G'day we've got a couple of Hobie 18's on our coast at another club the sailors have never known how to set the boat's up. When I visited last week one had soft and one had hard diamond wires could someone give me simple specs on mast rake, rig tightness etc. I'd like to get them more competative and perhaps get them sailing more

Check here: http://www.hobieclass.com/site/hobie/ihca/downloads/hobieu/HobieU.pdf

This should get you in the ballpark.

There is also a section for the TheMightyHobie18 in the back of Rick White's book "Catamaran Sailing for the 90's"

Soft diamonds allow the mast to bend, depowering the main - good for high wind. Hard diamonds do just the opposite - good for light air.

That depends on whether or not you have raked spreaders or the straight spreaders. Hobie had both varieties depending on the age of the boat.

Hmmm... never came across one with spreaders raked enough to properly prebend the mast. I've certainly read a little about it, but from what I hear these days, the current higher-level TheMightyHobie18 sailors (the very few that are left) don't seem to mess with it.

There is only one style of spreaders for a Hobie 18 - they have minimal rake adjustment determined by positioning a pin in one of the spreader arms. Virtually all racers run with the spreaders raked as far back as possible (there are only like two or three possible settings).

As far as diamond wire tension, if you have a comptip, you want to run the diamond wires snug to tight (sorry, don't have a quantative number). 18's are pretty underpowerd boats by today's standards and the comptip is quite flexible, so you want to stiffen the lower part of the mast as much as possible to keep some power down low.

Shrouds should be snug enough that the mast doesn't flop around, but loose enough that you can rotate the mast to 90 degrees easily.

I've been racing these boats for about 20 years and I don't find them to be overly sensitive to tuning. I rig mine the same way every time regardless of wind conditions. Your main tools are mainsheet, traveller, and downhaul. Make sure they work efficiently and you're in good shape. Having a good set of rudders and a balanced helm is also critical.

sm

Thanks for the info, both are old boats, I can lend them Ricks book for a while not sure if they are keen enough to read it though. The mast section looks like my Nacra 5.8 mast without a comp tip, at least now I can take this info and tune the boats a bit for them. Would you know how soft is soft on the diamond wires for instance on the Nacra if you push on the diamond wires you can nearly touch the mast 18 inches from the base in heavy weather? If I tied a rope to the end of the trap and measured to the bridal tang where would the rope be at the rear hatch for proper rake?

As I said, I've found the 18 to work with a pretty wide range of tuning. There really aren't any hard and fast numbers. For diamond wire tension, the traditional method for measuring tension was to place marks at 12, 24, & 36 inches up from the diamond wire bolt. The tension is determined by where the wires touch the mast with moderate inward pressure. So between the 12 to 24 inch marks would be tight to moderate tension. I don't recall seeing anyone with loose/floppy diamond wires in recent years. Everyone has them at least snug, even the ligt guys.

For mast rake, again I don't know numbers as I haven't measured a boat in many years. I have non-low profile mainsheet blocks (i.e. the bottom block is a triple on top of the ratchet) and in a strong breeze there is about 2 to 3 inches between the lower mainsheet block and the block on the boom. That's more or less how I measure my rake. It's about as far back as possible without the possibility of going two-blocked. After that, its a matter of having the helm dialed in to a slight weather helm and once I achieve that, I don't want to screw with any adjustments.

sm

srm is spot on for how we used to measure. 12' up for light wind, 24' up for medium, and 36" up for high wind. In the US we got away from this technique with the introduction of the comptip. Now in the US most sail with snug diamonds. Rake was measured by placing mark on mast 4 feet up (I think that was right). Measure from for stay anchor to mark. Range was between 105.?? and 107.??". If they are heavy put them at 105 for power, if light put at 107. Side stays were loose enough to allow mast to rotate 90 for downwind. (pretty loose compared to todays F18).

Thats the info I'm after guys, I'm race officer at our regatta for the next 2 days and I wont have much time to set these boats up so now I can use these quick measurements to get them started

That 105-107" measurement is from the bridle tang located on the hull near the bow ... to ... the mark measured up the mast .... it does not involve the sidestays/shrouds.

You may wish to goto the "Hobie Forum" ... look for TheMightyHobie18/h18SX ... there is alot of information there as we constantly re-post information ....

Harry
H18Mag/P19MX

On mine I ran the diamonds tight (not quite enough to pre-bend on its own), then cranked the downhaul when needed to depower - kept the mast from bending side to side into the slot (it'll bend on the major axis like a pre-bent mast). The boats are tail draggers - keep your weight forward, especially in light conditions. If you're anywhere near a bit heavy and it's not blowing, stand the mast all the way forward or you'll be dead downwind. If you have the original molded rudders ditch them for a set of racing blades. Upwind I ran the jib cars full back to twist the jib and keep the slot open. Downwind, cars full forward. See how it sets with your sails and adjust accordingly.