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Plats för några IOM -ägare över hela världen

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I love setting these rigs up.

How does the GIZMO work.  

Whilst I am going to play with my rigs for a few months before I start adding complications, I was very interested to see what the GIZMO does by looking at the rig on a new Grunge from Robot Yachts.  

There are two pictures below showing the sheeting lines for the main and then the jib and I will describe what the GIZMO does to each.  Graham Bantock also has a nice plan showing the layout on the Sailsetc web site.  The GIZMO lever is clearly visible bolted to the base of the mast on the starboard side.  The cord connected to the top end of the Lever is part of the mainsheet.  At the top of the mainsheet post are two plastic balls through which the mainsheet is threaded. When you sheet in, the boom is brought in to the distance of the two balls from the mainsheet post so you cannot oversheet.  If you did not have a GIZMO the story stops here.   But with the GIZMO you sheet in a bit more and you pull the lever in the direction of the mainsheet.  There are 3 cords attached to the other end of the lever.  2 to adjust the main and one to adjust the jib.  Here are the pictures of the GIZMO sheeting arrangement and a video below of the sheet movement caused by the rotation of the lever

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Application of the GIZMO lever tightens the leach of the main slightly at the same times as flattening the foot, at the same time as increasing the cunningham, whilst on the jib, the jib boom is pulled down slightly but the clever bit is as the jib boom is pulled down, the leach line is eased to maintain the same leech twist.  In addition the jib is sheeted in slightly.  So the overall effect of the LAM is to close the main leech, tighten the jib luff and sheet in slightly and I guess you point higher.  Here are two videos that show the LAM in action on land.

Of course the key to effectively use of the GIZMO is setting up the rig in the first place.  Get this wrong and the GIZMO is of no use to you

How do you move the GIZMO using the transmitter.  You can either set a toggle switch to engage the GIZMO or use the fine adjustment.  The only challenge with the fine adjustment is you might forget it is applied or not.  My preference would be for the toggle approach as the GIZMO is either on or off.

Bear in mind, if the GIZMO is applied with a large amount of movement on the lever there will be a force applied to the winch and this will burn up battery power.


What might need doing on my boat.  

The immediate things on the current rig are to lower the Jib boom to get the jib closer to the deck

The first outing against competition at Abbey Meads lake

I always thought this would not be an easy entry into the Marblehead class with oldish sails and rig.  Today we sailed in near calm conditions and discovered three immediate problems with the swing rig.  Firstly it would not swing easily and for the first few races I was sailing downwind with the sails stuck as though on a beat.  Second the jib thought it would be fun to maintain a central position in the light breeze and lastly the main remained inverted after a tack if there was little or no wind.  When the wind was up, 4 knots or so the boat took off and I could race competitively.  As soon as the wind died the boat stopped.  I liked it to being in a boxing match with one hand tied behind your back

Results were poor and I retired from the first two races as I could not run downwind with the boom out.  I can sort the jib out but believe I may need a light wind rig If I am to sail in these conditions competitively.

My thanks to Roger an Peter Stollery for organising/setting up and packing up and Hugh McAdoo for acting as race officer.  It was a great day with relatively warm sunshine.

At home I got my thinking cap on and took a close look at the mast bearings on and under the deck. I removed the additional cord at the bottom bearing and cleaned the bearings adding some PTFE spray which has no residue and will not attract dirt or dust. The mast is now rotating freely.


The jib requires a bit more work. Like an IOM I believe a straight boom should sort the problem and will allow me to lower and adjust the jib height a little as well as moving the end point of the jib boom closer to the sheet fairlead which gives more precise sheeting.


Here is a picture of the current jib configuration..

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I have a couple of bits of IOM spars to play with. I will use a straight piece of 11mm tube as a yard from the gooseneck and use 10mm lightweight jib boom. Without a Gizmo the rigging is so simple and I will continue with the grommet for sheeting until I eventually fit a Gizmo and replace the booms with carbon. The jib clew will be tied down and a bowsie run to the end of the boom to adjust the foot.


What I cannot cure is the mainsail inverting when I tack the boat in calm conditions. The cloth is too stiff and there is too much luff curve. I could apply massive prebend but this will tighten the jib luff and reduce the ability for the jib boom to swing freely. The only cure is a lightweight rig. I will save that one for later


Another annoying issue is the mainsheet post is glued in. There is a tube that runs from the deck to the floor which fits a Sailsetc mainsheet post nicely. When I drilled it out, there was an inch of a sailsetc mainsheet post and then an inch and a half of another post. Anyway its all out now and I can fit a new post and be able to adjust the height of the post which is key for the B and C rigs as the booms are higher.


Finally got round to reprogramming the RMG Smartwinch to increase the range of the sheet movement so I can get the main boom at 90 degrees to the centreline of the boat.  Here is the link to the programming guide on RMG Web site

As an aside, the boat came with an unused 2018 set of BG sails for the swing rig so I will get them measured and try them out.


There are a couple of events in January/february where I can get a better understanding of how the boat goes.


Lastly I weighed the various components of the boat to see how I stood against the current thinking.


  • Swing rig 356gm (OK I think as there is no data. Could use lighter cloth)

  • Hull 924gm (Recommended 900 -1000gms. New Pro boats 800-900gms)

  • Fin/bulb 3.618kg (3.2-3.4kg is recommended so I may have the opportuntiy to lose 200gms but I will wait until I have race data before making any adjustments here.

  • Total 4.898kg (recomendation is 4.5 to 4.8 so I am within this range if I lighten the fin


Thats it for now. Lots sorted. I guess that is life with a new second hand boat as you work it up for competitive sailing. Waiting for the bits from Sailsetc to complete the changes and then it is off to Chipstead in January. My schedule will be going up on the results page.  There are only 12 Marblehead events so progress and learning might be a bit slow.

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