A-frame vs single mast rig, loads & weight on a cat

Very interesting, as I'm in the process of making a cheap A frame mast for my classic offshore lifeboat hull up rebuild. It did have a very weak telescopic mast that was in no way suitable for serious offshore use or long delivery trips.
I've noted all the negative comments about reduced performance, but most of them do not apply to a lifeboat hull, as trying to get closer than 50 degrees apparent does not work too well due to the lack of a keel. Also I'm far more interested in strength than performance and the easy installation of a lookouts seat on a croos beam. I also want to be able to lower the rig and replace parts when overseas. So I've based my design on standard 20ft thick walled alloy scaffolding tubes that are easy to obtain. The short cross beam for the seat will be made of stainless.
My lifeboat is 27ft at present, but will be 31ft LOA when I add a bow sprit to increase the area of the headsail. For light winds, the plan is to use 2 more 20ft poles clamped together to provide a 30 ft Lateen pole. I've done a fair amount of research into all the different types of Lateen rigs and sails. At present the one that is the simplest and safest to use, is the symmetrical loose footed one. 2 of the poles arrived today, and I'm going to find out how well it sails with a big headsail and small loose footed main first. The Lateen pole could also be used for a square sail, but time will tell all. I did look at other simple rigs like the Gaff, but most involved a risk of getting bashed on the head during an accidental gybe or lowering the sail. Anyone with sailing time using an A frame or Lateen rig would be good to hear from.

 

One problem with your symmetrical Lateen idea is that it will net only about 225 sf. And if it is used by itself, it is hardly a good light air sail for a boat that size.

A 35 ft yard would get you close to 300 sf, which would be a good working sail plan.

Another option would be to add a jib, which many Lateen sailboats, I have seen on YouTube, have.
As for the A frame mast itself, there is considerable risk of it buckling, while under hard press of sail. This is because the loads will be off sides of each of the two legs. With a conventional mast, the compression loads are in line with the mast, more or less.

Another possible problem is an unexpected jibe.

With the yard hanging between the legs of the "A" frame, a jibe could turn the yard into a huge crow bar to pry the two legs appart at the top.

Both of these potential problems can be worked out. But they need to be considered.

 

Thanks, but after looking at the complications with tacking a Lanteen and storing it, I've decided that it's just a bit too complicated and as I'm really looking for a downwind sail, I've decides a square sail with just an upper boom and battens for the foot is much simpler with only one 20 ft pole.