I was reading Rick + Mary's Catamaran Racing: for the 90's and had a few questions about mast prebend. How tight should I make the diamond wires? Do I need to use a tension gauge to get them even? Are the spreaders on the H-18 raked back far enough with the stock setting? If not how far back should I rake them? After sailing should I loosen the diamond wires? Any input would be greatly appreciated. Thanks, Bob.

The Hobie 18 does not use prebend. It uses the 'soft' rig system where the mast is allowed to bend sideways slightly by slacker diamond wires.

just tighten the diamond wires finger tight and look up the mast track [no sail up] to check that the mast is straight.

point the spanner at the shrouds when sailing, ease it off towards front beam when it gets windy

Just FYI, spanner = mast rotation arm

Back when I was sailing the TheMightyHobie18 we set the spreaders as far aft as possible, which is really not far enough.
Then we tightened the wires as tight as possible until you could see a slight bend in the mast.
Then when downhaul was applied the mast would bend on its major axis.
We did a lot of speed testing and found this setup allowed the boat to point better.
Rick

Ignore what I said - do what Rick said!

According to Hobie the mast needs no prebend. I have heard the debate both ways. Prebend will point higher and may go to weather a little faster, downwind the prebend is slower supposedly. From what I've read the top 18 racers use a loose diamond setup and most use the 18" mark to set from that is detailed in the Phil Berman performance manual.

That was the old way. The later 18 sailors definitely sailed much faster with a little prebend. As I said, you really did not bend it much, just got it coaxed to bend on the major axis, not the minor axis when adding downhaul.
Phil raced the 18 before we started playing with prebend.
Rick

Rick-
Did you guys upgrade the downhaul considerably also?

Kirt

I used to run my 18 like Rick says. Diamonds just tight enough to keep the mast bending sideways, downhaul to do the rest. The boat just sailed better that way, IMO.

Yes, the downhaul was not stock. Can't remember the purchase now, but we were still class legal. A minimum of 16:1 is recommended today, since there is no class anyway.
The reason so much is not to have the power to downhaul, but to be able to uncleat the downhaul while on the trapeze. If less, the crew has to get of the trap to release it when the air lightens up.
Rick

There may be no class where you are, but there is still an active racing Hobie 18 class in many parts of the country.

There were 18 boats at the North Americans last year, and there are over 100 members of the HCA-NA that list the Hobie 18 as their primary boat.


By making a non-factual, negative comment regarding the Hobie 18 class, you have once again demonstrated your bias against the Hobie Class Association and one-design racing.

BTW, max CLASS LEGAL downhaul purchase for the 18 is 8:1. A 16:1 downhaul will rip the tack grommet out of the sail unless it's reinforced.

16:1 downhaul purchase is beyond overkill for the stock 18 mainsail. You'll have ton's of extra line strewn about the trampoline. However, I don't think you'd pull the tack grommet out of the sail, you'll just bottom out the system on the gooseneck fitting.

We run a 6:1 downhaul with good harken blocks and dual exit blocks and my crew can work the downhaul from the trap with no problem.

sm

see ya at (come to) Lake McConaughy, Nebraska in September for this years' NAC's.
Get that 18 on the road, you'll have a blast! And I'm sure Mister Sohn & Mister Cooley can be coersed in to another tag-team, tuning clinic.

The class legal 8:1 cunningham lets you crank up the class legal dacron sail enough to sound like a nice snare drum. That's what we ran on our 18.

IMHO, 8:1 is not enough DH purchase to make playing it from the wire a reality. I've raced all the Hobie classes (except 17) and think you're kidding yourself pretending to go upwind like a Tornado, N20 or F18. The 8:1, and less, allowed by Hobie rules is not enough purchase to make the DH anymore effective than a set-it and forget it function a on "class legal" Hobie boat.

Different strokes for different folks, I guess. We race the 18 fairly extensively in one of the more active divisions. 6:1 purchase is all my (female) crew needs to play the downhaul from the wire in 95% of the conditions we sail. If we actually need it bottomed out, she will hand it to me to finish the job if need be, but usually she doesn't need to.

Fine tuning the downhaul on the Hobie 18 may not be quite as critical as on some of the modern boats, but it certainly makes a difference and is by no means a set-and-forget adjustment.

sm

Yup, guess so...where were you at Havasu? Is Dean from your Division? He was fast. All us midwest boys could squeak out on an ole '82 was fifth place. Come on out to Nebraska sm and enjoy some ice cream.

You jumped down his throat there a bit!

is there some history?

How many new H18s sold last year?

I can answer that. None. A few new hulls...

But... there are a core group of guys working very diligently all around the country to try and pipe-up the TheMightyHobie18 numbers at regattas. Hence, the OPs question.

Nice pic Matt!

Right, Matt loves me.
BTW, I think I have done a helluva lot to promote Hobie sailing for the last 30 years.

My point was very simple -- you cannot play the downhaul from the trapeze with low ratios. The 16:1 is not there to play Magilla so you are not going to rip ANYTHING out, and as for line on the deck, you can make it continuous.

Sorry I offended you, Matt, but you simply don't see one of my favorite boats around much anymore (TheMightyHobie18) and that is too bad.

Hmmm, I think I remember we did use an 8:1, but put a cascade on it -- probably a gray area.
Think the rules were there so people would not break masts and stuff. But, a higher ratio on the downhaul would be a big help in sailing the boat.


Rick

Newer vs later guys and pre-bend...

First I ever saw a pre bent TheMightyHobie18 mast was at the Port Macquarie Worlds in Australia in 1985. Not sure that ever caught on here unless for sailing in higher winds... not Southern Cal for sure. For me, I always used the 18" loose diamonds rule, but I was also sailing at minimum weight and needed to de-power.