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Author Topic: Goth IOM build  (Read 14118 times)

pompebled

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Re: Goth IOM build
« Reply #25 on: November 20, 2013, 05:44:03 PM »

This advice is a little too late for this build...
Why?
You can always put a coat of UV reststant varnish as a last coat over the epoxy to prevent it from getting yellow (and brittle) over time.

Regards, Jan.
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Twister

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Re: Goth IOM build
« Reply #26 on: November 20, 2013, 09:30:18 PM »

Hi Jan,


I suppose the point I was making was that with a future build (and the right epoxy formulation) it wouldn't be necessary to apply an additional coat of UV protecting varnish.


Although my current build is traditional (a J Class) most of my model boat building knowledge has come from friends building Marbleheads & AC120 class yachts where any weight saving is hugely beneficial - more weight can be put to work where it matters!!


Cheers,


Row
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pompebled

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Re: Goth IOM build
« Reply #27 on: November 20, 2013, 10:33:25 PM »

Hi Row,

You're right.
Using the right materials from the start (of the finish) will save additional weight.

Regards, Jan.
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CJ1

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Re: Goth IOM build
« Reply #28 on: February 05, 2014, 06:54:57 PM »

Got back to the build again for a short while.
I made the deck from two pieces of 2.5mm balsa joined down the centreline. The hollow for the vang was made from tapered pieces of balsa joined to a circular former on the bulkhead.
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CJ1

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Re: Goth IOM build
« Reply #29 on: February 05, 2014, 07:21:38 PM »

I then built a sacrificial skeleton on the foredeck on which to form the raised, rounded, foredeck proper. Once the glue on this had dried, the plan is to cut away everything underneath except the longitudinal rib and a shadow in line with the jib attachment for strength. The longitudinal rib needs to stop short of the bulkhead for the mast ram later.



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CJ1

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Re: Goth IOM build
« Reply #30 on: February 05, 2014, 07:28:17 PM »

The two access holes were cut out. One for the servos and electronics and the other for access to the rudder linkage. The outside of the deck then received a layer of 100gm glass with two coats of resin. The underside, I plan to use resin only except in line of high stress areas, where a layer of glass will be applied too.
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CJ1

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Re: Goth IOM build
« Reply #31 on: February 05, 2014, 07:34:37 PM »

Although I already have a rudder I can use, I've made another one to Frank Russell's design so that I can compare the two. Three layers of balsa around a PJ Sails rudder stock with two layers of glass and resin have produced a very stiff and fair shape.
The simple brass rudder tube was resined in place and will receive a cross brace later for rigidity.
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CJ1

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Re: Goth IOM build
« Reply #32 on: February 06, 2014, 09:17:15 AM »

Then in with a PJ Sails mainsheet post and bend up some wire hoops for the jib attachments, jib sheet leads and shroud/backstay fittings. These will be epoxied in through the deck.
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CJ1

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Re: Goth IOM build
« Reply #33 on: May 24, 2014, 04:28:46 PM »

The keel box was next to make. I tried in GRP but failed miserably. Next attempt was in glass covered balsa. This seemed to do the trick. The servo tray is to be bonded to the back edge of the keel box to brace it and the top of the keel box is going to be epoxied to the underside of the deck. That should take the loads properly, especially with the compound curves of the deck here.



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CJ1

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Re: Goth IOM build
« Reply #34 on: May 24, 2014, 04:34:30 PM »

When glassed into place, it lined up on the centre line correctly. I set up a jig so that the keel was already inside the box (covered by clear parcel tape to stop the epoxy sticking to it). The screw is the one that goes into the top of the keel. It gave me an accurate reference to make sure the keel was vertical.
 The mast tube is part of the deck now. That sits just in front of the keel box and extends all the way down to the hull for support.
I used wooden braces to align the rudder and keel so that both pointed in the same direction while the epoxy set.







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CJ1

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Re: Goth IOM build
« Reply #35 on: May 24, 2014, 04:37:11 PM »

And then the moment of truth. Would it leak/float/look like a Goth? Only one way to find out. Bung it on the water. The deck is just loosely in place for the photos!



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CJ1

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Re: Goth IOM build
« Reply #36 on: May 24, 2014, 04:41:20 PM »

Yes, that works. So, next job is to glue the deck on. I checked that I had put everything in place that I wouldn't be able to get to later and bit the bullet.
Epoxy thickened up with a little colloidal silica was the joining medium I used, plus a new reel of good quality masking tape to hold it together.
Can anyone spot the deliberate mistake?
 

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CJ1

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Re: Goth IOM build
« Reply #37 on: May 24, 2014, 04:44:51 PM »

When I made the deck, I put in place the top bearing for the rudder in a fit of enthusiasm. That meant I had to have the rudder in place when the deck went on as a reference to make sure it lined up again. There's no room underneath on the building jig so that's why it's upside down, looking for all the world like a Goth with a wind vane.
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mrzippy

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Re: Goth IOM build
« Reply #38 on: May 26, 2014, 12:44:17 PM »

Hi Chris,

Nice to see the updates to your cracking Goth build,
a great insight into modern light weight construction, superb workmanship!

I have a question please - re the inverted U shaped wire jib attachment/sheet leads -
are they literally epoxied into the balsa decking and that's it job done,
or is there more to the wire U shapes we cannot see in the pix or extra reinforcement etc ?

I appreciate your thinking, going for the lightest possible option,
but there appears at first glance, to be a great deal riding on a simple wire into balsa glued joint ??

I am considering building a modern competitive IOM from plans myself,
guessing Goth is the latest plan to become available to the general public.

By nature a very slow builder,
I need to start a build with the most up to date design possible,
to have a fighting chance of a competitive model when eventually finished,
not a nicely planked antique!
many thanks, keep up the interesting posts.

Regards Paul
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pompebled

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Re: Goth IOM build
« Reply #39 on: May 26, 2014, 04:57:48 PM »

Hi Paul,

In view of the forces the deck fittings have to cope with, on other builds the eyelets are extended down through the keel, folded and embedded in the the wood where they're covered with glasscloth and epoxy.

If the eyelets are not extended with the same material as the eyelets, than a piece of polyester, or Dyneema line, attached onto the eyelet is extended down through the keel.

I expect Chris will have a similar construction, or the eyelets will get ripped out one way or another...

Regards, Jan.
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CJ1

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Re: Goth IOM build
« Reply #40 on: May 26, 2014, 08:26:17 PM »

Hi guys,


Yes, you are right. The shroud and backstay eyelets you can see are the through deck extensions of a shape that goes down the hull sides and epoxied and glassed over and for the foredeck, are bent aft either side of a midline stringer and then epoxied and glassed over. The hull also has an extra layer of glass internally from gunwhale to gunwhale in line with the keel/shroud complex. The number one jib attachment point also has a lateral half bulkhead to take the upward load. Sorry, I didn't take photos of those before I bonded the deck on.


Chris
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mrzippy

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Re: Goth IOM build
« Reply #41 on: May 27, 2014, 05:03:27 PM »

Hi Guys,


Thank you for the info re the wire deck fittings, it's all perfectly clear now.


regards Paul
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CJ1

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Re: Goth IOM build
« Reply #42 on: May 30, 2014, 05:03:16 PM »

With the deck edge join tidied up, it was time to see if the old rig fitted. I have an old Bantock Ikon, which is the donor boat for this hull. So the fin and bulb, servos and rig are all being transfered over. The idea is to have a wide beam boat (the Ikon) and this one to compare. The Ikon is 3inches, 8cms, wider than the Goth.
The hull and deck with fin box, mast box, servo tray and all deck fittings (but not servos or battery) and a couple of coats of clear primer has come out at 605gms, so on target so far.
I have to say that I'm new to IOM racing, and at the moment with the Ikon, usually at the back of the fleet, so I'm hoping a newer, narrower design will help me improve!
Chris


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CJ1

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Re: Goth IOM build
« Reply #43 on: May 31, 2014, 04:58:18 PM »

Here's the difference between the two.

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Si2

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Re: Goth IOM build
« Reply #44 on: June 04, 2014, 02:10:44 PM »

this is a beautiful boat build and is very inspirational.
Exceptionally well done - I hope it sails as well as it looks.

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CJ1

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Re: Goth IOM build
« Reply #45 on: September 29, 2014, 09:27:00 PM »

Thanks for your kind words.
I've finally raced the Goth, in Andratx harbour, Mallorca. Quite quick despite a rubbish, twice mended, mast (still can't buy IOM masts in Mallorca!).
Here's the link:-


http://youtu.be/rKBHwZBwhWQ


Chris
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CJ1

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Re: Goth IOM build
« Reply #46 on: December 26, 2014, 07:36:39 PM »

Again, in Andratx harbour taken by one of the club members.
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Chris G

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Re: Goth IOM build
« Reply #47 on: December 27, 2014, 03:52:50 PM »

Very impressed with this build and I hope that CJ1 does not object to me attempting to build similar. Having just completed a Aero-Naut yacht kit I think I am ready to have a go at something more challenging.
Some coincidence, I have spent many happy hours in the marina at Port Andratx not sure I would trust a beautiful build on that large expanse of water.
Happy New Year Chris G
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CJ1

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Re: Goth IOM build
« Reply #48 on: December 27, 2014, 05:05:50 PM »

Thanks for the comments Chris. One thing I had to bear in mind when I built this boat was that the local guys race on open water here in Mallorca and in quite big seas at time. Early this year, with the Ikon up at Can Picafort yacht club, I got hit by a breaking wave and rolled the boat enough to have the keel bulb out of the water. That focuses the mind when you're building a new boat! But these IOMs are tough little things, so in the relatively sheltered water at Andratx, it copes well. And the organisation and support from the yacht clubs is excellent so we always have a rescue boat provided.
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CJ1

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Re: Goth IOM build
« Reply #49 on: July 02, 2015, 11:31:53 PM »

Last race of the season in Mallorca. Down to the last 6 or 7 of us racing as the weather gets hotter.


My Goth is ESP 25. Still dry inside and slowly getting faster.


https://youtu.be/eD8YtHYMLKs


(you can change the setting to 720HD)


Chris
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