the ice has finally past and have rerigged my blade. i thought i would sail this year initially uni without the jib. am experiencing a lot of weather helm however compared to when i used to sail with the jib. Are these related or could the helm be due to how i happened to set the rig up this year with the rake? also on my club races when i take on the monhulls (being the only multi in the fleet) am i theoretically faster uni with or without the jib in our usually light wind thursday races. cheers

Sailing one-up, you would have to leave the jib on the beach to be true to your Portsmouth rating. If you put the jib on you would be exposed to an adjustment of your rating.

You sound as if you are unsure where your mast was raked last year. I think that would be the first thing to look at regarding your helm. Also look at your rudders, do you have the port and starboard rudders installed correctly? Are you getting them pulled down completely?

rudders havent changed. and I am at the next to bottom hole for the forestay so if anything there is less rake set up for this year. when i petitioned our race committee to be allowed to race with the monohulls they gave me the lowest/worst of the 2 ratings and we don't change it. they dont care either way for these thursday night races but i wasnt sure whether i'd get more speed with jib, point higher? tack easier or if i should just leave it in the locker.

Theory says that the uni rig points higher. Where the jib becomes advantageous is on the reaches that are too high to sail with spinnaker. I can't speak to actual because I also tend to race mostly against the mono's and I leave the jib on the beach.
I am using the bottom hole of the forestay and still measure rake a couple of inches down the transom using the trap line technique.

In light air you will definately go faster with the jib. In medium air you will be faster with the jib too, only in big wind will you be better off to leave it in the box unless you have crew, then take it. I assume you have a self tacking jib. It's very easy to trim it and forget about it in the tacks even if you are sailing alone. BUT, when you raise up the spinnaker, be sure to let the jib out quite a bit so the air can freely pass through the slot.

I have a question about that. If you are sailing one-up on the F16, can you choose to sail with just main and jib instead of main and spinnaker?

Nope - rules say you can't use a jib one up:

1.11 The sails in general

1.11.1 The sail plan in the doublehanded configuration comprises a mainsail, a jib and a gennaker.
1.11.2 The sail plan in the singlehanded configuration comprises a mainsail and a gennaker.
1.11.3 Racing with fewer sails than those named for each configuration is permitted.

Rules shown are for fleet racing. For Portsmouth racing, there are modification factors wher you can add a jib with an adjustment
http://www.ussailing.org/portsmouth/tables06/modifications06.asp
or use a different modification factor for sailing a 2 up single handed?

In theory, adding the jib should reduce weather helm, as it should move the centre of effort forwards. In fact, I find the exact opposite, but this is because I only ever sail 2-up with the jib, and 1-up without, and by the time you're twin-wiring the rudder loads are much higher than when you only have one person on board, amplifying any weather helm.

Checking the forestay position is not a great way of measuring rake, as the rigging will stretch a bit over time.

As others have said, you'll be faster with the jib up to the point where you're getting overpowered. This is especially true if you get set reaching courses.

Paul