Sinking IOMs or How to Loose you IOM

Discuss IOM design, building an IOM, information on suppliers, tuning an IOM, results of recent events, etc

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David Alston
Posts: 9
Joined: 17 Nov 2016, 23:19
Sail number: 11
Club: Bournville
Design: V9

Sinking IOMs or How to Loose you IOM

Post by David Alston » 10 May 2018, 10:56

I came upon a post on IOMIC forum about fitting flotation buoyance bags to an IOM. and as usual how the Class Rules do not specifically permit such buoyance bags and therefore are not permitted. The usual ...

I thought that it might be more interesting to understand WHY/ HOW an IOM can take on water so quickly and sink rather than Rule Changes and to share my Near Miss experience.

I have a V9 and love it to bits, the infamous 11.

The hatch cover is a polythene re-sealable food container lid as you would find on Baby Formula Container or Gravy Granule Container.

My Near Miss

The main sheet between the Sheet Post and the Deck Pulley became snagged under the flange of lid when I spend some time head to wind with lots of sheet flapping about in the breeze.

When I sheeted in, the boat took off on a port tack but the lid popped off and a tonne of water came in very quickly. I saw this because I was only 15 meters or so away from the boat so I freed off.

RMG winches have incredible pulling power.

Fortunately I was sailing at Bourneville, a small inland fresh water pond and I made it back with some freeboard. An RMG winch does not seem to mind running immersed in fresh water.

I have sailed this boat for 4 1/2 years or so, in at least 2450 heats and this has only happened 3 times.
I do actually keep a rough log because I have reached the point where each heat has cost 70 pence in boat .

On at least one of these occasions, the lid popping off was caused by MY not being fastidious about ensuring the lid was properly fitted and once I actually trapped the sheet under the lid.

One might suspect the other reported incidents of boat losses are related to this remote set of conditions. Many current designs have adopted the polythene Baby Formula Re-sealable Food Container lid in preference to the Honey Jar with screw on lid.

No Criticism, I much prefer this approach, it provides better access and removes the need for deck patches for access.

Deck patches can and do come off if you apply / reuse them on a wet deck , as we all have done from time to time.

What near misses have you experienced ?

Do you know the secret of which product is sold with that size of Re-sealable Food Container lid ?
I have spent ages wandering around Tesco and ASDA with a vernier calliper


Bruce Andersen
USA NCA Officer
Posts: 761
Joined: 25 Nov 2003, 00:06
Sail number: USA 16
Club: Famous Potatoes Sailing Club
Location: USA 16

Re: Sinking IOMs or How to Loose you IOM

Post by Bruce Andersen » 17 Aug 2018, 04:42

Just finished an experiment with IOM flotation and posted it on the forum. You can get to it using this link:
Bruce Andersen - USA 16

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