I'm adjusting the mast rake on a new H-20 and I'm looking for some opinions. My crew and I are 300 pounds and always struggle in heavy wind. I'm assuming more rake is better in this situation, but I know this changes with diamond wire tension. What are other lightweight teams doing and what is the best way to measure the rake?
This is from "Sailing the Hobie 20 in a Breeze by Bob Curry"
Mast Rake
Start by marking off in 1" increments from behind the rear beam 5 through 10 inches. To check your mast rake: After you have marked off the increments, as I suggested, take the crew's trapeze ring. Detach it from the bungie cord. Tie a line to the ring and take the line forward to the top of the pin that connects the bridle wire to the hull. Pull the line/trapeze wire combination tight to that point and hold that point on the line tightly with your thumb and a finger. Now walk with the line to the back of the boat and again pull the line taut and mark on your hull behind the rear beam where your thumb hits, and see what number setting it is at. We will want to set the rake at 7" behind the rear beam for starters. This will allow the sailplan to generate lots of lift in the lulls. This is a great setting because it doesn't hurt in puffs near 25 mph. If the sustained wind was in the mid-20 range, then we would want to begin our mast rake at 10" behind the rear beam. If the sustained winds are upper 20's with gust in the 30's, rake all the way back (Remember to set your rig tension to your racing setting before you check your mast rake.)
Hope this helps
Jon
H20, TheMightyHobie18
Do as Bob's article says and then in the back you should be able to touch the upper rudder pin with the line. That's where I like it.
Mike Hill
H20 #907
Mike is right; the newer sails like lots of mast rake. Use the transom as if it were the rear beam for the tuning articles. One question: where is your spreader sweep/diamond tension?
Bob 
This is really helpfull. My spreaders are raked at 1.5 inches. I've been told that because we are at the low end of light for crew weight that I should go for more rake in all but the lightest conditions. As I said, we have a very tough time keeping the boat down in wind over 20 knots. I think this gives me a great start for some trial and error (hopefully less error).
I would go with 2" of rake at your weight. That is with the wires with almost no tension. Put a straight edge against the wires not the spreader ends. This measurement should be 2". This measurement will change as you increase or decrease diamond wire tension.
Mike Hill
H20 #907
Actually the spreader rake measurement won't change as diamond wire tension increases; the spreaders are fixed in their relationship to that section of mast. The top and bottom of the mast bend, and the angle of the wire around the spreader changes, but the spreaders stay fixed the same distance away. MIGHT get some minor deflection of the spreaders themselves. Minor point, but it does make it easier to measure. Still need to drop tension to change spreader rake, though.
My question is can you point with the mast raked back past the sterns in light air, even with the new sails?
That's the other issue for us. On my previous H-20 I had a new main with an older jib and we raked the mast back to keep the boat managable in heavy air, but in most conditions we were consistently out-pointed, particularly in light air. Some of that had to do with the droopy jib and improper jib-car placement, the latter I discovered after quizing some other light crews on thier techniques. The more dramatic mast rake certainly creates more weather helm, and in light air has caused the boat to round up when a puff fills in.
I think that more spreader rake would add more pre-bend and flatten the sail, which is good for our weight, and would allow us to stand the mast up a little bit more so we could point with the bid dogs. Does this make sense to anyone/everyone?