IOM desin

So Cougar…

How far down the track are you with your IOM design? Making progress?


<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by Muzza

Don asked

“Is there a “standard” size for keel trunk slots?”.

No such luck<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>

There isn’t a “standard” as such, but the SAILSetc keel and mast box is installed on quite a number of boats, including home builds. It is their part number 344D and can be seen by clicking on the “i” icon at

It has a “standard” tongue thickness of 10 mm, and a “standard” tongue profile, rhomboid, 84 mm base (3 1/4") tapering to a 41 mm top (1 5/8") and a height of 93 mm (3 3/4"). If you run with that, your fins become interchangeable with quite a few other boats. Most IOM fins are now thinner than 10 mm, usually around 8 mm, but this isn’t a problem using the provision for 10 mm thickness. SAILSetc insert a couple of 10 mm M2 set screws in the tongue of a thin fin, and adjust them to correctly centre the tongue, and hence the fin, in the slot.

Lester Gilbert

Thanks for the infro on the triple crown boat Cougar. I just finished a “footy” looking for something bigger. Maybe I’ll scale it up and make a “yardie”[:D]