Originally Posted by TedFlack

The rule is that the lower band must be 60mm to 100mm from the deck mark. So the height of the rig is pretty much controlled by that rule.



C.7.4 MAST
(a) DIMENSIONS
minimum maximum
Lower point to deck limit mark as defined in D.1.5 ................................................. 60 mm .... 100 mm

And variation between rigs +/- 5 mm.
The deck mark can be on any bit of "deck" adjacent to the mast whether the mast is mounted in a pit or on top of a platform! Possibly no one has got inventive and the rule was written in the days of flat decks.

Jerry

expat,

We went through a debate here in the USA a few years ago and decided that the + or - 5mm was not between rigs but for how much each rig can me moved. The reason we decided that was the idea is because the rule clearly states "each rig" not "between rigs"

From the class rules:

Within these limits, the variation in height of
lower point for each rig .................................................. .. ...... ± 5 mm

The rule for the "Deck Limit Mark" is that it is supposed to be on the hull center-line near the mast, of course "Near" is kind of vague as to location.

This is probably open for debate.

Ted

Thanks guys.

Sorry if this is a dumb question but what if you built a really high deck. is there a measurement from waterline to deck?

Originally Posted by D design

Thanks guys.

Sorry if this is a dumb question but what if you built a really high deck. is there a measurement from waterline to deck?

No.

One thing that you will quickly learn in sailing an IOM is that the A rig mast is a noodle. The rules limit the things you can do to control the mast, eg no lower shrouds, so a crucial tool to control the mast is the mast ram. To make the ram work needs a raised foredeck and a low mast heel. This allows you to generate the force necessary to control the shape of the lower third of the mast, and it has a marked effect on the control of the main leach and twist too.

Another factor is that the A rig carries a lot of sail area and keeping that area as low as possible helps carry the A rig longer. A high deck raises the rig and would lead to an early switch to the B rig compared to other boats.

John

Thank im finding forums very helpful

Although seldom seen, a set of "check stays" are permitted that also do what the
mast ram does (but probably not as well).

Chris B.

Originally Posted by old dodger

although seldom seen, a set of "check stays" are permitted that also do what the
mast ram does (but probably not as well).

Chris b.

bg sc4:d

anybody tried reverse bows?

Originally Posted by D design

anybody tried reverse bows?

How about a "Double Ender" by Dave Creed.

Great name!!

END GAME

Guys,
In the mid to late 80's a (Double Ender) Marblehead design called 'Vivacity' was produced by Mr David Creed. 'Vivacity' was sailed to success in numerous Vane (Freesailing) Marblehead Championships by Peter Maskell, Martin Roberts and Walter Jones. Later an updated version of this Marblehead was produced but unfortunately, it wasnt successful as the original 'Vivacity' yacht.

The Double Ender (IOM) is of the same theme as 'Vivacity', that was produced in the 80's. I just wished I had some pictures of the original boat...

JT

if you didn't know what I meant, has anybody tried a back-to-front bow on an IOM?

Anybody got any suggestions as far as clip on spreaders to fit my 12.3MM groovy rig from Ludwig rc yachts? Also isn't it a problem, when mast ram pressure is applied, doesn't which I noticed pushes the mast aft in the box that mast goes down into. This box on both my IOM's is longer fore and aft than the mast, which allows the mast to move fore and aft when I put on or take off turns on the mast ram. I put a plastic spacer in the box behind the mast on my Pikanto, but have yet to sail it to see if that allows what I think the mast ram should do which is play a role in how much bend the mast has.

If you cannot find what your looking for in your location PJSails in the UK should sort you out check out part Nr PW14d http://www.pjsails.co.uk/Rigfittings.PDF

Here's a picture of the first RC yacht I designed and built from scratch "fineline".
she had a half of a iom A rig for the main and jib,fibreglass man boom,mast, and carbon fibre jib boom and servo mounts. Made of cedar strip plank glass both sides and the deck is foam core and glass. Had an unusual long fin keel that seems to work...Who knows. Went like a rocket! I'm missing this boat out on the water..

Nathan