Miffy and Spreaders

[Jon_P]

Hi All,
I'm after some help.
We've recently come back to the class having 5 years out and we've just bought 3466 - Miffy.  We're going to be sailing at West Oxforshire Sailing Club.  Hopefully we can encourage a few others to make the shift to the 12.
Had her first proper race today but I think I need some tuning help.  I dont have enough pre bend in the mast, the spreaders are not doing their job, whatever the rig tension.

The spreaders are not locking out and are bending forwards.  Anyone got any advice?  Rake seems to be in the right ball park, mast is seated properly.  Do I need to increase the length of the spreaders?

Thanks in advance.
Jon and Sarah
Miffy 3211

[John Meadowcroft]

Hi Jon and Sarah

Congratulations on your purchase!

Potentially a difficult question to answer online without any photos to ensure that I understand the question being posed.

However, let's have a go.

Firstly, you would only want a little if any pre bend in the mast to start with.  However, you also want a mast that will develop progressive bend.  If it is bending too much already then it will potentially bend excessively.

I dont think spreader length is the answer, it sounds like angle is the issue.  If you pull the spreader tips towards the back of the boat then they will push the mast towards the front.  Length could be an issue if they are less than 340mm long (guessed rather than accurate measurement).

A fun way to play with settings is to roll the boat over on its side and put insulating tape across the shrouds at deck level and from tip to tip of the spreaders.  viewing from the top of the mast you can fiddle with spreader angles to ensure spreaders are equal  and adjust rake.

Given it is a P&B foolish, Tom Stewart @ P&B will have a good set of numbers for you to check to if you cant get what you want this way.

John
N3543

[Jon_P]

Thanks John.  The boat came with 2 mains.  One was flatter and set ok on the straight mast but the 2nd newer fuller main was not so happy.  It looks happier with some kicker so I'm pretty sure a little mast bend is what I need

I'll give it a go again on her side.

I did have a quick play before we raced yesterday but because the spreaders are rotating forward the wing nuts were not coming into play, so angle adjustment was having no effect.
If I can't get things to behave I will post a few pictures thanks.
Jon
Miffy 3466 (not 3211 that was our old 12!)

[John Meadowcroft]

If they are P&B sails they are likely "too full".  This is so they have the necessary power to get you downwind.  The logic is that fullness can be removed upwind to get a flatter sail, but it is impossible to put fullness in to a flat sail. You have to remember that the mainsail on a 12 is also your principal downwind sail - it needs to be a spinnaker!  The sail is not too full, it is just sensitive to set up.  Whatever you do to make it flatter upwind you need to be able to reverse to get the power downwind.

The issue can be if it is very light that the sail has too much depth.  On occasion I will rig a simple tackle across the foredeck to pull the mast towards the bow and help remove some fullness.  

Sounds like you know which main is best for lighter airs.

Think about what your deck level mast bend control is doing.  This is a pretty vital part of the equation.

John

[andymck]

I used to own that boat, and never really had much of a problem. It did have a tendency to invert sometimes but. No more than my current boat. It may be worth checking the mast is straight when it is off the boat. Sometimes the track can stretch and leave the mast permanently inverting. If that is all ok, then if the spreaders are correct, the settings used to be in the p and b website, try a bit more shroud tension, or failing that, a penny under the back of the mast foot, will induce more pre bend, you need one on each side on the twelve. Sounds odd, but some 18 footer rigs won't tension up until you do that. 
Andy