Vintage - steel centre plate deployement

Interested Party · 03 Oct 2011, 01:06

I own Planet (672) a 'modified' 500 series National 12.
It has the old galvanised steel centre plate. I was thinking of trying a Firefly centre plate, but for the time being I am persevering with the steel one.
However the current arrangement for pulling it up and letting it down leaves much to be desired.
Currently the centre plate has a pulley attached to it and there are two others, either side of the kingpost. I also have a couple of bronze 'jammers' (bronze tube with a slot down one side) fixed to the front edge of the seats on either side, The single rope leads from one jammer to the closest king post pulley, then to the pulley on the plate, and then to the other pulley on the other side of the king post and finally to the opposite jammer forming an 'M'.
This should allow you to pull the plate up from either side of the boat.......If it were not for the jammers - which refuse let go of the rope unless the weight of the plate is removed...Currently achieved by puttings ones foot on the plate to push it forwards, allowing you to release the rope from the jammer.
Its a bit of a 'palava'. So what setups do other people have with thier vintage boats? Or do people just leave the thing down as its pretty thin anyway?

Interested Party · 03 Oct 2011, 01:13

Tring to add a picture form the modified 500 series design reference material that shows Planet
http://www.national12.org/class/JackHolt.htm#Jack_Holt

Interested Party · 05 Oct 2011, 10:22

No takers?
I would really like to see a picture of the inside of the cockpit of a similarly aged National 12 : (

JonathanReubin · 06 Oct 2011, 08:00

Steve, have a look at 443 on the database. She is my Uffa King which I usually sail single handed. The plate arrangement is similar to your boat but my jammers are on the deck. The plate weighs 48lbs and for a nipper crew the plate hard to lift and even an adult has difficulty. The technique I have developed requires speed accuracy and deft knees and fingers! I have to lean forward and pull the rope beween plate and keel pulley (either side), jam the plate with knee then pull slack through the tube cleat. I do not advise leaving it all the way down on a run especially in a blow as you will "trip over" it if you vere off course and in a high speed jibe, well you may as well jump over board in anticipation. On a run a third to half plate is enough. The deep v hull seems to give sufficient bite.
I suppose you could go in for a couple of blocks and a modern jammer but you will end up with a lot of rope on the floor. I am not sure the pre-war 12 sailors went in for micrometer plate adjustment and made do with all, half or smidgen!

Interested Party · 07 Oct 2011, 09:00

Thanks Jonathan.
I think my current arrangement is similar to yours especially with the use of the tube cleats. I have two issues:
1. The tube cleats will not release the rope unless you somehow remove the weight of the board from that rope - hence the acrobatics with the knee/foot to push the plate forwards. So I am going to do without them. I have a set of wooden cleats mounted in the same way as number 500 - Flip McGilda (see pic) mounted on the rear of the for decking - inside the cockpit. In the short term will put a couple of knots in the rope on each side representing up, half and down.
2. I feel that a 2:1 purchase would be helpful because of the weight of the plate. If I were to replace the blocks either side of the kingpost with double blocks and put the old single blocks underneath the cleats that I am going to bring back into use, I can achieve a 2:1 advantage....... and it will have the same rope run as it will have now.
I have also found a worn out jammer under the thwart that might have been used for an alternative arrangement but I do not see any other evidence of a cascade system.
Cheers