Mast cross sections

[Rum_Pirate]

<span style="color:blue">I appreciate that it would appear that most masts are of round and oval cross section.

Can anyone advise on the pros and cons of having a mast, for a gunter rig, that has a rectangular or squared cross section, given that the mast is say 3 1/2" square with 3/4" or 1" radius corners ? </span>

 

[Peterduck]

Many, if not most, of Francis Herreshoff's cruising yachts were designed with square section built-up masts. I think that number of Bill Atkin's designs were also like this. These people were designing for both professional and amateur builders. If you're thinking of a mast for your Penobscot 17, 3 1/2" sounds a bit beefy. Howard Chapelle gives a formula for calculation of appropriate mast section in his "Yacht Designing and Planning". I also saw an excellent article by Bill Garden which specified spar maximum section as a decimal fraction of the spar length.
Peter.

 

[Rum_Pirate]

The instructions give about 3 1/4" square tapering to around 2 1/4 at the head for the Penobscot 17 mast.

 

[Seanick]

Pros.....quick/unskilled/cheap

Cons....gaff jaws may not sit correctly on some points of sail/varnish may wear of the corners/drag/ugly appearence.

Mind you, can haf a million Mirror Dinghys be wrong??