The Solution.

Well it's because it feels so girly lacking in power compared to my 9.4 soft sail with the huge belly that now drives the EPS, centrally sheeted with the pulley right at the front with quite heavy sheet loads, so I was probably overpowered but it didn't feel like it. I also note in that video that I was up on my ear, yet I didn't think i was at that point so it needs some customisation. It's got a really flat sail even in the gusts I never ever felt threatened by it and I had a couple of long fast planing reaches where I'd have been doing one in the EPS, but it was all calm and collected in this tool.

Edited by Woodbotherer - 09 Mar 15 at 4:09pm

For the uninitiated, how does raking the rig back depower the boat?

Most sails are designed to work efficiently in the upright position, using both the actual wind and the created wind to form a flow over the sail parallel to the surface, raking the rig, moves the foil shape and positioning of the 'flow point' the peak of the curve that generates the pressure, so it becomes less efficient and depowers.  Is the simplest one explanation, there are other factors, but that to my mind is the most significant, it works the same way as flattening the sail reduced the depth of the curve and its ability to produce pressure difference which generates the force we use.

Edited by Woodbotherer - 09 Mar 15 at 8:03pm

In that case is it actually the slack rig that has the depowering effect by allowing the mast to lean to leeward (I dont think it bends more in gusts though) with backward rake being just a side effect.

If its anything like the Phantom the need to rake is more about sail shape than centre of effort and resistance. Yes it still applies but its not the dominating factor and therefore (IMHO) the mast needs to be used in the following three modes:-

Medium Wind (sitting on the side to max power i.e from sitting on the side to hiking)
The sail needs max depth so the mast should be upright (set to the suggested rake) and the lowers should be just biting when ashore. The wind will have sufficient strength to get round the back of the sail creating even flow over both sides. You will need to watch the amount of kicker to control the leech to give pointing. The centreboard is fully down.

Light Winds (sitting inside the boat)
The wind does not have enough strength to get round the back of the sail evenly causing you to sail lower to generate apparent wind to even the flow. You need to flatten off the entry so release the lowers and drop the rig back a little (its about 1.5- 2" on our forestay just to let the tension out of the shrouds). As you apply a little kicker to the mast (with no lowers) it will bend fore/ aft at the gooseneck flattening the entry. There is not enough wind for the mast to bend side to side hence no need for the lowers as that just increases the kicker load needed to bend the mast closing the leech too much. A flatter sail at the front will help to get even flow and therefore height. Having a slightly harder outhaul will also help as that will flatten the lower part. The board may need to be raised a little (a couple of cm) just to balance out the rake but different people have different views on that.

Above max power (You are fighting the boat to keep the boat flat and to control its direction)
To get some control you need to flatten off the sail so that the wind spills out with minimum disruption. The mast is now wanting to bend sideways as well as fore/ aft and needs some support low down especially to fight the kicker load. The lowers need to be tightened a bit (for the Phantom its about 1- 1.5cm from the Medium/ just biting setting) and the mast (rake) increasingly dropped back to flatten entry. The leech will need to be controlled so you need to apply lots of kicker also flattening off the upper part of the sail. I can easily get the top batten to be totally flat spilling all the wind out of the head in the gusts. The centreboard will need to be raised a bit to move the centre of resistance back which helps steering (if your still fighting the helm raise it a bit more). The back of the boom can get below the level of the sidedeck so you need to release kicker when you tack (before sailing mark the kicker cascade to the point where the boom can pass over the tiller at max rake or it will catch and you can practice your front crawl...)

I assume that the Solution requires the same principles so hope that helps. Glad you're enjoying the boat.

Cheers
Ian