn. You've got some nice tools there, so that helps.

I didnt use a station at "0" and only glued the planks up to "1". When planking was complete I fitted the stem piece and then drew planks together and glued with lots of CA. Worked fine.
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Old Oct 08, 2012, 03:47 AM
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Quote:
Originally Posted by Chris Jenkins View Post
I'm using SP epoxy, what quantity should I mix for these coats...dont want to mix too much, and there again need enough to cover.
This document allows to calculate the volume of epoxy, depending on the area of fiber glass cloth : Estimating Epoxy Amounts.

There is also a rule of thumbs : calculate the weight of the used fabric and prepare the same weight of epoxy, plus a little more (5% to 10%) for wasting. Of course, you need precise digital scale to use this rule.
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Old Oct 08, 2012, 06:42 PM
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Thanks JP. Appreciate your input.

I mixed the epoxy before reading your mail for the sealing coat, and needless to say mixed too much ! I have a better idea now of how this product covers, so hopefully will be okay.

I'm using SP epoxy with a slow set hardener...and it really is slow, as it took three hours to go off....which bodes well for the glassing process.

If the first coat is fully cured this evening I'll apply the filler coat of epoxy/microballoon mix. Not much filling to do actually, but it will allow a good surface preparatiojn for the glass cloth application over the weekend. Thats the plan anyway
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Old Oct 09, 2012, 02:12 PM
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Hi Chris. I also like the lines of the Goth, good choice. Be careful of too many coats of epoxy, the weight adds up fast. I sanded my balsa planking and used some lightweight filler where needed, then laid 4oz glass straight on the raw balsa (and filled areas). Then a layer of 2oz inside. All up, the boat was very close to minimum weight.
The top, molded glass boats come in around 150-200 grams underweight, just to give you an idea.
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Old Oct 10, 2012, 02:06 AM
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Quote:
Originally Posted by hew565 View Post
Hi Chris. I also like the lines of the Goth, good choice. Be careful of too many coats of epoxy, the weight adds up fast. I sanded my balsa planking and used some lightweight filler where needed, then laid 4oz glass straight on the raw balsa (and filled areas). Then a layer of 2oz inside. All up, the boat was very close to minimum weight.
The top, molded glass boats come in around 150-200 grams underweight, just to give you an idea.
Thanks Hew, good information ...and well noted. I'll keep a track on it.
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Old Oct 11, 2012, 08:18 PM
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Filler coat on, and complete hull sanded down to leave thin coat of epoxy remaining.

Glass cloth goes on tomorrow (100g/sq m) twill. So far so good
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Old Oct 11, 2012, 10:14 PM
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Looking good, can't wait to see when you mount the internal fin and mast box.
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Old Oct 13, 2012, 04:25 AM
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Thanks for the encouragement Mike.

Got the external glassing done today. The 100g twill cloth worked really nicely and it all went surprisingly easily. I'm using "Easy Composites" slow set epoxy...and it really is slow. Glassing coat took 5 hours to cure to finger hard. I think it will take 24 hours to cure fully. Slow set certainly took the pressure off this task.

The weave of the cloth now needs to be filled...any opinions on whether I should just cover with a straight epoxy coat, or use a micro balloon mix in with it ?

Here are some shots of the hull after the glassing.

Have a nice weekend all
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Last edited by Chris Jenkins; Oct 13, 2012 at 05:47 AM.
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