Twin poles and auto-launching alternatives
I have been looking at earlier posts (see: http://www.merlinrocket.co.uk/forum/main/topic.asp?topic=2699 and http://www.merlinrocket.co.uk/forum/main/topic.asp?topic=2085) around the topic of self-launching / self recovering poles.
The Old Trout
I currently sail with No 2 son (12 and 5ft), and have two rings on the mast. The lower one is just above the puller attachment point and c. 250mm below the normal ring height.
Regarding the elastic, the only force on the pole with the conventional system is upwards. The only risk if injury (It does happen) is if your crew is a little overzealous with the the throw back, so it does pay to be nice to them just before a gybe or drop!
What about (2 questions in one post!):
You don't need retreival elastic. The crew just gives it a "nudge" to clear the mainsheet.
The great thing about sailing a Merlin is you can try whatever arrangement you want for your spinny pole. Poles that launch on a bit of string have been tried by several people and it may work well for you with a particular crew on a particular bit of water. The consensus on this forum is that in general nothing else is as quick or snag-free as the standard twin pole system and that bits of elastic to bring the pole back in are not neccessary and may be dangerous. But give it a try, the simplest method I have seen has a pair of sheaves mounted at the pole ring height on the mast and string going to a turning block and cleat on the aft face of the foredeck by the mast. Keep the existing elastic for the pole to run on, the end of the string goes to the end of the pole, pull for up, uncleat and probably pull the pole a bit for down. Just be careful about drilling too many holes in particularly a carbon mast close to the gooseneck and lowers.
I've seen both Fireballs and Mirrors at Brightlingsea using the "pull the rope tolaunch" method which requires a different mast fitting, something like a ball and socket. Has anyone tried this?
The Fireballs tend to use a single pole, rather than twin poles. But they are restricted to an alloy pole (thicker / heavier). How they get away with injuries with their lower boom and narrower cockpit (less room for the crew / helm to avoid the flying pole) I don't know!
My old smokers from the 70's, had a rope launch system. It worked really well, the main advantage was that the crew did not need to move right up to the mast to attach the pole, keeping crew weight back in the boat (not burying the nose into a wave). This system does tend to knock the mast around a bit by the bracket, which is why I have assumed that it is not used on carbon spars. Would be interested if anyone knows about this. With regards to the pole being released back to the boom, care did need to be taken to ensure pole did not smack (normally the helm) someone in the head. This system sped launching and retreval up for most crews. However the guys at the top generally prefered the manual system. The pole had an eye at the back end which shock cord ran through. the shock cord was attached to the mast about 6 - 8 inches above the pole bracket, and ran back to the end of the boom, the pole only slid on the shock cord, gravity pulled it back. The front end of the pole was as the twin system is now.
One issue with blocks attached to the ring, is that the pole will not pull out to it's full extension. Also with part of thepoles down the side of the mast these can be broken if caught, they will also wear against the mast. If legal the P&B bracket would be best option.
The Old Trout
Having once crewed for Danno when he used self launching poles (the system described by Andrew M), I can only say it was damned hard work hauling on the out-haul to get the pole fully out (even with a 2:1 purchase). Furthermore, although the crew could control the rate at which the elastics pulled the pole back along the boom, if you did let go, ther poles shot back at high speed and at eye height.
^^ and this was probably with 5ft poles!^^